Climate sensitive diseases in the Mekong Region: Can we predict pests by climate factors?

A warmer, wetter world is likely to be sicker. TheMekong is a hotspot for human, animal and plant diseases, and some of themost important are highly sensitive to climate and climate changes. These diseases can impose enormous burdens on human health and the agricultural sector and hinder broader development. Better response to climate sensitive disease requires better information and tools. The objective of the project we are presenting here is to develop tools to forecast climate-sensitive animal and plant diseases in Vietnam and Laos. Key work packages will include (among others) developing and disseminating maps of hotspots for selected climate-sensitive animal and zoonotic diseases, piloting a real-time prediction system, and exploring the potential for weather-based forecasting for aflatoxin mitigation (only Vietnam). As climaticsensitive animal diseases and zoonoses leptospirosis and Japanese encephalitis have been identified in stakeholder consultations for Vietnam. Leptospirosis is caused by bacteria hosted by mammals, although the rodent-borne serovars are most often associated with serious human diseases which get infected through contact with contaminated water. Japanese encephalitis is a vector-borne viral disease transmitted by culicine mosquitoes from the amplifying hosts (e.g. pigs) to humans, where disease can be fatal. Aflatoxins, produced by Aspergillus spp in cereals, can cause acute or chronic aflatoxicosis in humans. The association of these diseases and meteorological conditions is evaluated and models will be built to predict future occurrence. If the models are successful in predicting disease, the aim is to provide policymakers and stakeholders with tools to aid in mitigating future disease and to make susceptible societies more resilient to future climate change. The ultimate outcome targets farming communities that are able to take practical action to reduce disease risk and/or benefit from risk-mitigating action provided by health providers. A framework which will guide through the various work packages will be presented and discussed. The project is funded by the CGIAR programme on Climate Change, Agriculture and Food Security (CCAFS)

Antimicrobial use in developing countries

We conducted a study on agriculture related antimicrobial resistance (AMR) in developing countries. AMR pathogens are commonly found in animals, animal food products and agro-food environments, but the lack of surveillance systems means there are no reliable national data on the level of AMR in animals and their products. While AMR infections in animals and their products contribute to AMR infections in people in developing countries the literature is insufficient to draw firm conclusions on the extent of this contribution, which is likely to vary in different contexts. For example, a recent study found high levels of multi-drug resistance in goats kept by pastoralists in remote, isolated areas and never given treatments by veterinarians or farmers. The key driver of agriculture-related AMR is the quantity and quality of use of antimicrobials in livestock production and aquaculture. In developing countries as much as several hundred thousand tons may be used every year, agricultural use probably exceeds medical use, and most use is probably in intensive systems. The underlying driver for antimicrobial use and development of AMR is the livestock and aquaculture revolution that is the rapid growth in intensive production systems in response to increased demand for livestock and fish products. Based on livestock intensification patterns, China, Brazil and India are current hotspots, and future hotspots with fastest growth of the intensive livestock sector in Myanmar, Indonesia, Nigeria, Peru and Vietnam. China is a hotspot for aquaculture and Indonesia, Thailand, Vietnam, Bangladesh, India and Chile are other countries where antimicrobial use in fish production may be problematic. AMR is intrinsically a global problem that can only be managed at supra-national scale and the current strong momentum to take action on AMR provides an opportunity to address the problem globally and comprehensively, addressing medical and veterinary use. This will require better evidence on the use of antimicrobials in agriculture, the impacts of this use on human and animal health, the acceptability and feasibility of stricter control of antibiotic use in agriculture, and the costs and benefits of stricter control taking into account trades offs between overuse and lack of access to antimicrobial drugs

Japanese Encephalitis in Small-Scale Pig Farming in Rural Cambodia: Pig Seroprevalence and Farmer Awareness

