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

[Equine piroplasmosis: Case descriptions and overview of the epidemiological situation in Europe with focus on Germany]

Equine piroplasmosis (EP) is caused by Babesia (B.) caballi and Theileria (T.) equi and is transmitted by hard ticks. Predominantly, the Mediterranean region is known as being endemic for both pathogens in Europe. However, autochthonous infections in central European countries such as Germany can no longer be ruled out due to individual case reports in horses without any stays abroad as well as the geographical expansion of the habitats of different tick species. The case reports presented underline the risk of infection for horses travelling to endemic areas and in horses imported from such areas to non-endemic countries. Clinical signs are often unspecific and include fever, icterus, lethargy, inappetence, weight loss, and reduced performance. Mild to severe anemia is the most common hematologic abnormality, but thrombocytopenia has also been described. Direct (polymerase chain reaction, microscopical analysis of blood smears) and indirect detection methods (detection of antibodies) are available for the diagnosis of pathogen contact and/or infection. Imidocarb-dipropionate is recommended as treatment of choice against EP. Infections with B. caballi can be cleared, while infections with T. equi often result in a life-long carrier status despite treatment. Prevention is limited to controlling or avoiding tick contact. Aside from potentially severe and life-threatening clinical signs, equine piroplasmosis has a significant economic impact on the international trade of horses worldwide. EP is classified as a notifiable disease according to WOAH guidelines, which recommend serological screening for B. caballi and T. equi according to the respective national guidelines when travelling across borders. To date, EP is not classified as a notifiable nor reportable disease in Germany.

Equine piroplasmosis in different geographical areas in France: Prevalence heterogeneity of asymptomatic carriers and low genetic diversity of Theileria equi and Babesia caballi

Equine piroplasmosis is a worldwide tick-borne disease caused by the parasites Theileria equi sensu lato and Babesia caballi, with significant economic and sanitary consequences. These two parasites are genetically variable, with a potential impact on diagnostic accuracy. Our study aimed to evaluate the frequency of asymptomatic carriers of these parasites in France and describe the circulating genotypes. We developed a species-specific nested PCR protocol targeting the 18S small sub-unit (SSU) rRNA gene and used it on blood samples collected from 566 asymptomatic horses across four National Veterinary Schools. The carrier frequency varied from 18.7 % around Paris (central-north) to 56.1 % around Lyon (southeast), with an overall prevalence of 38.3 %. Theileria equi carriers were ten times more frequent (91.7 %; 209/228 isolates) compared to B. caballi carriers (8.3 %; 19/228 isolates). Notably, T. equi carrier frequency was significantly lower in the northern region (Ile de France) compared to the southeastern regions. A positive relationship was observed between the frequencies of asymptomatic carriers and the frequency of previous acute piroplasmosis reported from the owner across all four geographic areas. Neither horse gender nor age showed a significant effect on the frequency of asymptomatic carriers. In some areas, a substantial proportion of horses (22.2 % to 37.5 %) carried T. equi before the age of three years, indicating high infection pressure. Genotyping of 201 T. equi isolates revealed a predominance of genotype E (98 %) and few isolates belonging to genotype A (2 %). Notably, two of the four T. equi genotype A isolates were detected in horses originating from Spain. All 19 B. caballi isolates belonged to the genotype A. The discussion section explores the link between these results, the tick distribution and abundance, and the frequency of detection of T. equi and B. caballi in febrile cases attributed to piroplasmosis.

Molecular Investigations of Babesia caballi from Clinically Healthy Horses in Southwestern Romania

Babesia caballi is a tick-borne hemoparasite that causes equine piroplasmosis. It has a significant economic impact, decreasing performance and affecting animal welfare. This study aimed to identify B. caballi DNA in the blood of horses from households in the southwestern and western regions of Romania. We included 310 animals, from which blood was collected via EDTA. To test the samples for the B. caballi parasite genome, we used real-time PCR and conventional PCR. The prevalence of B. caballi was 5.81% (18/310) in apparently healthy horses, suggesting that this parasite is enzootic in the regions studied, although veterinarians did not indicate any symptoms resembling clinical babesiosis. In Romania, there are insufficient epidemiologic data on equine babesiosis, and the results of the present study suggest the need for further investigations into the dynamics of transmission and to identify potential prevention and control strategies.

