Epidemiology of Taenia solium in Nepal: is it influenced by the social characteristics of the population and the presence of Taenia asiatica?

The transmission of the zoonotic pork tapeworms Taenia solium and T. asiatica depends on a combination of specific risk factors, such as open defecation, backyard pig raising and the consumption of raw or undercooked pork and viscera. A community-based survey was conducted among 289 households in south-eastern Nepal to study the heterogeneity of these risk factor frequencies as a function of the social composition of the population. The frequency of open defecation, backyard pig raising and pork consumption differed significantly (P < 0.005) among the different coexisting caste and ethnic groups. In the same survey, the taeniosis prevalence was examined among the different groups. Tapeworm carriers were identified at a high prevalence among the Dum, one of the most disadvantaged communities of Nepal. A PCR-RFLP assay revealed that all collected tapeworm specimens were T. asiatica, a species thus far not known to occur in South Asia. These results can help to understand the epidemiology of T. solium in Nepal, which appears to be more complex than thought so far.

Visceral leishmaniasis in Nepal during 1980-2006.

Visceral leishmaniasis (VL) or Kala-azar is a potentially fatal vector-borne zoonotic disease caused by a protozoan parasite, Leishmania donovani. Nepal, together with India, Bangladesh, Brazil and Sudan constitutes the five countries of the world where more than 90% of VL occurs. In Nepal, the disease affects eastern Terai region which lies adjacent to the Bihar state of India. Although leishmaniasis is regarded as a significant health problem in Nepal by the Ministry of Health, there is no active case detection programme in the country. Information on the morbidity and mortality is thus very limited. The objectives of this study were to determine the up-to-date morbidity and mortality trend for VL in Nepal. Data collected from eight zonal hospitals in the Terai region suggests that the first confirmed case of VL was recorded in 1980. By 2003, the disease has spread to 14 districts of central and eastern regions of Nepal, and nearly six million people residing in these districts were at the risk of acquiring the disease. A total of 25890 cases with 599 deaths were reported during the year 1980-2006 (up to July). The case fatality rate (CFR) varied from 0.23% to 13.2%. District-wise analysis showed that, during 2003, highest incidence (per 100,000) was in Mahottari district (184), followed by Sarlahi (100) and Sunsari (96). The highest CFR was in Dhanusha (2.9%) followed by Bara (2.4%) and Saptari (2.0%). Majority (70.9%) of persons affected by VL were aged 15 years and above, followed by 10-14 years (13.9%), 5-9 years (11.9%) and 1-4 years (3.3%). The incidence of VL in Nepal seems to be increasing at a faster rate indicating that the existing control programs have been ineffective. To achieve success in control programs, the existing ones should be amended as there is evolution of resistance in the parasite as well as the vector. Public health education, to make the people aware about preventive aspects of the disease is important. The possibility of the existence of animal reservoirs should also be considered and checked out for better control measures.

Improving meat inspection and control in resource-poor communities: the Nepal example.

Meat is an important source of protein and a valuable commodity in resource-poor communities. In many developing countries, lack of appropriate slaughtering facilities and unsatisfactory slaughtering techniques are causing unnecessary losses of meat as well as invaluable by-products from animal carcasses. Slaughtering places are frequently contaminated and may not be protected against dogs, rodents and insects. Meat products coming from such conditions are often deteriorated due to bacterial infection or contaminated, which may cause food poisoning or diseases in consumers. In many developing countries, regulations concerning meat inspection and/or control are inadequate or non-existent allowing consumers to be exposed to pathogens including zoonotic parasites. In Nepal, buffaloes contribute about 64% of the meat consumed, followed by goat meat (20%), pork (7%), poultry (6%) and mutton (2%). Goat and poultry meat is acceptable to all castes of people while buffalo meat is consumed mainly by the Newar ethnic group. Previously, pork was consumed only by people belonging to low castes, however, in recent years, the consumption of pork has increased in higher castes as the caste system has become more relaxed. Until recently, there were no official meat inspection regulations in the country, however, in 1999, the national government legislated an as-yet-to-be implemented Animal Slaughtering and Meat Inspection Act which mandates slaughterhouse construction and meat inspection and control. Due to the lack of implementation of the Meat Inspection Act and resultant absence of meat inspection, meat from sick or parasite-infected animals is serving as a source of infection to humans as well as other animals. In addition, meat quality is adversely affected by careless handling conditions in the slaughtering places as well as in the meat markets or shops. For improvement in animal slaughtering and meat inspection in both rural and urban areas of Nepal, several strategies are to be recommended. Sustainable capacity building should be introduced including training of veterinarians, meat inspectors and butchers as well as building of slaughter facilities. Government policies on slaughter procedures including ante-mortem examination, meat inspection and stamping of meat should be implemented. Programmes should be instituted with strong focus on prevention and control of meat-borne diseases to reduce infection risk of consumers and meat handlers and to avoid contamination of the environment. Lastly, emphasis should be put on improving the animal husbandry system in Nepal. These same actions can be undertaken in other developing countries to assist with improving meat inspection and control, thus helping with prevention and control of cysticercosis as well as other important meat-borne diseases.

