Pathological changes caused by Anoplocephala perfoliata in the mucosa/submucosa and in the enteric nervous system of equine ileocecal junction

A dominance of Mu class glutathione transferases within the equine tapeworm Anoplocephala perfoliata

The most common equine tapeworm, Anoplocephala perfoliata, has often been neglected amongst molecular investigations and has been faced with limited treatment options. However, the recent release of a transcriptome dataset has now provided opportunities for in-depth analysis of A. perfoliata protein expression. Here, global, and sub-proteomic approaches were utilized to provide a comprehensive characterization of the A. perfoliata soluble glutathione transferases (GST) (ApGST). Utilizing both bioinformatics and gel-based proteomics, GeLC and 2D-SDS PAGE, the A. perfoliata ‘GST-ome’ was observed to be dominated with Mu class GST representatives. In addition, both Sigma and Omega class GSTs were identified, albeit to a lesser extent and absent from affinity chromatography approaches. Moreover, 51 ApGSTs were localized across somatic (47 GSTs), extracellular vesicles (EVs) (Whole: 1 GST, Surface: 2 GSTs) and EV depleted excretory secretory product (ESP) (9 GSTs) proteomes. In related helminths, GSTs have shown promise as novel anthelmintic or vaccine targets for improved helminth control. Thus, provides potential targets for understanding A. perfoliata novel infection mechanisms, host–parasite relationships and anthelmintic treatments.

Horse and donkey parasitology: differences and analogies for a correct diagnostic and management of major helminth infections

In June 2022, at the XXXII Conference of the Italian Society of Parasitology, the parallels of the main endoparasitic infections of horses and donkeys were discussed. Although these 2 species are genetically different, they can be challenged by a similar range of parasites (i.e. small and large strongyles, and Parascaris spp.). Although equids can demonstrate some level of resilience to parasites, they have quite distinct helminth biodiversity, distribution and intensity among different geographical locations and breeds. Heavily infected donkeys may show fewer clinical signs than horses. Although parasite control is primarily provided to horses, we consider that there may be a risk of drug-resistance parasitic infection through passive infection in donkeys when sharing the same pasture areas. Knowing the possible lack of drug efficacy (<90 or 80%), it is advocated the use of selective treatment for both species based on fecal egg counts. Adult horses should receive treatment when the threshold exceeds 200–500 eggs per gram (EPG) of small strongyles. Moreover, considering that there are no precise indications in donkeys, a value >300 EPG may be a safe recommendation. We have highlighted the main points of the discussion including the dynamics of helminth infections between the 2 species.

Gastrointestinal Helminths in Horses in Serbia and Various Factors Affecting the Prevalence

PURPOSE

Data on gastrointestinal infections in horses in Southeastern Europe are limited; thus, this study aimed to add to the existing knowledge on this topic by reporting on the prevalence of intestinal parasites of horses in the territory of the Republic of Serbia.

METHODS

In the period from April 2017 to December 2018, parasitological examination of 548 samples from horses of different breed, age and sex from four regions and 18 districts of the country was performed. Coprological diagnostic was done by using qualitative methods without concentration and qualitative methods with concentration of parasitic elements. Quantification of the obtained results was performed using semi-qualitative faecal egg count.

RESULTS

Four helminthoses were detected in the examined samples: P. equorum (8.57%), O. equi (3.65%), strongylid eggs (71.17%) and Anoplocephala spp. (0.91%). The total prevalence of helminthoses was 77.19%. Monoinfections were significantly more present 70.07% compared to coinfections (7.12%). The highest prevalence of helminthoses was detected in free-ranging horses (93.10%-27/29), in autumn 86.67% (117/135) and winter 79.71% (165/207), in Šumadija and West Serbia region (100%), and in the youngest category (100%). Significant difference (p < 0.001) was detected in the prevalence of monoinfections by strongylids and O. equi and also coinfections by strongylid/P. equorum between horses of different age categories.

CONCLUSION

Obtained results are of great contribution to clinical parasitology and pathology, especially from the aspect of animal health, welfare and preservation of horse population.

