Fred Unger

Endemicity of zoonotic diseases in pigs and humans in lowland and upland Lao PDR: Identification of socio-cultural risk factors

In Lao People’s Democratic Republic pigs are kept in close contact with families. Human risk of infection with pig zoonoses arises from direct contact and consumption of unsafe pig products. This cross-sectional study was conducted in Luang Prabang (north) and Savannakhet (central-south) Provinces. A total of 59 villages, 895 humans and 647 pigs were sampled and serologically tested for zoonotic pathogens including: hepatitis E virus (HEV), Japanese encephalitis virus (JEV) and Trichinella spiralis; In addition, human sera were tested for Taenia spp. and cysticercosis. Seroprevalence of zoonotic pathogens in humans was high for HEV (Luang Prabang: 48.6%, Savannakhet: 77.7%) and T. spiralis (Luang Prabang: 59.0%, Savannakhet: 40.5%), and lower for JEV (around 5%), Taenia spp. (around 3%) and cysticercosis (Luang Prabang: 6.1, Savannakhet 1.5%). Multiple correspondence analysis and hierarchical clustering of principal components was performed on descriptive data of human hygiene practices, contact with pigs and consumption of pork products. Three clusters were identified: Cluster 1 had low pig contact and good hygiene practices, but had higher risk of T. spiralis. Most people in cluster 2 were involved in pig slaughter (83.7%), handled raw meat or offal (99.4%) and consumed raw pigs’ blood (76.4%). Compared to cluster 1, cluster 2 had increased odds of testing seropositive for HEV and JEV. Cluster 3 had the lowest sanitation access and had the highest risk of HEV, cysticercosis and Taenia spp. Farmers which kept their pigs tethered (as opposed to penned) and disposed of manure in water sources had 0.85 (95% CI: 0.18 to 0.91) and 2.39 (95% CI: 1.07 to 5.34) times the odds of having pigs test seropositive for HEV, respectively. The results have been used to identify entry-points for intervention and management strategies to reduce disease exposure in humans and pigs, informing control activities in a cysticercosis hyper-endemic village.

Zoonotic Emerging Infectious Disease in Selected Countries in Southeast Asia: Insights from Ecohealth

Most emerging diseases of humans originate in animals, and zoonotic emerging infectious diseases (EIDs) threaten human, animal, and environment health. We report on a scoping study to assess actors, linkages, priorities, and needs related to management of these diseases from the perspective of key stakeholders in three countries in Southeast Asia. A comprehensive interview guide was developed and in-depth interviews completed with 21 key stakeholders in Vietnam, Lao People’s Democratic Republic, and Cambodia. We found numerous relevant actors with a predominance of public sector and medical disciplines. More capacity weaknesses than strengths were reported, with risk analysis and research skills most lacking. Social network analysis of information flows showed policy-makers were regarded as mainly information recipients, research institutes as more information providers, and universities as both. Veterinary and livestock disciplines emerged as an important “boundary-spanning” organization with linkages to both human health and rural development. Avian influenza was regarded as the most important zoonotic EID, perhaps reflecting the priority-setting influence of actors outside the region. Stakeholders reported a high awareness of the ecological and socioeconomic drivers of disease emergence and a demand for disease prioritization, epidemiological skills, and economic and qualitative studies. Evaluated from an ecohealth perspective, human health is weakly integrated with socioeconomics, linkages to policy are stronger than to communities, participation occurs mainly at lower levels, and equity considerations are not fully considered. However, stakeholders have awareness of ecological and social determinants of health, and a basis exists on which transdisciplinarity, equity, and participation can be strengthened.

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

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.

Quantitative risk assessment of human salmonellosis in the smallholder pig value chains in urban of Vietnam

ObjectivesTo quantify salmonellosis risk in humans through consumption of boiled pork in urban Hung Yen Province, Vietnam, using a quantitative microbial risk assessment.MethodsWe collected 302 samples along the pork value chain in Hung Yen between April 2014 and February 2015. We developed a model in @Risk, based on microbiological, market, and household surveys on cooking, cross-contamination and consumption, and conducted sensitivity analysis.ResultsSalmonella prevalence of pen floor swabs, slaughterhouse carcasses and cut pork were 33.3, 41.7 and 44.4%, respectively. The annual incidence rate of salmonellosis in humans was estimated to be 17.7% (90% CI 0.89–45.96). Parameters with the greatest influence risk were household pork handling practice followed by prevalence in pork sold in the central market. Wide confidence interval in the incidence estimate was mainly due to the variability in the degree of reduction in bacteria concentration by cooking, and pork consumption pattern.ConclusionsThe risk of salmonellosis in humans due to boiled pork consumption appears to be high. Control measures may include improving the safety of retailed pork and improving household hygiene.

