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.     

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.     

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.     

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.     

Correlates of helminth community in the red-legged partridge (Alectoris rufa L.) in Spain

Between 1992 and 1996, 587 wild red-legged partridges (Alectoris rufa) from 16 Spanish provinces were examined to study the variations of helminth communities in this game species across a broad geographical area. The survey revealed 13 species of helminth parasites. Dicrocoelium sp.. Rhabdometra nigropunctata, and Cheilospirura gruweli were the most common species, whereas Raillietina bolivari, Choanotaenia infundibulum, Tetrameres sp., and Capillaria anatis were the most rare. Subulura suctoria, Heterakis gallinarum, Heterakis tenuicaudata, Capillaria contorta, Trichostrongylus tenuis, and Raillietina tetragona occurred with intermediate frequencies. The abundance of C. gruweli, S. suctoria, H. tenuicaudata, T. tenuis, and R. tetragona was inversely correlated to latitude and directly correlated to yearly mean temperature, whereas the abundance of Dicrocoelium sp. was directly correlated to latitude and inversely correlated to yearly mean temperature. The abundance of R. tetragona was inversely correlated to latitude and yearly mean humidity. The number of helminths per partridge and the number of helminth species per partridge were lower in young birds than in adults. Partridge body condition was inversely correlated to abundance of C. contorta. Richer infracommunities were linked to richer component communities. At the infracommunity level, total number of helminths per partridge and number of helminth species per partridge were inversely correlated to latitude and directly correlated to yearly mean temperature. At the component community level, both species richness and diversity (Simpson's index) were inversely correlated to latitude and directly correlated to mean temperature. Across the broad geographical range of the study area, the helminth parasite communities of red-legged partridges had marked geographical variation in their structure. Our results suggest that this variation is determined by the distribution of both intermediate and definitive hosts. We discuss the implications of this variation for the hypothesis that supplementary releases of captive-bred partridges for sport hunting can affect the helminth fauna of wild red-legged partridges.     

Helminth parasites of the wild boar,Sus scrofa,in Luristan province,western Iran and their public health significance

Seven helminth species were obtained from 12 wild boars (Sus scrofa) during a survey from 2000 to 2001 in Luristan province, western Iran. These species include the cestode larvae Cysticercus tenuicollis (25%), C. cellulosae (8.3%), the nematodes Metastrongylus apri (41.6%), M. pudendotectus (16.6%), M. salmi (8.3%), Trichuris suis (8.3%) and the acanthocephalan Macracanthorhynchus hirudinaceus (41.6%). No trematodes were found. Seven wild boars (58.3%) were identified as having at least one helminth species. A single infection was detected in 16.6% of cases, but a three species infection covered the highest rank (25%). All these helminths have been reported from other areas of Iran including the north, northeast and southwest, but not in Luristan. Among seven helminths identified, at least three species are transmissible to humans. The public health significance of these helminths is discussed.     

The component helminth community in six sympatric species of Ardeidae

We studied the helminth communities in 6 sympatric species of Ardeidae (Ixobrychus minutus (Linnaeus, 1766), Nycticorax nycticorax (Linnaeus, 1758), Bubulcus ibis (Linnaeus, 1758), Egretta garzetta (Linnaeus, 1766), Ardea cinerea (Linnaeus, 1758), and Ardea purpurea (Linnaeus, 1766)) from "La Albufera de Valencia," Spain. The survey revealed 13 species of helminth parasites: 5 digeneans, 2 cestodes, and 6 nematodes. The component helminth communities of the Ardeidae examined are depauperate and conform to the pattern typically found in isolationist communities, probably because of their high trophic dependence on a few prey species. Evenness was positively correlated with richness and abundance, but host body weight was not correlated with the number of helminth species or with the total number of helminths. Ardea cinerea is more heavily infected than E. garzetta by Apharyngostrigea cornu, and B. ibis is more heavily infected than both Ardea cinerea and E. garzetta by Desportesius spinulatus. Apharyngostrigea cornu was positively associated with Desmidocercella numidica and D. spinulatus in A. cinerea.     

