Molecular and serological detection of Theileria equi and Babesia caballi in donkeys (Equus asinus) in Brazil

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Seroprevalence of Babesia caballi and Theileria equi in the Swiss horse population

In Switzerland, the prevalence and incidence of equine piroplasma parasite (EPP) infections are unknown. In order to obtain a first insight into the prevalence, a representative sample of 689 sera of horses from Switzerland was serologically tested for the presence of antibodies directed against T. equi and B. caballi using the Indirect Fluorescence Antibody Test (IFAT). A total of 50 (7.3%) horses were seropositive for EPP: overall, the seroprevalence of T. equi was significantly higher than that of B. caballi (p=0.002). The seropositivities in indigenous horses (animals bred and raised in Switzerland) and in imported horses were 4.8% (11/230) and 8.5% (39/459), respectively. Unlike in indigenous horses, where no significant difference in seroprevalences could be observed between the two parasite species, the seroprevalence of T. equi was significantly higher (p<0.001) than that of B. caballi in imported horses. Horses imported from France, Spain and Portugal exhibited a significantly higher seroprevalence, and horses imported from Germany a significantly lower seroprevalence of EPP compared to indigenous horses. There were no associations between sex, age, weight loss, surgery or blood transfusions with T. equi and B. caballi seroprevalences. The overall seroprevalence of 7.3% clearly shows that infection with EPP is a threat to the health of the horses in Switzerland. With the presumed expansion of permissive tick vectors, EPP infections will potentially increase in importance in the future. Therefore, continuous monitoring is mandatory.

Production of recombinant EMA-1 protein and its application for the diagnosis of Theileria equi using an enzyme immuno assay in horses from São Paulo State, Brazil

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Aproximación al diagnóstico y epidemiología de la anemia en los équidos de Gran Canaria

Programa de Doctorado: Medicina Clínica y Sanidad Animal.

Equine piroplasmoses at the reintroduction site of the Przewalski's horse (Equus ferus przewalskii) in Mongolia

Piroplasmosis has been identified as a possible cause of mortality in reintroduced Przewalski's horses (Equus ferus przewalskii) in the Dsungarian Gobi (Mongolia). A cross-sectional and a longitudinal study were conducted in a representative sample (n = 141) of the resident domestic horse population and in 23 Przewalski's horses to assess the prevalence of Theileria equi and Babesia caballi. Piroplasms were detected in blood by light microscopy in 6.7% (95% confidence interval [CI]: 3.6-12.2%) of the domestic horse samples. Antibody prevalence was 88.6% (95% CI: 82.4-92.9%) for T. equi and 75.2% (95% CI: 67.4-81.6%) for B. caballi. Antibody prevalence did not change over time, but antibody prevalence for both piroplasms were significantly lower in animals less than 1 yr of age. For both piroplasms, the prevalence of presumably maternal antibodies (falling titers) in foals was 100%. Only one of 16 foals seroconverted against T. equi during the study period, despite that piroplasms were found in two other individuals. The incidence density (ID) of T. equi in foals was therefore 0.0012 seroconversions per horse day (95% CI: 0.00029-0.0057). In contrast, yearlings had an ID of 0.0080 (95% CI: 0.0049-0.010) for T. equi and 0.0064 (95% CI: 0.0036-0.0093) for B. caballi, and in seven individuals piroplasms were detected. The seroprevalence of both piroplasms rose from 20% in spring to 100% in autumn. Comparison of domestic and Przewalski's horses resulted in a standardized prevalence ratio (SPR) of 0.98 (95% CI: 0.80-1.24, not significant) for B. caballi; in contrast, the prevalence of T. equi in Przewalski's horses was significantly lower than expected (SPR = 0.51, 95% CI: 0.50-0.64).

Validation of a Competitive Enzyme-Linked Immunosorbent Assay for Detection of Babesia bigemina Antibodies in Cattle

A competitive enzyme-linked immunosorbent assay (cELISA) based on a broadly conserved, species-specific, B-cell epitope within the C terminus of Babesia bigemina rhoptry-associated protein 1a was validated for international use. Receiver operating characteristic analysis revealed 16% inhibition as the threshold for a negative result, with an associated specificity of 98.3% and sensitivity of 94.7%. Increasing the threshold to 21% increased the specificity to 100% but modestly decreased the sensitivity to 87.2%. By using 21% inhibition, the positive predictive values ranged from 90.7% (10% prevalence) to 100% (95% prevalence) and the negative predictive values ranged from 97.0% (10% prevalence) to 48.2% (95% prevalence). The assay was able to detect serum antibody as early as 7 days after intravenous inoculation. The cELISA was distributed to five different laboratories along with a reference set of 100 defined bovine serum samples, including known positive, known negative, and field samples. The pairwise concordance among the five laboratories ranged from 100% to 97%, and all kappa values were above 0.8, indicating a high degree of reliability. Overall, the cELISA appears to have the attributes necessary for international application.

