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Papers by Kip Bett

Research paper thumbnail of A Transport Model for the Spread of Bird Flu

A Transport Model for the Spread of Bird Flu

tropentag.de

Highly Pathogenic Avian Influenza (HPAI) is a major threat to the poultry industry worldwide. In ... more Highly Pathogenic Avian Influenza (HPAI) is a major threat to the poultry industry worldwide. In developing countries backyard poultry production is often an important livelihood activity for women who use the additional income for unexpected household expenses. The disease ...

Research paper thumbnail of Animal-level risk factors for Trypanosoma evansi infection in camels in eastern and central parts of Kenya

Animal-level risk factors for Trypanosoma evansi infection in camels in eastern and central parts of Kenya

The Onderstepoort journal of veterinary research, 2002

Point prevalences and animal-level risk factors for Trypanosoma evansi infection were investigate... more Point prevalences and animal-level risk factors for Trypanosoma evansi infection were investigated in a cross-sectional study that involved 2227 camels from eastern and central parts of Kenya. The screening tests used were haematocrit centrifugation technique (HCT), mouse inoculation and latex agglutination (Suratex). All camels were screened with HCT, while 396 and 961 of them were, in addition, screened with mouse inoculation and Suratex tests, respectively. Parasitological and Suratex test results were used in parallel to determine the number of camels exposed to T. evansi infections. Statistical analyses were conducted using Statistical Analysis Systems. Parasitological and Suratex test results in parallel were dependent variables in multivariable logistic regression models that determined risk factors for T. evansi infection. Herd-level clustering was corrected with general estimation equations. The prevalences were 2.3% and 19.6%, using parasitological and Suratex tests, respe...

Research paper thumbnail of The 2006-2007 Rift Valley fever outbreak in Kenya: sources of early warning messages and response measures implemented by the Department of Veterinary Services

Revue scientifique et technique (International Office of Epizootics)

The authors characterised sources of early warning messages about occurrences of Rift Valley feve... more The authors characterised sources of early warning messages about occurrences of Rift Valley fever (RVF) and examined the response measures that were used by the Department of Veterinary Services (DVS) to manage the 2006-2007 RVF outbreaks in Kenya. The study was conducted between November 2009 and March 2010 and it included national, provincial and district veterinary officers who were involved in the management of the outbreak. Structured questionnaires were used to collect the data. Although the majority of the respondents reported having limited capacity to implement response measures, they perceived that the measures implemented were effective. Vaccination, movement control and market closures were the main response measures implemented, particularly in districts that had cases in both livestock and humans. Vaccination, however, was implemented too late and the coverage achieved was too low to be effective. The authors suggest ways to improve the capacity of the DVS to respond ...

Research paper thumbnail of Health risk in the context of climate change and adaptation - Concept and mapping as an integrated approach

Health risk in the context of climate change and adaptation - Concept and mapping as an integrated approach

Climate change has been stated as being one of the greatest challenges to global health in the cu... more Climate change has been stated as being one of the greatest challenges to global health in the current century. Climate change impacts on human health and the socio-economic and related poverty consequences are however still poorly understood. While epidemiological issues are strongly coupled with environmental and climatic parameters, the social and economic circumstances of populations might be of equal or even greater importance when trying to identify vulnerable populations and design appropriate and well-targeted adaptation measures. The inter-linkage between climate change, human health risk and socio-economic impacts remains an important - but largely outstanding - research field. We present an overview on how risk is traditionally being conceptualised in the human health domain and reflect critically on integrated approaches as being currently used in the climate change context. The presentation will also review existing approaches, and how they can be integrated towards ada...

Research paper thumbnail of An Expost Economic Impact Assessment of the Intervention against Highly Pathogenic Avian Influenza in Nigeria

An Expost Economic Impact Assessment of the Intervention against Highly Pathogenic Avian Influenza in Nigeria

The risk of spread of HPAI in Nigeria was derived by using a compartmental model to outline endem... more The risk of spread of HPAI in Nigeria was derived by using a compartmental model to outline endemic and burn-out scenarios. Two paths, low and high mortality risks, were associated to each of the scenarios. The estimated risk parameters were then used to stochastically simulate the trajectory of the disease; without intervention and with an intervention. The intervention costs the country US$ 41 million obtained through a World Bank IDA loan of US$ 50million yearly disbursed over the 2006-2010 period. The key output variables (net social welfare gain – with incremental net benefits as proxy, disease cost, and benefit cost ratio) were estimated for each randomly drawn risk parameter. On average, the results show that such an intervention would make economic sense under the endemic scenario with high mortality. The discounted costs (12% discount rate) of the disease without intervention would have amounted to US$ 145 million in total over the 2006-2010 period. The model indicates that...

Research paper thumbnail of Learning the Lessons of the 2006/7 Rift Valley Fever Outbreak in Kenya and Tanzania

Research paper thumbnail of Persistence of Rift Valley fever virus in East Africa

Persistence of Rift Valley fever virus in East Africa

Rift Valley fever virus (RVFv) is a mosquito-borne pathogen of livestock, wildlife and humans tha... more Rift Valley fever virus (RVFv) is a mosquito-borne pathogen of livestock, wildlife and humans that causes severe outbreaks in intervals of several years. One of the open questions is how the virus persists between outbreaks. We developed a spatially-explicit, individual-based simulation model of the RVFv transmission dynamics to investigate this question. The model, is based on livestock and mosquito population dynamics. Spatial aspects are explicitly represented by a set of grid cells that represent mosquito breeding sites. A grid cell measures 500 by 500m and the model considers a grid of 100 by 100 grid cells; the model thus operates on the regional scale of 2500km2. Livestock herds move between grid cells, and provide connectivity between the cells. The model is used to explore the spatio-temporal dynamics of RVFv persistence in absence of a wildlife reservoir in an east African semi-arid context. Specifically, the model assesses the importance of local virus persistence in mosq...

Research paper thumbnail of Spatial-temporal analysis of the of the risk of Rift Valley Fever in Kenya

Spatial-temporal analysis of the of the risk of Rift Valley Fever in Kenya

Historical data on Rift Valley Fever (RVF) outbreaks in Kenya covering the period 1951 - 2010 wer... more Historical data on Rift Valley Fever (RVF) outbreaks in Kenya covering the period 1951 - 2010 were analyzed using a logistic regression model to identify factors associated with RVF occurrence. The analysis used a division, an administrative unit below a district, as the unit of analysis. The infection status of each division was defined on a monthly time scale and used as a dependent variable. Predictors investigated include: monthly precipitation (minimum, maximum and total), normalized difference vegetation index, altitude, agro-ecological zone, presence of game, livestock and human population densities, the number of times a division has had an outbreak before and time interval in months between successive outbreaks (used as a proxy for immunity). Both univariable and multivariable analyses were conducted. The models used incorporated an auto-regressive correlation matrix to account for clustering of observations in time, while dummy variables were fitted in the multivariable mo...