Evidence of Immune Modulators in the Secretome of the Equine Tapeworm Anoplocephala perfoliata

Anoplocephala perfoliata is a neglected gastro-intestinal tapeworm, commonly infecting horses worldwide. Molecular investigation of A. perfoliata is hampered by a lack of tools to better understand the host-parasite interface. This interface is likely influenced by parasite derived immune modulators released in the secretome as free proteins or components of extracellular vesicles (EVs). Therefore, adult RNA was sequenced and de novo assembled to generate the first A. perfoliata transcriptome. In addition, excretory secretory products (ESP) from adult A. perfoliata were collected and EVs isolated using size exclusion chromatography, prior to proteomic analysis of the EVs, the EV surface and EV depleted ESP. Transcriptome analysis revealed 454 sequences homologous to known helminth immune modulators including two novel Sigma class GSTs, five α-HSP90s, and three α-enolases with isoforms of all three observed within the proteomic analysis of the secretome. Furthermore, secretome proteomics identified common helminth proteins across each sample with known EV markers, such as annexins and tetraspanins, observed in EV fractions. Importantly, 49 of the 454 putative immune modulators were identified across the secretome proteomics contained within and on the surface of EVs in addition to those identified in free ESP. This work provides the molecular tools for A. perfoliata to reveal key players in the host-parasite interaction within the horse host.

Pathological lesions of the digestive tract in free-ranging mountain gorillas (Gorilla beringei beringei)

The finding of parasites and bacterial pathogens in mountain gorilla feces and oral lesions in gorilla skeletal remains has not been linked to pathological evidence of morbidity or mortality. In the current study, we conducted a retrospective study of digestive tracts including oral cavity, salivary glands, esophagus, stomach, intestines (gastrointestinal tract [GI]), liver, and pancreas of 60 free-ranging mountain gorillas from Uganda, Rwanda, and the Democratic Republic of Congo that died between 1985 and 2007. We reviewed clinical histories and gross pathology reports and examined histological sections. On histology, enteritis (58.6%), gastritis (37.3%), and colitis (29.3%) were the commonest lesions in the tracts. Enteritis and colitis were generally mild, and judged likely to have been subclinical. Gastritis was often chronic and proliferative or ulcerative, and associated with nematodiasis. A gastro-duodenal malignancy (carcinoid) was present in one animal. A number of incidental lesions were identified throughout the tract and cestodes and nematodes were frequently observed grossly and/or histologically. Pigmentation of teeth and tongue were a common finding, but periodontitis and dental attrition were less common than reported from past studies of skeletal remains. Despite observing numerous GI lesions and parasites in this study of deceased free-living mountain gorillas, we confirmed mortality attributable to gastroenteritis in just 8% (5/60) cases, which is less than that described in captive gorillas. Other deaths attributed to digestive tract lesions included cleft palate in an infant, periodontal disease causing systemic infection in an older adult and gastric cancer. Of all the parasitic infections observed, only hepatic capillariasis and gastric nematodiasis were significantly associated with lesions (hepatitis and gastritis, respectively). Understanding GI lesions in this endangered species is key in the management of morbidity associated with GI ailments.

Parasite Occurrence and Parasite Management in Swedish Horses Presenting with Gastrointestinal Disease-A Case-Control Study

All grazing horses are exposed to intestinal parasites, which have the potential to cause gastrointestinal disease. In Sweden, there is a concern about an increase in parasite-related equine gastrointestinal disease, in particular Strongylus vulgaris, since the implementation of prescription-only anthelmintics approximately 10 years ago. In a prospective case-control study, parasitological status, using fecal analyses for strongyle egg counts, the presence of Anoplocephala perfoliata eggs and S. vulgaris Polymerase chain reaction (PCR) as well as serology for S. vulgaris, were compared between horses presenting with or without gastrointestinal disease at a University hospital during a one-year period. Information regarding anthelmintic routines and pasture management was gathered with an owner-filled questionnaire. Although the prevalence of S. vulgaris PCR was 5.5%, 62% of horses were positive in the enzyme-linked immunosorbent assay (ELISA) test and horses with peritonitis showed higher antibody levels for S. vulgaris, as compared to other diagnoses or controls. Overall, 36% of the horse owners used only fecal egg counts (FEC), 32% used FEC combined with specific diagnostics for S. vulgaris or A. perfoliata, and 29% dewormed routinely without prior parasite diagnostics. Effective management methods to reduce the parasitic burden on pastures were rare and considering exposure to S. vulgaris appears high; the study indicates a need for education in specific fecal diagnostics and pasture management.

