Tissue (re)distribution of Trypanosoma equiperdum in venereal infected and blood transfused horses

A systematic review and meta-analysis of the prevalence of parasitic infections in equids in Ethiopia

We performed this review to determine the weighted prevalence of equids parasitic infections in Ethiopia. Article searches on parasites of equids were conducted using PubMed, PubMed Central, Google Scholar, Science Direct, Web of Sciences, Scopus, AJOLs and Research Gate. A random effects model was used to estimate the weighted prevalence and to study heterogeneity. The primary searches generated, 3082 potential studies, of which 66 reports met the inclusion criteria and were included in the meta-analysis. There were 32 reports involving two or more equids species, eighteen on donkeys, and sixteen on horses. Moreover, fifty of the reports mentioned helminth infections in equids, thirteen on protozoans, and three on ectoparasites. The estimated weighted prevalence of parasitic infections in equids was 58.3% (95% CI 50.8-65.4%, I2 = 99%). Helminths were the most prevalent parasites in equids, accounting for 77.1% (95% CI 71.4%, 82%, I2 = 98.5%), followed by ectoparasites at 35.4% (95% CI 33.4-37.52%, I2 = 88.2%) and haemoparasites (protozoans) at 10.84% (95% CI 6.6%, 17.3%, I2 = 98.1%). Furthermore, with a prevalence of 82.3% (95% CI 75.9-87.3%, I2 = 97.4%), donkeys were the most affected equids with helminth parasites. From the reports, we found forty-three species of helminth parasites affecting equids, including thirty-four nematode species (Strongylus, Cyathostomum, Coronocyclus, Cylicocyclus, Cylicostephanus, Trichostrongylus, Oesophagodontus, Strongyloides, Triodontophorus, Gyalocephalus, Poteriostomum, Dictyocaulus, Oxyuris, Habronema, Draschia, Parascaris, Setaria, and Probstmayria species), three trematodes (two Fasciola and one Gastrodiscus species), three cestodes (two Anoplocephala and one Anoplocephaloides species) and three botfly larvae (one Rhinoestrus and two Gasterophilus species). Trypanosoma species (T. congolense, T. vivax, T. brucei, T. equiperdum, and T. evansi), piroplasms (Theileria equi and Babesia caballi), and Eimeria species have also been reported to affect equids. Ticks (Amblyomma variegatum, A. gemma, Rhipicephalus decoloratus, R. evertisi evertisi, R. pulchellus, R. muhsame, R. sanguineus, Hyalomma rufipes, and Hy. truncatum) and lice (Bovicola equi and Haematopinus asini) were the ectoparasites recorded to affect equids. The risk of publication bias across studies was likely to be high due to differences in publication year and diagnostic techniques. In conclusion, parasitic infections of equids are common in Ethiopia and are caused by a variety of parasite species, putting the performance and well-being of these packing animals at risk. Therefore, more research is needed to identify infection risk factors and raise awareness of the consequences of parasitism in order to provide strategies to mitigate the problems in equids.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12639-023-01598-3.

Epididymitis in mice experimentally infected with Trypanosoma equiperdum: a histopathological and immunohistochemical study

Trypanosoma equiperdum is a causative agent of dourine in equids and is transmitted from stallions to mares by coitus. Dourine-affected stallions develop orchitis and epididymitis, and these lesions are considered to be responsible for the sexual transmission of T. equiperdum during coitus. However, the parasitic site of trypanosomes in the reproductive organs and the mechanisms underlying transmission have not yet been elucidated histopathologically. We examined the reproductive organs of male mice infected with T. equiperdum histopathologically and identified severe epididymitis with sperm granulomas. Many trypanosomes were detected in the epididymal interstitium and a few were seen within tubular lumen. Interstitial inflammatory cells mainly consisted of Iba1-, iNOS- and CD204-positive cells with a few CD3-, FOXP3- or PAX5-positive cells. There was diffuse immunolabelling of tumour necrosis factor-α (TNF-α) within these inflammatory foci. While caspase-3-positive epithelial cells in the epididymis were not observed in control mice, they were detected multifocally in infected mice and were frequently associated with loss of immunolabelling of zonula occludens-1 (ZO-1), a major protein that forms tight junctions between epididymal epithelial cells. Anti-laminin immunofluorescence revealed an indistinct basement membrane of the epididymal duct. These results suggest that trypanosomes in the epididymal interstitium induce the infiltration of TNF-α-secreting macrophages. Secreted TNF-α may impair the tight junctions of the epididymal duct by inducing apoptosis and downregulating ZO-1 expression.

Histopathological lesions in reproductive organs, distal spinal cord and peripheral nerves of horses naturally infected with Trypanosoma equiperdum

Background

Dourine, a venereal transmitted trypanosomosis caused by Trypanosoma equiperdum, has different clinical signs related to the reproductive and nervous system. Pathologic tissue changes associated with the disease are poorly described. The present study describes the histopathological lesions in naturally T. equiperdum-infected horses in the chronical stage of dourine.

Results

Four chronically dourine diseased horses underwent a post-mortem examination. They were Woo test negative, but CATT/T. evansi positive, had a low packed cell volume (PCV) and exhibited obvious clinical signs of dourine. Post-mortem examination did not reveal gross lesions in the organs assumed to be responsible for the symptomatology. On histopathology, genital organs were affected, with mononuclear cell infiltration and erosions and degeneration of seminiferous tubules and perivascular lymphoplasmacytic cuffing in the uterus. In the nervous system, mononuclear cell infiltration was located in peripheral nerves, ganglia and in the spinal cord, leading to axonal degeneration. Real-time PCR using ITS primer revealed the presence of trypanosomes in these organs and conventional PCRs using maxicircle and RoTat1.2 primers further confirmed the involvement of T. equiperdum since the DNAs from the vagina, testicle, distal spinal cord, sciatic and obturator nerves found to be positive for maxicircle and negative for RoTat 1.2.

Conclusions

The histopathological lesions in the spinal cord and peripheral nerves explain the incoordination of the hind legs in T. equiperdum-infected horses, whilst its presence in the genital tract exemplifies the venereal transmission.