Research paper thumbnail of Using participatory epidemiology to estimate disease transmission parameters

This is a case study on using PE to characterize Type A H5N1 highly pathogenic avian influenza (H... more This is a case study on using PE to characterize Type A H5N1 highly pathogenic avian influenza (HPAI) outbreaks, and using similar methods to understand diseases in other settings. In Indonesia, a list of all outbreaks of HPAI that were diagnosed in the past year was derived. 1-3 outbreaks per district were randomly selected for investigation. An infection tree reconstruction approach was used to trace chickens and households in outbreak neighborhoods. Investigations started with a checklist guided focus group interview. Mapping was used to document all households, poultry kept in each, and households and species affected by the outbreak. Spread through the neighborhood was recorded. The index, 2nd affected and closest unaffected households were geo-referenced. Risk factors were discussed. Individual interviews were held with up to five heads of affected households. Timelines were used to determine morbidity, mortality, slaughter and sales rates. Transect walks were used to triangul...

Research paper thumbnail of Antibody response and risk factors for seropositivity in backyard poultry following mass vaccination against highly pathogenic avian influenza and Newcastle disease in Indonesia

Epidemiology and Infection, 2014

SUMMARYA large-scale mass vaccination campaign was carried out in Java, Indonesia in an attempt t... more SUMMARYA large-scale mass vaccination campaign was carried out in Java, Indonesia in an attempt to control outbreaks of highly pathogenic avian influenza (HPAI) in backyard flocks and commercial smallholder poultry. Sero-monitoring was conducted in mass vaccination and control areas to assess the proportion of the target population with antibodies against HPAI and Newcastle disease (ND). There were four rounds of vaccination, and samples were collected after each round resulting in a total of 27 293 samples. Sampling was performed irrespective of vaccination status. In the mass vaccination areas, 20–45% of poultry sampled had a positive titre to H5 after each round of vaccination, compared to 2–3% in the control group. In the HPAI + ND vaccination group, 12–25% of the population had positive ND titres, compared to 5–13% in the areas without ND vaccination. The level of seropositivity varied by district, age of the bird, and species (ducksvs.chickens).

Research paper thumbnail of Transmission Rate and Reproductive Number of the H5N1 Highly Pathogenic Avian Influenza Virus During the December 2005-July 2008 Epidemic in Nigeria

Transboundary and Emerging Diseases, 2014

We quantified the between-village transmission rate, b (the rate of transmission of H5N1 HPAI vir... more We quantified the between-village transmission rate, b (the rate of transmission of H5N1 HPAI virus per effective contact), and the reproductive number, R e (the average number of outbreaks caused by one infectious village during its entire infectious period), of H5N1 highly pathogenic avian influenza (HPAI) virus in Nigeria using outbreak data collected between December 2005 and July 2008. We classified the outbreaks into two phases to assess the effectiveness of the control measures implemented. Phase 1 (December 2005-October 2006) represents the period when the Federal Government of Nigeria managed the HPAI surveillance and response measures, while Phase 2 (November 2006-July 2008) represents the time during which the Nigeria Avian Influenza Control and Human Pandemic Preparedness project (NAICP), funded by a World Bank credit of US$ 50 million, had taken over the management of most of the interventions. We used a total of 204 outbreaks from 176 villages that occurred in 78 local government areas of 25 states. The compartmental susceptible-infectious model was used as the analytical tool. Means and 95% percentile confidence intervals were obtained using bootstrapping techniques. The overall mean b (assuming a duration of infectiousness, T, of 12 days) was 0.07/day (95% percentile confidence interval: 0.06-0.09). The first and second phases of the epidemic had comparable b estimates of 0.06/day (0.04-0.09) and 0.08/day (0.06-0.10), respectively. The R e of the virus associated with these b and T estimates was 0.9 (0.7-1.1); the first and second phases of the epidemic had R e of 0.84 (0.5-1.2) and 0.9 (0.6-1.2), respectively. We conclude that the intervention measures implemented in the second phase of the epidemic had comparable effects to those implemented during the first phase and that the R e of the epidemic was low, indicating that the Nigeria H5N1 HPAI epidemic was unstable.

Research paper thumbnail of Estimating the Transmissibility of H5N1 and the Effect of Vaccination in Indonesia

Estimating the Transmissibility of H5N1 and the Effect of Vaccination in Indonesia

Transboundary and Emerging Diseases, 2013

The spread of H5N1 avian influenza continues to pose an economic burden and a public health risk ... more The spread of H5N1 avian influenza continues to pose an economic burden and a public health risk worldwide. Despite this, estimates of the transmissibility of infection exist in only a handful of settings and vary considerably. Using final size methods and flock-level infection data from a field trial of mass vaccination, we obtained the first estimates of the transmissibility of infection between and within flocks in Indonesia. We also found that outbreaks in areas designated as vaccination zones were less transmissible than in non-vaccination zones. However, this reduction is only comparable with a limited degree of protective vaccination coverage. Quantifying the overall effect of vaccination in these zones remains challenging. However, this result would appear to imply that, although the interventions applied in vaccination zones were not sufficient to completely prevent transmission in all areas, when outbreaks occur, they are less transmissible than those in areas where vaccination was not applied. This could be either a direct or an indirect effect of vaccination. Given the dynamism of small-scale poultry production in Indonesia, more regular vaccination may be required to ensure that infection is fully controlled in vaccination zones.

Research paper thumbnail of The Effectiveness of Preventative Mass Vaccination Regimes Against the Incidence of Highly Pathogenic Avian Influenza on Java Island, Indonesia

The Effectiveness of Preventative Mass Vaccination Regimes Against the Incidence of Highly Pathogenic Avian Influenza on Java Island, Indonesia

Transboundary and Emerging Diseases, 2013

We conducted an operational research study involving backyard and semicommercial farms on Java Is... more We conducted an operational research study involving backyard and semicommercial farms on Java Island, Indonesia, between April 2008 and September 2009 to evaluate the effectiveness of two preventive mass vaccination strategies against highly pathogenic avian influenza (HPAI). One regimen used Legok 2003 H5N1 vaccine, while the other used both Legok 2003 H5N1 and HB1 Newcastle disease (ND) vaccine. A total of 16 districts were involved in the study. The sample size was estimated using a formal power calculation technique that assumed a detectable effect of treatment as a 50% reduction in the baseline number of HPAI-compatible outbreaks. Within each district, candidate treatment blocks with village poultry populations ranging from 80 000 to 120 000 were created along subdistrict boundary lines. Subsequently, four of these blocks were randomly selected and assigned one treatment from a list that comprised control, vaccination against HPAI, vaccination against HPAI + ND. Four rounds of vaccination were administered at quarterly intervals beginning in July 2008. A vaccination campaign involved vaccinating 100 000 birds in a treatment block, followed by another 100 000 vaccinations 3 weeks later as a booster dose. Data on disease incidence and vaccination coverage were also collected at quarterly intervals using participatory epidemiological techniques. Compared with the unvaccinated (control) group, the incidence of HPAI-compatible events declined by 32% (P = 0.24) in the HPAI-vaccinated group and by 73% (P = 0.00) in the HPAI- and ND-vaccinated group. The effect of treatment did not vary with time or district. Similarly, an analysis of secondary data from the participatory disease and response (PDSR) database revealed that the incidence of HPAI declined by 12% in the HPAI-vaccinated group and by 24% in the HPAI + ND-vaccinated group. The results suggest that the HPAI + ND vaccination significantly reduced the incidence of HPAI-compatible events in mixed populations of semicommercial and backyard poultry.

