Life cycle, host restriction and longevity of Cyrilia nili (Haemogregarina nili Wenyon, 1909) n. comb.
Morphometric and morphological observations on C. nili in an experimentally infected fish (using the leech vector Batracobdeloides tricarinata for the first time) revealed two successive types of merogonic cycles occurring within the fish erythrocytes. In the first cycle large meronts produced eight small merozoites each while in the second cycle smaller meronts produced four merozoites each. Merozoites of the second cycle were destined to become gamonts. The gamonts were somewhat larger than merogonic stages and comprised the majority of the parasitic stages during parasitemia for up to 8 months. In the leech crop, gamonts released from the fish erythrocytes, became associated in syzygy and fused. The formed zygote underwent sporogony within the intestinal tissues and up to 60 sporozoites were produced from an ovoid or round oocyst. The produced sporozoites migrated toward the salivary and the proboscis tissues. The parasite survived in the leech over a period of 8 months involving 5 meals after the initial meal provided the fasting period did not exceed 75-105 days. Survival was attributed to residual stages in the proboscis and salivary tissues. Cross transmission experiments between fishes via B. tricarinata revealed that the fish haemogregarines were not host specific. Previously described African fresh water fish haemogregarines were indistinguishable and on the basis of the current results, they are regarded as a single species Cyrilia nili.
Negm-Eldin
M M
MM
Dept. Parasitology, Fac. Vet. Med., Benha University Tukh Moushtohour, Egypt.
D000818:Animals; D003044:Coccidia / Q000254:growth & development / Q000502:physiology*; D003048:Coccidiosis / Q000469:parasitology / Q000635:transmission / Q000662:veterinary*; D004199:Disease Vectors; D004912:Erythrocytes / Q000469:parasitology; D005393:Fish Diseases / Q000469:parasitology*; D005399:Fishes; D007422:Intestines / Q000469:parasitology; D007865:Leeches / Q000469:parasitology; D013045:Species Specificity