Visceral helminth communities of an insular population of feral swine

Nine species of helminths, all nematodes, were recovered from the viscera of 48 feral swine (Sus scrofa) from Cumberland Island, Georgia. Both the overdispersed frequency distributions and the abundances of the four common species of helminths (Stephanurus dentatus, Metastrongylus apri, M. pudendotectus and Gongylonema pulchrum) did not vary significantly across the main and interactive effects of host sex and/or seasons. Whether or not the present low population densities of feral swine on Cumberland Island has influenced the pattern of fluctuations in abundances of helminth species across seasons as often observed in helminth communities from other hosts was not resolved. The apparent recent decline in prevalences and abundances, and the loss of certain species from the helminth communities of feral swine on the island may be explained partially by the decreasing transmission potentials of direct life cycle species caused by a recent marked reduction of numbers of individuals in the host population. Conversely, the apparent increased prevalence and abundance of three species of helminths (S. dentatus, M. apri and M. pudendotectus) may be related to their common utilization of earthworms as paratenic or intermediate hosts. Gongylonema pulchrum was the only helminth in which abundances seemed to remain unchanged. This was the only species that was not strictly host specific to feral swine. We found no evidence that helminth infections were responsible for morbidity or mortality in this feral swine population.     

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.     

Effects of season and physical condition on the gastrointestinal helminth community of white-tailed deer from the Texas Edwards Plateau

Eighty-six adult female white-tailed deer, Odocoileus virginianus (Zimmermann), collected over a 12-mo period in the Texas Edwards Plateau, harbored six species of nematodes (Haemonchus contortus, Gongylonema pulchrum, Oesophagostomum venulosum, Ostertagia ostertagi, Cooperia sp., and Apteragia odocoilei), and two cestodes (Moniezia sp. and Taenia hydatigena). The patterns of distribution of the three common species of gastrointestinal helminths (H. contortus, O. venulosum, and G. pulchrum) were overdispersed. When analyzed for the main and interactive effects of the extrinsic and intrinsic variables of season and physical condition, respectively, aggregated abundances in H. contortus and O. venulosum appeared to result from the main effect of seasonal changes operating over the collective populations of these two species rather than from the intrinsic factor of physical condition operating within selected subpopulations. Abomasal parasite counts do not appear to be a useful index for monitoring herd condition of white-tailed deer from this geographic region.     

Visceral helminth communities of sympatric mule and white-tailed deer from the Davis Mountains of Texas

Hybridizing populations of mule (Odocoileus hemionus) and white-tailed deer (O. virginianus) from the Davis Mountains of Texas were examined to determine similarities in species composition of their helminth communities and if abundances of helminth species in those communities varied across host species and seasonal factors. Only three cestode and three nematode species were recovered. There were very low abundances of species and little diversity in the helminth communities of both hosts. Common helminth species were shared by both deer, and the significant variance in abundances of three of the four most common helminth species appeared to result from differences in habitat preferences of the respective hosts. Our results indicated that analyses of helminth communities of deer from this geographical area do not provide a useful quantification technique for determining deer condition, degree of hybridization, or levels of intraspecific competition.     

Parasites of the collared peccary from Texas

Results of a survey of the parasites of the collared peccary (Dicotyles tajacu angulatus) in Texas are presented. Three ectoparasites, Amblyomma cajennense, Dermacentor variabilis, and Pulex porcinus were very common on peccaries from south Texas, but less common or absent in arid west Texas. Sucking lice, Pecaroecus javalii, were common on peccaries from west Texas, but were not found in south Texas. The known range of this louse in Texas is extended into the Big Bend area. Two ticks, Amnblyomma inornatumn and Haemaphysalis leporis-palustris, were found infrequently. Five of nine species of endoparasites found in this survey (Dirofilaria acutiuscula, Parabronema pecatriae, Parostertagia heterospiculum, Physocephalus sp., and Texicospirura turki) were prevalent. Three species, D. acutiuscula, Gongylonema baylisi, and Fascioloides magna, are reported from North American peccaries for the first time. The geographic distribution of the large American liver fluke, F. magna, coincided with an area where the parasite is enzootic in white-tailed deer. It is concluded that parasitism was of little importance in population control of peccaries during the period of the study.     

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.     

