Danny B. Pence

QUANTIFICATION OF HEMATOZOA IN BLOOD SMEARS

Ten thin blood smears from mourning doves (Zenaida macroura) infected with Haemoproteus maccallumi were examined by each of two observers using identical techniques and microscopy in an attempt to delineate the factors necessary to provide an accurate estimate of the number of parasites/n erythrocytes. The number of erythrocytes examined must be actually counted, not estimated from extrapolated partial counts or from the number of fields of view examined. Doubling the number of erythrocytes counted (1) decreased the overdispersed frequency distribution patterns in only 25% of the replicate counts for numbers of H. maccallumi/100 erythrocytes for a series of 2,000 versus 4,000 erythrocytes counted; and (2) did not significantly increase the accuracy for determining parasite intensities. Thus, the number of erythrocytes that must be counted to determine parasite intensities could be considerably reduced from the 10,000 or 20,000 estimated for most studies, and still provide an accurate determination of the number of parasites/n erythrocytes in datasets collected from hosts with moderate to high levels of parasitemia. This resulted in a decreased amount of time expended by the observer on each blood smear examined. With two equivalently trained individuals, differences between observers examining the same blood smears were minimal. This study suggests an approach by which a more standardized methodology for quantifying blood parasite intensities could be developed.

The epizootiology and pathology of sarcoptic mange in coyotes, Canis latrans, from south Texas.

An epizootic of sarcoptic mange in coyotes from south Texas, Canis latrans , was studied over a 7-yr period, 1975 through 1981. From a four-county area centered in Webb County, Texas the epizootic radiated centrifugally to include a 27-county area. The disease progressed from initial, scabby encrustations on the ischium and fore and hind legs to severe, thickened, slate-gray hyperkeratotic lesions with almost complete alopecia. There were significant decreases in alpha-globulin and albumin, significant increases in gamma-globulin, and significant decreases in fat deposits and total body weight indicative of a chronic infection with establishment of a humoral antibody response as the infection progressed in severity. Significant differences in prevalence of mange across habitat variables of host age and sex, and across seasons were related to the juvenile/adult ratio in the coyote population at any particular time because the infection progressed more rapidly in juveniles. Population dynamics and abundance of coyotes were generally unaffected by the mange epizootic. Although higher mortality was associated with mange-infected animals, this had no effect on overall mortality in the coyote population.

