Transmission of Cowdria ruminantium by Amblyomma gemma from infected African buffalo (Syncerus caffer) and eland (Taurotragus oryx) to sheep.

Two African buffalo (Syncerus caffer), an eland (Taurotragus oryx) and a waterbuck (Kobus defassa) were intravenously inoculated with Cowdria ruminantium (Kiswani). Amblyomma gemma nymphs were fed on the animals at 3 weekly intervals. Jugular blood was also collected at 3 weekly intervals and inoculated into sheep. Nymphal ticks that fed on one buffalo on days 16 and 37 and on the other buffalo on day 58 after infection transmitted the disease as adults to sheep. Nymphs that were applied to the eland 16 days after infection also transmitted the disease to sheep. No nymphs that had fed on the waterbuck transmitted the disease. This is the first report of transmission of heartwater by Amblyomma gemma from infected wild ruminant species to a susceptible domestic ruminant species.

Cowdria ruminantium identified in Amblyomma gemma using a DNA probe pCS20.

Amblyomma gemma ticks were collected from wild animals on a 20,000 acre game ranch in a heartwater endemic area in Kenya, close to Nairobi. A. variegatum is the main vector of heartwater in Kenya. E.A. LEWIS, 1947, in a one sentence report has implicated A. gemma to be a vector of heartwater without giving any details. Adult A. gemma were collected from giraffe Giraffa camelopardalis, hartebeest Alcephalus busephalus, Eland Taurotragus oryx and ostrich Struthio camelus during cropping exercises. The unengorged ticks were fed on 3 susceptible Dorper sheep which were monitored daily for the clinical symptoms of heartwater. All the ticks, including those that were fed on sheep were dissected and the guts probed for the presence of Cowdria ruminantium using a cloned DNA probe, the pCS20. None of the sheep on which the ticks were fed showed heartwater symptoms up to 60 days from the attachment of the ticks. The DNA probe identified Cowdria ruminantium in the ticks collected from eland and giraffe.

Isolation of Borrelia burgdorferi (Spirochaetales: Spirochaetaceae) from Ixodes scapularis and Dermacentor albipictus ticks (Acari: Ixodidae) in Oklahoma.

Borrelia burgdorferi was isolated from Ixodes scapularis Say and Dermacentor albipictus Packard that were removed as partially fed adults from white-tailed deer, Odocoileus virginianus Zimmermann, in Oklahoma. Isolation in media was accomplished only after homogenates of pooled field-collected ticks were inoculated into laboratory-reared Peromyscus leucopus and reisolated from the urinary bladder into BSK II media. Both isolates were confirmed by western blot analysis and reactivity with monoclonal antibody H5332. These are the first reported isolates of B. burgdorferi from Oklahoma from these two tick species and are the first isolates from ticks from the south-central United States that were infective for laboratory-reared P. leucopus.

Attempted transmission of Borrelia burgdorferi (Spirochaetales: Spirochaetaceae) (JDI strain) by Ixodes scapularis (Acari: Ixodidae), Dermacentor variabilis, and Amblyomma americanum.

Laboratory-reared Ixodes scapularis Say, Amblyomma americanum (L.), and Dermacentor variabilis (Say) were fed on New Zealand white rabbits experimentally infected with Borrelia burgdorferi (JDI strain). At repletion, spirochetes could be detected by dark-field microscopy only in I. scapularis. Acquisition rates were 18 and 21%. When previously exposed nymphs of each species were fed on susceptible rabbits, I. scapularis was the only tick of the three species that transmitted B. burgdorferi. When a single rabbit was experimentally infected with B. burgdorferi and infested at 7-d intervals with I. scapularis, A. americanum, D. variabilis, and a second time with I. scapularis, B. burgdorferi was detected again only in cultures from the two groups of I. scapularis. When molted nymphs from each tick species were allowed to feed on susceptible rabbits, spirochetes again were isolated only at necropsy from the rabbits on which the two groups of I. scapularis fed.

A redescription of schizogony of Cytauxzoon felis in the domestic cat.