Japanese encephalitis (JE) is endemic in Cambodia, but circulation of JE virus (JEV) among domestic pigs has previously only been studied in the southern part of the country. The main purpose of this study was to determine the seroprevalence of JEV antibodies in smallholder pigs held in rural areas of Kampong Thom, Preah Vihear, Ratanakiri, and Stung Treng provinces, northeastern Cambodia. Another purpose was to identify possible associations between serologic status and other factors, such as reproductive disorders, and to investigate the farmers' knowledge of mosquito-borne diseases and use of preventive measures. In October 2019, 139 households were visited throughout the study area, and 242 pigs were sampled for blood. The sera were analysed with ELISA for JEV antibodies. Household representatives were interviewed, and data were recorded for each sampled pig. The apparent seroprevalence was 89.1% in pigs between 3 and 6 months of age, and 100% in pigs over 6 months of age. In total, 93.0% of the pigs tested positive. Province appeared to be the only factor significantly associated with serologic status (p < 0.001). Almost all (97.8%) respondents knew that mosquitos could transmit diseases, and 70.5% had heard of JE. However, only one respondent knew that JEV is transmitted to people through mosquito bites. Very few respondents knew that pigs can become infected with JEV, and no one knew that mosquitos transmit the virus. All families used some sort of mosquito protection for themselves, but only 15.1% protected their pigs from mosquito bites. The children were vaccinated against JE in 93 households, while adults only were vaccinated in eight households. The results suggest that JEV transmission is intense in northeastern Cambodia, and that people's knowledge about the transmission route of JEV and the role of pigs in the transmission cycle is low. Fortunately, people are well aware of mosquito-borne diseases in general and use mosquito protection, and many children are vaccinated against JE. Nonetheless, it is important that national vaccination is continued, and that people-especially in rural areas where pigs are commonly kept-are educated on the ecology and transmission of JEV

Quantitative risk assessment of salmonellosis in Cambodian consumers through chicken and pork salad consumption

Salmonella is a globally important foodborne bacterial pathogen that poses a high risk to human health. This study aimed to estimate the risk to Cambodian consumers from acquiring salmonellosis after consuming chicken and pork salad, using a quantitative microbial risk assessment (QMRA). Chicken and pork salads are typical Cambodian dishes containing raw vegetables and boiled chicken meat or pork. As previously described, chicken meat and pork samples (n = 204 of each) were collected from traditional markets in 25 Cambodian provinces to generate data on Salmonella contamination. Salad preparation and consumption practices were surveyed in 93 Cambodian households and this information was used to design an experiment to assess Salmonella cross-contamination from raw meat to ready-to-eat salad. In the part of the study reported here, data on consumption, Salmonella in salad, dose-response, and predicted salmonellosis were modeled using Monte Carlo simulations at 10,000 iterations. The prevalence of Salmonella in chicken meat and pork were set to 42.6 and 45.1%, respectively, with average most probable number (MPN) per gram of Salmonella in chicken meat was 10.6 and in pork 11.1 MPN/g, based on an earlier study. Half of the interviewed households cooked meat for the salad directly after purchase. The QMRA model showed that the modeled annual risk of salmonellosis from consuming chicken salad, pork salad and both chicken and pork salad were 11.1% probability of illness per person per year (90% CI 0.0–35.1), 4.0% (90% CI 0.0–21.3), and 14.5% (90% CI 0.0–33.5), respectively. The factors most influencing the estimate were cross-contamination while preparing the salad, followed by the prevalence of Salmonella in chicken meat and pork at the market. The wide confidence interval for the incidence was mainly due to the variability in reducing bacteria concentration by cooking and salad consumption. The predicted risk of salmonellosis due to chicken and pork salad consumption is high, and the study provides evidence supporting control measures of improving the safety of retailed chicken and pork obtained from markets to households and improving food preparation methods in the household

Risk factors of dengue fever in an urban area in Vietnam: a case-control study

BackgroundDengue is a mosquito-borne flavivirus present in many metropolitan cities of tropical countries.MethodsDuring and after the dengue season (September 2018 to January 2019), we conducted a case-control study in order to determine the risk factors for dengue fever in Hanoi city, Vietnam. 98 dengue patients and 99 patients with other acute infections, such as Hepatitis B virus infection, were recruited at Department of Infectious Disease of Bach Mai national hospital in Hanoi. Patients were interviewed using a structured questionnaire covering demographic, housing, environmental factors and knowledge, attitude, and practice on dengue prevention and control. Univariate analysis and multivariable logistic regression were used to determine the risk factors of dengue status.ResultsThe mean score of knowledge items and practice items was only 7.9 out of total 19 points and 3.9 out of total 17 points, respectively. While the mean score of attitude items was 4.8 out of total 6 points. Multivariable logistic regression indicated that older patients had lesser risk of getting dengue infection as compared to younger adults aged 16-30, and patients living in peri-urban districts were less likely to suffer of dengue fever than patients living in central urban districts (OR=0.31; 95% CI 0.13-0.75). This study could not find any association with occupation, water storage habit, knowledge, attitude, or practice on dengue prevention.ConclusionsAll patients had a relatively low level of knowledge and practice on dengue prevention and control. However, the attitude of the participants was good. We found that age group and living district were the risk factors correlated with the dengue status. Communication programs on raising dengue awareness should be repeated all year round and target particular groups of adolescents, younger adults, landlords and migrants from other provinces to improve their knowledge and encourage them to implement preventive measures against dengue fever

