Biomedical subjects
Publications and source records attributed to E C Greiner.
A new species of Leucocytozoon with elongate gametocytes and unique morphology is described from a Thailand thrush, Zoothera marginata, and represents the first fusiform leucocytozoid named from a passeriform. This species appears to be restricted with respect to geography and host.
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Three hundred and nine mourning doves (Zenaida macroura) from Lancaster County, Nebraska, were examined for species of Haemoproteus. Older doves possessed higher Haemoproteus prevalences than younger doves. Mean total prevalence for each dove age group was as follows: adults, 61% H. sacharovi and 83% H. maccallumi; immatures, 35% H. sacharovi and 42% H. maccallumi; and nestlings, 31% H. sacharovi and 16% H. maccallumi. Yearly prevalences were less variable in mature doves than in immature and nestling doves. No correlation between nestling and parent Haemoproteus infections were observed, but nestmates in 10 or 18 nests harbored equivalent infections. Stilbometopa podopostyla and Microlynchia pusilla (Hippoboscidae) were collected from Nebraska doves. Hippoboscidae were collected from doves of all ages from April to August. Dove baited fly traps yielded Culex tarsalis and C. pipiens in Nebraska and Culicoides haematopotus, C. crepuscularis, and Simulium aureaum in Ames, Iowa.
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The perception that bluetongue virus (BTV), once introduced to a country, would decimate its sheep industry, grew from the acceptance in the late 1950s that it was an emerging virus with Africa as its source. Epidemiological studies in the 1960s and early 1970s confirmed that the geographic distribution of BTV infections included regions of the world, outside the traditionally defined areas where BT was observed. This was interpreted at the time as representing serious and rapid spread of the virus. This review provides evidence to rebut this earlier view. What has emerged through the 1980s is: (a) the recognition that BTV is a common infection of ruminant livestock throughout the tropics and sub-tropics apparently within several separate ecosystems; (b) in most areas of the world, infection is sub-clinical; (c) incursions of virus (with accompanying disease) into temperate climates do occur at certain key locations, but "die out" usually within the same year; (d) recognition of the vector competence of Culicoides spp in the different ecosystems of the world is critical for understanding the epidemiology of disease; (e) persistent infection in ruminants is no longer considered important in the long term perpetuation of the virus.
Unilateral chorioretinitis caused by ophthalmomyiasis interna posterior in a 5-month-old, female spayed Dachshund is reported. Larva removal by pars plana vitrectomy was performed after an unsuccessful photocoagulation of the organism. The larva was intact after surgical removal and was identified as a first stage instar Cuterebra spp. larva. The eye remains visual and comfortable with no signs of residual or recurrent inflammation postoperatively. This report describes, for the first time, the successful surgical retrieval of an intravitreal fly larva in a dog using vitrectomy techniques without sacrificing either the globe or vision, and taxonomic identification of the parasite.
Quantitative hepatobiliary scintigraphy using 99mTc-mebrofenin was performed on eight normal cats and on the same cats after induction of experimental cholangiohepatitis by infection with the liver fluke Platynosomum concinnum. Hepatobiliary scintigraphy was performed 3 times at 10 weeks, 4 months and 6 months after infection. In addition, routine biochemical tests, hepatic ultrasound and ultrasound guided hepatic biopsy samples were obtained at the same time points, and the results compared with hepatobiliary scintigraphy. The normal hepatic extraction fraction was determined to be 85%, and the normal hepatic excretion half time (T 1/2) was 14 minutes. There was no significant change in scintigraphic parameters compared to pre-infection values at any time following infection with the liver fluke. No correlation between scintigraphic parameters and histologic scores was found; however, significant correlation was identified between parasite burden and histologic scores 6 months following infection. Despite the presence of severe multifocal histologic abnormalities, minimal clinical, biochemical and scintigraphic derangements were identified using this model of cholangiohepatitis. Based on this study, hepatobiliary scintigraphy appears to be an insensitive test for structural hepatobiliary abnormalities. The role of hepatobiliary scintigraphy in functional hepatobiliary abnormalities of the feline liver has not been determined.
Clinical manifestations of subcutaneous filariasis in a yellow-collared macaw (Ara auricollis) included lameness induced by subcutaneous nodule formation, which was attributed to the presence of the filarial parasite Pelecitus sp. Following anthelmintic and corticosteroid therapeutic failure, the problem was resolved by surgically removing the adult worms.
Severe anemia and intraerythrocytic stages of an unusual Plasmodium sp. were identified in the blood of a 5-month-old female emu (Dromaius novaehollandiae) that had a 4-week history of malaise. Examination of blood taken 3 days prior to the death of the bird revealed a packed cell volume of 10%. Erythrocytes showed a marked regenerative response. Approximately 4% of erythrocytes had intracytoplasmic inclusions, mainly within immature cells, resembling malarial parasites. The schizonts were a combination of the Haemamoeba and Huffia subgenera type with 8-16 merozoites in mature forms. The gametoctyes were elongate. The abnormal morphology was probably a reflection of a new host-parasite relationship. Exoerythrocytic parasite stages were not identified at necropsy. The anemia was tentatively attributed to the Plasmodium infection.