Regional variation in pig farmer awareness and actions regarding Japanese encephalitis in Nepal: implications for public health education.

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.

The burden of parasitic zoonoses in Nepal: a systematic review.

BACKGROUND: Parasitic zoonoses (PZs) pose a significant but often neglected threat to public health, especially in developing countries. In order to obtain a better understanding of their health impact, summary measures of population health may be calculated, such as the Disability-Adjusted Life Year (DALY). However, the data required to calculate such measures are often not readily available for these diseases, which may lead to a vicious circle of under-recognition and under-funding. METHODOLOGY: We examined the burden of PZs in Nepal through a systematic review of online and offline data sources. PZs were classified qualitatively according to endemicity, and where possible a quantitative burden assessment was conducted in terms of the annual number of incident cases, deaths and DALYs. PRINCIPAL FINDINGS: Between 2000 and 2012, the highest annual burden was imposed by neurocysticercosis and congenital toxoplasmosis (14,268 DALYs [95% Credibility Interval (CrI): 5450-27,694] and 9255 DALYs [95% CrI: 6135-13,292], respectively), followed by cystic echinococcosis (251 DALYs [95% CrI: 105-458]). Nepal is probably endemic for trichinellosis, toxocarosis, diphyllobothriosis, foodborne trematodosis, taeniosis, and zoonotic intestinal helminthic and protozoal infections, but insufficient data were available to quantify their health impact. Sporadic cases of alveolar echinococcosis, angiostrongylosis, capillariosis, dirofilariosis, gnathostomosis, sparganosis and cutaneous leishmaniosis may occur. CONCLUSIONS/SIGNIFICANCE: In settings with limited surveillance capacity, it is possible to quantify the health impact of PZs and other neglected diseases, thereby interrupting the vicious circle of neglect. In Nepal, we found that several PZs are endemic and are imposing a significant burden to public health, higher than that of malaria, and comparable to that of HIV/AIDS. However, several critical data gaps remain. Enhanced surveillance for the endemic PZs identified in this study would enable additional burden estimates, and a more complete picture of the impact of these diseases.

Comparative spatial dynamics of Japanese encephalitis and acute encephalitis syndrome in Nepal.

Japanese Encephalitis (JE) is a vector-borne disease of major importance in Asia. Recent increases in cases have spawned the development of more stringent JE surveillance. Due to the difficulty of making a clinical diagnosis, increased tracking of common symptoms associated with JE-generally classified as the umbrella term, acute encephalitis syndrome (AES) has been developed in many countries. In Nepal, there is some debate as to what AES cases are, and how JE risk factors relate to AES risk. Three parts of this analysis included investigating the temporal pattern of cases, examining the age and vaccination status patterns among AES surveillance data, and then focusing on spatial patterns of risk factors. AES and JE cases from 2007-2011 reported at a district level (n = 75) were examined in relation to landscape risk factors. Landscape pattern indices were used to quantify landscape patterns associated with JE risk. The relative spatial distribution of landscape risk factors were compared using geographically weighted regression. Pattern indices describing the amount of irrigated land edge density and the degree of landscape mixing for irrigated areas were positively associated with JE and AES, while fragmented forest measured by the number of forest patches were negatively associated with AES and JE. For both JE and AES, the local GWR models outperformed global models, indicating spatial heterogeneity in risks. Temporally, the patterns of JE and AES risk were almost identical; suggesting the relative higher caseload of AES compared to JE could provide a valuable early-warning signal for JE surveillance and reduce diagnostic testing costs. Overall, the landscape variables associated with a high degree of landscape mixing and small scale irrigated agriculture were positively linked to JE and AES risk, highlighting the importance of integrating land management policies, disease prevention strategies and promoting healthy sustainable livelihoods in both rural and urban-fringe developing areas.