Helminth communities of two green frogs (Rana perezi and Rana saharica) from both shores of the Alboran Sea

The helminth communities of two populations of green frogs from both shores of the Alborón Sea (Western Mediterranean) were studied. Of the 79 frogs examined for helminths, 39 individuals of the species Rano saharica were collected from Bob-Taza (Morocco), and 40 of the species Rona perezi were collected from the Natural Park of the Sierra de Grazalema (Spain). Although the species richness of helminths was identical in the two sampled areas, the differences observed in the structure of the helminth infracommunities were quite important. Statistically, significant differences were found between the species richness and the diversity of the infracommunities of R. perezi female population and the other three studied statistical populations. The helminth component communities of these two green frogs can be considered as depauperate, although their infracommunities present interactive features.     

Structure in parasite component communities in wild rodents: predictability, stability, associations and interactions .... or pure randomness?

Experimental data establish that interactions exist between species of intestinal helminths during concurrent infections in rodents, the strongest effects being mediated through the host's immune responses. Detecting immune-mediated relationships in wild rodent populations has been fraught with problems and published data do not support a major role for interactions in structuring helminth communities. Helminths in wild rodents show predictable patterns of seasonal, host age-dependent and spatial variation in species richness and in abundance of core species. When these are controlled for, patterns of co-infection compatible with synergistic interactions can be demonstrated. At least one of these, the positive relationship between Heligmosomoides polygyrus and species richness of other helminths has been demonstrated in three totally independent data-sets. Collectively, they explain only a small percentage of the variance/deviance in abundance data and at this level are unlikely to play a major role in structuring helminth communities, although they may be important in the more heavily infected wood mice. Current worm burdens underestimate the possibility that earlier interactions through the immune system have taken place, and therefore interactions may have a greater role to play than is immediately evident from current worm burdens. Longitudinal studies are proposed to resolve this issue.     

Helminth and leech community structure in tadpoles and caudatan larvae of two amphibian species from Western Nebraska

Currently no comparative studies exist on helminth and leech community structure among sympatric anuran tadpoles and salamander larvae. During June-August 2007-2009, we examined 50 bullfrog tadpoles, Rana catesbeiana , 50 barred tiger salamander larvae, Ambystoma mavortium , and 3 species of snails from Nevens Pond, Keith County, Nebraska for helminth and leech infections. The helminth and leech compound community of this larval amphibian assemblage consisted of at least 7 species, 4 in bullfrog tadpoles and 4 in barred tiger salamander larvae. Bullfrog tadpoles were infected with 2 species of nematodes ( Gyrinicola batrachiensis and Spiroxys sp.) and 2 types of metacercariae ( Telorchis sp. and echinostomatids), whereas barred tiger salamander larva were infected with 1 species of leech ( Placobdella picta ), 2 species of adult trematodes ( Telorchis corti and Halipegus sp.), and 1 species of an unidentified metacercaria. The component community of bullfrog tadpoles was dominated by helminths acquired through active penetration, or incidentally ingested through respiratory currents, or both, whereas the component community of larval salamanders was dominated by helminths acquired through ingestion of intermediate hosts (χ2 = 3,455.00, P < 0.00001). Differences in amphibian larval developmental time (2-3 yr for bullfrog tadpoles versus 2-5 mo for salamander larvae), the ephemeral nature of intermediate hosts in Nevens Pond, and the ability of bullfrog tadpole to eliminate echinostome infections had significant effects on mean helminth species richness among amphibian species and years (t = 12.31, P < 0.0001; t = 2.09, P = 0.04). Differences in herbivorous and carnivorous diet and time to metamorphosis among bullfrog tadpoles and barred tiger salamander larvae were important factors in structuring helminth communities among the larval stages of these 2 sympatric amphibian species, whereas size was important in structuring helminth and leech communities in larval salamanders, but not in bullfrog tadpoles.     