Determinants of Vaccination Coverage and Consequences for Rabies Control in Bali, Indonesia

Maintaining high vaccination coverage is key to successful rabies control, but mass dog vaccination can be challenging and population turnover erodes coverage. Declines in rabies incidence following successive island-wide vaccination campaigns in Bali suggest that prospects for controlling and ultimately eliminating rabies are good. Rabies, however, has continued to circulate at low levels. In the push to eliminate rabies from Bali, high coverage needs to be maintained across all areas of the island. We carried out door-to-door (DTD) questionnaire surveys (n = 10,352 dog-owning households) and photographic mark–recapture surveys (536 line transects, 2,597 observations of free-roaming dogs) in 2011–2012 to estimate dog population sizes and assess rabies vaccination coverage and dog demographic characteristics in Bali, Indonesia. The median number of dogs per subvillage unit (banjar) was 43 (range 0–307) for owned dogs estimated from the DTD survey and 17 (range 0–83) for unconfined dogs (including both owned and unowned) from transects. Vaccination coverage of owned dogs was significantly higher in adults (91.4%) compared to juveniles (<1 year, 43.9%), likely due to insufficient targeting of pups and from puppies born subsequent to vaccination campaigns. Juveniles had a 10–70 times greater risk of not being vaccinated in urban, suburban, and rural areas [combined odds ratios (ORs): 9.9–71.1, 95% CI: 8.6–96.0]. Free-roaming owned dogs were also 2–3 times more likely to be not vaccinated compared to those confined (combined Ors: 1.9–3.6, 95% CI: 1.4–5.4), with more dogs being confined in urban (71.2%) than in suburban (16.1%) and rural areas (8.0%). Vaccination coverage estimates from transects were also much lower (30.9%) than household surveys (83.6%), possibly due to loss of collars used to identify the vaccination status of free-roaming dogs, but these unconfined dogs may also include dogs that were unowned or more difficult to vaccinate. Overall, coverage levels were high in the owned dog population, but for future campaigns in Bali to have the highest chance of eliminating rabies, concerted effort should be made to vaccinate free-roaming dogs particularly in suburban and rural areas, with advertising to ensure that owners vaccinate pups. Long-lasting, cheap, and quick methods are needed to mark vaccinated animals and reassure communities of the reach of vaccination campaigns.

Exposure assessment of chemical hazards in pork meat, liver, and kidney, and health impact implication in Hung Yen and Nghe An provinces, Vietnam

ObjectivesThis study assesses the risk of exposure to hazardous chemical residues in pork meat, liver, and kidney collected at wet markets in Nghe An and Hung Yen provinces and discusses health impact implication.Methods514 pig feed, kidney, liver, and pork samples were pooled and qualitatively and quantitatively analyzed for tetracyclines, fluoroquinolones, sulphonamide, chloramphenicol, β-agonists, and heavy metals. We compare the results with current regulations on chemical residues and discuss health implications.ResultsLegal antibiotics were found in feed. Tetracycline and fluoroquinolones were not present in pork, but 11% samples were positive with sulfamethazine above maximum residue limits (MRL); 11% of packaged feed and 4% of pork pooled samples were positive for chloramphenicol, a banned substance; two feed, two liver, and one pork samples were positive for β-agonists but did not exceed current MRL; 28% of pooled samples had lead, but all were below MRL; and all samples were negative for cadmium and arsenic. Thus, the health risks due to chemical hazards in pork in Hung Yen and Nghe An seemed not as serious as what were recently communicated to the public on the mass media.ConclusionsThere is potential exposure to sulphonamide, chloramphenicol, and β-agonists from pork. Risk communication needs to focus on banned chemicals, while informing the public about the minimal risks associated with heavy metals.

Quantitative value chain approaches for animal health and food safety

Economic impact assessments are increasingly important in the context of animal health and food safety, although much of the existing literature does not address the broader systems context in which disease transmission takes place. In this paper, we discuss the role of system dynamics modeling in addressing the value chain impacts associated with animal health and food safety issues. System dynamics methods hold promise as a means of capturing the complex feedbacks that exist between the biology, economics, and behavioral aspects of food safety and animal health systems. We provide a proof-of-concept of this approach in the context of food safety and animal health in the smallholder pig sector of Viet Nam. Results highlight the important tradeoffs that exist between policy objectives and the costs required to achieve them.