Determinants of helminth infection in a subterranean rodent, the Cape dune mole-rat ( Bathyergus suillus )

The helminth fauna of the largest bathyergid, the Cape mole-rat ( Bathyergus suillus ) was studied throughout an entire calendar year. The species richness encountered was low, with only 3 species of nematodes ( Longistriata bathyergi , Mammalakis macrospiculum, and Trichostrongylus sp.) and 2 species of cestodes ( Taenia sp. and Rodentolepis sp.). At less than 10%, the prevalence for all helminths species was similarly low and may be a result of the solitary lifestyle and the subterranean habitat exploited by this rodent. Clear seasonal patterns were apparent for the most common nematode ( L. bathyergi ), and prevalence and abundance were highest among non-pregnant females compared to males and pregnant females. Dispersal patterns associated with the mating system of the host could explain this pattern. In contrast, the prevalence of the most common cestode ( Taenia sp.) was neither determined by season nor host sex, suggesting that foraging habits may constantly expose B. suillus to this parasite.     

Helminth community composition, structure, and pattern in six dove species (Columbiformes: Columbidae) of South Texas

The helminth community composition and structure of 6 species of columbids residing in south Texas are reported and compared herein. Sixty individuals of the following species, rock pigeons (Columba livia [RP]), mourning doves (Zenaida macroura [MD]), Eurasian collared-doves (Streptopelia decaocto [ECD]), white-winged doves (Zenaida asiatica [WWD]), and common ground doves (Columbina passerina [CGD]), and 48 Inca doves (Columbina inca [ID]) were collected during the summer of 2006 and examined for helminths. Twelve helminth species were found (9 nematodes and 3 cestodes), representing 486 individuals. Nematodes numerically dominated the component community in all host species. Overall, helminth prevalence was similar among host sex within all dove species. However, prevalence of Skrjabinia bonini and Hymenolepis sp. in RPs was significantly different among host age groups (P = 0.01, P = 0.0002, respectively). Likewise, prevalence of Killigrewia delafondi was higher (P = 0.0001) in adult WWDs. Based on percent similarity and Jaccard's coefficient of community indices, helminth component communities were dissimilar, and the number of shared helminth species varied among host species. Data from this study suggest that the environment surrounding preferred host habitat and foraging strategies of each host species is the driving force behind helminth component communities. This study emphasizes the importance of examining co-occurring hosts at both local and regional scales to elucidate helminth community structure and patterns.     

Helminths in Leuciscus cephalus from the river Adda, Lombardy, Northern Italy

Chubs (Leuciscus cephalus) were caught at various locations along the river Adda and from Lake of Como (Lombardy, Northern Italy) and endoparasitic helminths were studied in order to integrate the knowledge on distribution of helminth fauna of chubs in Lombardy and to investigate on the structure of its parasite infracommunities with respect to different habitat typologies. The following species of parasites were isolated: Pomphorynchus laevis, Allocreadium markewitschi, Parasymphylodora markewitschi, Raphidascaris acus, Hysterothylacium aduncum and Molnaria intestinalis. P laevis resulted the most common species (P = 56.52%). The mean abundances and the prevalence of helminths were different in chubs according to the sampling site. The mean abundances were lower in chubs sampled in the lake than those sampled in the river. Particularly, P. laevis showed the highest prevalences in fish captured in the river sites. The trematodes (P. markewitschi and A. markewitschi) seem to be more related with "lake" typology. These results are discussed and related to differences in life cycle of these parasites and to other factors like sampling period and the conditions of the aquatic sites that could influence the richness of parasite species.     

A study of the internal parasites of small rodents from woodland areas in Surrey

The occurrence of helminth parasites and leptospires from the Long-tailed field mouse, Apodemus sylvaticus , the Bank vole, Clethrionomys giareolus and the Short-tailed vole, Microtus agrestis has been studied from four woodland areas in Surrey. The composition of the helminth fauna of these rodents, particularly A. sylvaticus and C. giareolus , differs from that of previous studies carried out in the British Isles in consisting largely of cestodes and fewer species of digeneans and nematodes. On the other hand the degree of infection of the rodents with nematodes as in the case of A. sylvaticus infected with the trichostrongylid Nematospiroides dubius and theoxyurid Syphacia stroma and of C. giareolus with thecap-illarid Capillaria muris sylvatici is greater than the cestode and digenean infections and is probably linked with the monoxenous nature of the nematode life cycles.
Differences in the number, incidence and degree of infection of mice and voles with species of helminths is undoubtedly linked with differences in the feeding habits of the respective hosts but the present study has also confirmed that infection levels in both leptospires and helminths are influenced by the age/sex relationships of the host together with season and habitat. The relationship between the distribution of rodents infected with leptospires and some helminths suggests similarities in the mode of their transmission.     

