Santosh Dhakal | Ohio State University (original) (raw)

Papers by Santosh Dhakal

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... Mishra and Shah (1990/91) detected brucellosis serologically in cow, buffalo, goat, sheep and... more ... Mishra and Shah (1990/91) detected brucellosis serologically in cow, buffalo, goat, sheep and pig in Nepal. ... Textbook of Veteirnary Microbiology. Vikash Publishing House, India. p.187. ... 73, klZrdf~rn If]qLo :jR5 :j:Yo kz' jw k|s[of df;' hfFr Joj:yfkg tflnd k|ltj]bg, g]kfnL, 99933-47-70-4. ...

ABSTRACT Since late 1980s Japanese encephalitis has been endemic in Terai and inner Terai region ... more ABSTRACT Since late 1980s Japanese encephalitis has been endemic in Terai and inner Terai region of Nepal (60-300masl). After the first report from Kathmandu valley in 1997, this disease also reported from other districts of hill region (300-2000masl). Beyond the conventional logic of high altitude, the mountain districts (2,000-8,848masl) previously silent for this disease also started reporting cases from 2005. Till now 54 out of 75 districts of Nepal have reported Japanese encephalitis cases and the number of districts endemic for this disease are increasing. Presence of mosquito vector and infection in pig reported from those hill and mountain districts are also confirming the geographical expansion of Japanese encephalitis, making this disease a public health concern in Nepal. However, the transmission pattern is complex and not yet clear. Heavy rice farming under flooded irrigation, inflated pig husbandry without sanitary considerations, climate change favoring adaptation of vectors to hitherto cold climates, lack of awareness and preventive measures are regarded responsible for this expansion. A huge gap existing on geographical expansion of Japanese encephalitis calls for extensive research focusing on association of this disease with land use pattern, pig husbandry, vector ecology, human-animal interaction, socio-economic aspects of Japanese encephalitis risk and so on.

PRRSV infection induces poor anti-viral innate IFN and cytokine responses, which results in weak ... more PRRSV infection induces poor anti-viral innate IFN and cytokine responses, which results in weak adaptive immunity. One of the strategies in next generation vaccine construction is to manipulate viral proteins/genetic elements involved in antagonizing host immune response. The PRRSV nsp1β was identified to be a strong innate immune antagonist. In this study, two basic amino acids, R128 and R129, in a highly conserved GKYLQRRLQ motif were determined to be critical for nsp1β function. Mutations introduced into these two residues attenuated virus growth and improved the innate and adaptive immune responses in infected animals. Technologies developed in this study could be broadly applied to current commercial PRRSV MLV vaccines and other candidate vaccines.

Porcine epidemic diarrhea virus (PEDV) is an economically devastating enteric disease in the swin... more Porcine epidemic diarrhea virus (PEDV) is an economically devastating enteric disease in the swine industry. The virus infects pigs of all ages, but it cause severe clinical disease in neonatal suckling pigs with up to 100% mortality. Currently, available vaccines are not completely effective and feedback methods utilizing PEDV infected material has variable success in preventing reinfection. Comprehensive information on the levels and duration of effector/memory IgA and IgG antibody secreting B cell response in the intestines and lymphoid organs of PEDV‑infected sows, and their association with specific antibody levels in clinical samples such as plasma, oral fluid, and feces is important. Therefore, our goal in this study was to quantify PEDV specific IgA and IgG B cell responses in sows at approximately 1 and 6 months post‑infection in commercial swine herds, including parity one and higher sows. Our data indicated that evaluation of both PEDV specific IgA and IgG antibody levels in the plasma and oral fluid (but not feces) samples is beneficial in disease diagnosis. PEDV specific B cell response in the intestine and spleen of infected sows decline by 6 months, and this associates with specific antibody levels in the plasma and oral fluid samples; but the virus neutrali‑ zation titers in plasma remains high beyond 6 months post‑infection. In conclusion, in sows infected with PEDV the presence of effector/memory B cell response and strong virus neutralization titers in plasma up to 6 months post‑ infection, suggests their potential to protect sows from reinfection and provide maternal immunity to neonates, but challenge studies are required to confirm such responses.

