The effect of temperature, age and density of gametocytes, and changes in gas composition on exflagellation of Leucocytozoon simondi

Abstract

The rate of initiation of exflagellation of microgametocytes of Leucocytozoon simondi was studied in relation to temperature, age and density of gametocytes, and changes in gas composition. Observations were made in vitro through examination of fresh blood, and thin blood films were prepared at appropriate intervals. An inverse relationship between temperature and the time required for initiation of ex-flagellation was demonstrated. There was a decrease in the time required for initiation of exflagellation as the temperature increased from 15 to 26C. Between 26 and 40C exflagellation usually occurred in 1–1½ min. Exflagellation at 40C, which approximates the body temperature of the host, indicates that a drop in temperature per se is not necessary for the initiation of exflagellation. Gametocytes appear to be capable of exflagellation for about 5 days postmaturity. Differences in density of parasitemia do not affect the time for initiation of exflagellation. The presence of O2 and a decrease in CO2 are important stimuli for exflagellation. The effect of the above factors on the initiation of exflagellation is discussed in relation to the uptake of infected blood by the simuliid vector of the parasite, and compared with the situation in related Haemosporina