Dr. Kassai Tibor szerk.: Parasitologia Hungarica 1. (Budapest, 1968)

rasite egga may remain viable in the soil for aa long as 2 years although the ovum-transmitted agent of blackhead deteriorates in a few months. Therefore, care should be taken to place the turkey flock in „virgin" premises, where neither turkeys nor chickena have been kept for the preceding two years, or at least one. Experience with material designated „Orosháza" emphasise the importance of this particular requirement. Within a given area, containing farms not far distant from each other, blackhead occurred only where chickens and turkeys had been kept during the preceding year. Farms where this was not the case remained free of blackhead. Another method of preventing blackhead is to rear turkey poults up to 3-4 weeks' age in isolation on a deep litter not infected with Heterakis egga. If subsequent exposure is inevitable, losses can be minimized by starting preventive medication at the proper time. Summary A field trial of the feed additive H e p.a m 1 x, containing 2amino-5-nitrothiazole at a concentration of 10 was carried out Eig. 5. Microscopic lesions in the liver of a turkey affected with blackhead. Inflammatory foci containing detritus, granulocytes and fungus-like parasites. Hematoxylin and eosin. X 150 Kórszövettani elváltozások blackheades pulyka májában. Gyulladásos gócok a májban, törmelékkel, granul

ocytákkal és gombaszerü élősködőkkel. Hem-eozin. 150 X Eig. 6. Microscopic picture of liver in the convalescent stage after blackhead. Note healthy liver in the centre. Hematoxylin and eosin. X 150 A blackhead gyógyuló esete, a középen az érintetlen májszövet. Hem-eozin. 150 X