Prevalence of Aflatoxin- and Fumonisin-Producing Fungi Associated with Cereal Crops Grown in Zimbabwe and Their Associated Risks in a Climate Change Scenario

Abstract

In most sub-Saharan African countries, staple cereal grains harbor many fungi and some produce mycotoxins that negatively impact health and trade. Maize and three small grain cereals (sorghum, pearl millet, and finger millet) produced by smallholder farmers in Zimbabwe during 2016 and 2017 were examined for fungal community structure, and total aflatoxin (AF) and fumonisin (FM) content. A total of 800 maize and 180 small grain samples were collected at harvest and during storage from four agroecological zones. Fusarium spp. dominated the fungi associated with maize. Across crops, Aspergillusflavus constituted the main Aspergillus spp. Small grain cereals were less susceptible to both AF and FM. AF (52%) and FM (89%) prevalence was higher in maize than in small grains (13–25% for AF and 0–32% for FM). Less than 2% of small grain samples exceeded the EU regulatory limit for AF (4 µg/kg), while <10% exceeded the EU regulatory limit for FM (1000 µg/kg). For maize, 28% and 54% of samples exceeded AF and FM Codex guidance limits, respectively. Higher AF contamination occurred in the drier and hotter areas while more FM occurred in the wetter year. AF exposure risk assessment revealed that small grain consumption posed low health risks (≤0.02 liver cancer cases/100,000 persons/year) while maize consumption potentially caused higher liver cancer rates of up to 9.2 cases/100,000 persons/year depending on the locality. Additionally, FM hazard quotients from maize consumption among children and adults were high in both years, but more so in a wet year than a dry year. Adoption of AF and FM management practices throughout the maize value chain coupled with policies supporting dietary diversification are needed to protect maize consumers in Zimbabwe from AF- and FM-associated health effects. The higher risk of health burden from diseases associated with elevated concentration of mycotoxins in preferred maize during climate change events can be relieved by increased consumption of small grains.

Contributions of integrated aflatoxin management strategies to achieve the sustainable development goals in various African countries

“…Although changing dietary habits may be difficult (food scarcity, high food prices, resilience to change diet type), farmers and value chain actors are encouraged to consume more foods prepared with non-susceptible crops. In both Uganda and Zimbabwe, millets were found to be less susceptible to aflatoxin and other mycotoxins than the most preferred maize and sorghum and the authors recommended greater consumption of millets (Bandyopadhyay et al, 2007;Wokorach et al, 2020;Akello et al, 2021).…”

Mycotoxin Profile of ‘Tom Bran’, a Cereal-legume Weaning Food Preparation

“…18,26 It was asserted that the manner of field collection and storage condition of certain grains accounted for reduced ZEA contamination of certain farm produce. [37][38][39][40] The Seasonal timing of collection of produce could also contribute to the trend observed in the result, since the samples were obtained during the very dry weather of December. Investigations revealed that climate and weather are also significant determinants of cereals and legumes predisposition to mycotoxin contamination.…”

Pest Management in the Postharvest Agricultural Supply Chain Under Climate Change

“…Indeed, under the most probable scenario of warming (e.g., +2°C), aflatoxin B 1 was predicted to become a food safety issue in maize in Europe within 100 years (Battilani et al, 2016). Improperly stored commodities may see increases in mycotoxins (Paterson and Lima, 2010;Magan et al, 2011;Medina et al, 2015;Akello et al, 2021). Increased weather extremes, including flooding or drought, greatly affects water quality in a region and can result in increased pathogen transfer in post-harvest handling (Atanda et al, 2011).…”

“…More recently, Medina et al (2017) found Aspergillus flavus was likely to be unaffected by climate change factors (elevated CO 2 , temperature, moisture), but that there was a significant stimulation in the production of its mycotoxin, aflatoxin B 1 in vitro and in vivo in corn. However, cereal grains grown in drier and hotter areas of Zimbabwe had higher A. flavus contamination, while there was more fumonisin content in wetter years (Akello et al, 2021). In Malawi, warmer and drier conditions from climate change are predicted to make pre-harvest conditions more favorable to aflatoxin B 1 contamination, with contamination risk increasing at more northern regions (Warnatsch et al, 2020).…”