Helminths of rabbits (Lagomorpha, Leporidae) deposited in the Helminthological Collection of the Oswaldo Cruz Institute

"Till death do us apart": The common destiny of brown hare and its parasite community

Although parasites may threaten individual hosts' survival and reproduction, their role as an essential part of ecosystem functioning and biodiversity has been recognized. In Northern Italy, the hare population has evidently declined since 2008. This paper aims to assess the relationship between host demographic trends and helminth parasite community diversity in a two-year survey in Northern Italy to evaluate the impact of parasites on hosts and confirm the hypothesis that endangered host populations are poor in parasites. In 2013 and 2015 the viscera of 54 and 61 hares legally hunted in agro-ecosystems of the Po Plain were collected. This area is characterized by heavy anthropic pressure: more than 60% of the landscape is represented by agricultural or urbanized territories. No intestinal cestodes were detected. Trichuris sp. and Micipsella numidica were collected in 2015 only; Trichostrongylus retortaeformis, Taenia pisiformis cysticercosis and bronchopulmonary lesions caused by small strongyles were observed in both years. The richness and evenness appeared increased in the second year of the survey, although lower than those obtained by literature data from similar populations examined in the last two decades of 1900. The dominant helminth, T. retortaeformis, was more abundant in individuals with higher weight, while pathological findings were mostly unrelated to this nematode infection; this is consistent with a reduced action, even no harm, of the parasites on the individual host or population level. Our results suggest that the conservation of hosts, environment, and parasites cannot be achieved separately and that parasites and wildlife hosts' destinies are intimately linked, confirming the complexity of ecosystems and the need to contemplate parasite biodiversity in conservation strategies.

Specifics of the morphological identification of the pathogen of passaluariasis of rabbits

Passalurus ambiguus (Nematoda, Oxyuroidae) is one of the most common parasites of digestive tract of domestic and wild rabbits and rodents. Passalurus spp. are cosmopolitan, and the mature nematodes are localized in the appendages and large intestine of animals. The passaluariasis infections remain quite relevant in modern rabbit breeding, because the disease is highly contagious, with the possibility of unlimited spread inducing significant economic losses. The aim of the study was to determine the identifying morphological species characteristics of P. ambiguus nematodes, which were isolated from the colon of domestic rabbits (Oryctolagus cuniculus domesticus). The identifying characters of Passalurus include morphological features, namely the presence of a spherical bulb in the esophagus, and the presence of three teeth in the oral capsule. Males of P. ambiguus have a characteristic structure of the tail end, namely the presence of papillary protrusions and a massive narrowed part with a spicule handle, and five papillae around the cloaca. Twenty-eight metric indicators are proposed that characterize the size of the body, oral capsule, esophagus in different parts of it, the tail end, spicules, the location of the cloaca. Two different morphotypes of mature females of P. ambiguus were revealed – short-tailed and long-tailed, which were larger by 19 indicators (by 3.2–43.6%). The morphotypes of P. ambiguus females are characterized; the length of the tail, body length and width in different areas, depth of the oral capsule, esophageal size and its structural elements, the location of the vulva and nerve ring, the width of the caudal process. At the same time, the parameters of esophageal bulb length and caudal process in short-tailed females were higher (by 13.9% and 11.9%, respectively) than in the long-tailed females. A total of 25 morphometric parameters were proposed for the identification of P. ambiguus females. The obtained data indicate the feasibility of further research on the causes of occurrence of such morphotypes in P. ambiguus females and the need to take into account the existence of such forms of females for their differential diagnosis taking into account their proposed morphometric parameters.

Prevalence, Morphological and Molecular Phylogenetic Analyses of the Rabbit Pinworm, Passalurus ambiguus Rudolphi 1819, in the Domestic Rabbits Oryctolagus cuniculus

INTRODUCTION

Passalurus ambiguus, a pinworm nematode parasite, infects domestic and wild rabbits, hares, and rodents worldwide.

MATERIALS AND METHODS

The current parasitological study was performed during January-December 2016, to investigate helminth parasites infecting the domestic rabbit species Oryctolagus cuniculus at the Department of Animal Production, Faculty of Agriculture, Cairo University, Cairo, Egypt.

RESULTS

Of the twenty rabbit specimens examined for gastrointestinal nematodes, 75% were infected with adult oxyurid species, which were morphologically characterized using light and scanning electron microscopy studies. The oxyurid species had a triangular mouth opening surrounded by simple lips with four cephalic papillae and a pair of lateral amphidial pores with three teeth-like structures, an esophagus divided into a cylindrical corpus and globular bulb supported internally with tri-radiate valvular apparatus, and four caudal papillae distributed on the posterior end of males with a single short protruding spicule and ovijector apparatus opening ventrally by the vulva, surrounded by protruded lips in female worms. The species were compared morphometrically with other Passalurus species described previously; light differences were found in different body part sizes. Molecular characterization based on 18 small subunit (SSU) rDNA sequences showed ~ 85% similarity with other Chromadorea species. A preliminary genetic comparison between the 18S rDNA sequences of the isolated parasite and those of other oxyurid species suggested that it belonged to Passalurus ambiguus. The 18S rDNA sequence of the parasite was deposited in GenBank (accession no., MG310151.1).

