Alan M. Fedynich

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.

EVIDENCE OF AN OXYSPIRURA PETROWI EPIZOOTIC IN NORTHERN BOBWHITES (COLINUS VIRGINIANUS), TEXAS, USA

Abstract We captured 36 Northern Bobwhites (Colinus virginianus) in Mitchell County, Texas in June–September 2013, and examined them for the eyeworm Oxyspirura petrowi. We recovered 334 eyeworms from 28 of 29 adult bobwhites (97%); infections ranged from 1–40 worms and mean (±SD) abundance of 11.9±13.0. Three of seven juveniles were infected, and those infected had one eyeworm each. Prevalence of eyeworms was similar among months. However, mean abundance of eyeworms peaked in July and August (3.3±2.1, 13.5±15.0, and 16.9±15.5), and decreased in September (6.3±3.0). We suggest that several previous studies may underreport prevalence and abundance because in those studies only the eye surface and nictitating membrane were examined, and not eye-associated tissue, ducts, glands, or sinuses.

Survival of Trichomonas gallinae in white-winged dove carcasses.

Survival of Trichomonas gallinae was examined in white-winged dove (Zenaida asiatica) carcasses to assess whether birds that have been dead up to 8 hr can be sampled reliably for this protozoan. Carcasses of 100 T. gallinae-positive white-winged doves were separated into four groups of 25 birds, representing 2, 4, 6, and 8 hr post mortem sampling intervals and placed into an environmental chamber maintained at 27 C and 75% relative humidity. Live T. gallinae were isolated in 96, 100, 100, and 92% of the carcasses at each of the respective post mortem intervals. The experiment was repeated with another 100 carcasses of T. gallinae-positive white-winged doves placed in the environmental chamber, this time maintained at 27 C and 40% relative humidity. Live T. gallinae occurred in 96, 100, 96, and 100% of the carcasses at each of the respective post mortem intervals. Across both trials, the overall ability to detect positive birds from sampling carcasses up to 8 hrs post mortem was 97%. An a posteriori experiment was conducted in which 23 and 18 carcasses from the second trial were maintained in the environmental chamber at 27 C and 40% relative humidity and resampled at 24 and 48 hr post mortem, respectively. Live trichomonads were isolated from 91 and 44% of the carcasses at 24 and 48 hr, respectively. Results suggest live T. gallinae can be obtained from dove carcasses reliably up to 8 hr and possibly up to 24 hr after host death. The ability for T. gallinae to survive within this time interval can aid wildlife personnel in monitoring this protozoan at hunter check stations or obtaining samples from recently killed birds.

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.

Pathological Response of Northern Bobwhites to Oxyspirura petrowi Infections

Abstract:  The effects of Oxyspirura petrowi infections in northern bobwhites (Colinus virginianus) are not well understood. While studies have reported O. petrowi infections, none has histopathologically examined the eye surface and intraorbital glands to assess cellular-level impacts associated with infection. This study is the first to document the histopathology associated with O. petrowi infections. Oxyspirura petrowi occurred on the eye surface as well as in the conjunctiva, lacrimal ducts, lacrimal glands, and Harderian glands. Histopathology showed infections of O. petrowi caused cellular damage to these tissues, scarring and interstitial keratitis of the cornea, and acinar atrophy of the Harderian gland.

EVALUATION OF ALLOZYME AND MICROSATELLITE VARIATION IN TEXAS AND FLORIDA MOTTLED DUCKS

Abstract Genetic variation was evaluated in Florida Mottled Ducks (Anas fulvigula), and Mottled Ducks from the larger Texas population using 22 allozyme and 5 microsatellite loci. Both marker types revealed differences in allele frequencies between populations and each population possessed rare and unique alleles. Overall allelic distributions were significantly different between the two populations, primarily due to significant differences at three allozyme and four microsatellite loci. Significant genetic differentiation was revealed between populations with both marker types, however, over all loci, only 5–6% of the variation detected was partitioned between populations. The Florida population possessed lower levels of allozyme heterozygosity and allelic diversity than the Texas population. In contrast, microsatellite heterozygosities and allelic diversity were similar between populations. These data indicate that there is limited gene flow between populations, suggesting that populations should continue to be managed separately. Evaluación de la Variación en Aloenzimas y Microsatélites en Anas fulvigula en Texas y Florida Resumen. Se evaluó la variación genética en el pato Anas fulvigula en Florida y en una población más grande de Texas, utilizando 22 aloenzimas y 5 loci microsatelitales. Ambos marcadores revelaron que existen diferencias entre las poblaciones en sus frecuencias alélicas, y cada población presentó alelos raros y únicos. La distribución general de alelos fue significativamente diferente entre las dos poblaciones, debido principalmente a diferencias significativas en tres aloenzimas y cuatro loci microsatelitales. Se encontró una diferenciación genética significativa entre las poblaciones considerando ambos marcadores, sin embargo, considerando los loci en conjunto, sólo el 5–6% de la variación detectada estuvo repartida entre las poblaciones. La población de Florida presentó niveles menores de heterocigocidad y diversidad alélica en las aloenzimas que la población de Texas. En contraste, la heterocigocidad y la diversidad alélica de los microsatélites fueron similares entre las poblaciones. Estos datos indican que el flujo génico entre las poblaciones es limitado, sugiriendo que deben seguir siendo manejadas de modo separado.