Ecology of Helminth Parasitism in the Bobcat from West Texas

One trematode, 2 cestode, 11 nematode, and 1 acanthocephalan species were collected from 66 bobcats, Felis rufus, in the Rolling Plains of West Texas between 1973 and 1977. These helminths included Alaria marcianae (5% of the bobcats infected), Taenia rileyi (91%), Mesocestoides corti (36%), Physaloptera praeputialis (88%), Cyathospirura chevreuxi (80%), Cylicospirura felineus (70%), Didelphonema longispiculatum (5%), Toxascaris leonina (91%), Toxocara mystax (17% ), Ancylostoma tubaeforme (58%), Pterygondermatites cahirensis (3%), Vogeloides felis (80%), Metathelazia californica (73%), Capillaria aerophila (3%), and Oncicola canis (14%). Scarring of the aorta due to Spirocerca lupi was observed in 35% of these animals. All hosts were infected with from 2 to 11 helminth species (x = 7.4 species). Simpsons index for all helminth species was low (0.10) indicating a lack of dominance of particular species in the helminth population of this host. Comparison of the helminth fauna of bobcats in West Texas with those of 4 other geographic areas in North America using Sorensons index of similarity indicated a basic dissimilarity in helminth faunas of bobcats in different regions. Associations between the more prevalent helminth species were determined using frequency of occurrence and mean levels of infections. Significant relationships were noted in the frequency of occurrence of 8 pairs of helminth species. Coles coefficient of association indicated a positive association between these species. Analysis of mean infection levels indicated significant relationships between 6 pairs of helminth species. A clumped distribution was indicated among the several species of spirurid nematodes occurring in the bobcat. These associations are explained in terms of the food habits (intermediate and paratenic hosts) and age of the host. Comparison of helminth species with the sex of the host based on frequency of occurrence indicated males were significantly more often infected with C. felineus and M. californica. Comparison of mean levels of infection indicated males had significantly higher levels of infection with C. chevreuxi, V. felis, and T. rileyi. Helminth parasitism has been sporadically examined in the bobcat, Felis rufus, from various localities in North America (Rollings, 1945; Pollack, 1949; Progulske, 1952; Miller and Harkema, 1968; Little et al., 1971). This host is distributed through widely varying habitats in the United States and Canada. It has recently become an economically important furbearer and is the only wild felid likely to remain in any abundance in Texas (Russell, 1971) and probably most of the United States. The present study was initiated in order to better understand the nature, prevalence, and intensity of helminth parasitism and to elucidate certain ecological relationships of parasitism including concentration of dominance, Received for publication 3 June 1977. * Department of Range and Wildlife Management, Texas Tech University, Lubbock, Texas 79409. Present address: Department of Forest Zoology, College of Environmental Science and Forestry, State University of New York, Syracuse, New York 13210. t Department of Pathology, Division of Comparative Pathology, Texas Tech University Health Sciences Centers, Lubbock, Texas 79409. similarity of helminth faunas between different geographic areas, and the nature of distributions of aggregations of helminth species in this host. MATERIALS AND METHODS Sixty-six bobcats were collected in the Rolling Plains of Texas in King, Knox, and Dickens counties between December 1973 and January 1977. The study area is characterized by gently rolling plains dominated by honey mesquite, Prosopis glandulosa, and native grasses intermingled with vast erosion beds of very uneven topography (breaks) with redberry juniper, Juniperus pinchotii, native grasses, and cacti as the predominant vegetation. Although interspersed with some land suitable for dryland farming, the area is principally utilized as rangeland. The majority of bobcats were obtained as carcasses from fur trappers. Body weights, measurements, and age determinations were obtained from 63 hosts prior to skinning. Usually, viscera were frozen in the field and later examined in the laboratory. The stomach of each animal was examined for prey remains, the results of which will be reported elsewhere (Stone and Pence, in preparation). Musculature and subcutaneous tissues were examined for filariids and a 2-cm square portion of diaphragm from each host was viewed microscopically in a muscle press for Trichinella

Population Dynamics across Selected Habitat Variables of the Helminth Community in Coyotes, Canis latrans, from South Texas

The effects of selected intrinsic variables operating on host subpopulations and of extrinsic variables across the collective host population on the distributions of 10 common helminth species from coyotes in south Texas were compared. The intrinsic variables of host sex and presence and severity of sarcoptic mange had little effect on the distributions of most helminth species. The combined influences of (1) seasonal changes across the collective host population and (2) host subpopulations delineated by age were responsible for the overdispersed distributions of Oncicola canis, Physaloptera rara, and Protospirura numidica. Overdispersion in Ancylostoma caninum, Alaria marcianae, and Spirocerca lupi populations resulted almost exclusively from the heterogeneity of factors contributing to their rates of establishment, survival, and reproduction as generated across host age subpopulations. Aggregated abundances of A. caninum and A. marcianae occurred in young hosts, but were cumulative in older animals infected with S. lupi. The hypothesis that heterogeneity within the host population, rather than across the collective host population, is the main factor generating overdispersion in natural populations was confirmed for only 3 of 10 helminth species (A. caninum, A. marcianae, and S. lupi). The effects of extrinsic factors operating across the collective host population appeared to be equal to, or in some instances of greater importance than, these forces operating over host subpopulations in determining the dispersion patterns of some helminth species (O. canis, P. rara, and P. numidica). The distributions of Taenia pisiformis, Mesocestoides lineatus, Oslerus osleri, and Toxascaris leonina were not affected, or only minimally influenced, by these intrinsic or extrinsic variables. The effects of these habitat variables on dispersion patterns are highly correlated with the life cycle and mode of transmission of the respective helminth species.