CONCLUSION

The 18S rDNA gene of P. ambiguus was shown to yield a unique genetic sequence that confirms its taxonomic position within the Oxyuridae family.

Pathomorphological changes in the large intestine of rabbits parasitised by Passalurus ambiguus (Nematoda, Oxyuridae)

Passaluriasis is a common infestation of lagomorphs, which clinically manifests in intense itching around the anus, various disorders of digestion and loss of weight. We performed a study of infested rabbits of the seryi veleten breed, which were kept in individual farms in Poltava Oblast (Ukraine). During the autopsy, in the cavity of the large intestine, there were found small, spindle-like helminths of white colour. Out of 10 rabbits, 846 nematodes were extracted (369 males and 477 females, identified as Passalurus ambiguus (Rudolphi, 1819) Dujardin, 1845. It was determined that the extensity of infestation in female rabbits reached 56.4%, male rabbits – 43.6%. The results of metric parameters of the nematodes are as follows: mean body length of males equaled 4.6 ± 0.4, females – 9.7 ± 1.21 mm, and maximum width – 257.4 ± 17.8 and 546.2 ± 37.1 µm respectively. A common feature of mature nematodes of this species is the presence of a rounded extension (bulbus) at the end of the esophagus. During chronic course of passaluriasis in rabbits, pathomorphological changes developed in the large intestine. The upper epithelium of the large intestine was damaged in some places, certain epithelian cells were found in the lumen of the intestine. The intestinal glands are widened, filled with slimy content of mostly dark blue-violet colour, especially in the upper sections of the glands. In the deep sections of the glands, slime was almost transparent. In deep sections of the glands the slime was almost transparent. In the epithelium cells of the glands, slimy granules were also of basophilic colour. The muscularis mucosae of the mucous membrane, especially between the intestinal glands was swollen, had practically no colour, the collagen fibers were stretched, thinned-out. Edemas were also recorded in the tela submucosa. In some preparations, the muscularis mucosae was notably infiltrated by lymphoid cells and histiocytes. On large extensions, we found some signs of hypersecretion of slime in goblet cells of the intestinal glands as accumulations of granules of slime in the cytoplasm, which had poorly developed colouration. On the side of the muscular and serous membranes, no pathological changes were found. The information presented here indicates the relevance of passaluriasis infestation as an etiological factor of occurrence of chronic catarrhal colitis with lymphohistiocytosis.

Helmintos endoparasitos de vertebrados silvestres em Mato Grosso do Sul, Brasil

RESUMO Uma lista de espécies de vertebrados silvestres e as espécies de helmintos endoparasitos associadas foi organizada para o estado de Mato Grosso do Sul. Foram encontrados registros de 291 espécies de helmintos endoparasitos, sendo 9 de Acanthocephala, 226 de Nematoda e 65 espécies de Platyhelminthes (23 de Cestoda e 42 de Trematoda) associadas a 20 espécies de peixes, nove de anfíbios, 17 de répteis, 103 de aves e 27 espécies de mamíferos. Apenas 12% dos vertebrados do estado foram estudados quanto a sua parasitofauna, ressaltando o quanto a biodiversidade de helmintos parasitos no estado ainda é subestimada.

The future biological control of pest populations of European rabbits, Oryctolagus cuniculus

European rabbits are exotic pests in Australia, New Zealand, parts of South America and Europe, and on many islands. Their abundance, and the damage they cause, might be reduced by the release of naturally occurring or genetically modified organisms (GMOs) that act as biological control agents (BCAs). Some promising pathogens and parasites of European rabbits and other lagomorphs are discussed, with special reference to those absent from Australia as an example of the range of necessary considerations in any given case. The possibility of introducing these already-known BCAs into areas where rabbits are pests warrants further investigation. The most cost-effective method for finding potentially useful but as-yet undiscovered BCAs would be to maintain a global watch on new diseases and pathologies in domestic rabbits. The absence of wild European rabbits from climatically suitable parts of North and South America and southern Africa may indicate the presence there of useful BCAs, although other explanations for their absence are possible. Until the non-target risks of deploying disseminating GMOs to control rabbits have been satisfactorily minimised, efforts to introduce BCAs into exotic rabbit populations should focus on naturally occurring organisms. The development of safe disseminating GMOs remains an important long-term goal, with the possible use of homing endonuclease genes warranting further investigation.