Research paper thumbnail of Field trial of a synthetic tsetse-repellent technology developed for the control of bovine trypanosomosis in Kenya

Preventive Veterinary Medicine, 2010

We conducted a field trial among Maasai cattle-keepers in Nkuruman and Nkineji areas of Kenya to ... more We conducted a field trial among Maasai cattle-keepers in Nkuruman and Nkineji areas of Kenya to evaluate the effectiveness of a synthetic tsetse-repellent technology developed for the control of trypanosomosis in cattle. The technology was a repellent (2-methoxy 4-methylphenol) emitted from dispensers attached to collars worn by cattle. Treatment was allocated at the herd level to ensure adequate protection of all the animals in a herd, with measurements of effectiveness conducted at the individual-animal level. The trial began in April 2005 and ran for 16 months including a baseline phase of 4 months. We recruited 12 herds in each area using a restricted random-sampling technique and distributed them equally into intervention (repellent) and control groups. Sample size was determined using a formal power calculation. Effectiveness or minimal worthwhile difference was defined as a 50% reduction in the incidence of trypanosome infection in the treated versus control group (effectiveness below which the technology was considered by experts as not viable compared to existing control techniques). All the animals in the recruited herds were screened monthly (buffy-coat technique) for trypanosome infections. The analysis followed the principle of intention-to-treat by which subjects are analysed according to their initial treatment assignment, regardless of the mechanical performance of the device. Crude and adjusted effects of the technology were 23% (p < 0.001) and 18% (p = 0.08) reduction in the infection incidence in the treatment compared to the control groups, respectively. The impact of the technology estimated in this study did not achieve the threshold of 50% reduction in the trypanosome infection incidence set a priori to indicate effectiveness (p < 0.001). We therefore concluded that the prototype repellent technology package was not sufficiently effective in reducing trypanosome infection incidence under natural tsetse challenge to merit commercial development.

Research paper thumbnail of Population attributable fractions of farm vector tick (Rhipicephalus appendiculatus) presence on Theileria parva infection seroprevalence under endemic instability

Population attributable fractions of farm vector tick (Rhipicephalus appendiculatus) presence on Theileria parva infection seroprevalence under endemic instability

Preventive Veterinary Medicine, 2013

The primary objective of this study was to assess the impact of Rhipicephalus appendiculatus tick... more The primary objective of this study was to assess the impact of Rhipicephalus appendiculatus tick presence (exposure variable) on Theileria parva infection seroprevalence (outcome variable) in a group of cattle belonging to a farm using population attributable fractions (PAF). The analyses were based on a representative sample of 80 traditional smallholder mixed farms. The farms were selected by first stratifying the population administratively and implementing a multistage random sampling in Mbeere district in Kenya. The PAFs were estimated using the stratified, Bruzzi, and sequential partitioned PAF approaches. A secondary objective was, thus, to evaluate the impact of the approaches on the PAF estimates. The stratified and Bruzzi approaches estimated proportion of T. parva infection cases directly attributable to the exposure after controlling for confounding by agro-ecological zone (AEZ). The sequential partitioned PAF approach estimated a PAF associated with exposure after adjusting for any effect that the AEZ may have had by influencing the prevalence of the exposure. All analyses were carried out at the farm level where a farm was classified as infested if the tick was found on cattle on a farm, and infected if at least one animal on a farm was positive for T. parva antibodies. Variance estimation for PAFs was implemented using &amp;amp;amp;amp;#39;delete-a-group&amp;amp;amp;amp;#39; jackknife re-sampling method. The stratified PAF (26.7% [95% CI: 9.0%, 44.4%]) and Bruzzi PAF (26.4% [95% CI: 9.6%, 43.2%]) were consistent in estimating a relatively low impact of farm vector tick presence with a relatively high level of uncertainty. The partitioned PAF (15.5% [95% CI: 1.5%, 29.6%]) suggested that part of the impacts estimated using the stratified PAF and Bruzzi approaches was driven by AEZ effects. Overall, the results suggested that under endemic instability in Mbeere district, (1) presence of R. appendiculatus was not a good indicator of T. parva infection occurrence on a farm; (2) ecological variation could play a role in determining infection impacts. This study provides a preliminary basis for evaluating the potential value and utility of estimating PAFs for variables amenable to control in tick-borne diseases (TBDs) epidemiological studies.

Research paper thumbnail of Incidence of Highly Pathogenic Avian Influenza H5N1 in Nigeria, 2005-2008

Transboundary and emerging diseases, 2012

Outbreaks of highly pathogenic avian influenza (HPAI) H5N1 occurred in Nigeria between December 2... more Outbreaks of highly pathogenic avian influenza (HPAI) H5N1 occurred in Nigeria between December 2005 and July 2008. We describe temporal and spatial characteristics of these outbreaks at State and Local Government Area (LGA) levels. A total of 25 of 37 States (67.6%; Exact 95% CI: 50.2-82.0%) and 81 of 774 LGAs (10.5%; Exact 95% CI: 8.4-12.8%) were affected by HPAI outbreaks over the period from 2005 to 2008. The incidence risk of HPAI outbreak occurrence at the State level was 5.6% (0.7-18.7%) for 2005, 50.0% (30.7-69.4%) for 2006, 54.5% (29.9-80.3%) for 2007 and 0% for 2008. Only very few LGAs experienced HPAI outbreaks within the affected States. The incidence risk of HPAI outbreak occurrence on a LGA level was 0.3% (0.0-0.9%) for 2005, 6.6% (4.9-8.6%) for 2006, 4.2% (2.9-6.0%) for 2007 and 0% for 2008. The mean period between farmers noticing HPAI outbreaks and reporting them to veterinary authorities, and between reporting HPAI outbreaks and the depopulation of infected premise...

Research paper thumbnail of Characterisation of shops selling veterinary medicines in a tsetse-infested area of Kenya

Preventive veterinary …, 2004

In a tsetse-infested area of Kenya, we characterised veterinary-drug outlets based on personnel a... more In a tsetse-infested area of Kenya, we characterised veterinary-drug outlets based on personnel and business characteristics to assess their capacities to provide clinical veterinary services. Structured questionnaires were administered to the retailers and sought information on the characteristics of the owners, salespersons and businesses. A total of 41 retail outlets (20 agro-veterinary, 11 pharmacy, and 10 general shops) were identified. There was poor response to questions on owner characteristics. Proprietors, who had no more than secondary education owned 15 out of 28 shops. Few shops (4/29) were owned by proprietors, who had professional qualifications (in animal health). Most salespersons had only secondary education but no qualifications. Animal-health assistants (AHAs), veterinarians and manufacturer's package inserts (drug leaflets) were the preferred information sources for the retailers. We concluded that drug retailers were poorly equipped with the technical knowledge necessary for drug dispensation and advice.