New insights into the altered adhesive and mechanical properties of red blood cells parasitized by Babesia bovis

Sequestration of parasite-infected red blood cells (RBCs) in the microvasculature is an important pathological feature of both bovine babesiosis caused by Babesia bovis and human malaria caused by Plasmodium falciparum. Surprisingly, when compared with malaria, the cellular and molecular mechanisms that underlie this abnormal circulatory behaviour for RBCs infected with B. bovis have been relatively ignored. Here, we present some novel insights into the adhesive and mechanical changes that occur in B. bovis-infected bovine RBCs and compare them with the alterations that occur in human RBCs infected with P. falciparum. After infection with B. bovis, bovine RBCs become rigid and adhere to vascular endothelial cells under conditions of physiologically relevant flow. These alterations are accompanied by the appearance of ridge-like structures on the RBC surface that are analogous, but morphologically and biochemically different, to the knob-like structures on the surface of human RBCs infected with P. falciparum. Importantly, albeit for a limited number of parasite lines examined here, the extent of these cellular and rheological changes appear to be related to parasite virulence. Future investigations to identify the precise molecular composition of ridges and the proteins that mediate adhesion will provide important insight into the pathogenesis of both babesiosis and malaria.

Observation of a novel babesia spp. in eastern grey kangaroos (macropus giganteus) in australia

The roles and epidemiological features of tick-borne protozoans are not well elicited in wildlife. Babesia spp. are documented in many domestic animals, including cattle, horses, pigs, dogs and cats. Three cases affecting eastern grey kangaroos are described. The kangaroos exhibited neurological signs, depression and marked anaemia, and microscopic examination of blood smears revealed intraerythrocytic piroplasms. One to seven intraerythrocytic spherical, oval, pyriform and irregularly-shaped parasites consistent with Babesia spp. were seen in the blood smears and the percentage of infected erythrocytes was estimated to be approximately 7% in each case. Data suggest that the tick vector for this kangaroo Babesia sp. is a Haemaphysalis species. For Case 2, ultrastructural examination of the erythrocytes of the renal capillaries showed parasites resembling Babesia spp. and 18 of 33 erythrocytes were infected. DNA sequencing of the amplified 18S rDNA confirmed that the observed intraerythrocytic piroplasms belong to the genus Babesia. The phylogenetic position of this new kangaroo Babesia sp. (de novo Babesia macropus), as a sister species to the new Australian woylie Babesia sp., suggests a close affinity to the described Afro-Eurasian species Babesia orientalis and Babesia occultans suggesting perhaps a common ancestor for the Babesia in kangaroos. © 2012 Australian Society for Parasitology.

A retrospective study of Babesia macropus associated with morbidity and mortality in eastern grey kangaroos (Macropus giganteus) and agile wallabies (Macropus agilis)

This is a retrospective study of 38 cases of infection by Babesia macropus, associated with a syndrome of anaemia and debility in hand-reared or free-ranging juvenile eastern grey kangaroos (Macropus giganteus) from coastal New South Wales and south-eastern Queensland between 1995 and 2013. Infection with B. macropus is recorded for the first time in agile wallabies (Macropus agilis) from far north Queensland. Animals in which B. macropus infection was considered to be the primary cause of morbidity had marked anaemia, lethargy and neurological signs, and often died. In these cases, parasitised erythrocytes were few or undetectable in peripheral blood samples but were sequestered in large numbers within small vessels of visceral organs, particularly in the kidney and brain, associated with distinctive clusters of extraerythrocytic organisms. Initial identification of this piroplasm in peripheral blood smears and in tissue impression smears and histological sections was confirmed using transmission electron microscopy and molecular analysis. Samples of kidney, brain or blood were tested using PCR and DNA sequencing of the 18S ribosomal RNA and heat shock protein 70 gene using primers specific for piroplasms. The piroplasm detected in these samples had 100 sequence identity in the 18S rRNA region with the recently described Babesia macropus in two eastern grey kangaroos from New South Wales and Queensland, and a high degree of similarity to an unnamed Babesia sp. recently detected in three woylies (Bettongia penicillata ogilbyi) in Western Australia.

Cross-sectional estimation of Babesia bovis antibody prevalence in cattle in two contrasting dairying areas in Tanzania

The crude prevalence of antibodies to Babesia bovis infection in cattle was estimated by serology using indirect ELISA during the period January to April, 1999. Sera were obtained from 1395 dairy cattle (of all ages, sexes and breeds) on smallholder farms, the majority being kept under a zero grazing regime. The crude prevalence of antibodies to Babesia bovis was 6 % for Tanga and 12 % for Iringa. The forces of infection based on the age sero-prevalence profile, were estimated at six for Iringa and four for Tanga per 100 cattle years-risk, respectively. Using random effect logistic regression as the analytical method, the factors (variables) of age, source of animals and geographic location were hypothesised to be associated with sero-positivity of Babesia bovis in the two regions.