Food safety in Vietnam: where we are at and what we can learn from international experiences

Food-borne diseases are attracting a lot of attention in Vietnam as a result of repeated episodes of adulterated and unsafe food. In this paper, we provide some perspectives on food safety in Vietnam from the point of view of an international research institution working on food safety with partners in the country. We argue that one of the key issues of food safety in Vietnam is that certain food value chain stakeholders lack ethics, which leads to the production and trading of unsafe foods in order to make profits irrespective of adverse health effects on consumers. In turn, the shortfall in ethical behaviours around food can be attributed to a lack of incentives or motivating factors.Although food safety causes panic in the population, it is unclear how much contaminated food contributes to the burden of food-borne diseases and food poisonings in Vietnam. However, globally, the biggest health problem associated with food are infections from consuming food contaminated with viruses, bacteria or parasites. A major food safety challenge is the inappropriate way of communicating food risks to the public. Another key constraint is the inherent difficulty in managing food in wet markets and from smallholder production. On the other hand, local foods, and local food production and processing are an important cultural asset as well as being essential to food safety, and these aspects can be put at risk if food safety concerns motivate consumers to purchase more imported foods.In this paper, we also discuss good experiences in food safety management from other countries and draw lessons learnt for Vietnam on how to better deal with the current food safety situation.

An integrative approach to enhancing small-scale poultry slaughterhouses by addressing regulations and food safety in northern -Thailand

BackgroundIn Asian countries, small-scale rural poultry meat production can face challenges due to food safety policies that limit economic growth and hinder improvement of sanitation and disease prevention. In this study, an integrative, participatory research approach was used to elucidate the sanitation and disease prevention practices in small-scale poultry slaughterhouses in rural northern Thailand.MethodsInitial steps included the identification of key stakeholders associated with the meat production chain, development of a research framework, and design of a methodology based on stakeholder consultations. The framework and methodology combine issues in five major areas: (1) public health, (2) socioeconomics, (3) policy, (4) veterinary medicine, and (5) communities and the environment. Methods used include questionnaires, direct observation, focus groups, and in-depth interviews. In addition, a microbiological risk assessment approach was employed to detect Salmonella contamination in meat processing facilities. The microbial risk assessment was combined with stakeholder perceptions to provide an overview of the existing situation, as well as to identify opportunities for upgrading slaughterhouses in order to more effectively address matters of food safety, processing, and government licensing.ResultsThe conceptual framework developed elucidated the complex factors limiting small-scale slaughterhouse improvement including a lack of appropriate enabling policies and an apparent absence of feasible interventions for improvement. Unhygienic slaughterhouse management was reflected in the incidence of Salmonella contamination in both the meat and the surrounding environment.ConclusionThere is potential for the use of an integrative approach to address critical problems at the interface of rural development and public health. The findings of this study could serve as a model for transdisciplinary studies and interventions related to other similar complex challenges.

Risk factors associated with Salmonella spp. prevalence along smallholder pig value chains in Vietnam

The objective of this study was to investigate the prevalence of, and risk factors for, Salmonella contamination along the smallholder pig value chain in northern Vietnam. Repeat cross-sectional (for farm and pork shops) and longitudinal (for slaughterhouses) studies were carried out in Hung Yen and Nghe An provinces in four sampling periods over a year (April 2014 to February 2015). In total, 72 pig farms and 217 pork shops were visited during the period, and 13 slaughterhouses were visited four times. Information on management and hygiene practices was collected using checklists and questionnaires, and risk factor analyses at the farm, slaughterhouse, and pork shop levels were performed using generalized mixed-effects models with the significant levels 10%. Salmonella prevalence was 36.1%, 38.9%, and 44.7% on pig pen floors, pig carcasses in slaughterhouses, and cut pork in pork shops, respectively. The risk factor for Salmonella prevalence on pig pen floors were having a pig pen next to a household (p = 0.06) and free access to the farm by visitors (p = 0.06). Our slaughterhouse model found a single risk factor for carcass contamination: slaughter area close to lairage without hygienic measures (p = 0.03). For pork shops, presence of flies or insects on pork at shop (p = 0.02) and use of a cloth at pork shop (p = 0.02) were risk factors. The Salmonella prevalence on pig carcass and cut pork was significantly lower in winter compared to that in other seasons. Our study results highlighted the need of improving farm hygiene at farm level, and pork hygiene practices to avoid cross-contamination at the slaughterhouse and market levels, to reduce the risk of salmonellosis through pork consumption in northern Vietnam.