Research paper thumbnail of Epidemiological factors that influence time-to-treatment of trypanosomosis in Orma Boran cattle raised at Galana Ranch, Kenya

Veterinary parasitology, 2004

Four thousand nine hundred and seventy-one trypanosomosis-surveillance records from an open popul... more Four thousand nine hundred and seventy-one trypanosomosis-surveillance records from an open population of Orma Boran cattle raised under natural trypanosomosis challenge in Galana Ranch, Kenya between the years 1990 and 2000 were analysed. The objective of the analysis was to identify epidemiological factors that influenced time-to-treatment of trypanosomosis cases. Under the surveillance programme, blood was being examined fortnightly for trypanosomosis using buffy coat technique. Infected animals were treated when their packed cell volumes (PCV) fell to 25% or lower. The number of days between the first diagnosis and treatment of trypanosomosis cases was obtained from the difference between diagnosis and treatment dates. Days-to-treatment clustered around the screening periods; therefore, time-to-treatment was represented by a series of time points 0-8 at 14-day intervals. Factors postulated to affect the outcome (time-to-treatment) were age of an animal at time of diagnosis, sex, number of trypanosome infections, trypanosome species and season of the year. Five animal generations were generated from birth dates and treated as nuisance parameters. Conditional logistic regression and Cox proportional hazards models were fitted to the data, the former to analyse factors that influenced treatment after time 0 (outcome dichotomised as time 0 or >0) and the latter to analyse factors that influenced time-to-treatment for cases that were treated after time 0, excluding all cases treated on time 0. The majority of the cases (89.5%) were treated on the same day of diagnosis. Trypanosome infections were more likely to be treated after time 0 in dry than in wet season. Similarly, the rate of treatment was lower in the dry than the wet season. An increase in number of previous trypanosome infections reduced the odds of an animal being treated after time 0. Animals that had been exposed to many infections before had higher rates of treatment than those that had minimal experiences. We offer possible reasons for these observations and conclude that selection of animals for breeding purposes in programmes geared

Research paper thumbnail of Evaluation of antigen and antibody rapid detection tests for Trypanosoma evansi infection in camels in Kenya

Veterinary parasitology, 2003

The card agglutination test for Trypanosoma evansi (CATT/T. evansi) for the detection of antibodi... more The card agglutination test for Trypanosoma evansi (CATT/T. evansi) for the detection of antibodies, and Suratex ® for the detection of circulating antigens were compared in a crosssectional study involving camels in eastern and central parts of Kenya. Of the 2227 camels screened, 2038 were owned by nomadic pastoralists in T. evansi endemic areas in eastern Kenya. A herd of 86 camels were from a ranch in Mugwoni. In Athi River area, 35 camels belonged to Kenya Trypanosomiasis Research Institute, and 68 were slaughter animals. Diagnostic sensitivity estimates were obtained by testing sera from 51 camels that had been found to be parasitologically positive by the haematocrit centrifugation technique, buffy-coat technique and mouse inoculation. Diagnostic specificity was estimated by testing sera from 35 camels known to be trypanosome-free. Positive and negative predictive values (NPVs) were calculated using a range of prevalence values. The sensitivity of CATT/T. evansi (68.6%) was higher than that of Suratex ® (58.8%), but not significantly. Both tests had equally high specificity (100%). The overall prevalence was 2.3% (51 out of 2227) by parasite detection, 32.2% (327 out of 1017) by CATT/T. evansi and 19.6% (188 out of 961) by Suratex ®. Overall, there was a positive association between CATT/T. evansi and Suratex ® though the strength of association was low (McNemar's test=46.12, P=0.001; kappa=0.26, CI: 0.20-0.33). Parasite prevalence ranged from 0% in several herds to 27.8% in a herd in Isiolo. Prevalence was highest in Isiolo with 2.5% (51 out of 2030) by parasitological detection, 38.8% (321 out of 828) by CATT/T. evansi and 21.9% (169 out of 772) by Suratex ®. In Mugwoni prevalence was 7 and 18% by CATT/T. evansi and Suratex ® , respectively, and no parasites were detected. In Athi River Suratex ® detected 2.9% (3 out of 103) positive while CATT/T. evansi and parasitological methods gave negative results. At prevalence values between 10 and 100%, CATT/T. evansi as well as Suratex ® had infinitely high positive predictive values, whereas Suratex ® had a lower NPV than CATT/T. evansi. In conclusion, results of this study showed that CATT/T. evansi and Suratex ® were able to detect aparasitaemic infections rapidly and were more sensitive than parasitological methods in revealing the true extent of trypanosomosis in a herd. The tests effectively complemented parasitological methods in the detection of T. evansi infections in camels.

Encouraging learners to avoid exams irregularities

Research paper thumbnail of A Transport Model for the Spread of Bird Flu

A Transport Model for the Spread of Bird Flu

tropentag.de

Highly Pathogenic Avian Influenza (HPAI) is a major threat to the poultry industry worldwide. In ... more Highly Pathogenic Avian Influenza (HPAI) is a major threat to the poultry industry worldwide. In developing countries backyard poultry production is often an important livelihood activity for women who use the additional income for unexpected household expenses. The disease ...

Research paper thumbnail of Animal-level risk factors for Trypanosoma evansi infection in camels in eastern and central parts of Kenya

Animal-level risk factors for Trypanosoma evansi infection in camels in eastern and central parts of Kenya

The Onderstepoort journal of veterinary research, 2002

Point prevalences and animal-level risk factors for Trypanosoma evansi infection were investigate... more Point prevalences and animal-level risk factors for Trypanosoma evansi infection were investigated in a cross-sectional study that involved 2227 camels from eastern and central parts of Kenya. The screening tests used were haematocrit centrifugation technique (HCT), mouse inoculation and latex agglutination (Suratex). All camels were screened with HCT, while 396 and 961 of them were, in addition, screened with mouse inoculation and Suratex tests, respectively. Parasitological and Suratex test results were used in parallel to determine the number of camels exposed to T. evansi infections. Statistical analyses were conducted using Statistical Analysis Systems. Parasitological and Suratex test results in parallel were dependent variables in multivariable logistic regression models that determined risk factors for T. evansi infection. Herd-level clustering was corrected with general estimation equations. The prevalences were 2.3% and 19.6%, using parasitological and Suratex tests, respe...

Research paper thumbnail of The 2006-2007 Rift Valley fever outbreak in Kenya: sources of early warning messages and response measures implemented by the Department of Veterinary Services

Revue scientifique et technique (International Office of Epizootics)

The authors characterised sources of early warning messages about occurrences of Rift Valley feve... more The authors characterised sources of early warning messages about occurrences of Rift Valley fever (RVF) and examined the response measures that were used by the Department of Veterinary Services (DVS) to manage the 2006-2007 RVF outbreaks in Kenya. The study was conducted between November 2009 and March 2010 and it included national, provincial and district veterinary officers who were involved in the management of the outbreak. Structured questionnaires were used to collect the data. Although the majority of the respondents reported having limited capacity to implement response measures, they perceived that the measures implemented were effective. Vaccination, movement control and market closures were the main response measures implemented, particularly in districts that had cases in both livestock and humans. Vaccination, however, was implemented too late and the coverage achieved was too low to be effective. The authors suggest ways to improve the capacity of the DVS to respond ...

