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Biomedical subjects

A A Kocan

Publications and source records attributed to A A Kocan.

At least 19 recordsLinked to original sources
PubMed1992

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.

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PubMed1992

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.

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PubMed1992

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.

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PubMed1992

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.

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PubMed1992

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.

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PubMed1991

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.

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PubMed1991

Gastropod availability and habitat utilization by wapiti and white-tailed deer sympatric on range enzootic for meningeal worm.

Gastropod occurrence and the utilization of habitat by sympatric populations of wapiti (Cervus elephus) and white-tailed deer (Odocoileus virginianus) on range enzootic for meningeal worm (Parelaphostrongylus tenuis) were studied on Cookson Hills Wildlife Management Area (WMA) in eastern Oklahoma. Visual observations and fecal pellet group transect data indicated that wapiti spent the majority of their time in open fields and meadows where we recovered the least numbers of gastropods. Although deer were frequently observed in open areas, visual sightings and transect data indicated that they spent more time in forested areas where we recovered the most gastropods. Gastropods harbored low numbers of P. tenuis larvae (0.00 to 0.06 larvae/gastropod) in all habitat types with the greatest recovery from red oak white oak-hickory forests (0.34 larvae/gastropod). Our results indicate that the reason a viable wapiti herd exists on Cookson Hills WMA in a P. tenuis enzootic area is at least partially because of the habitat preference by wapiti and the reduced availability of infected gastropods in the selected areas prefered by the wapiti. We were not able to detect any free-ranging wapiti that were shedding P. tenuis larvae nor were we able to detect past or sub-clinical infections with P. tenuis in wapiti.

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PubMed1989

Serological prevalence and isolation of Babesia odocoilei among white-tailed deer (Odocoileus virginianus) in Texas and Oklahoma.

Serum samples collected from 581 white-tailed deer (Odocoileus virginianus) from Texas and from 124 white-tailed deer from Oklahoma were tested by the indirect fluorescent antibody technique against Babesia odocoilei. Prevalence of seropositive reactors varied from site to site in both states. Prevalence rates were statistically ranked as high, intermediate or low. Deer less than 12-mo-old had a significantly lower prevalence than all other age classes.

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PubMed1988

Tick paralysis.

Explore the source record for details and available documents.

Animals↗
PubMed1988

Susceptibility of Amblyomma americanum to natural and experimental infections with Theileria cervi.

One hundred fifty Amblyomma americanum were examined between March and September 1986 from Cookson Hills Wildlife Refuge in eastern Oklahoma (USA). Of these ticks, 11% (17 of 150) were infected with Theileria cervi. Field-collected nymphal ticks had an 8% (3 of 37) prevalence of infection averaging 1.0 infected acini/nymph. Female ticks had a 16% prevalence of infection averaging 1.6 infected acini/female; T. cervi was not observed in salivary glands of field-collected male ticks. When laboratory reared A. americanum nymphs were allowed to feed on experimental white-tailed deer (Odocoileus virginianus) with varying T. cervi parasitemias (less than 1, 2, 6 and greater than 20%), only ticks which fed on deer with parasitemias greater than 1% became infected. Although prevalence and intensity of infection varied in the infected ticks, there was no significant difference in prevalence of infection between males and females. However, females did acquire significantly greater intensities than males. The data from these studies confirm that T. cervi overwinters in A. americanum and suggests that the prevalence, intensity and abundance of infection of T. cervi in ticks is influenced by the parasitemia of the deer host. Furthermore, fawns may play a more important role in the epidemiology of T. cervi transmission than do adult deer because of the coordination between tick activity patterns and deer fawning.

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PubMed1987

Evidence of a limited schizogonous cycle for Cytauxzoon felis in bobcats following exposure to infected ticks.

Schizogonous tissue stages of Cytauxzoon felis (Apicomplexa: Theileridae) were not observed by microscopic evaluation of impression smears of liver, spleen, lung and lymph nodes in 10 bobcats (Lynx rufus) from Oklahoma with naturally occurring piroplasm infections. Schizogonous stages were observed in similar tissues from experimentally-infected bobcats at 11 days postexposure to infected Dermacentor variabilis, but not at 30 days following tick feeding. The schizogonous cycle of this parasite appears to be short, although the bobcat appears to be a long-term carrier.

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PubMed1987

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.

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PubMed1987

Bluetongue and epizootic hemorrhagic disease in white-tailed deer from Oklahoma: serologic evaluation and virus isolation.

Blood samples were collected from 194 white-tailed deer from 27 locations in Oklahoma from 1977 through 1984. Sixty-eight (35%) of the deer had antibody against bluetongue virus (BTV) and 78 (40%) had antibody against epizootic hemorrhagic disease virus. Seropositive deer were detected in each of the 4 geographic quadrants of the state. Virus isolation was attempted in 40 deer from the northeast quadrant of Oklahoma (1983 through 1984); BTV was isolated from 11 deer, but epizootic hemorrhagic disease virus was not isolated. The isolation of BTV serotype 11 from these deer from 1983 through 1984 coincided with reported isolations of this serotype in other ruminants in Oklahoma during this time.

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PubMed1987

The ultrastructure of sporogony in Theileria cervi (Bettencourt et al., 1907) in salivary glands of female Amblyomma americanum (L.) ticks.

The process of sporogony of Theileria cervi in salivary glands of unfed and feeding Amblyomma americanum females that were infected as nymphs was studied by light and electron microscopy (SEM and TEM). Sporogony was observed only in granular acini type III and in cells classified as complex granular. Infected acini in salivary glands of both unfed and feeding ticks were enlarged. Some stages of parasite development were evident with light microscopy and SEM, but the specific events of sporogony could be documented only with TEM. Nuclear division was evident in unfed adults and continued throughout the developmental process. As the ticks fed, the parasite syncytium became increasingly complex and branches formed that were connected by thin processes. Sporozoites appeared to form by rapid sequential fission of the multinucleate sporont. Initially, sporozoites were oblong in shape and became rounded when mature. Rhoptries and micronemes were located at the hemisphere of the sporozoite that was opposite from the nucleus. Experimentally infected A. americanum transmitted T. cervi to susceptible fawns with a prepatent period of 14 and 20 days. This is the first ultrastructural description of sporogony in T. cervi in tick salivary glands.

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