Redescription of Parafilaria bovicola Tubangui, 1934 (Nematoda: Filarioidea) from Swedish cattle

"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.

Bovine parafilariosis - New autochthonous cases from Germany and summary of recent reports from Europe

Bovine parafilariosis is an emerging fly-borne disease in central Europe, characterized by seasonal occurrence of hemorrhagic exudations ('bleeding spots') from the end of winter to end of summer. In two cases from Germany reported here, one animal of a small herd in Bavaria and 20 animals on a farm in Baden-Württemberg presented bleeding spots from late March and late April 2020, respectively. Exudate samples from both cases were positive for larvated Parafilaria eggs. Examination of the skin and trimmed tissue after slaughter of the animal from Bavaria resulted in the collection of 11 nematodes (two males, eight females, one specimen in fragments). The animal's carcass presented typical yellow-greenish areas and bloody spots on the subcutaneous tissue of the flesh side of the skin. The nematodes were microscopically determined as Parafilaria bovicola. Basic morphometric measurements of two (one intact) male and six female nematodes are within the ranges of published data; length (male/female) 28.8/48.0-64.5 mm; width, 397.6 μm/430.7-527.6 μm; distance of cervical papillae to anterior end, 177.6/248.9-337.4; left spiculum/right spiculum (male), 365.3-379.4/149.5-180.3 μm; gubernaculum 45.0-48.1 μm; distance of vulva to anterior end (female), 37.3-66.0 mm. In order to gain information on P. bovicola in its vector, 91 cattle-visiting Musca autumnalis flies were collected from the affected animal in Bavaria (36 flies) and from co-pastured animals (55 flies) for PCR analysis and sequencing. A total of 14 flies were PCR-positive for filarial DNA, and sequencing of a fragment of the cox1 gene resulted in identification of P. bovicola (n = 10) and Thelazia gulosa (n = 5). This report presents further cases of bovine parafilariosis in Germany, provides morphometric data on male and female P. bovicola nematodes retrieved from cattle and identified DNA of P. bovicola and T.gulosa in M. autumnalis flies collected at a site of occurrence of bovine parafilariosis.

Emergence of Parafilaria bovicola in Austria

Simple Summary

Bovine parafilariosis is a disease caused by the helminth Parafilaria bovicola (Filariidae, Nematoda). Flies transmit the parasite, which grows to adulthood in an unknown location in the affected animals. The adult female worms are located in nodules under the skin, which they penetrate and lay their eggs in the fluid leaking from the site. There is virtually no information about Parafilaria bovicola in Austria. In this study, these parasites were documented in the provinces of Lower Austria, Upper Austria, Styria, Salzburg, Carinthia, and Tyrol. With a high number of cases during the 2020 study period, it can be assumed that the number of reports will increase in the near future.

Abstract

Veterinarians reported cases of cutaneous bleeding in cattle in Austria in the spring and summer of 2020. It was our goal to confirm the tentative diagnosis of parafilariosis by identifying Parafilaria bovicola in exudate samples using molecular methods for the first time in Austria. We asked veterinarians in the field to collect exudate from typical lesions on cattle. We performed polymerase chain reactions (PCRs) and sequenced a 674-bp section of the mitochondrial cytochrome oxidase subunit I in all positive samples. Overall, in 57 of 86 samples, P. bovicola was confirmed by PCR in cattle from Lower Austria, Upper Austria, Styria, Salzburg, Carinthia, and Tyrol. Sequencing detected four different haplotypes or genotypes, respectively, indicating multiple routes of introduction. We conclude that parafilariosis has spread in Austria and we expect that the number of reports of clinical signs and losses due to carcass damage will increase in the future.

Evidence for bovine parafilariosis in Italy: first isolation of Parafilaria bovicola (Tubangui, 1934) from autochthonous cattle

In May and July 2010 and in March 2011, the presence of multiple bleeding nodules at the level of the neck, shoulders, withers, back and rump in five cattle from three herds in north-central Italy were observed. A diagnosis of parafilariosis was made. Fragments of adult females of Parafilaria bovicola could be identified from the derma of three to five bioptic extirpates. Larvated eggs and free larvae were observed in serohemorrhagic exudates. This paper is the first report of the occurrence of parafilariosis in Italy and subsequent to the various outbreaks reported, it can now be said that bovine parafilariosis is also currently present in Italy.

First isolation of Parafilaria bovicola from clinically affected cattle in Belgium

The observation of the first two outbreaks of bovine parafilariosis in Belgium led to a preliminary epidemiological investigation conducted through a telephone survey among veterinarians in a limited area around the outbreaks. Typical clinical signs consisting of bleeding spots and areas of oedema were recorded, and the aetiology was confirmed through the observation of typical embryonated eggs of Parafilaria bovicola in the exudate. The localisation of the lesions on the withers, neck, back and, to a smaller extent, the rump of the animals, and their first appearance in early spring, were additional useful epidemiological observations. The clinical herd prevalence in the area was 14.1 per cent (95 per cent confidence interval 11.3 to 17.2 per cent), suggesting that bovine parafilariosis is established in the area.

Filarioid nematodes in cattle, sheep and horses in Finland

Background

In autumn 2006, Finnish meat inspection data revealed lesions in tendons, muscles and ligaments of bovine hind legs leading to partial condemnation of carcasses. In gross pathological examination at Finnish Food Safety Authority Evira, Oulu (now Fish and Wildlife Health) Research Unit, Onchocerca sp. (Filarioidea; Onchocercidae) nematodes were detected in lesions. Due to this, a pilot study was made in order to find out what filarioid nematodes do occur in cattle, horses and sheep in Finland.

Methods

Ventral skin biopsies from 209 dairy cattle and 42 horses, as well as blood samples from 209 cattle, 146 horses and 193 sheep, were collected from different parts of Finland and examined for microfilariae. Visceral organs and other tissues from 33 cattle with parasitic lesions were studied histopathologically.

Results

Onchocerca sp. microfilariae (mf), 240 μm long, range 225–260 μm, 5.4 μm thick, were found in 37% of the skin biopsies of cattle. All blood samples from cattle, horses and sheep and skin biopsies from horses were negative for mf. Ventral skin microfilaria prevalence in cattle was higher in southern Finland than in the North (p = 0.001). Animal age and sampling time was not associated with mf prevalence. The infection was evenly distributed among young and older animals. Macroscopic lesions on tissues included greenish-grey discolouration and often oedema. In most of the lesions, small pale nodules were seen on the fasciae. Histopathologic examination of the samples revealed mild to intense infiltration with eosinophilic granulocytes and multifocal nodular lymphoplasmacytic aggregations were seen. In some samples, there were granulomatotic lesions with central necrotic tissue and cell detritus, surrounded by eosinophilic granulocytes, lympho-, plasma- and histiocytes and some multinucleated giant cells. Around living nematodes no or only weak inflammatory changes were observed.

Conclusion

Onchocerca sp. infection in cattle was found to be common in Finland, but the amount of pathological changes leading to condemnation of infected parts is low compared to the mf prevalence. Pronounced pathological changes are distinct but rare and mild changes are difficult to distinguish. No other filarioid nematodes were observed from the animals and it appears that horses and sheep may be free from filarioid nematodes in Finland.