Plasmodium forresteri n. sp., from Raptors in Florida and Southern Georgia: Its Distinction from Plasmodium elongatum Morphologically within and among Host Species and by Vector Susceptibility

Abstract

Plasmodium forresteri n. sp. naturally infects eastern screech-owls (Otus asio), great horned owls (Bubo virginianus), barred owls (Strix varia), bald eagles (Haliaeetus leucocephalus), red-shouldered hawks (Buteo lineatus), broad-winged hawks (Buteo platypterus), and red-tailed hawks (Buteo jamaicensis) in Florida and southern Georgia. Schizonts occur in mature or nearly mature erythrocytes, produce 2-6 merozoites arranged most commonly in fan or cruciform configuration, with mean dimensions among host species varying from 3.7 to 4.8 x 2.5 to 3.4 microns. Gametocytes are elongate, with mean dimensions among host species varying from 11.5 to 13.1 x 2.0 to 2.4 microns. One or both gametocyte margins are irregular and often crenulate. Gametocytes seldom fill the space between the erythrocyte nucleus and margin. Species characteristics were maintained in isodiagnostic Japanese quail (Coturnix japonica) and Pekin ducks (Anas platyrhynchos). In mosquito infection studies, only Culex restuans could support sporogony of P. forresteri, in contrast to Plasmodium elongatum of raptor origin that completed sporogony in both Cx. restuans and Culex nigripalpus.

Island and Taxon Effects in Parasitism Revisited: Avian Malaria in the Lesser Antilles

“…The primary vectors for Haemoproteus parasites are biting midges of the genus Culicoides (Diptera: Ceratopogonidae) (Wirth 1974;Harwood and James 1979;Kettle 1982) and louse-flies (Diptera: Hippoboscidae) (Bequaert 1954;Kettle 1982). Avian Plasmodium is transmitted most commonly by Culex mosquitoes (Forrester et al 1980;Atkinson and van Riper 1991;Telford et al 1997;Nayar et al 1998). The parasite genera also differ in that Plasmodium undergoes asexual multiplication in the peripheral blood, whereas Haemoproteus does not.…”

Vector Ability of Mosquitoes for Isolates of Plasmodium elongatum from Raptors in Florida

“…nigripalpus for the 3 isolates of P. elongatum obtained from 3 species of raptors, red-tailed hawk, bald eagle, and eastern screech owl were similar. Once they had been passaged for 3 times in ducks, they showed similar characteristics as regards the prepatent periods and the morphology of the parasites, e.g., presence of asexual stages in immature erythroid cells and of mature schizonts and segmenters with 8-12 nuclei in mature erythrocytes (Telford et al, 1997). The morphology of P. elongatum remained consistent both after blood transfers and after transmission of sporozoites by bite of infected mosquitoes or by injection of sporozoites.…”

“…The parasites were identified using taxonomic characters of Plasmodium spp. (Greiner et al, 1975;Telford et al, 1997). The subinoculated ducks were maintained in a mosquito-proof isolation room at the Animal House Facility of the Florida Medical Entomology Laboratory (FMEL), Vero Beach, Florida.…”

“…They were monitored daily from Monday to Friday for 2 wk by preparing blood smears starting on the ninth day after subinoculation of infected blood. The blood smears were air dried, fixed in absolute methanol, and stained by standard Giemsa technique for 1 hr at pH 7.0 (Telford et al, 1997). Infected ducks were used for determining susceptibility of different species of mosquitoes.…”

“…salinarius) are also competent natural and/or experimental vectors of wild turkey malaria, Plasmodium hermani, in Florida (Young et al, 1977;Forrester et al, 1980;Nayar and Forrester, 1985;Nayar et al, 1981aNayar et al, , 1981b. This prompted us to try infection of P. elongatum in turkey poults to verify that P. elongatum and P. hermani are separate species belonging to the subgenus Huffia (Garnham, 1966;Telford and Forrester, 1975).…”