Rapid screening for aflatoxins in maize at the subsistence farm level

Aflatoxin is a potent mycotoxin that contaminates 25% of crops worldwide. Chronic exposure to aflatoxins is a risk factor for hepatocellular carcinoma, while acute exposure can result in aflatoxicosis and subsequent hepatic injury or death. Food monitoring, used widely in developed countries to detect aflatoxins in contaminated commercial maize is a highly effective prevention measure; however, its use at the subsistence farm level is untested. Since 2004, 477 aflatoxin poisonings have occurred in Eastern Kenya due to contaminated, homegrown maize (41% case-fatality rate). Currently, local officials use visual inspection methods to screen maize for mold; however, food without visual mold may still contain aflatoxins. To improve detection of aflatoxins in maize, an existing chromatographic rapid screening tool (RST) was modified for use in rural Kenya. To evaluate the tool, 421 households were randomly selected from affected districts. Maize was collected from each household and screened using visual inspection and RST. The sensitivity and specificity of visual inspection and the RST to detect aflatoxins above the regulatory limit (20ppb) were determined by comparing screening results to results from VICAM^TM immunoaffinity fluorometric methods, representing the gold standard. RST sensitivity and specificity were 90% and 96%. Visual inspection sensitivity and specificity were 29% and 81%. At very high levels of contamination (>200ppb), rapid screening sensitivity was 100%, while visual screening sensitivity was 32%. RST performed better than visual screening, particularly at the highest levels of contamination. Findings suggest that rapid screening may improve early detection and control of aflatoxin contamination in Kenya.