Helminths of sympatric striped, hog-nosed, and spotted skunks in west-central Texas

Twenty-eight hog-nosed skunks (Conepatus leuconotus), 23 striped skunks (Mephitis mephitis), and nine spotted skunks (Spilogale gracilis) from an area of sympatry in west-central Texas were examined for helminth parasites. Shared helminth species among all three host species were one nematode (Physaloptera maxillaris), two acanthocephalans (Pachysentis canicola, Macracanthorhynchus ingens), and one cestode (Mathevotaenia mephitis). Two nematodes (Gongylonema sp. and Filaria taxidaea) occurred in both the striped and hog-nosed skunks. One nematode (Filaroides milksi) and one acanthocephalan (Oncicola canis) were collected only from C. leuconotus. The most common helminth infections for striped and hog-nosed skunks were P. maxillaris and P. canicola. Helminth species richness was highest in hog-nosed skunks, but striped skunks had the highest prevalences and intensities of all the common helminth species. The helminth fauna of spotted skunks was markedly depauperate in terms of species richness and helminth abundance compared to the other two host species. Differences in helminth communities across these three sympatric skunks may be related to differences in their relative abundance, behavior, food habits, and geographic range.     

Helminth infections of wild boars (Sus scrofa) in the Bursa province of Turkey

The present study aimed to investigate the status of helminth infections in wild boars in the Bursa province of Turkey. For this purpose, during 2007-2008, 27 wild boars were necropsied and examined for helminths. Individual samples of tongue and diaphragm from 27 necropsied wild boars and an additional 22 tongue and diaphragm samples provided by hunters were examined by trichinoscopy and artificial digestion for Trichinella spp. larvae. Twenty animals (74%) were identified as being infected with at least one helminth species. Twelve species of helminths were detected, with the following prevalence rates: Metastrongylus apri (59%), Metastrongylus salmi (52%), Metastrongylus pudendotectus (52%), Dicrocoelium dendriticum (33%), Globocephalus urosubulatus (22%), Macracanthorhynchus hirudinaceus (19%), Gongylonema pulchrum (11%), Physocephalus sexalatus (7%), Trichuris suis (7%), Ascarops strongylina (4%), Hyostrongylus rubidus (4%) and Taenia hydatigena larvae (4%). Generally, lungworms were the predominant helminths. The highest mean abundance was observed for M. pudendotectus, and the lowest was determined for T. hydatigena larvae. Significant differences in the prevalence and intensity were found for D. dendriticum with respect to host age and sex, respectively. The mean intensity of M. pudendotectus was significantly influenced by the sex and age of the wild boars. This study is the first report describing the presence of M. salmi, M. pudendotectus, D. dendriticum, G. urosubulatus, M. hirudinaceus, P. sexalatus, A. strongylina and H. rubidus in wild boars in Turkey. All analysed muscle samples were negative for Trichinella spp. larvae.     

Helminth communities of native and introduced fishes in Lake Pátzcuaro, Michoacán, México

In Lake Pátzcuaro in the Mesa Central of México, a total of 19 species of helminths was found in 598 fishes and comprised five digeneans, two monogeneans, four cestodes, one acanthocephalan and seven nematodes, of which ten species were represented by larval or immature states. The richest and most diverse helminth communities were found in the native carnivorous goodeid Alloophorus robustus. In general, the helminth communities in the different fish species were not particularly species rich and the parasite assemblages were numerically dominated by larvae of the bird trematode, Posthodiplostomum minimum. Patterns of helminth community richness and diversity were similar to those previously observed in north-temperate freshwater fishes. Most enteric helminths occurred with low abundance and only a small proportion of the gut helminth communities was numerically dominated by any one species. Helminths dominating their enteric communities showed some level of host specificity. Helminth communities in carnivorous fish species were generally richer than those in herbivores and detritivores, with the exception of the predominantly herbivorous Goodea atripinnis. The helminth fauna of introduced fishes, Cyprinus carpio, Micropterus salmoides and Oreochromis niloticus , consisted of either few or no host-specific adult helminth(s) translocated from their original geographical areas and by larval stages of helminths of piscivorous birds. Based on the geological history of the area and the biogeography of the endemic fish fauna, it is hypothesized that host-switching and relationships with the nearctic fauna have been fundamental in determining the helminth fauna of the endemic fish hosts.     