丹江口水库鲤肠道寄生蠕虫群落结构与季节动态

2004年2月到2005年11月在丹江口水库库区206尾鲤(Cyprinus carpio)肠道中检获蠕虫11种,其中复殖吸虫3种,线虫5种,棘头虫2种,绦虫1种。总体感染率为45.63%,平均感染丰度为4.23±12.65,平均感染强度为9.29±17.48,其中饭岛盾腹吸虫(Aspidogaster ijimai)的总感染率(25.24%)和平均感染丰度(1.76±6.46)最大,瓣睾鲫吸虫(Carassatrema lamellorchis)的感染强度(25.00±46.68)最大。除部分平均感染丰度较低的线虫如鲤带巾线虫(Cucullanus cyprini)外,其他蠕虫的分布类型均为聚集分布,蠕虫群落多样性指数为4.63,均匀度指数为0.60,对群落多样性的季节动态分析表明,各季节群落多样性和均匀度波动较大,并无明显变化规律。每尾鲤感染蠕虫种数多在1—4种之间,所有感染的11种蠕虫中优势种为饭岛盾腹吸虫;次优势种为日本侧殖吸虫(Asymphylodora japonica)、中华许氏绦虫(Khawia sinensis)、瓣睾棘吸虫和鲤长棘吻虫(Rhadinarhynchus cyprini);非优势种为对盲囊线虫(Contracaecum sp.)、鲤带巾线虫、鲤杆咽吸虫(Rhabdochona cyprini)、黄颡刺盖线虫(Spinitectus gigi)、毛细线虫(Capillaria sp.)和木村小棘吻虫(Micracanthorhynchina motomurai)。在种间协调关系方面,鲤杆咽线虫和瓣睾鲫吸虫、鲤长棘吻虫和饭岛盾腹吸虫、对盲囊线虫和木村小棘吻虫、鲤长棘吻虫和木村小棘吻虫之间分别存在显著正关联。对优势种和次优势种蠕虫中种群的季节动态分析表明,鲤寄生蠕虫各组分的感染率和平均感染丰度存在显著的季节差异,在秋、冬季节的感染水平普遍比较高,而到春夏则急剧下降,但中华许氏绦虫无显著季节变化。     

Richness and diversity of helminth communities in the Japanese grenadier anchovy, Coilia nasus, during its anadromous migration in the Yangtze River, China

To determine the relationship between the species richness, diversity of helminth communities, and migration distance during upward migration from coast to freshwater, helminth communities in the anadromous fish Coilia nasus were investigated along the coast of the East China Sea, the Yangtze Estuary, and 3 localities on the Yangtze River. Six helminth species were found in 224 C. nasus . Changes in salinity usually reduced the survival time of parasites, and thus the number of helminth species and their abundance. Except for the 2 dominant helminths, the acanthocephalan Acanthosentis cheni and the nematode Contracaecum sp., mean abundance of other 4 species of helminths was rather low (<1.0) during the upward migration in the Yangtze River. Mean abundance of the 2 dominant helminths peaked in the Yangtze Estuary and showed no obvious decrease among the 3 localities on the Yangtze River. Mean species richness, Brillouin's index, and Shannon index were also highest in the estuary (1.93 ± 0.88, 0.28 ± 0.25, and 0.37 ± 0.34, respectively) and did not exhibit marked decline at the 3 localities on the Yangtze River. A significant negative correlation was not seen between the similarity and the geographical distance (R = -0.5104, P = 0.1317). The strong salinity tolerance of intestinal helminths, relatively brief stay in the Yangtze River, and large amount of feeding on small fish and shrimp when commencing spawning migration perhaps were responsible for the results.     

Helminth infracommunities of a population of the Gran Canaria giant lizard Gallotia stehlini

A survey of gastro-intestinal helminth communities of Gallotia stehlini (Sauria: Lacertidae) from Gran Canaria island (Canary Archipelago, Spain), was conducted to determine the prevalence, abundance and species diversity of intestinal parasites in these lizards. Pharyngodonid nematodes were the most common intestinal helminths, three species being Gallotia specialists. Helminth infracommunities of G. stehlini were rich and appear to be closer to the interactive end of the continuum isolationist-interactive helminth communities, according to the high values of helminth diversity. It is the first case of a saurian reptile showing this kind of diverse helminth infracommunity, produced by a large size, a wide-ranging plant diet and exposure to helminths with direct life-cycles.     