A cross-sectional study was conducted on four major pig raising districts of eastern and mid-west... more A cross-sectional study was conducted on four major pig raising districts of eastern and mid-western region of Nepal from February to May
2014 to find out the seroprevalence of Trichinella spp. A total of 184 serum samples of pigs were collected and antibodies against trichinella
were detected using ID screen trichinella indirect multi- species ELISA kit. The study revealed prevalence rate of 3.8% and difference in
prevalence rate according to age, sex, breed, rearing system, ecozone, region & district were statistically insignificant (P>0.05) as analysed
by Chi-square test using PHStat version 2.5 and Fisher’s exact test. This study confirms that antibodies of Trichinella spp. are circulating in
pigs of Nepal. Further, the knowledge, attitude and practices survey of meat borne helminthic zoonoses was conducted among 50 pig raisers
and pork consumers by face to face interview using a semi-structure questionnaire. This survey concludes that although there were significant
portion of the respondents aware of meat borne helminthic zoonoses but there were still a noticeable proportion of respondents who didn’t
have a proper knowledge that upsurge public health risks. Moreover, present-day situation of their pig raising practices & pork consumption
system possess them to a menace of public health zoonoses.

Very little information is available regarding the demographics of the demodicosis in canines of ... more Very little information is available regarding the demographics of the demodicosis in canines of Kathmandu valley and in Nepal as a whole.
In this study, we determined the prevalence of the demodicosis and its associated risk factors from 110 canines of Kathmandu valley including
both sheltered and free-roaming. The skin scrapping collected was dissolved in 10% KOH for the microscopic diagnosis of the mites. The
overall prevalence of demodectic mange was found to be 29.1%. There was significant difference (p<0.05) between the prevalence rate among
puppy (49.0%), adult (6.9%) and senior (33.33%). Whereas, there was no significant difference (p>0.05) between the prevalence rate among
female (22.9%) and male (36.7%). Similarly, there was no significant difference (p>0.05) between the prevalence rate among short hair
(40.7%), medium (25.67%) and long hair (28.5%). The association between the prevalence rate among good health status (10.7%) and poor
health status (55.5%) is significant (p<0.05). Similarly, there was significant difference (p<0.05) between the prevalence rate among the freeroaming
(48.9%) and the owned dogs (13.1%). At last, there was no significant association (p>0.05) between the prevalence rate among the
pure breed (27.7%), cross (25.9%) and mongrel (37.5%). This study shows that demodectic mange is somewhat serious skin infection in
canines of Kathmandu valley. The high significant association of age, health status and management with its prevalence suggests that the
disease is more common in dogs which are left uncared and whose immune system is disturbed. Whereas, sex, breed and type of the hair of
the dog did not have such significant relation with its prevalence. As demodicosis is a huge problem in street dogs, concerned organizations
and authorities should develop proper planning for street dog management and their health care.

Porcine reproductive and respiratory syndrome (PRRS) is a highly infectious viral disease of swin... more Porcine reproductive and respiratory syndrome (PRRS) is a highly infectious viral disease of swine. This disease is becoming threat to pig
industry of every corner of the world. As the status of this disease in Nepal is not properly understood so far, a cross-sectional sero-prevalence
study was carried out in four development regions. A total of 200 blood samples were collected from major pig producing areas of eight
districts of four development regions of Nepal and the serum samples were tested for antibodies against PRRS virus by rapid antibody detection
kit (Immunochromatographic test using colloidal gold immunoassay: Schenzhen Lvshiyuan biotechnology Co. Ltd, China). Among the tested
serum samples, 37 were found to be positive for PRRS indicating 18.5% prevalence of the disease. Statistically the prevalence difference was
significant between different development regions and between topographical regions (P<0.05) of the country, but no significant difference
was observed in age, sex and housing systems of pigs.
Presence of antibodies in serum against PRRSV in the unvaccinated pig population of the country clearly indicates that pigs of the surveyed
regions of Nepal have already been exposed to PRRS virus and the disease should be given adequate attention during differential diagnosis of
porcine respiratory diseases in Nepal. Further studies are needed for molecular characterization of the virus and to develop control strategies
against this disease in the country.

A survey was carried out to determine the population of street dogs and people's opinion about th... more A survey was carried out to determine the population of street dogs and people's opinion about their persistence in Pokhara Valley, Nepal. Information of street dog population was necessary to construct a future animal birth control (ABC) plans. For this, mark-resight survey method was used. Further, local residents were interviewed to know their opinion about the persistence of street dog population in that area. Among total 1767 dogs, 1072 (60.66%) were male, 641 (36.28%) were female and 54 (3.06%) were puppies. About 367 (57.25%) of the female street dogs were already spayed. A total of 371 local residents were interviewed to know their opinion about the causes of persistent street dogs in Pokhara Valley. Numerous reasons were put forward including unmanaged slaughter house (24.5%), abandoned due to disease (15.4%) and abandoned due to unmanageable estrus behavior (10.2%). Future ABC programs may need to consider these factors responsible for maintaining persistent street dog population, to enable control over street dog population in an efficient and sustainable manner.