Research paper thumbnail of Health risk in the context of climate change and adaptation - Concept and mapping as an integrated approach

Health risk in the context of climate change and adaptation - Concept and mapping as an integrated approach

Climate change has been stated as being one of the greatest challenges to global health in the cu... more Climate change has been stated as being one of the greatest challenges to global health in the current century. Climate change impacts on human health and the socio-economic and related poverty consequences are however still poorly understood. While epidemiological issues are strongly coupled with environmental and climatic parameters, the social and economic circumstances of populations might be of equal or even greater importance when trying to identify vulnerable populations and design appropriate and well-targeted adaptation measures. The inter-linkage between climate change, human health risk and socio-economic impacts remains an important - but largely outstanding - research field. We present an overview on how risk is traditionally being conceptualised in the human health domain and reflect critically on integrated approaches as being currently used in the climate change context. The presentation will also review existing approaches, and how they can be integrated towards ada...

Research paper thumbnail of An Expost Economic Impact Assessment of the Intervention against Highly Pathogenic Avian Influenza in Nigeria

An Expost Economic Impact Assessment of the Intervention against Highly Pathogenic Avian Influenza in Nigeria

The risk of spread of HPAI in Nigeria was derived by using a compartmental model to outline endem... more The risk of spread of HPAI in Nigeria was derived by using a compartmental model to outline endemic and burn-out scenarios. Two paths, low and high mortality risks, were associated to each of the scenarios. The estimated risk parameters were then used to stochastically simulate the trajectory of the disease; without intervention and with an intervention. The intervention costs the country US$ 41 million obtained through a World Bank IDA loan of US$ 50million yearly disbursed over the 2006-2010 period. The key output variables (net social welfare gain – with incremental net benefits as proxy, disease cost, and benefit cost ratio) were estimated for each randomly drawn risk parameter. On average, the results show that such an intervention would make economic sense under the endemic scenario with high mortality. The discounted costs (12% discount rate) of the disease without intervention would have amounted to US$ 145 million in total over the 2006-2010 period. The model indicates that...

Research paper thumbnail of Learning the Lessons of the 2006/7 Rift Valley Fever Outbreak in Kenya and Tanzania

Research paper thumbnail of Persistence of Rift Valley fever virus in East Africa

Persistence of Rift Valley fever virus in East Africa

Rift Valley fever virus (RVFv) is a mosquito-borne pathogen of livestock, wildlife and humans tha... more Rift Valley fever virus (RVFv) is a mosquito-borne pathogen of livestock, wildlife and humans that causes severe outbreaks in intervals of several years. One of the open questions is how the virus persists between outbreaks. We developed a spatially-explicit, individual-based simulation model of the RVFv transmission dynamics to investigate this question. The model, is based on livestock and mosquito population dynamics. Spatial aspects are explicitly represented by a set of grid cells that represent mosquito breeding sites. A grid cell measures 500 by 500m and the model considers a grid of 100 by 100 grid cells; the model thus operates on the regional scale of 2500km2. Livestock herds move between grid cells, and provide connectivity between the cells. The model is used to explore the spatio-temporal dynamics of RVFv persistence in absence of a wildlife reservoir in an east African semi-arid context. Specifically, the model assesses the importance of local virus persistence in mosq...

Research paper thumbnail of Spatial-temporal analysis of the of the risk of Rift Valley Fever in Kenya

Spatial-temporal analysis of the of the risk of Rift Valley Fever in Kenya

Historical data on Rift Valley Fever (RVF) outbreaks in Kenya covering the period 1951 - 2010 wer... more Historical data on Rift Valley Fever (RVF) outbreaks in Kenya covering the period 1951 - 2010 were analyzed using a logistic regression model to identify factors associated with RVF occurrence. The analysis used a division, an administrative unit below a district, as the unit of analysis. The infection status of each division was defined on a monthly time scale and used as a dependent variable. Predictors investigated include: monthly precipitation (minimum, maximum and total), normalized difference vegetation index, altitude, agro-ecological zone, presence of game, livestock and human population densities, the number of times a division has had an outbreak before and time interval in months between successive outbreaks (used as a proxy for immunity). Both univariable and multivariable analyses were conducted. The models used incorporated an auto-regressive correlation matrix to account for clustering of observations in time, while dummy variables were fitted in the multivariable mo...

Research paper thumbnail of Using participatory epidemiology to estimate disease transmission parameters

This is a case study on using PE to characterize Type A H5N1 highly pathogenic avian influenza (H... more This is a case study on using PE to characterize Type A H5N1 highly pathogenic avian influenza (HPAI) outbreaks, and using similar methods to understand diseases in other settings. In Indonesia, a list of all outbreaks of HPAI that were diagnosed in the past year was derived. 1-3 outbreaks per district were randomly selected for investigation. An infection tree reconstruction approach was used to trace chickens and households in outbreak neighborhoods. Investigations started with a checklist guided focus group interview. Mapping was used to document all households, poultry kept in each, and households and species affected by the outbreak. Spread through the neighborhood was recorded. The index, 2nd affected and closest unaffected households were geo-referenced. Risk factors were discussed. Individual interviews were held with up to five heads of affected households. Timelines were used to determine morbidity, mortality, slaughter and sales rates. Transect walks were used to triangul...

Research paper thumbnail of Antibody response and risk factors for seropositivity in backyard poultry following mass vaccination against highly pathogenic avian influenza and Newcastle disease in Indonesia

Epidemiology and Infection, 2014

SUMMARYA large-scale mass vaccination campaign was carried out in Java, Indonesia in an attempt t... more SUMMARYA large-scale mass vaccination campaign was carried out in Java, Indonesia in an attempt to control outbreaks of highly pathogenic avian influenza (HPAI) in backyard flocks and commercial smallholder poultry. Sero-monitoring was conducted in mass vaccination and control areas to assess the proportion of the target population with antibodies against HPAI and Newcastle disease (ND). There were four rounds of vaccination, and samples were collected after each round resulting in a total of 27 293 samples. Sampling was performed irrespective of vaccination status. In the mass vaccination areas, 20–45% of poultry sampled had a positive titre to H5 after each round of vaccination, compared to 2–3% in the control group. In the HPAI + ND vaccination group, 12–25% of the population had positive ND titres, compared to 5–13% in the areas without ND vaccination. The level of seropositivity varied by district, age of the bird, and species (ducksvs.chickens).

