Detection of Adenovirus in Fresh Fruit, Vegetables, Wastewater and Manure from Irrigated Farms in Ouagadougou, Burkina Faso

Enteric viral pathogens are responsible for numerous epidemics associated with the consumption of fresh fruit and vegetable, whether raw or minimally processed. The aim of the present study was to assess agricultural practices and the presence of adenovirus (AdV) in fruits and vegetables, manure and irrigation wastewater sampled in the urban and peri-urban perimeters of Ouagadougou. A total of 286 samples including 30 lettuces, 42 tomatoes, 30 carrots, 30 strawberries, 74 manures and 80 wastewater samples were collected from four market garden sites in and around Ouagadougou. Nested PCR was performed with specific primers to detect adenoviruses (AdVs). A face-to-face survey was carried out using a questionnaire on market garden production practices. Overall, adenoviruses prevalence was 5.9% [IC95, 3.2% - 8.7%] in all samples analyzed. It was specifically 7.14% (3/42) from tomatoes, 6.7% (2/30) from lettuces, 20% (6/30) on strawberries and 7.5% (6/80) in irrigation water. The survey showed that irrigation water came from untreated sources (dam, well, canal) and then 52% of farms used untreated manure. No farms have implemented measures to limit access by domestic and wild animals. This work shows the presence of human adenoviruses in surface irrigation water and fresh produce, which is of concern when fresh produce is consumed raw. To reduce the public health risks associated with consuming these foods, it is essential to follow good hygiene and cultivation practices.

Detection and analysis of indicator and pathogenic bacteria in conventional and organic fruits and vegetables sold in retail markets

Produce-associated food-borne outbreaks have been increasingly implicated as the significant proportion of the annual incidence of food-borne ilness worldwide.The objectives of this study were to determine the concentrations of indicator bacteria and the presence of Salmonella spp.Shigella spp..Escherichia coli(E.coln 0157:H7,and Listeria monocytogenes(L.monocytogenes),and to characterize predictors associated with Salmonella contamination of retail produce from fresh markets and supermarkets in Bangkok,Thailand.A total of 503 samples were col-lected during May 2018 and February 2019,comprised of sweet basil,spring onion,coriander,cabbage,lettuce,cucumber,and tomato,with conventional items from fresh open-air markets(n=167),conventional items from supermarkets(n=168),and organic items from supermarkets(n=168).The overall prevalence in these 503 items for fecal coliforms and E.coli was 84.3%and 71.4%,with mean concentrations(±standard deviation)of fecal coliforms and E.coli being(3.0×10^(5)±1.3×10^(5))most probable number(MPN)/g and(1.8×10^(5)±1.1×10^(5))MPN/g,respectively.The concentrations of fecal coliforms and E.coli were higher in produce sampled from fresh open-air markets than produce from supermarkets;simi-larly,these bacterial indicators were higher from produce grown under conventional methods than certified organic produce.The prevalence of Salmonella and Shigella was 4.8%and 0.4%,respectively,but no positives were found for E.coli 0157:H7 and L.monocytogenes.The predom-inant Salmonella serovar was Stanley(30.8%).Based on logistic regression,the odds of Salmonella contamination were significantly(P<0.05)higher during the rainy versus dry season,produce grown using conventional versus organic agriculture,sweet basil versus other commodities,and using ice tank versus dry refrigeration for overnight retail storage.This study indicated that fruits and vegetables are important sources of microbial contamination.Hence,monitoring and surveillance of pathogen contamination to produce is needed to strengthen food safety.