Helminth infracommunities of the frogs Rana catesbeiana and Rana clamitans from Turkey Marsh, Michigan

One hundred twenty-seven bullfrogs, Rana catesbeiana, and 120 green frogs, Rana clamitans, collected in July and August 1987 from Turkey Marsh, Michigan, were examined for helminths. Of the 16 helminth species found, Falcaustra catesbeianae had the highest prevalence and mean intensity in bullfrogs. In green frogs, Megalodiscus temperatus had the highest prevalence and Haematoloechus parviplexus had the highest mean intensity. Taxonomically, 1,030 (30.5%) trematodes and 2,348 (69.5%) nematodes occurred in bullfrogs; 2,874 (96.4%) trematodes, 2 (0.1%) cestodes, and 105 (3.5%) nematodes were found in green frogs. The larger and more aquatic of the 2 hosts, R. catesbeiana, had the highest mean number of helminth species, helminth intensity, diversity, and evenness. Adult frogs of both species had a significantly higher mean number of helminth species than did juveniles. Significant correlations existed between the number of helminth species and frog length. Although the helminth communities of Turkey Marsh frogs are isolationist in character, they are more diverse than other helminth communities studied in amphibians.     

The helminth community of the wood mouse, Apodemus sylvaticus, in the Sierra Espuna, Murcia, Spain

The helminth community of the wood mouse, Apodemus sylvaticus, in the Sierra Espuna was characterized after a complete analysis of its helminth community component and infracommunity structure relative to host age, sex and year of capture. The helminth community comprised 13 species: one trematode, four cestodes and eight nematodes. The cestode Pseudocatenotaenia matovi and the nematode Syphacia frederici were the most prevalent and abundant helminth species, respectively. Sixty four percent of mice analysed presented helminths with a direct cycle and 42% presented helminths with an indirect cycle. The helminth community presents a low diversity with infracommunities usually made up of only one or two helminth species. Host age and year of capture seem to play a major role in determining species richness and helminth diversity, but not in determining the abundance of helminths. Host sex does not seem to affect the infection rate nor the diversity. Further studies on more samples of wood mice and other small mammal species in this regional park are needed to explore any possible interactions between helminth communities in the host populations.     

A predictable suite of helminth parasites in the long-billed dowitcher, Limnodromus scolopaceus, from the Chihuahua desert in Texas and Mexico

Eighty-eight long-billed dowitchers, Limnodromus scolopaceus, were examined for helminth parasites, 62 from Texas and 26 from Mexico. In total, 3,558 helminth parasites were obtained from this host, 2,273 from Texas birds and 1,285 from birds from Mexico. The component communities consisted of 22 species of helminths in Texas, and 19 in Mexico. Of a total of 26 helminth species recorded from the 2 localities, 15 were common to both, 7 found only in Texas, and 4 only in Mexico. Fifty-nine of 62 Texas birds and 25 of 26 birds from Mexico were infected. The most prevalent helminth for Texas was the cestode Shipleya inermis. The cestode Aploparaksis retroversa was the most abundant, accounting for 37% of the total abundance, and was second highest in prevalence. Five species of cestodes, A. retroversa, Aploparaksis diagonalis, Aploparaksis occidentalis, Aploparaksis rissae, and Shipleya inermis accounted for 79% of total abundance. In the sample from Mexico, S. inermis was also highest in prevalence, followed by the nematode Hystrichis tricolor. The cestode A. retroversa was highest in abundance at 50% of the total, and was third highest in prevalence. Mean species richness, diversity, and evenness were similar among the component communities of Texas and Mexico. A predictable suite of aploparaksid cestodes, together with the cestode S. inermis, constituted 79%, and 61%, of total abundance for the component communities of Texas and Mexico, respectively, and were present in all component communities for locality, season, and year. The cestodes, A. retroversa and S. inermis, were the dominant species in all component communities. Differences among component communities and low similarities for all other comparisons were largely caused by less predictable suites of helminth species. A checklist of helminth parasites reported for long-billed dowitchers is included.     

