Pediatric diarrheal disease remains the second most common cause of preventable illness and death among children under the age of five, especially in low and middle-income countries (LMICs). However, there is limited information regarding the role of food in pathogen transmission in LMICs. For this study, we examined the frequency of enteric pathogen occurrence and co-occurrence in 127 infant weaning foods in Kisumu, Kenya, using a multi-pathogen PCR diagnostic tool, and assessed household food hygiene risk factors for contamination. Bacterial, viral, and protozoan enteric pathogen DNA and RNA were detected in 62% of the infant weaning food samples collected, with 37% of foods containing more than one pathogen type. Multivariable generalized linear mixed model analysis indicated type of infant food best explained the presence and diversity of enteric pathogens in infant food, while most household food hygiene risk factors considered in this study were not significantly associated with pathogen contamination. Specifically, cow’s milk was significantly more likely to contain a pathogen (adjusted risk ratio = 14.4; 95% confidence interval (CI) 1.78–116.1) and more likely to have higher number of enteric pathogen species (adjusted risk ratio = 2.35; 95% CI 1.67–3.29) than porridge. Our study demonstrates that infants in this low-income urban setting are frequently exposed to diarrhoeagenic pathogens in food and suggests that interventions are needed to prevent foodborne transmission of pathogens to infants.

Humans are susceptible to over 1400 pathogens. Co-infection by multiple pathogens is common, and can result in a range of neutral, facilitative, or antagonistic interactions within the host. Soil-transmitted helminths (STH) are powerful immunomodulators, but evidence of the effect of STH infection on the direction and magnitude of concurrent enteric microparasite infections is mixed. We collected fecal samples from 891 randomly selected children and adults in rural Laos. Samples were analyzed for 5 STH species, 6 viruses, 9 bacteria, and 5 protozoa using a quantitative reverse transcription polymerase chain reaction (qRT-PCR) assay. We utilized logistic regression, controlling for demographics and household water, sanitation, and hygiene access, to examine the effect of STH infection on concurrent viral, bacterial, and protozoal infection. We found that STH infection was associated with lower odds of concurrent viral infection [odds ratio (OR): 0.48, 95% confidence interval (CI): 0.28–0.83], but higher odds of concurrent bacterial infections (OR: 1.81, 95% CI: 1.06–3.07) and concurrent protozoal infections (OR: 1.50, 95% CI: 0.95–2.37). Trends were consistent across STH species. The impact of STH on odds of concurrent microparasite co-infection may differ by microparasite taxa, whereby STH infection was negatively associated with viral infections but positively associated with bacterial and protozoal infections. Results suggest that efforts to reduce STH through preventive chemotherapy could have a spillover effect on microparasite infections, though the extent of this impact requires additional study. The associations between STH and concurrent microparasite infection may reflect a reverse effect due to the cross-sectional study design. Additional research is needed to elucidate the exact mechanism of the immunomodulatory effects of STH on concurrent enteric microparasite infection.

Though the health risks associated with poor access to water, sanitation, and hygiene (WASH) are well established, recent large-scale WASH trials have found limited impact on enteric disease. The aims of this study were to: 1. estimate the prevalence of enteropathogens among children <5, school-aged children, and adults; 2. model associations between WASH transmission pathways and enteropathogen infections; and 3. quantify clustering of enteropathogen infections at the household- and village-level. We conducted a cross-sectional survey in 50 villages in Saravane Province, Lao People’s Democratic Republic. From 297 households, we collected 891 fecal samples from one child <5, one school-aged child, and one adult living in the same household, and collected survey and observational data on household demographics, WASH access, and animal ownership. Fecal samples were analyzed for 25 enteropathogens using a qRT-PCR assay. We observed near universal infection with at least one enteropathogen (98.3%). Few household or village-level WASH covariates were statistically associated with enteropathogen infection. Concordant household infection was higher than expected under the independence assumption for 14 of the 21 pathogens for which we had sufficient data, indicating strong household correlation for many infections. Median Odds Ratios (MORs), a measure of cluster-level (e.g. village and household) influence on an individual’s odds of infection, were elevated at the village level, particularly for viruses (MOR: 3.89; 95% Confidence Interval [CI]: 2.64, 6.69), protozoa (MOR: 2.07; 95% CI: 1.59, 3.10), and soil-transmitted helminths (MOR: 2.46; 95% CI: 1.89, 3.56), indicating strong village-level differences in individuals' odds of enteric infections. WASH access, as hypothesized, is associated with fewer enteroinfections, but WASH access as currently defined does not reveal a measurably protective association with infection for many etiologies. Household- and community-level factors beyond WASH access, such as intra-household pathogen transmission, exposure to animal feces, and contextual factors in the public domain may be important risk factors for enteric infections. clinicaltrials.gov (NCT02342860). Despite clear linkages between poor access to water, sanitation, and hygiene (WASH) and risk of enteric diseases, there is mixed evidence of the ability of WASH interventions to mitigate these diseases based on findings from the “gold standard” randomized controlled trials. This study examines drivers of enteric diseases by exploring associations between household- and community-level WASH access and enteropathogen infections. We found that enteropathogen infections were nearly universal across age groups, with 98.3% of subjects having at least one infection. Few household or village-level WASH covariates were statistically associated with enteropathogen infection; WASH access generally trended towards lower infection, though trends varied by transmission pathway. Factors other than WASH access, such as intra-household transmission, animal feces exposure, and environmental contamination may be important risk factors for enteric infections. These results highlight the challenges of addressing enteric infections using many of the existing WASH intervention approaches.