Spatial distribution of Culex mosquito abundance and associated risk factors in Hanoi, Vietnam

Japanese encephalitis (JE) is the major cause of viral encephalitis (VE) in most AsianPacific countries. In Vietnam, there is no nationwide surveillance system for JE due to lack of medical facilities and diagnoses. Culex tritaeniorhynchus, Culex vishnui, and Culex quin-quefasciatus have been identified as the major JE vectors in Vietnam. The main objective of this study was to forecast a risk map of Culex mosquitoes in Hanoi, which is one of the most densely populated cities in Vietnam. A total of 10,775 female adult Culex mosquitoes were collected from 513 trapping locations. We collected temperature and precipitation information during the study period and its preceding month. In addition, the other predictor variables (e.g., normalized difference vegetation index [NDVI], land use/land cover and human population density), were collected for our analysis. The final model selected for estimating the Culex mosquito abundance included centered rainfall, quadratic term rainfall, rice cover ratio, forest cover ratio, and human population density variables. The estimated spatial distribution of Culex mosquito abundance ranged from 0 to more than 200 mosquitoes per 900m2. Our model estimated that 87% of the Hanoi area had an abundance of mosquitoes from 0 to 50, whereas approximately 1.2% of the area showed more than 150 mosquitoes, which was mostly in the rural/peri-urban districts. Our findings provide better insight into understanding the spatial distribution of Culex mosquitoes and its associated environmental risk factors. Such information can assist local clinicians and public health policymakers to identify potential areas of risk for JE virus. Risk maps can be an efficient way of raising public awareness about the virus and further preventive measures need to be considered in order to prevent outbreaks and onwards transmission of JE virus

Effect of light-touch intervention and associated factors to microbial contamination at small-scale pig slaughterhouses and traditional pork shops in Vietnam

Traditional pork value chains dominate the production and distribution of pork in Vietnam; however, the high level of microbiological contamination in pork may increase the risk of food-borne disease for consumers. There is limited evidence about how to feasibly and scalably reduce microbial contamination in pork sold in traditional markets. This study aimed to assess the effectiveness of light-touch interventions for changing worker behaviour in small-scale slaughterhouses and vendors at traditional pork shops, as well as to identify risk factors for pork contamination. The intervention packages consisted of providing hygiene tools and delivering a food safety training which had been designed in a participatory way and covered 10 small-scale slaughterhouses and 29 pork shops. Pig carcasses, retailed pork, contact surfaces, and hands were sampled to measure the total bacterial count (TBC) and Salmonella contamination before, three and six weeks after the intervention, and trainee practices were observed at the same time. Linear and generalized linear mixed effects models were constructed to identify risk factors for TBC and Salmonella contamination at the slaughterhouses and pork shops. The interventions at slaughterhouses and pork shops both showed a slight reduction of TBC contamination in pig carcasses and Salmonella prevalence in retailed pork, while the TBC in retailed pork decreased only marginally. For slaugh-terhouses, the regression model indicated that smoking or eating during slaughtering (indicating poor hygienic practices) was associated with TBC increasing, while cleaning floors and wearing boots reduced TBC contami-nation. For pork shops, using rough materials (cardboard or wood) to display pork was the only factor increasing TBC contamination in pork, whereas cleaning knives was associated with lower TBC. Besides, the presence of supporters and wearing aprons reduced the probability of Salmonella contamination in pork. The findings highlight the effectiveness of light-touch interventions in reducing microbial contamination in pig carcasses at small-scale slaughterhouses and pork at traditional shops over the study period