Analysis of caecal mucosal inflammation and immune modulation during Anoplocephala perfoliata infection of horses

Anoplocephala perfoliata is the commonest equine tapeworm, the adult parasites are attached in groups close to the ileocaecal valve causing marked inflammatory pathology. This work aimed to characterize the nature of the in vivo mucosal immune response to A perfoliata, and to investigate the role of A perfoliata excretory-secretory components in modulating in vitro immune responses. Real-time PCR detected elevation of IL13 and TGFβ transcription in early-stage A perfoliata infection. In late-stage infection, IL-13, IL4 and Ifn transcripts were reduced while the regulatory cytokines, TGFβ, IL10 and the transcription factor FOXP3 were increased in tissue close to the site of A perfoliata attachment; indicating downregulation of T-cell responses to A perfoliata. In vitro, A perfoliata excretory-secretory products induced apoptosis of the Jurkat T-cell line and premature cell death of ConA stimulated equine peripheral blood leucocytes. Analysis of cytokine transcription patterns in the leucocyte cultures showed a marked inhibition of IL-1 and IL-2 suggesting that a lack of T-cell growth factor transcription underlies the mechanism of the induced equine T-cell death. These preliminary findings suggest A perfoliata may have the ability to down-regulate host T-cell responses.

Validation of a novel saliva-based ELISA test for diagnosing tapeworm burden in horses

BACKGROUND

Tapeworm infections pose a significant threat to equine health as they are associated with clinical cases of colic. Diagnosis of tapeworm burden using fecal egg counts (FECs) is unreliable, and, although a commercial serologic ELISA for anti-tapeworm antibodies is available, it requires a veterinarian to collect the blood sample. A reliable diagnostic test using an owner-accessible sample such as saliva could provide a cost-effective alternative for tapeworm testing in horses, and allow targeted deworming strategies.

OBJECTIVES

The purpose of the study was to statistically validate a saliva tapeworm ELISA test and compare to a tapeworm-specific IgG(T) serologic ELISA.

METHODS

Serum samples (139) and matched saliva samples (104) were collected from horses at a UK abattoir. The ileocecal junction and cecum were visually examined for tapeworms and any present were counted. Samples were analyzed using a serologic ELISA and the saliva tapeworm test. The test results were compared to tapeworm numbers and the various data sets were statistically analyzed.

RESULTS

Saliva scores had strong positive correlations with both infection intensity (0.74) and serologic results (Spearman's rank coefficients; 0.74 and 0.86, respectively). The saliva tapeworm test was capable of identifying the presence of one or more tapeworms with 83% sensitivity and 85% specificity. Importantly, no high-burden (more than 20 tapeworms) horses were misdiagnosed.

CONCLUSIONS

The saliva tapeworm test has statistical accuracy for detecting tapeworm burdens in horses with 83% sensitivity and 85% specificity, similar to those of the serologic ELISA (85% and 78%, respectively).

Comparison of the sensitivity of coprological methods in detecting Anoplocephala perfoliata invasions

The autopsy of 487 slaughter horses revealed the presence of Anoplocephala perfoliata in 36 animals. The invasions varied in the intensity (3 to 2,069 tapeworms) and in the level of tapeworms’ proglottid maturity. Twenty nine horses were found to contain tapeworms with gravid proglottid. Fecal samples collected from the rectum were tested using following techniques: flotation with solution-saturated NaCl, decantation, McMaster’s, and modified sedimentation-flotation methods (50 g feces samples, flotation solution-saturated NaCl and sucrose, specific gravity 1.25 g/ml). The number of A. perfoliata positive fecal samples was significantly higher using the sedimentation-flotation methods 21 (58.33 %) than flotation 6 (16.66 %), decantation 3 (8.33 %), and McMaster’s 1 (2.77 %) techniques. The sensitivities of the coprological methods during the patent period were 20.69, 10.34, 3.45, and 72.41 % for the flotation, decantation, McMaster’s, and sedimentation-flotation method, respectively. Sedimentation–flotation techniques proved to be more sensitive than other one. The lowest intensity of invasion possible to detect using this method was nine tapeworms with gravid proglottid.