Host-parasite relationships of longnose dace, Rhinichthys cataractae, from the Ford River, Michigan.

A total of 1,115 longnose dace, Rhinichthys cataractae (family Cyprinidae), were examined for parasites from May 1983 through October 1986 from 3 localities in the Ford River in Michigan's Upper Peninsula. Thirteen parasite species (1 Monogenea, 2 Digenea, 2 Cestoda, 4 Nematoda, 1 Acanthocephala, 3 Protozoa) infected dace. The parasite faunas of dace, taxonomically and in species number, were similar between localities. Posthodiplostomum minimum minimum, Neascus sp., and Rhabdochona canadensis were the most common helminths infecting dace from each locality. The first 2 species did not exhibit consistent seasonal infection patterns between years, whereas the prevalence and mean intensity of R. canadensis in dace from the downriver locality were higher in summer 1983, 1984, and 1985. The intensity of infection of each of these helminth species significantly increased with host length. The prevalences and mean intensities of P. m. minimum, Neascus sp., and R. canadensis as well as the helminth infracommunity diversity were highest in dace from the upriver locality. The major factors that influenced parasite intensity were environmental factors that occurred when and where a fish began its life, the sequence of events that occurred in each habitat the fish encountered during its life, and the length of exposure (age of fish). Dace have isolationist helminth infracommunities arising from factors including ectothermy, a simple enteric system, restricted vagility, and being gape-limited. Allogenic helminths with indirect life cycles predominate in the depauperate helminth fauna of dace.     

The helminth fauna of wild and domestic ruminants in Mongolia—a review

The helminth fauna of eight species of wild ruminants and five species of domestic ruminants sharing common grassland in Mongolia was reviewed. A total of 108 species of helminths, belonging to 40 genera, 23 families, 11 superfamilies, 6 orders and 3 classes were reported in wild and domestic ruminants in Mongolia. Several new host–helminth associations have been recorded. Twenty seven helminth species have been found in certain host species for the first time in Mongolia. These included 2 species of trematodes, 2 species of cestodes and 23 species of nematodes. Helminths that are specific for some of the examined ruminant species were determined. However, wild animals may serve as a reservoir of helminth infections for domestic animals when sharing grassland in Mongolia. The helminth fauna of the ruminants with respect to occurrence, distribution, prevalence and intensity of infection was considered for six geographic regions of Mongolia.     

Helminth fauna of sandhill crane populations in Texas

Three species of trematode [Orchipedium jolliei Schell, 1967; Prohyptiamus grusi Kocan, Waldrup, Ramakka, and Iverson, 1982; Echinostoma revolutum (Froelich, 1802)], three species of nematode (Tetrameres grusi Shumakovich, 1946; Synhimanthus sp.; Contracaecum sp.), and one species of cestode (Anomotaenia sp.) were recovered from 146 sandhill cranes, Grus canadensis (Linnaeus), collected in Alaska, Canada, and two areas in Texas. The only common and abundant species were O. jolliei and T grusi. Of cranes collected in Texas, those that came from the Canadian breeding grounds had significantly greater abundances of O. jolliei and T. grusi than those from Alaska. However, cluster analysis using rank abundances of helminth species across the four geographic regions and stepwise multiple discriminant analysis using the grouping variable of the presence or absence of a subspecies-specific pancreatic protein indicated that classification of cranes into populations based on helminth abundances was impractical as a management technique.     

Parasitic helminths of red-bellied woodpeckers (Melanerpes carolinus) from the Apalachicola National Forest in Florida

Seventy-four red-bellied woodpeckers (Melanerpes carolinus) from the Apalachicola National Forest (30 degrees 10'N, 84 degrees 40'W) in northwest Florida were examined for helminths. The most prevalent parasites were the nematode Aproctella stoddardi (11%) and the acanthocephalan Mediorhynchus centurorum (11%). New host records include Pseudaprocta samueli, A. stoddardi, Tridentocapillaria tridens, Diplotriaena americana, Dispharynx nasuta, Procyrnea pileata, Orthoskrjabinia rostellata, and Brachylaima fuscatum. The helminth fauna was characterized by low prevalences and intensities of infection and low numbers of species per bird (1.2). The frequency of prescribed burning and habitat understory flora composition did not influence the prevalences or intensities of helminths in red-bellied woodpeckers collected from 2 similar but differently managed sites within the forest.     