Japanese encephalitis (JE) is a mosquito borne zoonotic disease caused by JE virus (JEV). JE has ... more Japanese encephalitis (JE) is a mosquito borne zoonotic disease caused by JE virus (JEV). JE has been endemic in Terai region, the lowland plains of Nepal bordering India, since 1978. However, in recent years cases of JE has been continuously reported from high altitude zones of hills and mountains. Irrigated rice farming system, expanded pig husbandry practices, inadequate vaccine coverage, low level of public awareness and climate change favoring mosquito breeding in higher altitudes might be the probable risk factors for emergence and re-emergence of JE in Nepal. Repeated outbreak in endemic areas and geographical expansion to newer areas have created huge challenge for JE prevention and control. At present, JE is one of the major public health concern of Nepal. Expanding vaccine coverage, improving agricultural practices, generating public awareness, supporting for use of mosquito avoiding practices and regional collaboration at border against JE can be helpful in getting better control over it in future.

Japanese encephalitis: Challenges and intervention opportunities in Nepal. Available from: https://www.researchgate.net/publication/270958293_Japanese_encephalitis_Challenges_and_intervention_opportunities_in_Nepal [accessed Feb 5, 2016].

Background: Campylobacter is the primary cause of food borne gastroenteritis. Moreover, the emerg... more Background: Campylobacter is the primary cause of food borne gastroenteritis. Moreover, the emergence of multiple drug resistant campylobacters from poultry and pork has produced a potential threat to public health. Research addressing these issues is sparse in Nepal. So, this cross-sectional study aims at determining the prevalence, antibiogram and risk factors of campylobacters from dressed porcine carcass of Chitwan, Nepal.

Japanese encephalitis (JE) is a mosquito borne zoonotic disease caused by JE virus (JEV). JE has ... more Japanese encephalitis (JE) is a mosquito borne zoonotic disease caused by JE virus (JEV). JE has been endemic in Terai
region, the lowland plains of Nepal bordering India, since 1978. However, in recent years cases of JE has been continuously
reported from high altitude zones of hills and mountains. Irrigated rice farming system, expanded pig husbandry practices,
inadequate vaccine coverage, low level of public awareness and climate change favoring mosquito breeding in higher
altitudes might be the probable risk factors for emergence and re-emergence of JE in Nepal. Repeated outbreak in endemic
areas and geographical expansion to newer areas have created huge challenge for JE prevention and control. At present, JE is
one of the major public health concern of Nepal. Expanding vaccine coverage, improving agricultural practices, generating
public awareness, supporting for use of mosquito avoiding practices and regional collaboration at border against JE can be
helpful in getting better control over it in future.

The objectives of this cross-sectional study was to determine the seropositivity status of Japane... more The objectives of this cross-sectional study was to determine the seropositivity status of Japanese encephalitis virus (JEV) in pig
and ascertain the farm level risk factors in Nepal. Serum samples were collected from 181 pigs in 91 farms of Rupandehi and
Kapilbastu districts and tested for antibodies by IgG ELISA. Survey of farmers in each farm was carried out to determine the
farm level risk factors. A total of 20 out of 181 (11%) serum samples tested positive for JEV antibodies. There was no statistically
significant difference in seropositivity with age (p>0.05), sex (p>0.05) and breed (p>0.05) of pigs. Farm level infection was
significantly associated with closeness to rice fields (p<0.05), closeness to standing water sources (p<0.05), wild bird exposure
(p<0.05) and mosquito bite to pigs (p<0.05). These factors need to be addressed while formulating prevention, control and
management strategies of JEV in pig and hence in human.
Keywords: Japanese encephalitis; Japanese encephalitis virus; Pig; Risk factor

Introduction: Dengue is an emerging mosquito-borne viral disease in the world and is the serious ... more Introduction: Dengue is an emerging mosquito-borne viral disease in the world and is the serious public health problem of Nepal.

Methods: This study was designed to determine sero-epidemiology of dengue virus infectionduring the period (June-Nov) of 2010 among suspected patients with fever visiting Koshi Zonal Hospital (KZH), Biratnagar, Narayani sub-regional Hospital (NSH), Birgunj, Sukraraj Tropical and Infectious Disease Hospital (STIDH), Kathmandu and Dhading District Hospital (DDH), Dhadingbeshi. The sero-prevalence of anti-dengue IgM antibody was determined by enzyme linked immunosorbent assay (ELISA).

Results: Among 271 serum samples tested, the anti-dengue IgM positivity was 14.4%. Sero-positivity in male was 10.7% of total and that in female was 3.7%. Among different age groups, the highest positive cases 11.8% were from age group 15-50 years and found least among the age group above 50 years 0.4%. Out of 4 different hospitals, the highest positive positive cases from STIDH with 9.2% and the least positive cases were from DDH (0.4%). RT-PCR showed 4.7% positivity of 21 samples tested.