Systemic and mucosal IgE antibody responses of horses to infection with Anoplocephala perfoliata

Infection of horses with Anoplocephala perfoliata induces a severe inflammatory reaction of the caecal mucosa around the site of parasite attachment adjacent to the ileocecal valve. Lesions show epithelial erosion or ulceration of the mucosa with infiltration by eosinophils, lymphocytes and mast cells leading to oedema, gross thickening and fibrosis of the caecal wall. Despite this evidence of an inflammatory reaction to A. perfoliata within the mucosa of the caecum there is little information about the nature of the local immune response to A. perfoliata. An ELISA which assays serum IgG(T) antibodies to A. perfoliata excretory/secretory antigens has been developed as a diagnostic test. However, the specificity of the ELISA remains sub-optimal and the role of other isotypes in the immune response to A. perfoliata has not been reported. This study measured IgA, IgE and IgG(T) antibody responses to A. perfoliata excretory/secretory antigens in sera of 75 horses presented for slaughter. The prevalence of A. perfoliata infection, as confirmed by the presence of parasites in the terminal ileum, caecum or proximal colon, was 55%. A. perfoliata-specific IgG(T) and IgE antibodies were significantly elevated in infected horses compared to controls; IgA antibodies were also detected but did not differ between infected and control horses. Diagnosis by serum IgG(T) ELISA had a sensitivity of 78% and a specificity of 80%, by comparison the serum IgE ELISA had a sensitivity of just 44% with a specificity of 82% and therefore did not provide an improved diagnostic test. Western blots with sera from infected horses demonstrated IgE-binding to at least 10 separate components of excretory/secretory (E/S) antigens. A similar pattern was also found with IgG(T). Around 30% of horses had high levels of serum IgE which bound fucose-containing carbohydrate antigens on the parasite surface but this was unrelated to the presence of A. perfoliata infection. Immunoperoxidase staining detected numerous IgE-positive cells within lymphoid follicles in the caecal mucosa close to the site of A. perfoliata attachment and quantitative RT-PCR detected high levels of IgE transcription in the caecal mucosa of all horses. Mucosal synthesis of antibodies was confirmed by the demonstration of A. perfoliata-specific IgG(T) and IgE in the supernatant of lamina propria explant cultures that discriminated clearly between infected and uninfected horses. We conclude that there is an active immune response to A. perfoliata within the caecal mucosa involving local production of both IgG(T) and IgE antibody isotypes; but it remains unclear whether this immune response can reduce or eliminate parasite burden.

Equine cestodosis: a sero-epidemiological study of Anoplocephala perfoliata infection in Ethiopia

A 12/13 kDa antigen, tapeworm ELISA test, developed for use in horses, was used to detect parasite-specific serum antibody, IgG(T), in the serum of donkeys. In a pilot study the 12/13 kDa antigen was tested and proved to detect the antibody, IgG(T), in donkey sera. Blood samples from 797 donkeys, naturally exposed to cestode infection, from four geographical localities were collected and sera were prepared and analysed. There was substantial serological evidence that donkeys were potentially infected with A. perfoliata. A range of ELISA OD values were obtained from the serological assay. Over 26% and 7.5% of the donkeys were moderately and highly infected, respectively, showing at least a 34% sero-prevalence. The rest, 66.1%, were either with low infection intensity or negative for A. perfoliata infection. The risk of infections, both in sero-prevalence and intensity, as determined by ELISA optical density (OD), were highest in the highland areas of Ethiopia where pastures are low-lying and wet, and permanent pasture management is regularly practised. Sex, age and body condition of the donkeys had no significant effect either on prevalence of the infection or on the serum antibody level. These results indicate a risk of intestinal disorders, particularly, colic, associated with A. perfoliata infection in donkeys.