Aflatoxin in dried insects and fish in Zambia

Authors: KACHAPULULA, PAUL - University Of Arizona; AKELLO, JUILET - International Institute Of Tropical Agriculture (IITA); BANDYOPADHYAY, RANAJIT - International Institute Of Tropical Agriculture (IITA); Cotty, Peter

Submitted to: Journal of Food Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/8/2018
Publication Date: 8/17/2018
Citation: Kachapulula, P.W., Akello, J., Bandyopadhyay, R., Cotty, P.J. 2018. Aflatoxin in dried insects and fish in Zambia. Journal of Food Protection. 81(9):1508-1518.

Interpretive Summary: Aflatoxins are toxic fungal metabolites that can inhibit human development, cause cancer, and even induce death. Occurrence of these toxins greatly reduces the markets to which crops can be sold and the health of consuming populations. The fungi named Aspergillus flavus and A. parasiticus are the primary cause of aflatoxin contamination of several crops, insects and fish. In order to understand the epidemiology of contamination and the risk these fungi pose to human health and trade, aflatoxins were quantified and, and populations of A. flavus and A. parasiticus were examined in insects and fish from Zambia. Aflatoxins were detected in insects and fish. Aspergillus flavus and A. parasiticus were the most frequent fungi on insects and fish from Zambia. The current work suggests that consumption of insects and fish might result in human exposure to aflatoxins, and that aflatoxin mitigation is needed in insects and fish in Zambia.

Technical Abstract: Dried insects and fish are important sources of income and dietary protein in Zambia. Some aflatoxin-producing fungi are entomopathogenic and also colonize insects and fish after harvest and processing. Aflatoxins are carcinogenic, immunesuppressing mycotoxins that are frequent food contaminants worldwide. Several species within Aspergillus section Flavi have been implicated as causal agents of aflatoxin contamination of crops in Africa. However, aflatoxin producers associated with dried fish and edible insects in Zambia remain unknown, and aflatoxin concentrations in these foods have been inadequately evaluated. The current study sought to address these data gaps to assess potential human vulnerability through the dried fish and edible insect routes of aflatoxin exposure. Caterpillars (n¼97), termites (n¼4), and dried fish (n¼66) sampled in 2016 and 2017 were assayed for aflatoxin by using lateral flow immunochromatography. Average aflatoxin concentrations exceeded regulatory limits for Zambia (10 lg/kg) in the moth Gynanisa maja (11 lg/kg), the moth Gonimbrasia zambesina (Walker) (12 lg/kg), and the termite Macrotermes falciger (Gerstacker) (24 lg/kg). When samples were subjected to simulated poor storage, aflatoxins increased (P , 0.001) to unsafe levels in caterpillars (mean, 4,800 lg/kg) and fish (Oreochromis) (mean, 23 lg/kg). The L strain morphotype of A. flavus was the most common aflatoxin producer on dried fish (88% of Aspergillus section Flavi), termites (68%), and caterpillars (61%), with the exception of Gynanisa maja, for which A. parasiticus was the most common (44%). Dried fish and insects supported growth (mean, 1.3 3 109 CFU/g) and aflatoxin production (mean, 63,620 lg/kg) by previously characterized toxigenic Aspergillus section Flavi species, although the extent of growth and aflatoxigenicity depended on specific fungus-host combinations. The current study shows the need for proper storage and testing of dried insects and fish before consumption as measures to mitigate human exposure to aflatoxins through consumption in Zambia.