Page 1054 - Veterinary Toxicology, Basic and Clinical Principles, 3rd Edition

986 SECTION | XV Mycotoxins

VetBooks.ir favoring mold growth and mycotoxin production because and A. fumigatus isolated from tissues have shown these
fungi can produce AFs, and chemical analyses of infected
moisture equilibrium occurs at a slow rate. The high-
tissues have shown AFs to be present (Pepeljnjak et al.,
moisture seeds provide a niche with a high a w around the
seed that is favorable for the growth of toxigenic and 2004). Typically, aflatoxigenic fungi infect animals and
other fungi, which if allowed to grow, produces additional humans that are immunocompromised. A. nomius has
moisture and heat via microbial metabolic activity. The been identified as an etiology of keratitis.
probability of fungal infection in seeds increases when the
moisture content and temperature of the seed is increased.
AF formation can rapidly occur (Coppock et al., 1989, PREVENANCE OF AFLATOXINS IN
2012). High-moisture corn and sorghum lightly inoculated FEEDSTUFFS AND FOODS
with A. flavus produces ppm levels of AFs within 48 h. Sources and Occurrences of Aflatoxicosis
Over-mature sweet corn was shown to contain 2.36 ppm
AFB 1 and 0.21 mg of AFB 2 (Hall et al., 1989). Sweet Almost any food or feedstuffs that can support the growth
corn may be more hazardous than field corn because of of aflatoxigenic fungi can contain AFs. AFs and their
its higher free sugar content. Prevention of AF contamina- metabolites can be transferred from the feed to edible ani-
tion before harvest strategies are being investigated and mal products. Occurrences of contaminated cows’, goats’,
used. These include timing of irrigation, breeding maize, and human milk with AFM 1 (animal metabolite of AFB 1 )
and other plants to increase resistance to fungal infection, for human consumption have been identified (Fig. 69.1).
and use of nonaflatoxigenic strains of Aspergillus spp. to Under field conditions, essentially all species of domestic
displace toxigenic strains of Aspergillus spp. (Dorner, animals have been poisoned with AFs. Outbreaks of afla-
2008; Ehrlich, 2014; Warburton and Williams, 2014). toxicosis linked to foods, birdseed, and other wildlife
feeds have occurred and likely are under-reported. The
In Vivo Production of Aflatoxins sources of the AFs in pet foods have been primarily maize
and maize byproducts, rice, millet, and peanut byproducts.
A. flavus and A. fumigatus have also been identified as Food garbage, moldy bread, and other diverted foods to
pathogens in animals and humans. AFs can be produced animal feeds can be a source of AFs. Tree nuts, peanuts,
in tissues by toxigenic fungi. Assays of cultured A. flavus figs, oilseeds, tobacco, coconut, condiments and spices,

FIGURE 69.1 Chemical structures of aflatoxin B 1 (top left), aflatoxin G 1 (top right), aflatoxin M 1 (bottom right), and aflatoxin B 1 epoxide
(bottom left). (http://www.chemspider.com/Chemical-Structure.9078879.html)