The incidence of chronic aflatoxicosis in humans is unknown and is almost impossible to estimate because the symptoms are so difficult to recognise. However, human liver cancer is quite common in parts of the world where aflatoxin contamination of food is likely and there may be a link, although this remains unproven.
Acute human aflatoxicosis is rare, especially in developed countries, where contamination levels in food and monitored and controlled. However, there have been outbreaks in some developing countries, notably in sub-Saharan Africa, where maize and groundnuts can be an important part of the diet and where the climate is suitable for rapid mould growth on crops in the field and in storage.
A notable outbreak occurred in India in 1974 when almost 400 people became ill with fever and jaundice after eating maize contaminated with between 0.25 and 15 mg/kg aflatoxin and more than 100 died. Major outbreaks have also occurred in Kenya, the largest in 2004 when 317 people were affected and 125 died, probably as a result of eating contaminated maize.