Research paper thumbnail of Transmission Rate and Reproductive Number of the H5N1 Highly Pathogenic Avian Influenza Virus During the December 2005-July 2008 Epidemic in Nigeria

Transboundary and Emerging Diseases, 2014

We quantified the between-village transmission rate, b (the rate of transmission of H5N1 HPAI vir... more We quantified the between-village transmission rate, b (the rate of transmission of H5N1 HPAI virus per effective contact), and the reproductive number, R e (the average number of outbreaks caused by one infectious village during its entire infectious period), of H5N1 highly pathogenic avian influenza (HPAI) virus in Nigeria using outbreak data collected between December 2005 and July 2008. We classified the outbreaks into two phases to assess the effectiveness of the control measures implemented. Phase 1 (December 2005-October 2006) represents the period when the Federal Government of Nigeria managed the HPAI surveillance and response measures, while Phase 2 (November 2006-July 2008) represents the time during which the Nigeria Avian Influenza Control and Human Pandemic Preparedness project (NAICP), funded by a World Bank credit of US$ 50 million, had taken over the management of most of the interventions. We used a total of 204 outbreaks from 176 villages that occurred in 78 local government areas of 25 states. The compartmental susceptible-infectious model was used as the analytical tool. Means and 95% percentile confidence intervals were obtained using bootstrapping techniques. The overall mean b (assuming a duration of infectiousness, T, of 12 days) was 0.07/day (95% percentile confidence interval: 0.06-0.09). The first and second phases of the epidemic had comparable b estimates of 0.06/day (0.04-0.09) and 0.08/day (0.06-0.10), respectively. The R e of the virus associated with these b and T estimates was 0.9 (0.7-1.1); the first and second phases of the epidemic had R e of 0.84 (0.5-1.2) and 0.9 (0.6-1.2), respectively. We conclude that the intervention measures implemented in the second phase of the epidemic had comparable effects to those implemented during the first phase and that the R e of the epidemic was low, indicating that the Nigeria H5N1 HPAI epidemic was unstable.

Research paper thumbnail of Estimating the Transmissibility of H5N1 and the Effect of Vaccination in Indonesia

Estimating the Transmissibility of H5N1 and the Effect of Vaccination in Indonesia

Transboundary and Emerging Diseases, 2013

The spread of H5N1 avian influenza continues to pose an economic burden and a public health risk ... more The spread of H5N1 avian influenza continues to pose an economic burden and a public health risk worldwide. Despite this, estimates of the transmissibility of infection exist in only a handful of settings and vary considerably. Using final size methods and flock-level infection data from a field trial of mass vaccination, we obtained the first estimates of the transmissibility of infection between and within flocks in Indonesia. We also found that outbreaks in areas designated as vaccination zones were less transmissible than in non-vaccination zones. However, this reduction is only comparable with a limited degree of protective vaccination coverage. Quantifying the overall effect of vaccination in these zones remains challenging. However, this result would appear to imply that, although the interventions applied in vaccination zones were not sufficient to completely prevent transmission in all areas, when outbreaks occur, they are less transmissible than those in areas where vaccination was not applied. This could be either a direct or an indirect effect of vaccination. Given the dynamism of small-scale poultry production in Indonesia, more regular vaccination may be required to ensure that infection is fully controlled in vaccination zones.

Research paper thumbnail of The Effectiveness of Preventative Mass Vaccination Regimes Against the Incidence of Highly Pathogenic Avian Influenza on Java Island, Indonesia

The Effectiveness of Preventative Mass Vaccination Regimes Against the Incidence of Highly Pathogenic Avian Influenza on Java Island, Indonesia

Transboundary and Emerging Diseases, 2013

We conducted an operational research study involving backyard and semicommercial farms on Java Is... more We conducted an operational research study involving backyard and semicommercial farms on Java Island, Indonesia, between April 2008 and September 2009 to evaluate the effectiveness of two preventive mass vaccination strategies against highly pathogenic avian influenza (HPAI). One regimen used Legok 2003 H5N1 vaccine, while the other used both Legok 2003 H5N1 and HB1 Newcastle disease (ND) vaccine. A total of 16 districts were involved in the study. The sample size was estimated using a formal power calculation technique that assumed a detectable effect of treatment as a 50% reduction in the baseline number of HPAI-compatible outbreaks. Within each district, candidate treatment blocks with village poultry populations ranging from 80 000 to 120 000 were created along subdistrict boundary lines. Subsequently, four of these blocks were randomly selected and assigned one treatment from a list that comprised control, vaccination against HPAI, vaccination against HPAI + ND. Four rounds of vaccination were administered at quarterly intervals beginning in July 2008. A vaccination campaign involved vaccinating 100 000 birds in a treatment block, followed by another 100 000 vaccinations 3 weeks later as a booster dose. Data on disease incidence and vaccination coverage were also collected at quarterly intervals using participatory epidemiological techniques. Compared with the unvaccinated (control) group, the incidence of HPAI-compatible events declined by 32% (P = 0.24) in the HPAI-vaccinated group and by 73% (P = 0.00) in the HPAI- and ND-vaccinated group. The effect of treatment did not vary with time or district. Similarly, an analysis of secondary data from the participatory disease and response (PDSR) database revealed that the incidence of HPAI declined by 12% in the HPAI-vaccinated group and by 24% in the HPAI + ND-vaccinated group. The results suggest that the HPAI + ND vaccination significantly reduced the incidence of HPAI-compatible events in mixed populations of semicommercial and backyard poultry.

Research paper thumbnail of Field trial of a synthetic tsetse-repellent technology developed for the control of bovine trypanosomosis in Kenya

Preventive Veterinary Medicine, 2010

We conducted a field trial among Maasai cattle-keepers in Nkuruman and Nkineji areas of Kenya to ... more We conducted a field trial among Maasai cattle-keepers in Nkuruman and Nkineji areas of Kenya to evaluate the effectiveness of a synthetic tsetse-repellent technology developed for the control of trypanosomosis in cattle. The technology was a repellent (2-methoxy 4-methylphenol) emitted from dispensers attached to collars worn by cattle. Treatment was allocated at the herd level to ensure adequate protection of all the animals in a herd, with measurements of effectiveness conducted at the individual-animal level. The trial began in April 2005 and ran for 16 months including a baseline phase of 4 months. We recruited 12 herds in each area using a restricted random-sampling technique and distributed them equally into intervention (repellent) and control groups. Sample size was determined using a formal power calculation. Effectiveness or minimal worthwhile difference was defined as a 50% reduction in the incidence of trypanosome infection in the treated versus control group (effectiveness below which the technology was considered by experts as not viable compared to existing control techniques). All the animals in the recruited herds were screened monthly (buffy-coat technique) for trypanosome infections. The analysis followed the principle of intention-to-treat by which subjects are analysed according to their initial treatment assignment, regardless of the mechanical performance of the device. Crude and adjusted effects of the technology were 23% (p < 0.001) and 18% (p = 0.08) reduction in the infection incidence in the treatment compared to the control groups, respectively. The impact of the technology estimated in this study did not achieve the threshold of 50% reduction in the trypanosome infection incidence set a priori to indicate effectiveness (p < 0.001). We therefore concluded that the prototype repellent technology package was not sufficiently effective in reducing trypanosome infection incidence under natural tsetse challenge to merit commercial development.

