Over 185 species of fungus belong to the Aspergillus genus, and 20 of those can cause infections in humans. Aspergillus fungi grow all over the world. These fungi can cause severe allergy symptoms in people with asthma or cystic fibrosis. Aspergillus fungi can infect food crops either while the crops are growing or after harvest.
Where It Grows
Aspergillus flavus grows mainly on dead plant and animal material in the soil. This makes it an important agent in breaking down and recycling nutrients. It can also grow on living plant material, including food crops such as corn, nut trees and peanuts.
The Aspergillus flavus fungus survives the winter either as mycelium (the thread-like structure of a fungus) or a sclerotia (a hardened, compact mass of mycelium). The fungus reproduces in two ways. In the first, the sclerotia germinates, producing additional threads. In the second method, the sclerotia produces spores that disperse to other areas. This is the common way the fungus infects corn; insects or wind carries the spores to ears of corn. The spores germinate and the fungus infects the corn kernels.
While most species of fungi prefer cool, wet conditions, Aspergillus flavus grows best when it's hot and dry. Its best growth occurs when the temperature is above 98 degrees, but it can thrive in temperatures ranging from 77 to 108 degrees.
Aflatoxin is a toxic compound in Aspergillus flavus that can cause illness similar to allergies. In people with compromised immune systems, it can cause serious general infections that can be deadly. Aflatoxin is also carcinogenic (cancer-causing).
Aflatoxicosis is a condition causing necrosis (dead tissue), cirrhosis (disease affecting liver function) and carcinoma of the liver. It is not often reported in humans, but this may be due to the symptoms being attributed to another cause. Doctors may suspect aflatoxicosis when the cause of a patient's symptoms is not apparent, the illness is not transmissible to other people, or if antibiotic treatment has little or no effect.