Saurian malaria: development of sporozoites in two species of phlebotomine sandflies.

Sporolzoites of a lizard malaria parasite, Plasmodium mexicanum. developed in two spcies of sandfly-Lutzomyia vexatrix and Lutzomyia stewarti. Salivary g1ands were infected 11 days after the flies took an infective blood meal. This is the first report of a malaria parasite undergoing sporogonic development In an insect other than a mosquito and the first description of lizard malaria sporogenesis.

Trypanosome transmitted by Phlebotomus: first report from the Americas.

Transmission studies carried out in the laboratory incriminated Phlebotomus vexator occidentis as a vector of a species of trypanosome that infects Bufo boreas halophilus. Toads free of parasites contracted the trypanosome after eating infected flies and after intraperitoneal inoculation of flagellates cultured from the hindgut of flies that had fed on infected toads. Discovery of this vectorhost-parasite system in the Americas, and the localization of promastigote flagellates (leptomonads) in the hindgut of the vector, should assist in clarifying interpretative problems associated with infection of wild-caught flies in studies on leishmaniasis in the Americas and elsewhere.

Double-blind test of metronidazole and tinidazole in the treatment of asymptomatic Entamoeba histolytica and Entamoeba hartmanni carriers.

One hundred and fifteen persons with asymptomatic Entamoeba histolytica or E. hartmanni infection, or both, were given metronidazole (750 mg three times daily for 5 days), tinidazole (1 g twice daily on 2 consecutive days), or a starch placebo. Three post-treatment stools were examined in the 2 weeks following initiation of treatment. Cysts of E. histolytica reappeared in the stools of 37% of 30 given metronidazole, 62% of 34 given tinidazole, and 70% of 31 given placebo. Cysts of E. hartmanni reappeared in the stools of 46% of 24 given metronidazole, 69% of 16 given tinidazole, and 90% of 10 given placebo. Rapid absorption and short duration of treatment make both drugs ineffective for the treatment of ameba carriers.

A population of Pasmodium colmbiense sp. n. in the iguanid lizard, Anolis Auratus.

Plasmodium colombiense sp. n. is described from 274 naturally infected Anolis auratus from western Colombia. Host blood pictures, parasitemia, parasite structure, infection states, and host population dynamics are correlated. Local epidemics occur, but in contrast to temperate zone species there is little regional synchronization. Active infections occur year-around, being somewhat more common in dry seasons; however, chronic infections predominate. Mature schizonts have 3 to 14, usually 6, 8, or 10 merozoites, reduced to 4 to 6 in chronic infections. Gametocytes are round to oblong, measuring 6 by 5 mu, and the pigment in microgametocytes occurs in a single peripheral vacuole. Parasitemia averaged 2.5% and seldom surpassed 20 to 30%. Infections cause significant anemia, and parasites in active infections are most common in immature erythrocytes. Host response is similar to avian or primate infections, including erythropoiesis, phagocytosis, and interference with parasite growth.

Isospora manchacensis n. sp., an intranuclear coccidian from the Louisiana ground skink, Scincella lateralis (Say, 1823) (Lacertilia: Scincidae).

Isospora manchacensis n. sp. is described from ground skinks, Scincella lateralis (Say, 1823) from Louisiana. Overall prevalence at 6 sites near Lake Ponchartrain was 43.1% (59/137) and ranged from 8% (1/13) to as high as 60% (6/10). Endogenous stages develop inside the nuclei of epithelial cells in the small intestine. Infected hypertrophic nuclei migrate from the basal lamina of the host cell to the luminal striated border. Oocysts in freshly passed fecal pellets usually contain a single contracted sporont that divides to form 2 sporoblasts. These undergo a brief pyramid stage followed by sporulation within 45-50 hr. Sporulated oocysts have a single-layered wall and measure 25.0 X 22.6 (20.0-28.9 X 18.6-26.0) micron. The lemon-shaped sporocysts measure 12.8 X 10.2 (11.1-15.2 X 9.0-11.0) micron and contain a Steida body, a spherical to oval substeida body, and a dispersed, granular sporocyst residuum. Prepatent periods in skinks fed 700 and 1,400 oocysts ranged from 24 to 32 days. Experimentally infected skinks produced large numbers of oocysts continuously during the 3-4 wk they were monitored after the onset of patency, but exhibited no signs of disease. Experimental doses of 200 oocysts failed to produce infections in skinks monitored for as long as 7 wk.

Plasmodium pessoai sp. n. from two Costa Rican snakes.

A unique malaria parasite species was found in 1/1 Spilotes pullatus (Colubridae) and 1/70 Lachesis muta (Crotalidae) from the moist Atlantic lowland forests of eastern Costa Rica. It is distinguished by small, sausage-shaped gametocytes (x 10.4 by 4.6 mu), growing schizonts that often contain a noticeable digestive vacuole with the contents partially visible, and striking spherical or bouquet-shaped segmenters whose precise merozoite numbers are difficult to discern (about 22-32) because of an intensely staining magenta or rose-colored substance in the matrix of the surrounding vacuole.

Checklist, host index, and annotated bibliography of Plasmodium from reptiles.

World literature on Plasmodium of squamate reptiles (1909-1975) includes 156 published accounts on 54 valid species and subspecies. AFRICA: 30 reports on 9 species; AUSTRALIA, ASIA & OCEANIA: 12 reports on 6 species and 2 subspecies; AMERICAS: 116 reports on 37 species. More than half of these reports and new species descriptions appeared during the last 10 years. Most concern plasmodia in lizards of the Neotropics, Georgia (Plasmodium floridense, a Neotropical-Caribbean parasite) and California (Plasmodium mexicanum). African host species are all lizards: 4 agamids, 3 skinks, 2 chamaeleonids, one chordyline, and one gerrhosaurine. Australasian host species are also all lizards: 6 agamids, 9 skinks, 2 lacertids, one (or two?) gekkonids, and one varanid. Known American host species include 12 snakes and 87 lizards: 34 anoline species, 12 sceloporines (plus 11 others experimentally infected), 4 basiliscines, 5 tropidurines, 2 iguanines, 2 skinks (one questionable), 2 anguids (a total of 4 animals), 4 sphaerodactylines, 2 gekkonines and 11 teiid species.

Hepatocystis in Hypsignathus monstrosus (pteropinea) in Gaboon I. Hepatocystis malaria in a hammerhead bat population in Gaboon, West Africa.

Blood smears from 142 Hypsignathus monstrosus collected from one site in Gaboon were examined; 139 bats showed Hepatocystis infection; it seems that all animals have acquired Hepatocystis infection by the time they are 6 months of age. Intensity of parasitemias varies according to age, sex and for females to their reproductive status.