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Review of: Aspects of Fish Parasitology. Edited by Angela E. R. Taylor and R. Muller. SYMPOSIA OF THE BRITISH SOCIETY FOR PARASITOLOGY. Vol. 8.
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Parasitological information may be useful for managing economically important fisheries by providing insights into population dynamics and health effects. The Chinook salmon ( Oncorhynchus tshawytscha ), an invasive species with high socio-ecological importance in South America, supports recreational and incipient artisanal fisheries. In Southern Chile, the recent approval of coastal fisheries for returning Chinook salmon in some regions highlights the importance of understanding salmon foraging, habitat use, and commercial value. However, such information is lacking. Parasites have been extensively used as cost-effective biological tags to identify fish stocks. We conducted the first parasitological examination of the marine tapeworm Hepatoxylon trichiuri larvae in returning adult Chinook salmon from the Cisnes River to assess its potential as a biological tag for returning Chinook salmon in Patagonia. Of 61 Chinook salmon from the Cisnes River, 52.46% were infected by H. trichiuri , with 1.65 ± 1.26 parasites per infected salmon (mean ± SD). Infection prevalence and intensity did not differ significantly between males and females. Infection intensity was higher in larger salmon but decreased with increasing salmon condition. Infection intensity was not significantly related to length, mass, or body condition. Infection prevalence and intensity of H. trichiuri varied spatially among Patagonian river-basin populations of Chinook salmon, thereby supporting the use of H. trichiuri as a biological tag. Our findings provide important parasitological metrics that may enhance future management practices by informing geographic variability in foraging locations of adult salmon and their commercial value for human consumption.
Parasite infrapopulation size - the population of parasites affecting a single host - is a central metric in parasitology. However, parasites are small and elusive such that imperfect detection is expected. Repeated sampling of parasites during primary sampling occasions (e.g., each host capture) informs the detection process. Here, we estimate flea (Siphonaptera) infrapopulation size on black-tailed prairie dogs ( Cynomys ludovicianus , BTPDs) as a proof-of-concept for estimating parasite infrapopulations given imperfect detection. From Jun–Aug 2011, we live-trapped 299 BTPDs for a total of 573 captures on 20 plots distributed among 13 colonies at the Vermejo Park Ranch, New Mexico, USA. During each capture, an anesthetized BTPD was combed 3 times consecutively, 15 s each, to remove and count fleas. Each flea ( n = 4846) was linked to the BTPD from which it was collected and assigned an encounter history (’100’, ‘010’, ‘001’). We analyzed the encounter histories using Huggins closed captures models, setting recapture probabilities to 0, thereby accounting for flea removal from hosts. The probability of detecting an individual flea ( p ) increased with Julian date; field personnel may have become more efficient at combing fleas as the field season progressed. Combined p across 3 combings equaled 0.99. Estimates of flea infrapopulation size were reasonable and followed the negative binomial distribution. Our general approach may be broadly applicable to estimating infrapopulation sizes for parasites. The utility of this approach increases as p declines but, if p is very low, inference is likely limited.
This collection of abstracts provides an account of four presentations at the 19th International Conference of the World Association for the Advancement of Veterinary Parasitology (WAAVP) (held in New Orleans, LA, USA from 10–14 August 2003) in a symposium session on zoonotic protozoan parasites found in the marine environment and chaired by Ronald Fayer and David Lindsay. The focus was on three genera of parasites of veterinary and public health concern - Toxoplasma , Giardia , and Cryptosporidium with emphasis on their epidemiology in the marine environment.
Fish pathologists are often interested in which parasites would likely be present in a particular host. Parasite Co-occurrence Modeler (PaCo) is a tool for identifying a list of parasites known from fish species that are similar ecologically, phylogenetically, and geographically to the host of interest. PaCo uses data from FishBase (maximum length, growth rate, life span, age at maturity, trophic level, phylogeny, and biogeography) to estimate compatibility between a target host and parasite species–genera from the major helminth groups (Acanthocephala, Cestoda, Monogenea, Nematoda, and Trematoda). Users can include any combination of host attributes in a model. These unique features make PaCo an innovative tool for addressing both theoretical and applied questions in parasitology. In addition to predicting the occurrence of parasites, PaCo can be used to investigate how host characteristics shape parasite communities. To test the performance of the PaCo algorithm, we created 12,400 parasite lists by applying any possible combination of model parameters (248) to 50 fish hosts. We then measured the relative importance of each parameter by assessing their frequency in the best models for each host. Host phylogeny and host geography were identified as the most important factors, with both present in 88% of the best models. Habitat (64%) was identified in more than half of the best models. Among ecological parameters, trophic level (41%) was the most relevant while life span (34%), growth rate (32%), maximum length (28%), and age at maturity (20%) were less commonly linked to best models. PaCo is free to use at www.purl.oclc.org/fishpest .
