Parasitemia in Primary Leucocytozoon simondi Infections

Abstract

A study is reported of the primary parasitemia in ducklings naturally infected with L. simondi as a consequence of farm exposure in n. Michigan. Immature gametocytes attained maximal concn. at about the 4th day of patency. Mature parasites were most commonly observed for the 1st time on the 5th day of patency, their number increasing with the simultaneous decline in immature gametocytemia. Mature gametocytes generally reached their peak density by the 9th day of patency, while the absolute peak of parasitemia (total of all forms) occurred on the 6th day of the patent period. The primary parasitemia usually terminated within 30 days of the first appearance of parasites. A number of variations in the relative proportions of immature to mature parasites have been noted and are briefly discussed. There is suggestive, but as yet inconclusive, evidence that the immunity to this infection may be a very rapidly developing one.