Ecological analyses of helminth populations in the black bear, Ursus Americanus, from North America

Faunal similarity was examined using a data base of 23 helminth species from 104 black bears collected in the southeastern United States. With the eight common helminth species, analysis of faunal similarity indicated relative consistency across nested habitat variables of host age and sex, and some degree of maturity of interrelationships between species within this helminth fauna. A basic dissimilarity in the helminth faunas of black bears across 11 geographic regions in North America resulted from (1) a distinct helminth fauna in the southeastern United States, but with considerable variation across four subregions, (2) a disparity of helminth species in the primary community represented by Dirofilaria ursi and Baylisascaris transfuga, which were the only host-specific species approaching ubiquitous distribution across all regions in North America, and (3) considerable diversity resulting from numerous shared species of raccoon and canid origin comprising a large secondary community of rare to common helminth species across the respective regions. Studies such as this one may lead to a more decisive means of delineating predictive models for the parasite species involved in epidemics. Previous studies on the helminth communities of several species of wild Carnivora in North

Epizootic podoknemidokoptiasis in American robins.

Epizootics of scaly leg disease caused by infection with the submacroscopic mite Knemidokoptes jamaicensis (Acari: Knemidokoptidae) in migratory American robins (Turdus migratorius) from a residential area of Tulsa (Oklahoma, USA) are documented during the winters (December through February) of 1993–94 and 1994–95. Estimates of 60 to >80% of the birds in several different flights arriving in the area had lesions consistent with knemidokoptic mange. Epizootic occurrence of K. jamaicensis also is confirmed incidentally in American robins from Georgia (USA) in 1995 and 1998 and in Florida (USA) in 1991. These are the first confirmed epizootics of scaly leg attributed to infections with mites specifically identified as K. jamaicensis in North America. Severity of observed lesions in American robins ranged from scaly hyperkeratosis of the feet and legs to extensive proliferative lesions with loss of digits or the entire foot in some birds. Histologically, there was severe diffuse hyperkeratosis of the epidermis which contained numerous mites and multifocal aggregates of degranulating to degenerating eosinophilic heterophils; there was mild to severe superficial dermatitis with aggregates of eosinophilic heterophils and some mononuclear cells. Based on limited data from affected captive birds in Florida, we questioned the efficacy of ivermectin as an effective acaricide for knemidokoptiasis and propose that conditions associated with captivity may exacerbate transmission of this mite among caged birds. While knemidokoptic mange apparently can result in substantial host morbidity and possibly mortality, the ultimate impact of these epizootics on American robin populations presently is unknown.

Helminths of the ocelot from southern Texas.

In the USA, the ocelot (Leopardus pardalis) is a highly endangered felid found only in a few remaining vestiges of native thornshrub brushland in the Lower Rio Grande Valley (LRGV) of extreme southern Texas. From 1987–1998, carcasses of 15 adult ocelots that died of vehicular accidents or natural causes were examined for helminths. All cats had 1–8 (mean=3) helminth species. All were infected with 1–101 (mean±SE=32±7) Toxascaris leonina. Other helminths from these ocelots were Alaria marcianae, Brachylaima sp., Mesocestoides lineatus, Taenia rileyi, Oncicola canis, Dirofilaria immitis, Physaloptera rara, Ancylostoma tubaeformae, Cylicospirura chevreuxi, Vogeloides felis, and Metathelazia californica. Additionally, two cats had scarring of the aorta with lesions typical of those caused by Spriocerca lupi, although larval nematodes were not seen. A clinal variation in size of nearly three orders of magnitude was noted in the diplostomatid trematodes in the small intestine of one adult male ocelot. Despite the differences in size, all specimens appeared morphologically identical and were regarded as A. marcianae. Helminth prevalences and abundances, including those of potentially pathogenic species like D. immitis, were low. Although a single heartworm infection may have contributed to the death of one ocelot, helminth infections in general seemed to be of no great consequence to this endangered ocelot population. The helminth fauna of ocelots in the LRGV is reflective of that from wild felids in general; all have been reported previously from the bobcat (Lynx rufus) and mountain lion (Puma concolor) elsewhere in Texas.

