Milk Product Safety and Household Food Hygiene Influence Bacterial Contamination of Infant Food in Peri-Urban Kenya.

Vivian Hoffmann,Kevin Tsai,Jane Mumma,Sheillah Simiyu,Oliver Cumming,Kelly K Baker,Daniel K Sewell

doi:10.3389/fpubh.2021.772892

Abstract

BackgroundMilk is a common infant food in peri-urban Kenya that can transmit diarrhea-causing enteric pathogens. Little is known about how contamination of milk at point of purchase and household handling of milk-based infant foods contribute to infant exposure to enteric pathogens.ObjectiveTo compare the prevalence and concentrations of bacterial indicator organisms and enteric pathogens in unpackaged, fresh pasteurized, and ultra-high temperature (UHT) treated milk at purchase and assess the influence of the type of milk used to prepare infant food on contamination of this food.MethodsPaired samples of purchased milk and infant food prepared with this milk were obtained from 188 households in low-income neighborhoods in Kisumu, Kenya. Samples were cultured on selective media to isolate Salmonella enterica, Shigella spp., Klebsiella aerogenes, Proteus spp., and Escherichia coli, with pathogens validated by PCR. Probability of detection of these bacteria was compared by milk product treatment and packaging method, and between milk at point of purchase vs. food at point of infant consumption.ResultsUnpackaged milk was most contaminated at point of purchase, but bacterial contamination was also present in pasteurized and UHT milk at purchase. Presence of bacteria in UHT and fresh pasteurized milk at purchase predicted presence of the same bacteria type in infant food. Prevalence of bacterial contamination and concentration level for bacterial indicators generally increased between point of purchase and consumption in UHT and fresh pasteurized milk-based food but decreased in unpackaged milk-based food. Prevalence of the four fecal bacteria were similar in infant foods prepared with each type of milk.ConclusionBoth pre-market contamination and post-purchase handling influence the likelihood of infants ingesting foods contaminated by diarrheal pathogens.

Highlights

Morbidity and mortality among children under 5 years of age accounts for 40% of the global burden of foodborne disease [1]
Little is known about how contamination of milk at point of purchase and household handling of milk-based infant foods contribute to infant exposure to enteric pathogens
Unpackaged milk was most contaminated at point of purchase, but bacterial contamination was present in pasteurized and Ultra High Temperature treated (UHT) milk at purchase

Summary

Introduction

Morbidity and mortality among children under 5 years of age accounts for 40% of the global burden of foodborne disease [1]. Kenya’s dairy value chain is complex, with a variety of rural, peri-urban, and urban independent farms of small to large size that sell milk in bulk through dairy cooperatives to formal milk processing plants [8]. Previous quantitative risk assessments of disease transmission through milk in Kenya have focused on informally marketed raw milk These have used self-reported boiling behavior to estimate the proportion of households who boil milk prior to consumption and have assumed that boiling is 100% effective against Escherichia coli O157:H7 and Cryptosporidium spp. As the vast majority of households typically report boiling milk purchased from the informal market prior to consumption, previously estimated risks of exposure to foodborne bacteria through milk consumption have been small. Little is known about how contamination of milk at point of purchase and household handling of milk-based infant foods contribute to infant exposure to enteric pathogens

Methods

Results

Conclusion