Prevalence and Factors Associated With Aflatoxin Contamination of Staple Foods in Rural Busia County, Kenya

Abstract

Food safety is a major challenge in many Low- and Middle-Income Countries including Kenya. The most common food safety challenge in Kenya is aflatoxin contamination. Long term dietary exposure to low doses of these toxigenic fungi have been associated with chronic disease like liver cancer while exposure to high doses has been linked to hepatic failure in humans. This study aimed to determine the prevalence of aflatoxin in staple foods including maize, sorghum, millet, groundnuts and cassava consumed in households within Budalang’i, Nambale and Teso- South sub-counties in Busia County; describe factors associated with aflatoxin contamination of the cereals, groundnuts and cassava; to evaluate the effect of selected preparation methods on aflatoxin contamination levels in the cereals and to determine the consumption patterns of maize, sorghum, millet, groundnuts and cassava in the study households. This study utilized a convergent mixed methods design. Both quantitative and qualitative data were collected in parallel, analyzed separately and then merged at results and discussion levels. Household geo-coordinates, respondents’ socio demographic profile, food sources, storage practices and food consumption patterns were collected and entered data into an Open Data Kit (ODK). A household survey was conducted. Dietary diversity data, food frequency and 24 hr food recall data were collected and analyzed descriptively. Food samples collected from sampled households were tested to determine the levels of total aflatoxins using competitive ELISA method. Some contaminated food samples were either boiled, fermented and boiled or boiled in locally made alkaline solutions and levels of aflatoxin assessed after each process. Quantitative data were analyzed using SAS 9.4 software. Six focus-group discussions each with 11-12 participants and sixteen key informant interviews were also conducted and recorded using

Olympus recorder and analyzed using Nvivo version 10. In-depth information on the food sources, community diets, food storage and food preparation practices and awareness of aflatoxin among a sub-set of community members was gathered. Maize, sorghum, cassava and millet are the staples. However, frequency of maize consumption was highest of all the grains. All food samples collected and tested (n=493) had detectable levels of aflatoxin. The levels of aflatoxin ranged from 1-1584ppb in maize, 0.3 to 740ppb in sorghum, 0.5 to 15ppb in cassava, from 0.5 to 12 ppb in millet and 0.1 to 2.8 in groundnuts. Overall, maize recorded the highest level of contamination (mean 100ppb; SD 252.9; range 1-1584ppb) with 31% of samples above East African Community regulatory limits (10ppb). Aflatoxin contamination in maize was seemingly higher than in sorghum though not statistically significant (p=0.0568). Homegrown maize was less likely to have aflatoxin levels ˃10ppb when compared to market sourced grain (OR 1.185, CI 0.554, 2.534) but difference was not statistically significant (p= 0.0760). Sorghum stored in buckets had a 12.81 likelihood of having higher than allowable limits of aflatoxin (OR 12.82, CI 2.566, 63.992) (p=0.0096) relative to sorghum stored in nylon sacks. Though maize stored in a bucket had a 1.61 likelihood to have less aflatoxin than that stored in a nylon sack (OR 1.650, CI 0.840, 3.247) the association was not significant (p=0.2398). Residents of Teso South and Nambale were at highest risk of acute exposure as demonstrated by the hotspot analysis. Boiling of maize in alkaline solution (ash salt) recorded a 72-91% reduction of aflatoxin level while 24 hour fermentation then boiling of maize, sorghum and cassava composite flours recorded a 64% reduction of aflatoxin. Residents of Busia County exhibited very low levels of awareness of aflatoxins, aflatoxin mitigation practices and the possible negative health effects resulting from the exposure to these toxins mainly as a result of limited education and sensitization provided by the county’s ministries of agriculture and health.

Aflatoxins are prevalent in maize, sorghum millet, groundnuts and cassava in Busia County and residents are at risk of possible chronic exposure therefore there is need for instigation of aflatoxin mitigation measures. Surveillance of populations exposed to aflatoxin levels beyond KEBS acceptable limits is warranted and an aflatoxin sero-survey and a health impact assessment of this population is recommended. Awareness creation among farmers and retailers on pre and post-harvest food handling practices and on causes of aflatoxin occurrence and health implications, with the objective of encouraging voluntary compliance to public health regulations and improved food handling practices is advisable. Regulation of formal cross-border trade of these grains is also needed. Knowledge on current food safety situation and trends of occurrence in the food chain is vital. This knowledge should be continually updated through systematic food sample collection, analysis and interpretation of data and dissemination to guide public health decision making. Lastly, a longitudinal study that would collect samples at different times of the year from the same sites in addition to socioeconomic, temporal, and biophysical data to assess for other determinants of contamination is highly recommended. There is also need for further research and document prevalence of contamination of animal source products such as eggs, milk and pork in Busia.