Typhoid Fever in Chile 1969-2012: Analysis of an Epidemic and Its Control (original) (raw)
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PLoS neglected tropical diseases, 2018
Typhoid fever is endemic in many developing countries. In the early 20th century, newly industrializing countries including the United States successfully controlled typhoid as water treatment (chlorination/sand filtration) and improved sanitation became widespread. Enigmatically, typhoid remained endemic through the 1980s in Santiago, Chile, despite potable municipal water and widespread household sanitation. Data were collected across multiple stages of endemicity and control in Santiago, offering a unique resource for gaining insight into drivers of transmission in modern settings. We developed an individual-based mathematical model of typhoid transmission, with model components including distinctions between long-cycle and short-cycle transmission routes. Data used to fit the model included the prevalence of chronic carriers, seasonality, longitudinal incidence, and age-specific distributions of typhoid infection and disease. Our model captured the dynamics seen in Santiago acro...
The study sought to analyze the sociodemographic, epidemiological profile, and spatial-temporal distribution of typhoid fever in the municipality of Belém, Pará. For that, we used the confirmed cases of the disease obtained from SINAN by SESPA from 2007 to 2016. The data was categorized based on the sociodemographic, epidemiological profile, incidence rates, and monthly variation. For spatial distribution, we used the Kernel Density Estimator and the Buffer technique. Thus, we obtained 152 confirmed cases, with a higher proportion in males (67.76%), in the age group between 30 and 59 years (48.03%), and with high school education (19.08%). The transmission was mainly related to the ingestion of contaminated water and food (11.18%), with resolution at an outpatient level (69.08%), confirmed at a laboratory level (93.42%), without death records. The annual incidence rate varied from 0.07% in 2011 to 3.28% in 2014. It was also observed that the spatial distribution of the disease was concentrated in the districts of Guamá, Entroncamento, and near the Tucunduba watershed demonstrating that the greatest risk of transmission is in areas that present socioeconomic fragility and are precarious in basic sanitation. Thus there is a need for investments in sanitary infrastructure and health surveillance actions, aiming at reducing the disease in the municipality.
Temporal, spatial and household dynamics of Typhoid fever in Kasese district, Uganda
PLOS ONE
Typhoid fever affects 21 million people globally, 1% of whom succumb to the disease. The social, economic and public health consequences of this disease disproportionately affect people in Africa and Asia. In order to design context specific prevention strategies, we need to holistically characterise outbreaks in these settings. In this study, we used retrospective data (2013-2016) at national and district level to characterise temporal and spatial dynamics of Typhoid fever outbreaks using time series and spatial analysis. We then selected cases matched with controls to investigate household socioeconomic drivers using a conditional logistic regression model, and also developed a Typhoid fever outbreak-forecasting framework. The incidence rate of Typhoid fever at national and district level was~160 and 60 cases per 100,000 persons per year, respectively, predominantly in urban areas. In Kasese district, Bwera sub-county registered the highest incidence rate, followed by Kisinga, Kitholhu and Nyakiyumbu sub-counties. The male-female case ratio at district level was at 1.68 and outbreaks occurred between the 20 th and 40 th week (May and October) each year following by seven weeks of precipitation. Our forecasting framework predicted outbreaks better at the district level rather than national. We identified a temporal window associated with Typhoid fever outbreaks in Kasese district, which is preceded by precipitation, flooding and displacement of people. We also observed that areas with high incidence of Typhoid fever also had high environmental contamination with limited water treatment. Taken together with the forecasting framework, this knowledge can inform the development of specific control and preparedness strategies at district and national level.
Journal of Mathematical Biology, 2018
Typhoid fever is a systemic infection caused by Salmonella Typhi and occurs predominantly in association with poor sanitation and lack of clean drinking water. Despite recent progress in water and sanitation coverage, the disease remains a substantial public health problem in many developing countries. A mathematical model for the spread of typhoid has been formulated using non linear ordinary differential equations. The model includes a special treatment function to assess the effects of limited treatment resources on the spread of typhoid. It is shown that the model has multiple equilibria and using the center manifold theory, the model exhibits the phenomenon of backward bifurcation whose implications are discussed. The results suggest the need for comprehensive and accessible treatment facilities to curtail typhoid infection.
Environmental Surveillance as a Tool for Identifying High-risk Settings for Typhoid Transmission
Clinical Infectious Diseases, 2020
Enteric fever remains a major cause of morbidity in developing countries with poor sanitation conditions that enable fecal contamination of water distribution systems. Historical evidence has shown that contamination of water systems used for household consumption or agriculture are key transmission routes for Salmonella Typhi and Salmonella Paratyphi A. The World Health Organization now recommends that typhoid conjugate vaccines (TCV) be used in settings with high typhoid incidence; consequently, governments face a challenge regarding how to prioritize typhoid against other emerging diseases. A key issue is the lack of typhoid burden data in many low- and middle-income countries where TCV could be deployed. Here we present an argument for utilizing environmental sampling for the surveillance of enteric fever organisms to provide data on community-level typhoid risk. Such an approach could complement traditional blood culture-based surveillance or even replace it in settings where p...