Helminth parasites of intermingling axis deer, wild swine and domestic cattle from the island of Molokai, Hawaii

Helminth infections of axis deer (Cervus axis), wild swine (Sus scrofa) and domestic cattle (Bos taurus) were studied among intermingling herds on the Puu-O-Hoku Ranch, Molokai, Hawaii. Twenty-four species of helminths were collected from the 10 deer, 10 swine and 10 cattle. Capillaria bovis, Cooperia punctata, Haemonchus contortus and Trichostrongylus axei infected both axis deer and cattle, whereas Gongylonema pulchrum infected both axis deer and wild swine. None of the species of helminths occurred in both wild swine and cattle nor was any species found in all three hosts. Wild swine and domestic cattle supported separate and distinct helminth communities. In contrast, the helminth community of axis deer appeared to be derived from the helminth communities of cattle and wild swine and consisted only of those species capable of parasitizing either a broad range of ruminants or many mammalian taxa.     

Effect of short-term coyote removal on populations of coyote helminths

Coyote (Canis latrans) removal programs often are initiated despite the potential population regulatory mechanism of parasitism with increased coyote density. We investigated the effect of intensive, short-term coyote removal on population levels of helminths in juvenile and adult coyotes from western Texas. Coyotes were killed by aerial gunning every 3 mo for 2 yr on two 5,000 ha areas, which reduced the overall coyote density of these areas by about 50%. Two other 5,000 ha areas were used as comparison sites where a limited number of coyotes were killed each season. Densities on comparison sites remained stable throughout the study at a mean +/- 1 SE of 0.14 +/- 0.01 coyotes/km2. Twelve helminth species consisting of seven nematodes (Ancylostoma caninum, Physaloptera rara, Toxascaris leonina, Dirofilaria immitis, Spirocerca lupi, Oslerus osleri, and Capillaria aerophila), three cestodes (Taenia pisiformis, Taenia multiceps, and Mesocestoides sp.), one acanthocephalan (Oncicola canis), and one trematode (Alaria marcianae) were found in 252 coyotes. Of these, A. caninum, P. rara, T. multiceps, T. pisiformis, T. leonina, and S. lupi were common species. Rank-transformed values for the mean abundances of A. caninum and T. multiceps and A. caninum, T. multiceps, and S. lupi were reduced in juvenile and adult coyotes, respectively, from the removal sites compared to respective helminth abundances in similar age class coyotes from comparison sites. Because A. caninum has been suggested as a population regulator of coyotes, a coyote removal program that results in a reduced density of coyotes and at the same time causes a reduced abundance of A. caninum, may in fact negate the regulatory effect that A. caninum has on coyote populations.     

Body size,trophic level,and the use of fish as transmission routes by parasites

Within food webs, trophically transmitted helminth parasites use predator–prey links for their own transfer from intermediate prey hosts, in which they occur as larval or juvenile stages, to predatory definitive hosts, in which they reach maturity. In large taxa that can be used as intermediate and/or definitive hosts, such as fish, a host species’ position within a trophic network should determine whether its parasite fauna consists mostly of adult or larval helminths, since vulnerability to predation determines an animal’s role in predator–prey links. Using a large database on the helminth parasites of 303 fish species, we tested whether the proportion of parasite species in a host that occur as larval or juvenile stages is best explained by their trophic level or by their body size. Independent of fish phylogeny or habitat, only fish body length emerged as a significant predictor of the proportion of parasites in a host that occur as larval stages from our multivariate analyses. On average, the proportion of larval helminth taxa in fish shorter than 20 cm was twice as high as that for fish over 100 cm in length. This is consistent with the prediction that small fishes, being more vulnerable to predation, make better hosts for larval parasites. However, trophic level and body length are strongly correlated among fish species, and they may have separate though confounded effects on the parasite fauna exploiting a given species. Helminths show varying levels of host specificity toward their intermediate host when the latter is the downstream host involved in trophic transmission toward an upstream definitive host. Given this broad physiological compatibility of many helminths with fish hosts, our results indicate that fish body length, as a proxy for vulnerability to predators, is a better predictor of their use by helminth larvae than their trophic level based on diet content.