Hemosporid (Apicomplexa, Hematozoea, Hemosporida) Community Structure and Pattern in Wintering Wild Turkeys

The hemosporid community of 76 wild turkeys (Meleagris gallopavo silvestris) from South Carolina (USA) was examined using thin blood smears collected during January and February 1994. High prevalences and low abundances of hemosporids characterized this community. Leucocytozoon smithi and Haemoproteus meleagridis occurred in 100% and 54% of the turkeys, respectively; a Plasmodium sp. was found in one bird. Prevalence of H. meleagridis was significantly higher in juvenile turkeys than adults, but prevalences did not differ significantly among four trap sites or by host sex. Mean (±SE) intensities of L. smithi, H. meleagridis, and Plasmodium sp. were 3.4 ± 0.4, 1.8 ± 0.3, and 3.0 per 10,000 erythrocytes, respectively. Abundances of L. smithi, H. meleagridis, and Plasmodium sp. were 3.4 ± 0.4, 0.9 ± 0.2, and <0.1 ± <0.1 per 10,000 erythrocytes, respectively. Juvenile turkeys had higher rank abundance values of L. smithi than adults, whereas no differences were found among trap sites or between sexes. No differences in rank abundances of H. meleagridis were found among trap sites, host age, or host sex variables. Collectively, both common hemosporid species varied by host age, reflecting higher abundances in juvenile turkeys. Patterns of hemosporid prevalence appeared similar to patterns found in subtropical regions. Based on our data, we recommend using prevalence and abundance data to analyze the structure and pattern of hemosporid communities at the component community level.

EFFECTS OF HOST AND SPATIAL FACTORS ON A HAEMOPROTEID COMMUNITY IN MOURNING DOVES FROM WESTERN TEXAS

Two species of hematozoa, Haemoproteus columbae and H. sacharovi, were observed on thin blood smears from populations of mourning doves (Zenaida macroura) in the Rolling Plains (RP, a semiarid dryland farming and grazing area) and Southern High Plains (SHP, an intensively cultivated and irrigated agricultural region with playa lakes) of western Texas (USA). Prevalences of H. columbae and H. sacharovi were 91 and 18% in doves from the RP (n = 44 doves examined) and 81 and 36% in those from the SHP (n = 84), respectively. Although the prevalences of these species were not significantly different between the RP and SHP, the prevalence of H. sacharovi was significantly greater in juvenile versus adult doves from both localities. Mixed infections of both haemoproteid species occurred in 11 and 24% of the doves from the RP and SHP, respectively. The frequency distributions of the relative density values (numbers of parasites/2,000 erythrocytes counted) of H. columbae and H. sacharovi were overdispersed in hosts from both localities. Relative densities of H. columbae were significantly higher in mourning doves from the RP versus the SHP; likewise those of H. sacharovi were significantly greater in juvenile versus adult doves and between localities. Observed differences in prevalence and relative density of the two species in the haemoproteid community across spatial and host variables may reflect differences in vector transmission and in the physiological and immunological status of the host. This study emphasizes the importance of using adequately quantified density data versus only prevalence data when examining microparasite communities at the component community level.

Hematozoa in the Endangered Wood Stork from Georgia

Thin blood smears of 75 wood storks (Mycteria americana) from Georgia (USA) were made during the summers of 1994–96 and examined for blood parasites. Haemoproteus crnmenium was found in one of 71 juveniles and in two adults from a sample of two subadults and two adults. Intensity of infection in the juvenile and in each of the two adults was 11, 3, and 2 parasites/5,000 erythrocytes, respectively. This is the first record of H. crumenium in the wood stork from Georgia and the second published record of H. crumenium infecting this host in North America. Additionally, one juvenile was infected with a microfilarid.

Live Eyeworm (Oxyspirura petrowi) Extraction, In Vitro Culture, and Transfer for Experimental Studies

Abstract:  Northern bobwhite (Colinus virginianus) have experienced a dramatic decline in West Texas over the last 3 yr, and investigations are underway to evaluate the role of parasites in this decline. One of the key parasites being investigated is the eyeworm (Oxyspirura petrowi). Live eyeworms were extracted from both live and dead northern bobwhites, and in vitro survival was tested using 10 liquid media. Eyeworms placed in an egg white and physiological saline solution lived for at least 36 days. Live O. petrowi placed into the eyes of uninfected pen-raised bobwhites were monitored for 21 days to demonstrate successful transfer. Eyeworm behavior during feeding, mating, and development were monitored. This study is important to research that requires “banking” of live O. petrowi from wild-captured definitive hosts for life history studies and assessing the impact of O. petrowi on host individuals.