Structure, stability and species interactions in helminth communities of wood mice, Apodemus sylvaticus

The helminths of the alimentary tract of wood mice, Apodemus sylvaticus, were studied at two sites over a 33-month period. Nine helminth species were recovered regularly. All but one was absent for at least 1 month. Monthly samples from these helminth communities were more similar to samples taken in the following month than to samples taken at progressively greater intervals up to a year. Helminth communities at both sites, however, had cyclical elements. Comparison of mean similarity indices for helminth faunas from 33 monthly samples and those from data sets generated by four null models suggests that observed values did not differ from a model where relative abundance of each species was determined randomly with specific maxima of abundance and species absences based on observed data. Loss of helminth species may decrease measurements of community stability based on relative abundance while persistence of abundant species increases stability. Helminth faunas in samples of A. sylvaticus from six localities taken at the same time of year at 5-year intervals indicated that some changed radically while others remained virtually unchanged. The considerable variation in helminth communities from different localities was not related to proximity or gross habitat characteristics. Nematospiroides dubius, Corrigia vitta and Capillaria murissylvatici were important in discriminating between the parasite faunas at different sites. Abundance of Syphacia stroma varied considerably between spatial surveys reflecting differences in host population dynamics in the 2 years. The present report and data from elsewhere in Ireland suggest that species composition of the helminths associated with A. sylvaticus may be stable over a wider geographical scale. There were neither strong nor consistent positive or negative interactions between pairs of helminth species. It is concluded that the stability characteristics of this parasite community, in terms of species composition and relative abundance, are the product of the population biology of independent parasite species rather than interspecific interactions. Variation in the role of competition in parasite communities is discussed.     

Fascioloides magna (Bassi, 1875) in feral swine from southern Texas.

Between 1971 and 1975, Fascioloides magna was found in 46 of 67 (69%) feral swine (Sus scrofa) in southern Texas. Flukes were recovered from swine in areas where F. magna commonly has been recovered from white-tailed deer and cattle. One to 12 flukes were recovered from each infected animal. Their presence was indicated by black hematin pigment on the liver and various other internal organs. Eggs were not detected in the gallbladder or feces of infected animals although mature flukes and eggs were recovered in the livers suggesting that, like cattle, feral swine can be infected but are aberrant hosts for the parasite and do not disseminate eggs.     

Trichinella spiralis in an agricultural ecosystem. III. Epidemiological investigations of Trichinella spiralis in resident wild and feral animals

As part of a larger epidemiological study examining the transmission of Trichinella spiralis in an agricultural ecosystem, resident wild and feral animals were trapped to determine the extent of their involvement in the natural, on-farm cycling of the parasite among swine. During a 21-mo-study, seven of 15 skunks (Mephitis mephitis), one of three opossums (Didelphis virginiana), two of two feral domestic cats and a raccoon (Procyon lotor) were found to be infected, while five shrews (Blarina brevicauda) and 18 deer mice (Peromyscus spp.) were uninfected. Most of the former hosts probably became infected by scavenging dead infected swine or rats (Rattus norvegicus). However, infections obtained through predation of living rats, particularly with regard to the cats, cannot be excluded. Our observations do not suggest that there was transmission of T. spiralis from the wild animals to swine. Therefore, transmission of T. spiralis appeared to occur only from the farm's swine and rats to the associated wild and feral animals.     

Understanding the role of wild ruminants in anthelmintic resistance in livestock

Wild ruminants are susceptible to infection from generalist helminth species, which can also infect domestic ruminants. A better understanding is required of the conditions under which wild ruminants can act as a source of helminths (including anthelmintic-resistant genotypes) for domestic ruminants, and vice versa, with the added possibility that wildlife could act as refugia for drug-susceptible genotypes and hence buffer the spread and development of resistance. Helminth infections cause significant productivity losses in domestic ruminants and a growing resistance to all classes of anthelmintic drug escalates concerns around helminth infection in the livestock industry. Previous research demonstrates that drug-resistant strains of the pathogenic nematode Haemonchus contortus can be transmitted between wild and domestic ruminants, and that gastro-intestinal nematode infections are more intense in wild ruminants within areas of high livestock density. In this article, the factors likely to influence the role of wild ruminants in helminth infections and anthelmintic resistance in livestock are considered, including host population movement across heterogeneous landscapes, and the effects of climate and environment on parasite dynamics. Methods of predicting and validating suspected drivers of helminth transmission in this context are considered based on advances in predictive modelling and molecular tools.