Complexities in using sentinel pigs to study Taenia solium transmission dynamics under field conditions.

The transmission dynamics of the pork tapeworm, Taenia solium, remain a matter of research and debate. In a longitudinal field study performed in southeastern Nepal, 18 sentinel pigs were serologically monitored to study the field kinetics of Taenia antigens and anti-T. solium antibodies. At the end of the twelve months' study period, necropsy was performed and suspected lesions were subjected to molecular identification of the Taenia species. The study generated new hypotheses on the transmission dynamics of Taenia spp. and exposed crucial complexities in the use of sentinel pigs in longitudinal field studies. Sentinel pigs can be useful epidemiological tools, but their use should be thoroughly planned before initiating a study and carefully monitored throughout the course of the study. Important aspects to be considered are those affecting the pig's susceptibility to infection, such as passive immunity, age, hormonal levels, and infection with competing Taenia species. In addition, serological test results should be interpreted considering possible cross-reactions and with proper understanding of the significance of a positive test result.

Seroprevalence of zoonotic parasites in pigs slaughtered in the Kathmandu Valley of Nepal.

For several years, the demand for pork has been on the rise in Nepal. To assess the importance of pork as a carrier of zoonotic agents, we performed a cross-sectional study in the Kathmandu Valley of Nepal, in which we serologically determined the infection status of slaughtered pigs with regard to three of the most important parasites transmitted through pork consumption: Trichinella spp., Taenia solium cysticerci, and Toxoplasma gondii. From 2007 to 2010, 742 pigs were sampled at slaughter, of which 0.1% (95% confidence interval [CI] 0.0-0.7%) were found positive for Trichinella infection, 13.8% (95% credibility interval [CrI] 0.8-28.5%) for T. solium cysticercosis, and 11.7% (95% CI 5.2-17.5%) for Toxoplasma infection. Further monitoring of the related animal and human disease burden and strengthening of food safety protocols throughout the pork production chain are strongly recommended.

Visceral leishmaniasis in Nepal during 1980-2006.

Visceral leishmaniasis (VL) or Kala-azar is a potentially fatal vector-borne zoonotic disease caused by a protozoan parasite, Leishmania donovani. Nepal, together with India, Bangladesh, Brazil and Sudan constitutes the five countries of the world where more than 90% of VL occurs. In Nepal, the disease affects eastern Terai region which lies adjacent to the Bihar state of India. Although leishmaniasis is regarded as a significant health problem in Nepal by the Ministry of Health, there is no active case detection programme in the country. Information on the morbidity and mortality is thus very limited. The objectives of this study were to determine the up-to-date morbidity and mortality trend for VL in Nepal. Data collected from eight zonal hospitals in the Terai region suggests that the first confirmed case of VL was recorded in 1980. By 2003, the disease has spread to 14 districts of central and eastern regions of Nepal, and nearly six million people residing in these districts were at the risk of acquiring the disease. A total of 25890 cases with 599 deaths were reported during the year 1980-2006 (up to July). The case fatality rate (CFR) varied from 0.23% to 13.2%. District-wise analysis showed that, during 2003, highest incidence (per 100,000) was in Mahottari district (184), followed by Sarlahi (100) and Sunsari (96). The highest CFR was in Dhanusha (2.9%) followed by Bara (2.4%) and Saptari (2.0%). Majority (70.9%) of persons affected by VL were aged 15 years and above, followed by 10-14 years (13.9%), 5-9 years (11.9%) and 1-4 years (3.3%). The incidence of VL in Nepal seems to be increasing at a faster rate indicating that the existing control programs have been ineffective. To achieve success in control programs, the existing ones should be amended as there is evolution of resistance in the parasite as well as the vector. Public health education, to make the people aware about preventive aspects of the disease is important. The possibility of the existence of animal reservoirs should also be considered and checked out for better control measures.