Research paper thumbnail of Population attributable fractions of farm vector tick (Rhipicephalus appendiculatus) presence on Theileria parva infection seroprevalence under endemic instability

Population attributable fractions of farm vector tick (Rhipicephalus appendiculatus) presence on Theileria parva infection seroprevalence under endemic instability

Preventive Veterinary Medicine, 2013

The primary objective of this study was to assess the impact of Rhipicephalus appendiculatus tick... more The primary objective of this study was to assess the impact of Rhipicephalus appendiculatus tick presence (exposure variable) on Theileria parva infection seroprevalence (outcome variable) in a group of cattle belonging to a farm using population attributable fractions (PAF). The analyses were based on a representative sample of 80 traditional smallholder mixed farms. The farms were selected by first stratifying the population administratively and implementing a multistage random sampling in Mbeere district in Kenya. The PAFs were estimated using the stratified, Bruzzi, and sequential partitioned PAF approaches. A secondary objective was, thus, to evaluate the impact of the approaches on the PAF estimates. The stratified and Bruzzi approaches estimated proportion of T. parva infection cases directly attributable to the exposure after controlling for confounding by agro-ecological zone (AEZ). The sequential partitioned PAF approach estimated a PAF associated with exposure after adjusting for any effect that the AEZ may have had by influencing the prevalence of the exposure. All analyses were carried out at the farm level where a farm was classified as infested if the tick was found on cattle on a farm, and infected if at least one animal on a farm was positive for T. parva antibodies. Variance estimation for PAFs was implemented using &amp;amp;amp;amp;#39;delete-a-group&amp;amp;amp;amp;#39; jackknife re-sampling method. The stratified PAF (26.7% [95% CI: 9.0%, 44.4%]) and Bruzzi PAF (26.4% [95% CI: 9.6%, 43.2%]) were consistent in estimating a relatively low impact of farm vector tick presence with a relatively high level of uncertainty. The partitioned PAF (15.5% [95% CI: 1.5%, 29.6%]) suggested that part of the impacts estimated using the stratified PAF and Bruzzi approaches was driven by AEZ effects. Overall, the results suggested that under endemic instability in Mbeere district, (1) presence of R. appendiculatus was not a good indicator of T. parva infection occurrence on a farm; (2) ecological variation could play a role in determining infection impacts. This study provides a preliminary basis for evaluating the potential value and utility of estimating PAFs for variables amenable to control in tick-borne diseases (TBDs) epidemiological studies.

Research paper thumbnail of Incidence of Highly Pathogenic Avian Influenza H5N1 in Nigeria, 2005-2008

Transboundary and emerging diseases, 2012

Outbreaks of highly pathogenic avian influenza (HPAI) H5N1 occurred in Nigeria between December 2... more Outbreaks of highly pathogenic avian influenza (HPAI) H5N1 occurred in Nigeria between December 2005 and July 2008. We describe temporal and spatial characteristics of these outbreaks at State and Local Government Area (LGA) levels. A total of 25 of 37 States (67.6%; Exact 95% CI: 50.2-82.0%) and 81 of 774 LGAs (10.5%; Exact 95% CI: 8.4-12.8%) were affected by HPAI outbreaks over the period from 2005 to 2008. The incidence risk of HPAI outbreak occurrence at the State level was 5.6% (0.7-18.7%) for 2005, 50.0% (30.7-69.4%) for 2006, 54.5% (29.9-80.3%) for 2007 and 0% for 2008. Only very few LGAs experienced HPAI outbreaks within the affected States. The incidence risk of HPAI outbreak occurrence on a LGA level was 0.3% (0.0-0.9%) for 2005, 6.6% (4.9-8.6%) for 2006, 4.2% (2.9-6.0%) for 2007 and 0% for 2008. The mean period between farmers noticing HPAI outbreaks and reporting them to veterinary authorities, and between reporting HPAI outbreaks and the depopulation of infected premise...

Research paper thumbnail of Characterisation of shops selling veterinary medicines in a tsetse-infested area of Kenya

Preventive veterinary …, 2004

In a tsetse-infested area of Kenya, we characterised veterinary-drug outlets based on personnel a... more In a tsetse-infested area of Kenya, we characterised veterinary-drug outlets based on personnel and business characteristics to assess their capacities to provide clinical veterinary services. Structured questionnaires were administered to the retailers and sought information on the characteristics of the owners, salespersons and businesses. A total of 41 retail outlets (20 agro-veterinary, 11 pharmacy, and 10 general shops) were identified. There was poor response to questions on owner characteristics. Proprietors, who had no more than secondary education owned 15 out of 28 shops. Few shops (4/29) were owned by proprietors, who had professional qualifications (in animal health). Most salespersons had only secondary education but no qualifications. Animal-health assistants (AHAs), veterinarians and manufacturer's package inserts (drug leaflets) were the preferred information sources for the retailers. We concluded that drug retailers were poorly equipped with the technical knowledge necessary for drug dispensation and advice.

Research paper thumbnail of Epidemiological factors that influence time-to-treatment of trypanosomosis in Orma Boran cattle raised at Galana Ranch, Kenya

Veterinary parasitology, 2004

Four thousand nine hundred and seventy-one trypanosomosis-surveillance records from an open popul... more Four thousand nine hundred and seventy-one trypanosomosis-surveillance records from an open population of Orma Boran cattle raised under natural trypanosomosis challenge in Galana Ranch, Kenya between the years 1990 and 2000 were analysed. The objective of the analysis was to identify epidemiological factors that influenced time-to-treatment of trypanosomosis cases. Under the surveillance programme, blood was being examined fortnightly for trypanosomosis using buffy coat technique. Infected animals were treated when their packed cell volumes (PCV) fell to 25% or lower. The number of days between the first diagnosis and treatment of trypanosomosis cases was obtained from the difference between diagnosis and treatment dates. Days-to-treatment clustered around the screening periods; therefore, time-to-treatment was represented by a series of time points 0-8 at 14-day intervals. Factors postulated to affect the outcome (time-to-treatment) were age of an animal at time of diagnosis, sex, number of trypanosome infections, trypanosome species and season of the year. Five animal generations were generated from birth dates and treated as nuisance parameters. Conditional logistic regression and Cox proportional hazards models were fitted to the data, the former to analyse factors that influenced treatment after time 0 (outcome dichotomised as time 0 or >0) and the latter to analyse factors that influenced time-to-treatment for cases that were treated after time 0, excluding all cases treated on time 0. The majority of the cases (89.5%) were treated on the same day of diagnosis. Trypanosome infections were more likely to be treated after time 0 in dry than in wet season. Similarly, the rate of treatment was lower in the dry than the wet season. An increase in number of previous trypanosome infections reduced the odds of an animal being treated after time 0. Animals that had been exposed to many infections before had higher rates of treatment than those that had minimal experiences. We offer possible reasons for these observations and conclude that selection of animals for breeding purposes in programmes geared

Research paper thumbnail of Evaluation of antigen and antibody rapid detection tests for Trypanosoma evansi infection in camels in Kenya

