TRICHOTHECENE MYCOTOXICOSIS IN CHICKENS

These studies defined the clinical and pathological effects of T-2 toxin and diacetoxyscirpenol, structurally similar trichothecenes, in seven-day-old chickens and compared the effects produced by these trichothecenes with those produced by trichothecene toxins supplied as a culture of Fusarium sporotrichiella var. sporotrichioides. T-2 toxin and diacetoxyscirpenol dissolved in dimethylsulfoxide:saline (1:9 v/v) were given separately and in combinations by crop gavage. The 72-hour single-oral-dose LD(,50) for T-2 toxin was 4.0 mg/kg body weight and for diacetoxyscirpenol, it was 5.0 mg/kg. The 14-daily-oral-dose LD(,50) for T-2 toxin was 2.90 mg/kg body weight and for diacetoxyscirpenol and LD(,50) was 4.15 mg/kg. The two toxins given in various combinations had additive lethal effects in single- and multiple-dose tests. A single oral dose (T-2 toxin, 2.5 mg/kg body weight; diacetoxyscirpenol, 2.7 mg/kg) caused necrosis of lymphoid and hematopoietic tissues at postexposure hour 1, followed by rapid cell depletion and then repletion from hours 72 through 168. Necrosis of hepatocytes was accompanied by mild hyperplasia of bile ducts and by necrosis and inflammation of the gallbladder mucosa. Necrosis of intestinal epithelium was accompanied by atrophy of villi and reduced numbers of mitotic figures. Necrosis was present also in the mucosal epithelium of the ventriculus and proventriculus and in the feather epidermis. T-2 toxin and disacetoxyscirpenol given by crop gavage as 14 daily doses of 1.5, 2.0, 2.5, 3.0 and 3.0, 3.5 mg/kg body weight/day, respectively, caused dehydration, emaciation and death. In survivors, the body weight and hematocrit were reduced, feathers were malformed and the beak and legs were pale yellow. Lymphoid organs were atrophic, bone marrow was pale red or yellow, the liver was discolored yellow and the crop mucosa was ulcerated. Histopathologic changes included necrosis with cell depletion of lymphoid and hematopoietic tissues, necrosis of hepatocytes, bile ducts, enteric mucosa and germinal regions of feather barbs, lipid accumulation in hepatocytes and hyperplasia of biliary ducts. Thyroidal follicles were small, contained pale colloid and had tall epithelial cells. Lymphoid and hematopoietic lesions were more severe in T-2 toxin-treated chickens than in diacetoxyscirpenol-treated chickens in the single- and multiple-dose tests. Chickens given diets with T-2 toxin or diacetoxyscirpenol concentrations of 4 or 16 ppm for 21 days ate less feed and gained less weight than ad libitum controls. Focal yellow oral plaques that progressed to yellowish gray raised accumulations of exudate with underlying ulceration were oriented anatomically to salivary duct openings on the palate, tongue and floor, and were found also on the beak. Necrosis and ulceration of the mucosa with granulation tissue and inflammatory cells in the submucosa were accompanied by superficial crusts of exudate, bacterial colonies and feed components. The calculated LD(,50) for chickens fed T-2 toxin concentrations of 50, 100 or 300 ppm for 7 days, was about 10 mg/kg body weight, based upon average daily feed consumption. These higher dietary concentrations of T-2 toxin caused lesions similar to toxins given by gavage. Corn cultures of Fusarium sporotrichiella var. sporotrichioides (Bilay), a Hungarian isolate, fed at dietary concentrations of 10, 5, and 1 percent, had a 17-day lethal dietary concentration(,50) of 10 percent (5 ppm T-2 toxin and 0.5 ppm neosolaniol). The lethal dose(,50), calculated from the average daily feed consumption was 0.22 mg T-2 toxin/kg body weight/day and 0.02 mg neosolaniol/kg/day. Clinical signs, gross and microscopic lesions were as described for T-2 toxin and diacetoxyscirpenol given in single or multiple doses