Recent outbreaks of aflatoxicoses in eastern Africa

Aflatoxins are carcinogenic and acutely toxic fungal metabolites. Evidence is accumulating on the association of aflatoxin exposure with childhood stunting. Aflatoxin contamination of agricultural produce adversely affects food security and nutrition and is a major constraint to trade in affected commodities. This paper analyses outbreaks of acute aflatoxin poisoning in eastern Africa, mainly based on the extensive reports from Kenya. Lethal aflatoxicoses of humans have occurred for the last three decades in Kenya in association with consumption of contaminated maize. The biggest episode that occurred in 2004 claimed more than 125 lives. Studies consistently show high average levels of contamination ranging from 16-75% of maize samples testing above the allowable limit of aflatoxin. S-strain of Aspergillus flavus (phylogenetically distinct from other regions of the world), capable of producing large quantities of the more toxic B aflatoxins, has been associated with lethal aflatoxicoses. Erratic weather conditions, such as end of season drought, could expose the crop to stress leading to higher toxin accumulation. Moreover, in drought conditions fear of theft may derive farmers to harvest too early without adequate field drying. On the other hand, long rains can prevent drying properly which can result in harvesting prior to crop maturity. Improper crop production and postharvest handling practices aggravate contamination. The widespread occurrence of the toxin in maize and other dietary staples in the region suggests that the acute poisoning and tragic losses of human life could be the ‘tip-of-the-iceberg’ as compared to more pervasive effects of chronic exposure to aflatoxins. Holistic approaches integrating prevention of aflatoxin contamination through integrated value chain controls, effective regulatory mechanism and awareness generation are urgently needed. Further research towards increased understanding of the problem and developing appropriate and affordable technologies is warranted. Partnership between multiple players and avoiding duplication of efforts are key to dealing with the complex aflatoxin problem.

Presented at the World Mycotoxin Forum – 8th conference 10-12 November 2014, Vienna, Austria.