SCHISTOSOMA MATTHEEI INFECTION IN CATTLE - THE COURSE OF THE INTESTINAL SYNDROME, AND AN ESTIMATE OF THE LETHAL DOSE OF CERCARIAE

Three groups of young oxen were infected percutaneously with cercariae of Schistosoma mattheei. Three of five oxen infected with 248 cercari ae kg(-1) mass died or were killed in extremis 58-70 d after infection , a fourth survived extremely severe clinical schistosomosis and the f ifth was only slightly affected. None of seven calves infected with 18 7 cercariae kg(-1) died, while one of seven exposed to 119 cercariae k g(-1) was in extremis (possibly not from schistosomosis) when killed a fter 378 d. The LD50 appears to be in the region of the highest dose t ested (248 cercariae kg(-1)), but depends on variations in the viabili ty of the cercariae used. The clinical syndrome was characterized by a drastic, rapid loss in body mass; a severe diarrhoea containing blood clots; straining, gnashing of the teeth, occasional groaning, and oth er signs of abdominal pain; and markedly sunken eyes. Lethally infecte d oxen did not become recumbent until shortly before death. Some sever ely affected animals made remarkable, but slow, recoveries without tre atment. Schistosomes, in close association with granulomata, are descr ibed-apparently for the first time-in the omental veins of cattle. Mea n worm development in three calves that died or were killed in extremi s in the acute stage of the disease, was 55,5 %. In contrast to most p revious findings with S. mattheei, in two of these animals, more femal e than male worms developed. The worms were recovered by perfusion and , in one animal, a large number of intestinal veins were dissected ope n to estimate the efficiency of the perfusion method. Only 1,9 % of th e total worm burden had not been removed by perfusion in this animal.