MASTITIS IN DAIRY-CATTLE CAUSED BY CORYNEBACTERIUM-PSEUDOTUBERCULOSISAND THE FEASIBILITY OF TRANSMISSION BY HOUSEFLIES .1.

Morbidity due to Corynebacterium pseudotuberculosis infection occurred in 29 dairy herds, The disease appeared basically in three clinical f orms: cutaneous, mastitic, and visceral, The appearance of the disease showed a marked seasonality: in 23 herds it occurred during the sprin g and summer months (dry season) (March-October). The mastitic form oc curred in only 10 herds and the causative bacterium was isolated from 33 cows (5.8%), All the strains of C. pseudotuberculosis isolated from the milk samples were found not to be nitrate reducers. The bacterium was excreted in the milk of six cows from herd B during a period of 1 1 months, In the mastitic cows, a decrease in milk production and cons iderable increases in the somatic cell count were noted. C. pseudotube rculosis was isolated from houseflies collected over a cow lesion. Lab oratory-reared houseflies were successfully infected with C. pseudotub erculosis-contaminated milk, broth and sugar cubes, Flies infected wit h the bacterium from contaminated milk excreted the bacterium in their droppings for up to 4 h and from their saliva for up to 3 h post infe ction, The bacterium survived on the external organs of houseflies for no longer than 10 min post infection, after the flies had been dipped in contaminated broth.