Veterinary parasitology, 2003

The card agglutination test for Trypanosoma evansi (CATT/T. evansi) for the detection of antibodi... more The card agglutination test for Trypanosoma evansi (CATT/T. evansi) for the detection of antibodies, and Suratex ® for the detection of circulating antigens were compared in a crosssectional study involving camels in eastern and central parts of Kenya. Of the 2227 camels screened, 2038 were owned by nomadic pastoralists in T. evansi endemic areas in eastern Kenya. A herd of 86 camels were from a ranch in Mugwoni. In Athi River area, 35 camels belonged to Kenya Trypanosomiasis Research Institute, and 68 were slaughter animals. Diagnostic sensitivity estimates were obtained by testing sera from 51 camels that had been found to be parasitologically positive by the haematocrit centrifugation technique, buffy-coat technique and mouse inoculation. Diagnostic specificity was estimated by testing sera from 35 camels known to be trypanosome-free. Positive and negative predictive values (NPVs) were calculated using a range of prevalence values. The sensitivity of CATT/T. evansi (68.6%) was higher than that of Suratex ® (58.8%), but not significantly. Both tests had equally high specificity (100%). The overall prevalence was 2.3% (51 out of 2227) by parasite detection, 32.2% (327 out of 1017) by CATT/T. evansi and 19.6% (188 out of 961) by Suratex ®. Overall, there was a positive association between CATT/T. evansi and Suratex ® though the strength of association was low (McNemar's test=46.12, P=0.001; kappa=0.26, CI: 0.20-0.33). Parasite prevalence ranged from 0% in several herds to 27.8% in a herd in Isiolo. Prevalence was highest in Isiolo with 2.5% (51 out of 2030) by parasitological detection, 38.8% (321 out of 828) by CATT/T. evansi and 21.9% (169 out of 772) by Suratex ®. In Mugwoni prevalence was 7 and 18% by CATT/T. evansi and Suratex ® , respectively, and no parasites were detected. In Athi River Suratex ® detected 2.9% (3 out of 103) positive while CATT/T. evansi and parasitological methods gave negative results. At prevalence values between 10 and 100%, CATT/T. evansi as well as Suratex ® had infinitely high positive predictive values, whereas Suratex ® had a lower NPV than CATT/T. evansi. In conclusion, results of this study showed that CATT/T. evansi and Suratex ® were able to detect aparasitaemic infections rapidly and were more sensitive than parasitological methods in revealing the true extent of trypanosomosis in a herd. The tests effectively complemented parasitological methods in the detection of T. evansi infections in camels.

Research paper thumbnail of Analyses of the poultry value chain and its linkages and interactions with HPAI risk factors in Nigeria

HPAI Research Brief, 2009

HPAI disease-transmission pathways are linked to the economic incentives that chain actors face. ... more HPAI disease-transmission pathways are linked to the economic incentives that chain actors face. Disease transmission risk is strongly related to commercial practices and trade in poultry and poultry products. Consumer influences are insufficient to change governance and ...

Research paper thumbnail of MAAZIMIO YA KAZI KIDATO CHA TATU MUHULA WA KWANZA 2020 JU MA

Kitabu teule. 3-4 Fasihi andishi. Hadithi fupi: Utenzi wa moyoni. Kufika mwisho wa somo, mwanafun... more Kitabu teule. 3-4 Fasihi andishi. Hadithi fupi: Utenzi wa moyoni. Kufika mwisho wa somo, mwanafunzi aweze: Kutaja maudhui ya hadithi. Kujadili mbinu za lugha. Kujadili wahusika. Kusoma kwa sauti. Majadiliano. Uchambuzi. Kuandika. Kitabu cha Mayai MWM UK. 12. 5-6 Sarufi. Uakifishaji. Kufika mwisho wa somo, mwanafunzi aweze: Kuzitambua, kutaja na kueleza alama za uakifishaji na matumizi. Kuakifisha makala. Mifano ya alama. Matumizi ya alama Majadiliano. Mazoezi.

Research paper thumbnail of GENERAL OBJECTIVES

MADHUMUNI YA UJUMLA 1. Kuendeleza mafunzo ya Kiswahili yaliyoshughulikiwa katika shule za msingi.... more MADHUMUNI YA UJUMLA 1. Kuendeleza mafunzo ya Kiswahili yaliyoshughulikiwa katika shule za msingi. 2. Kumpa mwanafunzi uwezo wa kudumu wa kusikiliza, kuzungumza, kusoma na kuandika ipasavyo kwa lugha ya Kiswahili. 3. Kumwezesha kubuni, kuchambua na kujieleza wazi kimantiki. 4. Kutumia Kiswahili katika mawasiliano na shughuli za kila siku. 5. Kutambua, kudadisi, kuthamini na kustawisha aina na tanzu mbalimbali za lugha na fasihi kwa Kiswahili. 6. Kujifunza na kuthamini fani mbalimbali za tamaduni kwa kutumia Kiswahili. 7. Kuwa na utambuzi kwa mambo yanayohusu na yanayoiathiri jamii k.m. ukimwi, maendeleo ya kiteknolojia, usawa wa kijinsia n.k. 8. Kuhifadhi mazingira kwa ajili ya kudumisha uhai na kujitimizia mahitaji ya kila siku na ya maisha ya baadaye. 9. Kufurahia kujisomea na kujiendeleza mwenyewe kadiri ya uwezo wake. 10. Kuthamini, kufurahia na kujivunia Kiswahili kama lugha ya taifa na kimataifa. 1.1.0 KUSIKILIZA NA KUZUNGUMZA 1.1.1 Shabaha Kufikia mwisho wa mafunzo ya Kiswahili katika shule ya upili, mwanafunzi aweze:

Research paper thumbnail of MAAZIMIO YA KAZI KIDATO CHA TATU MUHULA WA KWANZA 2020 JU MA KIPI NDI MADA KUU MADA NDOGO SHABAHA NJIA ZA KUFUNDISHIA NYENZO

Research paper thumbnail of HISTORY AND GOVERNMENT

the end of the topic, the learner should be able to: a) explain the Bible as the word of God, its... more the end of the topic, the learner should be able to: a) explain the Bible as the word of God, its major divisions and its human authors; b) outline the translation of the Bible from the original languages (Hebrews, Greek) to local languages; c) discuss the effects of the translation of the Bible into African languages.

Research paper thumbnail of Sarufi na Matumizi ya Lugha F1 4

Bett, 2021

SARUFI NOMINO Nomino ni maneno yanayotumiwa kutajia mtu, kitu, hali au mahali maalum. Inafahamika... more SARUFI NOMINO Nomino ni maneno yanayotumiwa kutajia mtu, kitu, hali au mahali maalum. Inafahamika kuwa kuna aina sita za nomino mathalan; AINA ZA NOMINO (a) Nomino za pekee Hizi ni nomino ambazo huanza kwa herufi kubwa. Hasa hutaja vitu mahsusi kama vile, milima, nchi, watu, mito, maziwa n.k. Mifano ya katika sentensi i) MtoNzoiahufurika wakati wamasika. ii) Fatuma ameenda sokoni sasa hivi. iii) Nairobi ndio mji mkuu wa Kenya. iv) Ziwa Bogoria hupatikana katika eneo la Bonde la Ufa (b) Nomino za kawaida Hizi ni nomino ambazo hazianzi kwa herufi kubwa ila tu zinapotumika mwanzoni mwa sentensi k.m. i) Wanafunzi walishirikishwa kupanda miti mwaka huu. ii) Wanaiunzi watazuru ikulu ya raisi hiyo kesho. iii) Wananchi hupaswa kutii sheria za nchi kila mara. (c) Nomini za dhania