Conclusions: Enzyme immunoassay and RT-PCR serological marker can be used to diagnose the acute patients of dengue during outbreaks.

Japanese encephalitis (JE) is a mosquito-borne zoonotic disease that has pigs as the major amplif... more Japanese encephalitis (JE) is a mosquito-borne zoonotic disease that has pigs as the major amplifying hosts. It is the most important cause of viral encephalitis in people in Nepal and is spreading in its geographic distribution in that country. Pig farming is increasing in Nepal due to reducing cultural biases against pigs and government programs to support pig farming for poverty alleviation. Major strategies for JE prevention and control include education, vector control, and immunization of people and pigs. This study used a survey of 400 pig farmers in 4 areas of Nepal with different JE and pig farming histories to explore regional variations in farmer awareness and actions towards JE, the association of awareness and actions with farm and farmer variables, and the implications of these associations for public health education. Exposure to JE risk factors was common across pig farms and pig farming districts but there were significant district level differences in knowledge and practices related to on-farm JE risk reduction. Social factors such as literacy, gender, and cultural practices were associated with farmer attitudes, knowledge and practices for JE control. JE vaccine uptake was almost non-existent and mosquito control steps were inconsistently applied across all 4 districts. Income was not a determining factor of the differences, but all farmers were very poor. The low uptake of vaccine and lack of infrastructure or financial capacity to house pigs indoors or away from people suggest that farmer personal protection should be a priority target for education in Nepal. This study re-enforces the need to attack root causes of people’s personal disease prevention behaviours and take into account local variation in needs and capacities when designing health or agriculture education programs.

Zoonoses and Food Hygiene News, published four times a year, provides a medium for disseminating ... more Zoonoses and Food Hygiene News, published four times a year, provides a medium for disseminating technical information on matters related to zoonoses and food hygiene generated in the world, particularly in Nepal. The editors welcome submissions on these topics with appropriate illustrations and references. The views and opinions expressed in the News are those of the authors.

International Journal of Infection and Microbiology

Introduction: Brucellosis is a contagious disease of livestock with significant economic impact. ... more Introduction: Brucellosis is a contagious disease of livestock with significant economic impact. It is also a zoonotic disease, highly infectious for humans causing a disease called undulant fever or Malta fever. This study was carried out to determine the sero-status of Brucella spp. infection in cattle (cows), buffalo and goat in Kailali district of Far Western Region of Nepal.

Materials and Methods: This cross-sectional study was conducted in Kailali district of Nepal during a period from September, 2012 to January, 2013. A total of 233 animal blood samples (50 Cattle, 67 Buffalo and 116 Goat) were collected and tested for Brucella antibody by plate agglutination test (PAT).

Results: The seroprevalence of Brucellosis was 12% (28/233). Thirty two percentage (16/50) of cattle, 13.4% (9/67) of buffaloes, and 2.6% (3/113) goats were sero positive (p<0.05). Seroprevalence was higher in females (14.6% vs. 10.6%) (P>0.05) and was higher in younger cattles and older buffalo and goats (p>0.05).

Conclusions: This study showed that brucellosis exists as a potential threat in animals of Kailali district. This could be a potential source of infection to humans. Considering the high economic losses it can impart on livestock sector and the possible human health abnormalities, timely facilitation of awareness generation program and adoption of proper prevention and control strategies are recommended.

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Japanese encephalitis (JE) is a mosquito borne zoonotic disease caused by JE virus (JEV). JE has ... more Japanese encephalitis (JE) is a mosquito borne zoonotic disease caused by JE virus (JEV). JE has been endemic in Terai
region, the lowland plains of Nepal bordering India, since 1978. However, in recent years cases of JE has been continuously
reported from high altitude zones of hills and mountains. Irrigated rice farming system, expanded pig husbandry practices,
inadequate vaccine coverage, low level of public awareness and climate change favoring mosquito breeding in higher
altitudes might be the probable risk factors for emergence and re-emergence of JE in Nepal. Repeated outbreak in endemic
areas and geographical expansion to newer areas have created huge challenge for JE prevention and control. At present, JE is
one of the major public health concern of Nepal. Expanding vaccine coverage, improving agricultural practices, generating
public awareness, supporting for use of mosquito avoiding practices and regional collaboration at border against JE can be
helpful in getting better control over it in future.

Conclusions: Enzyme immunoassay and RT-PCR serological marker can be used to diagnose the acute patients of dengue during outbreaks.

International Journal of Infection and Microbiology