Cytauxzoon felis is a protozoan parasite that is transmitted by Dermacentor variabilis ticks and causes a uniformly fatal disease in domestic cats. In order to study schizogony and merozoite formation, D. variabilis nymphs were allowed to feed on domestic cats experimentally infected with C. felis, after which the molted adult ticks were fed on susceptible cats. Lung and liver tissues were collected from the cats during clinical cytauxzoonosis and were fixed for light and transmission electron microscopy. Some stages of parasite development were evident with light microscopy, but specific events associated with merogony could be documented only with electron microscopy. Schizogony was observed in endothelial macrophages of all tissues examined. The parasite appeared first as a multinucleated syncytium in which nuclear proliferation was evident. As the parasite syncytium developed, it became an increasingly elaborate labyrinth with extensive branches that were interconnected by thin processes of parasite cytoplasm. Organelles, including mitochondria and rhoptries, became apparent. Merozoite formation seemed to occur by rapid sequential fission along the margins of the multinucleated sporont in the cytoplasm of the host cell. As the sporont became smaller, merozoites were produced in a rosette-like configuration from the remaining parasite mass. Merozoites entered erythrocytes directly by endocytosis, without apparent injury to these cells. The sequence of events associated with merozoite formation in Cytauxzoon felis described herein differs from the previous description for this species and appears to be analogous to that described for the genus Theileria.

Serological survey for Lyme disease in domestic dogs and white-tailed deer from Oklahoma.

Sera from 223 randomly selected dogs and 489 white-tailed deer (Odocoileus virginianus) were tested for antibodies to Borrelia burgdorferi using an indirect kinetic ELISA. Dog samples were obtained in 1989 whereas deer samples were obtained between 1975 and 1990. Ten known negatives and two known positives from each group were run on each plate as controls. Samples showing mean mOD values above the mean of negatives + 3 SD were considered positive. Twenty-six dog (11.7%) and 22 deer (4.5%) samples were positive. Deer reactors were first detected among 1978 samples. Reactive deer were from central and eastern Oklahoma whereas reactive dogs were mostly from central Oklahoma. Confirmed human cases between 1986 and 1989 were distributed throughout the state, thus showing no correlation with either deer or dog results.

Isolation of Borrelia burgdorferi from Peromyscus leucopus in Oklahoma.

Borrelia burgdorferi was isolated from a field-caught Peromyscus leucopus from central Oklahoma (USA). The strain was identified as B. burgdorferi by reaction with monoclonal antibody H5332 specific for the outer surface protein OspA of B. burgdorferi. This represents the first isolation of B. burgdorferi from a wild mouse outside of the normal range of the known vectors Ixodes dammini and I. pacificus.

Activity of buparvaquone against Theileria cervi in white-tailed deer.

Buparvaquone, a naphthoquinone with known efficacy against Theileria parva parva in cattle, was tested for activity against Theileria cervi piroplasms in both an in vitro culture system and in vivo in experimentally infected white-tailed deer. The in vitro data showed a significant decrease in the incorporation of 3H-hypoxanthine by infected red blood cells treated with buparvaquone when compared to that seen with imidocarb and chloroquine treatment. In both intact and splenectomized deer treated with buparvaquone (2.5 mg kg-1) a gradual decrease in piroplasm parasitaemia was observed following treatment. However, in the splenectomized deer, parasitaemia levels returned to near pretreatment values after approximately 2 weeks.

Isolation of bovine herpesvirus-3 from African buffaloes (Syncerus caffer).

Eleven virus isolations were made from the blood of 45 free living healthy African buffaloes by long term cocultivation of their leucocytes with bovine thymus or spleen cells. The isolates were indistinguishable from each other or from herpesviruses isolated from a severely ill buffalo calf and from a dead buffalo. These viruses possessed the characteristics of the bovine herpesvirus-3 (BHV-3) group and were indistinguishable by serology and restriction endonuclease analysis from the BHV-3 type strains Movar 33/63 and DN599. There was a 93.6 per cent prevalence of indirect immunofluorescent antibody to BHV-3 in the sera of 94 buffaloes in the sample population. No clinical signs or viraemia were detected in five cattle inoculated with 10(8.7) log10 TCID50 of the isolate from the sick buffalo calf. Two of three cattle hyperimmunised with this virus resisted challenge with malignant catarrhal fever herpesvirus, which proved fatal for the other immunised animal and for three control cattle.

Failure to detect infection in fallow deer (Cervus dama) exposed to Theileria cervi from white-tailed deer.

A frozen stabilate was produced from Theileria cervi sporozoites in salivary glands of adult Amblyomma americanum. The stabilate was inoculated into three fallow deer (Cervus dama) and two white-tailed deer (Odocoileus virginianus). Following inoculation, the white-tailed deer developed parasitemias as determined by blood smear examination at 11 and 13 days postexposure. Repeat examination of blood from the three fallow deer for 30 days postexposure failed to reveal observable piro-plasms. These findings indicate that fallow deer are not as susceptible to the Theileria cervi found in white-tailed deer from North America. Thus, there are some questions regarding the taxonomic position of this organism.