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

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.

Assessing milk products quality, safety, and influencing factors along the dairy value chain in eastern Democratic Republic of the Congo

“…Indeed, the observed TAMF varied from 14.7 × 10 4 CFU/ml (for pasteurized milk) to 57.9 × 10 4 CFU/ml (for Mashanza). These results concur with the EAC standards (10 6 CFU/ml), the AFNOR (France standard) (5 × 10 5 CFU/ml) and the American standard (3 × 10 3 CFU/ml) (Mutwedu et al, 2018;Hoffmann et al, 2022). This contamination in the milk samples collected in the two provinces at farmers, collectors, vendors' level is influenced by different factors, including the hygienic condition of the milker and the mammary gland while milking (Mutwedu et al, 2018), storage and transport in unclean milk containers, prolonged time for milk storage and uncontrolled temperature during milk transportation (Mpatswenumugabo et al, 2019).…”

Environmental and behavioural exposure pathways associated with diarrhoea and enteric pathogen detection in 5-month-old, periurban Kenyan infants: a cross-sectional study

“…Animal-based foods, like cow milk, can pose a risk for zoonotic enteric pathogen transmission42 although pasteurisation is an effective means for making milk safer. In a parallel study, we showed enteric pathogens do occur in processed milk products in Kenya, but households contribute more to infant food contamination than food products 31. Pasteurised milk products may be risk factors in this study due to postpurchasing contamination from household surfaces, hands or utensils or storing milk for prolonged periods after opening.…”

“…Additional strengths include the use of an ordinal distribution representing pathogens codetection patterns for identifying many exposure risk factors that would have remained masked by using a simplistic pathogen presence/absence outcome. The utility of using microbial diversity in pathogen contamination for distinguishing between high and low risk conditions in settings where exposure is the norm has also been demonstrated in environmental studies of soil, water and food 18 31. We spiked around half of all stool specimens with MS2 virus as a sample transport and extraction process control.…”

“…Infant supplemental foods include street foods prepared by vendors, raw fruits and prepackaged commercial products (eg, pasteurised milk) that could contain contamination. Cooking (eg, porridge), washing (eg, fruit) or storing these foods can mitigate or enhance these external food system-based pathogen transmission risks 31. We hypothesise that access to a refrigerator for food storage moderates the pathway between supplemental foods and pathogens in infants such that a lack of refrigeration increases the association between supplemental food and pathogens in infants compared with households with refrigeration.…”

A Mixed Methods Process Evaluation of a Food Hygiene Intervention in Low-Income Informal Neighbourhoods of Kisumu, Kenya

“…Approximately 60% of the population in Kisumu city lives in lowincome settlements characterized by poverty, inadequate water and sanitation, and poor housing (National Council for Population and Development, 2013). Our prior and trialrelated research confirmed that supplemental foods are a source of faecal indicator and enteric pathogen exposure and that inadequate household food hygiene is a leading source of contamination (Hoffmann et al, 2020). Residents in the settlements, including those in Nyalenda have a mix of urban and rural lifestyle, with landowners constructing rental housing units to meet the growing demand for housing.…”