Temperature studies on chicks infected with Plasmodium gallinaceum (Brumpt, 1935) including some effects of cooling host and parasite

Abstract

It was confirmed that P. gallinaceum had a 36-hour period of development and was relatively synchronous. The period remained 36 hours even when a bird was infected with sporozoites three times, at consecutive 12 hours intervals. The rectal temperatures of young chicks showed an increase during the first two weeks of life. Fluctuations of temperature from day to day were generally about ±0.2 ° C. A 24-hour temperature cycle was found which was related to the birds' activity rhythm. The temperatures of infected birds were not affected by any stage of the parasites' 36-hour growth cycle, but abnormal temperatures occurred at the peak of parasitaemia. The degree of temperature abnormality was directly related to the severity of the infection. Infected birds were cooled to approximately 30 ° C and were revived after about six hours. Cooling delayed the growth of the parasite by causing the period of development to extend beyond the usual 36 hours. This extension was more marked when trophozoites predominated in the blood during the cooled period. There was no detectable difference between cooled birds and controls in the rate of parasitic increase, the morphology of the parasite, or the number of merozoites per schizont. Gametocytes from cooled birds infected mosquitoes and exoerythrocytic parasites were found in cooled birds 22 days after infection.