A 2-yr, seasonal, parasitological study of 1,435 fish, belonging to 4 species of native fishes and 7 species of nonnative fishes from the lower Little Colorado River (LCR) and tributary creeks, Grand Canyon, Arizona, yielded 17 species of parasites. These comprised 1 myxozoan (Henneguya exilis), 2 copepods (Ergasilus arthrosis and Lernaea cyprinacea), 1 acarine (Oribatida gen. sp.), 1 piscicolid leech (Myzobdella lugubris), 4 monogeneans (Gyrodactylus hoffmani, Gyrodactylus sp., Dactylogyrus extensus, and Ligictaluridus floridanus), 4 nematodes (Contracaecum sp., Eustrongylides sp., Rhabdochona sp., and Truttaedacnitis truttae), 3 cestodes (Bothriocephalus acheilognathi, Corallobothrium fimbriatum, and Megathylacoides giganteum), and 2 trematodes (Ornithodiplostomum sp. and Posthodiplostomum sp.). Rhabdochona sp. was the only adult parasite native to the LCR. Infection intensities of Ornithodiplostomum sp. and B. acheilognathi were positively correlated with length of the humpback chub Gila cypha. Adult helminths showed a high degree of host specificity, except B. acheilognathi, which was recovered from all fish species examined but was most abundant in cyprinids. Abundance of B. acheilognathi in the humpback chub was highest in the fall and lowest in the summer in both reaches of the LCR. There was no major taxonomic difference in parasite assemblages between the 2 different reaches of the river (LC1 and LC2). Parasite community diversity was very similar in humpback chub, regardless of sampling site or time. The parasite fauna of the LCR is numerically dominated by B. acheilognathi and metacercariae of Ornithodiplostomum sp. The richest and most diverse component community occurred in a nonnative species, the channel catfish Ictalurus punctatus, but infracommunity species richness was highest in a native host, humpback chub.
The documented range of the invasive and potentially pathogenic Asian fish tapeworm, Bothriocephalus acheilognathi Yamaguti, 1934 in the United States and Canada is updated based on examination of museum depositions and original field collections. Gravid specimens of B. acheilognathi were collected from the fathead minnow Pimephales promelas Rafinesque in Peter Lake, at the University of Notre Dame Environmental Research Center (UNDERC) Land o' Lakes, Wisconsin. A single immature specimen of the parasite was collected from a white bass, Morone chrysops (Rafinesque) in Lake Winnipeg, Manitoba, Canada. This is the first record of B. acheilognathi in Canada and extends its northern range in the interior of the continent by more than 600 miles over the last documented record. The previous record of B. acheilognathi in Canada, from the northern pikeminnow, Ptychocheilus oregonensis in British Columbia, is a misidentification of Eubothrium tulipai. Examination of selected records of intestinal cestodes from native cyprinids, in the Harold W. Manter Laboratory of Parasitology (HWML, n = 9) collection and in the United States National Parasite Collection (USNPC, n = 8), provided evidence of the parasite in Nebraska and possibly in the upper Colorado River basin. Introductions into Wisconsin-Michigan were due to the stocking of golden shiners, whereas the source of the introduction in Manitoba remains unknown.
Henneguya salminicola was described in 1919 by Dr. H. B. Ward from cysts found in the body musculature of a silver salmon ( Oncorhynchus kisutch Walbaum) taken from the Stickeen River in southeastern Alaska. Ward described the cysts as “pyriform, fairly uniform in size, and hard to the touch. . . . The cysts measured 3 to 6 mm in diameter and were found everywhere through the muscle mass.” Zschokke and Heitz (1914) had previously encountered cysts measuring 3 to 5 mm in a silver salmon during a parasitological survey of salmonid fishes of the Kamchatka peninsula. Myxosporidian spores within the cysts were identified by these workers as those of Henneguya aschokkei Gurley, although they gave no details as to the spores found and it seems quite probable that Kudo (1920) was correct in his assumption that these spores belonged to the same species which was later described by Ward as H. salminicola .
Spatial overlap between wildlife and related domestic animals can lead to disease transmission, with substantial evidence for viral and bacterial spillover. Domestic and wild animals can also share potentially harmful helminth parasites, many of which have environmental transmission stages that do not require direct contact between hosts. We used camera traps, fecal sampling, and mathematical modeling to evaluate the potential for hookworm parasites to spillover from domestic dogs to wild cats in the Osa Peninsula, Costa Rica. Traditional microscopy was found to be more sensitive than DNA-based diagnostics for parasites, though the methods were complementary. We found high hookworm ( Ancylostoma spp.) prevalence in domestic dogs (74.2%, 95% CI: 67.0%–80.7%, N = 155), and considerable spatial overlap with ocelots ( Leopardus pardalis ) and pumas ( Puma concolor ), particularly on trails and dirt roads. Pumas had hookworm prevalence of 36.4% (18.6%–57.2%, N = 22), and ocelots had 27.3% (7.6%–56.5%, N = 11); however, molecular identification of these parasites was inconclusive. We developed a macroparasite transmission model to infer the likelihood of spillover, compared with separate parasite cycles, or different parasite species in each host. According to the model, spillover of hookworm from dogs would lead to a prevalence of less than 10% in wild hosts. Low presumed compatibility between wild hosts and parasites adapted to domestic species limits the prevalence that could be reached in wild species, even under potentially higher overlap. The prevalence observed was more consistent with a model that assumes hookworms in wild cats in the Osa are a cat-specific parasite. The combination of parasitology, molecular diagnostics, and mathematical modeling used here could complement wildlife disease monitoring programs worldwide to shed light on understudied helminth–host dynamics at the domestic–wild animal interface.