COMPARISON OF THE HELMINTH FAUNAS OF TWO SYMPATRIC TOP CARNIVORES FROM THE ROLLING PLAINS OF TEXAS

Analysis of data collected from previous studies on the helminth parasites of the bobcat, Felis rufus, and the coyote, Canis latrans, from the Rolling Plains of Texas indicated that of the 28 different helminth species recovered, six were common to both carnivore hosts. Bobcats and coyotes harbored 16 and 18 helminth species, respectively. Simpsons indices for both hosts were very low (0.10 and 0.12 for coyotes and bobcats, respectively) indicating a lack of dominance by particular helminth species. An index of similarity and an overlap index (Jaccards coefficients) were low (29.5 and 21.4, respectively) indicating that the faunas of these two hosts were basically dissimilar with little sharing of helminth species. Im- portance indices of helminth faunas from both hosts revealed: 1) the bobcat with nine and coyote with seven dominant helminth species; 2) three and five codominant helminth species in the bobcat and coyote, respectively; 3) one and two successful immigrant species in the bobcat and coyote, respectively; and 4) the bobcat and coyote with three and four unsuccessful immigrant helminth species, respectively. Two common dominant species, Toxascaris leonina and Mesocestoides corti, were shared by both hosts. These hosts also shared two codominant species, Onicola canis and Alaria marcianae. Pterygondermatites ca- hirensis was a dominant species in the coyote, but an unsuccessful immigrant in the bobcat. Likewise, Spirocerca lupi was a codominant species in the coyote, but an unsuccessful immigrant in the bobcat. Chi-square analysis of the two dominant and two codominant helminth species shared between these hosts revealed a significantly greater frequency of occurrence of M. corti and 0. canis in the coyote. Comparison of mean infrapopulation densities of shared helminth species indicated that the coyote had a significantly greater mean worm burden of T. leonina and 0. canis than the bobcat. Thus, of the six shared helminths, two dominant species, T. leonina and M. corti, and two codominant species, 0. canis and A. marcianae, appeared to be successfully maintained by both carnivores, whereas the remaining two species, S. lupi and P. cahirensis, were parasites of coyotes and unsuccessful immigrants in the helminth fauna of bobcats.

Helminth and arthropod parasites of the brown pelican, Pelecanus occidentalis , in Puerto Rico, with a compilation of all metazoan parasites reported from this host in the Western Hemisphere

Seven species of helminths and six species of arthropods are reported from 23 of 40 brown pelicans, Pelecanus occidentalis , collected from various localities in Puerto Rico. Helminth parasites include three nematodes ( Contracaecum multipapillatum , Contracaecum mexicanum , and Eustrongylides sp.), three trematodes ( Galactosomum darbyi , Mesostephanus appendiculatoides , and Ribeiroia ondatrae ), and one cestode ( Tetrabothrium sulae ). Arthropod parasites include Colpocephalum occidentalis , Neottialges apunctatus , Ornithodoros capensis, Phalacrodectus pelecani, Phalacrodectus punctatissimus , and Phalacrodectus sp. The presence of R. ondatrae in the brown pelican is a new species host record, and P. pelecani, P. punctatissimus and N. apunctatus are new subspecies host records. C. multipapillatum , C. mexicanum , G. darbyi and M. appendiculatoides are new locality records for Puerto Rico, and N. apunctatus, P. pelecani, P. punctatissimus and T. sulae are new locality records for the Caribbean. Necrosis produced by C. multipapillatum , C. mexicanum , and R. ondatrae may have contributed to the emaciation and death of the brown pelicans examined in the present study.

Helminth Fauna of Beaver from Central Texas

Received for publication 25 October 1985. ‘To whom correspondence should be addressed. whether they may have been acquired locally. However, a number of ducks harboring immature specimens of Tetrameres were found also suggesting that local transmission may be possible (McLaughlin, unpubl. data). A single ovigerous specimen of Capillaria was found in the caecum of one coot and, as this genus has a direct life cycle, local transmission is clearly possible. I thank the late Dr. David Skead and his family for their generous hospitality during my stay at Barberspan and for his help in collecting coots. This work was supported by Natural Sciences and Engineering Research Council of Canada grant A6979.