Rapid and accurate testing of pathogenic Salmonella enterica in dairy products could reduce the risk of exposure to the bacterial pathogens for consumers. This study aimed to reduce the assessment time needed for enteric bacteria recovery and quantification in food using the natural growth properties of Salmonella enterica Typhimurium (S. Typhimurium) in cow's milk and efficiently using rapid PCR methods. Over 5 h of 37 °C enrichment, culture and PCR methods measured increases in the non-heat-treated S. Typhimurium concentration at similar rates, with an average increase of 2.7 log10 CFU/mL between the start of enrichment and 5 h. In contrast, no bacteria were recovered by culture after S. Typhimurium in milk received heat treatment, and the number of gene copies of heat-treated Salmonella detected by PCR did not increase with the enrichment time. Thus, comparing culture and PCR data over just 5 h of enrichment time can detect and differentiate between replicating bacteria and dead bacteria.

Background: Previous work in peri-urban communities within Kisumu County, Kenya, has shown that milk is a common weaning food and often contains enteric pathogens. Little is known about how milk and milk-based foods fed to infants become contaminated in peri-urban communities. Objective: To compare the bacterial indicator and enteric pathogen detection levels in unpackaged, fresh pasteurized, and ultra-high temperature (UHT) treated milk at purchase, and assess its association with contamination of food prepared with this milk and fed to infants. Methods: Paired samples of milk at point of sale and infant food prepared with this milk were obtained from 188 households enrolled as controls in the Safe Start trial. Samples were cultured to isolate Salmonella enterica, Shigella sonnei, Klebsiella aerogenes, Proteus spp., and E. Cole including Enterohemorrhagic (EHEC) E. coli 0157, with pathogens validated by PCR. Detection of these bacteria was compared across milk types, and between milk at purchase vs. point of infant consumption. Results: Unpackaged milk was most contaminated at point of purchase, but bacterial contamination was also present in pasteurized and UHT milk. Presence of bacteria in milk at purchase predicted presence of the same bacteria type in infant food. Contamination detection frequency and concentration level for bacterial indicators generally increased between point of purchase and consumption among users of UHT and fresh pasteurized milk, but decreased among those using unpackaged milk. Detection of the four fecal bacteria in infant food was not significantly related to the type of milk used. Conclusion: Kenyan infants are exposed to foodborne bacteria, including enteric pathogens, in milkbased foods. Both pre-market contamination and post-purchase handling influence the likelihood of milk given to infants being contaminated. Improvements in the safety of raw and pasteurized milk, and caregiver education on safe preparation and storage, are needed to reduce infant exposure to contaminated food. What is already known?: Globally, food is an important cause of diarrheal outbreaks although evidence on the importance of food as a source of child exposure to diarrheal pathogen, and the source of those pathogens, in low income nations is scarce. While household hygiene influences infant food safety, consumption of pre-packaged foods, like pasteurized milk, have grown rapidly in recent decades, especially in urban populations, highlighting possible roles for both food systems and households in foodborne exposure of children. What are the new findings?: Kenyan infants are frequently exposed to foodborne bacteria, including enteric pathogens, in milk-based supplemental foods. Pre-packaged pasteurized milk products are safer at point of purchase than unpackaged milk, although offered no protection for infants against bacterial exposure at point of consumption. Both purchased milk products and post-purchase household food handling behaviors influenced the likelihood of infant exposure to contaminated infant food. What do the new findings imply?: Joint interventions targeting improvements in the safety of raw and pasteurized milk production, as well as caregiver education on safe preparation and storage of food, are needed for preventing foodborne exposure of peri-urban Kenyan infants.

Pediatric diarrheal disease remains the 2nd most common cause of preventable illness and death among children under the age of five, especially in Low and Middle-Income Countries (LMICs). However, there is limited information regarding the role of food in pathogen transmission due to measuring infant food contaminations in LMICs. For this study, we examined the frequency of enteric pathogen occurrence and co-occurrence in 127 weaning infant foods in Kisumu, Kenya using a multi-pathogen rt-PCR diagnostic tool, and assessed household food hygiene risk factors for contamination. Bacterial, viral, and protozoa enteric pathogen DNA and RNA were detected in 62% of the infant weaning food samples collected, with 37% of foods containing more than one pathogen type. Multivariable generalized linear mixed model analysis indicated type of infant food best explained the presence and diversity of enteric pathogens in infant food, while most household food hygiene risk factors considered in this study were not significantly associated with pathogen contamination. Specifically, cow's milk was significantly more likely to contain a pathogen (adjusted Risk Ratio=14.4; 95% Confidence Interval (CI) 1.78-116.1) and contained 2.35 more types of pathogens (adjusted Risk Ratio=2.35; 95% CI 1.67-3.29) than porridge. Our study demonstrates that infants in this low-income urban setting are frequently exposed to diarrhoeagenic pathogens in food and suggests that interventions are needed to prevent foodborne transmission of pathogens to infants.