There is no typhoid frequency information from most low and center pay nations, so model-based evaluations offer bits of knowledge for decision makers without promptly accessible information. Methods: We built up a blended impacts model fit to information from 32 populace based investigations of typhoid rate in 22 areas in 14 nations. Our current research was conducted at General Hospital, Lahore Pakistan from May 2019 to April 2020. We tried the commitment of monetary and natural records for foreseeing typhoid frequency utilizing a stochastic hunt variable determination calculation. We performed out-of-test approval to survey the prescient exhibition of the model. Results: We assessed that 18.9 million instances of typhoid fever happen every year in LMICs (96 percent tenable span: 8.7±49.5 million). Focal Africa was anticipated to encounter the most elevated occurrence of typhoid, trailed by select nations in Central, South, and Southeast Asia. This usually crests in the advanced age set of 3±5 years. It was observed that models incorporating wide-ranging monetary and natural variables reflect frequency rather than invalid models. Conclusion: Late gauges of typhoid weight may under-gauge the quantity of cases and greatness of vulnerability in typhoid frequency. Our examination grants forecast of in general just as age-explicit frequency of typhoid fever in LMICs, and consolidates vulnerability around the model structure and gauges of the indicators. Future examinations are expected to additionally approve also, refine model forecasts and better comprehend year-to-year variety in cases.
Implementation of Interventions for the Control of Typhoid Fever in Low- and Middle-Income Countries
The American journal of tropical medicine and hygiene, 2018
Past research has focused on typhoid fever surveillance with little attention to implementation methods or effectiveness of control interventions. This study purposefully sampled key informants working in public health in Chile, India, Pakistan, Bangladesh, Thailand, Vietnam, South Africa, and Nigeria to 1) scope typhoid-relevant interventions implemented between 1990 and 2015 and 2) explore contextual factors perceived to be associated with their implementation, based on the Consolidated Framework for Implementation Research (CFIR). We used a mixed methods design and collected quantitative data (CFIR questionnaire) and qualitative data (interviews with 34 public health experts). Interview data were analyzed using a deductive qualitative content analysis and summary descriptive statistics are provided for the CFIR data. Despite relatively few typhoid-specific interventions reportedly implemented in these countries, interventions for diarrheal disease control and regulations for food...
Modeling the Potential Effect of Media Campaigns in Controlling Typhoid Fever
Pan African Journal of Life Sciences
Background: Typhoid fever, caused by Salmonella typhi, is still a serious problem in many developing countries. It is spread by eating or drinking food or water contaminated with the faeces of an infected person. Risk factors include poor sanitation and poor hygiene. This study presented a mathematical model with a media campaign component to evaluate the possible impact of media campaigns on typhoid fever awareness. Methods: Sixty-four We proposed a model based on the transmission dynamics of Typhoid disease, emphasizing the cumulative density of awareness programs for the disease. The total population at time t is denoted by N(t); which is subdivided into Susceptible S(t), Infected Class I(t), Susceptible Media Sm (t), Recovered, and Cumulative density of awareness program M(t), thus, N(t) = S(t) + I(t) + Sm(t) + R(t) + M(t). The study stresses that when media knowledge spreads among the general population, a section susceptible to infection becomes isolated from the infected ones...
An analysis of economic costs associated with an outbreak of typhoid fever
American Journal of Public Health, 1985
We examined the costs of a typhoid fever outbreak caused by exposures to contaminated food over a 47-day period at a restaurant. For the 49 respondents, the patient-related costs (+215,548) were primarily medical expenses (+183,902) and lost income or productivity (+28,603). The estimated patient-related costs for all 80 outbreak-associated cases was +351,920. Had contaminated food continued to be served, the prevention-related costs (+36,500) would have been offset by patient-related costs (+7,488/day) within 5 days.
On the heterogeneous spread of COVID-19 in Chile
Chaos, Solitons, and Fractals, 2021
Non-pharmaceutical interventions (NPIs) have played a crucial role in controlling the spread of COVID-19. Nevertheless, NPI efficacy varies enormously between and within countries, mainly because of population and behavioral heterogeneity. In this work, we adapted a multi-group SEIRA model to study the spreading dynamics of COVID-19 in Chile, representing geographically separated regions of the country by different groups. We use national mobilization statistics to estimate the connectivity between regions and data from governmental repositories to obtain COVID-19 spreading and death rates in each region. We then assessed the effectiveness of different NPIs by studying the temporal evolution of the reproduction number R t . Analyzing data-driven and model-based estimates of R t , we found a strong coupling of different regions, highlighting the necessity of organized and coordinated actions to control the spread of SARS-CoV-2. Finally, we evaluated different scenarios to forecast th...