Molecular and Serological Detection of Vector-Borne Pathogens Responsible for Equine Piroplasmosis in Europe between 2008 and 2021

Equine piroplasmosis (EP) is caused by Theileria (T.) equi and/or Babesia (B.) caballi. The aim was to assess the percentage of positive test results for EP in horses in Europe and to identify risk factors for pathogen contact/infection. This study included results from PCR and competitive enzyme-linked immunosorbent assay testing requested by European veterinarians between 2008 and 2021. Binary bivariate logistic regression was used to analyze risk factors. A total of 4060 horses were included. PCR testing was positive in 9.7% (154/1589), serology for T. equi in 15.2% (393/2591) and for B. caballi in 6.8% (175/2578). The odds of positive serology increased by 6.8% (B. caballi, p = 0.008) and 9.5% (T. equi, p < 0.001) each year. Regionality had a statistically significant impact on PCR (Eastern p = 0.047/OR = 1.605; Southern p = 0.029/OR = 1.451; Central p = 0.007/OR = 0.617) and serological testing for T. equi (Southern p < 0.001/OR = 2.521; Central p < 0.001/OR = 0.537; Northern p = 0.003/OR = 0.462), as well as breeds on seroprevalence of B. caballi (heavy horses: p = 0.016/OR = 2.239) and T. equi (ponies: p = 0.007/OR = 0.340; warmbloods: p = 0.025/OR = 1.602). In conclusion, there was a significant geographical impact on the results of PCR and serology, consistent with known vector habitats. The rising numbers of horses tested serologically positive highlights the importance of surveillance.

Low seroprevalence of equine piroplasmosis in horses exported from the Netherlands between 2015 and 2021

Equine piroplasmosis (EP) is a tick-borne disease affecting horses, donkeys, mules and zebras, caused by the intracellular apicomplexan protozoa Babesia caballi and Theileria equi. The geographical distribution of EP is closely related to the distribution of its vector tick species belonging to the genera of Dermacentor, Rhipicephalus and Hyalomma. Since the discovery of Dermacentor reticulatus ticks in 2007 and the first reported autochthonous cases in the South of the Netherlands in 2012, no data on the (sero)prevalence of EP in horses in the Netherlands have been reported and it remains unclear whether B. caballi and T. equi have been able to establish themselves in the Netherlands. This study aims to give an update on the current status of EP in horses in the Netherlands using data from serological tests performed in the context of export and screening of 12,881 horses from 2015 through 2020. Horses were categorized as “Dutch,” “Foreign,” or “Unknown” based on microchip number. The overall seroprevalence of EP in Dutch horses was found to be 0.5% (95% exact CI [0.4–0.7]), compared to 1.9% (95% exact CI [1.3–2.6]) in horses in the category “Foreign” and 1.7% (95% exact CI [1.2–2.3]) in horses in the category “Unknown.” In addition, the seroprevalence per country in the category “Foreign” ranged from 0% (0.95% exact CI [0–2.8]) for Ireland to 6.0% (0.95% exact CI [3.5–9.3]) for Spain. In light of the reports on the seroprevalence during the outbreak of autochthonous EP reported in 2012 and on seroprevalences of EP in other countries in Northwestern Europe, the seroprevalence of EP in horses exported from the Netherlands is very low. However, the higher seroprevalence of EP in horses from abroad warrants the need for the monitoring of EP, as tick vectors are present in the Netherlands and the import of horses from endemic areas increases the chances of EP becoming more prevalent in the Netherlands.

Seroprevalence of Anti-Theileria equi Antibodies in Horses from Three Geographically Distinct Areas of Romania

Equine piroplasmosis (EP) is an endemic tick-borne disease found in most countries around the world. It affects all species of Equidae, and it is caused by Theileria equi, Babesia caballi and T. haneyi. The research herein is the second study on the prevalence of piroplasms in Romania conducted in the past two decades. The aim of this study was to assess the seroprevalence of anti-Theileria equi antibodies and the geographical distribution of this disease in the southwest, west, and northwest regions of Romania in order to obtain a more thorough understanding of the parasitological status of horses in this country. This study included 522 apparently healthy, mixed-breed horses from three different counties. The serum samples were analysed using the cELISA Theileria equi Antibody Test Kit. The overall seroprevalence rate was 12.84%. From the total number of positive horses, 13.96% were females and 11.21% were males. Based on the distribution of positive cases into age groups, the following values were obtained: 0−60 months: 16.26%, 60−180 months: 10.03%, and >180 months: 15.83%. There was no statistically significant difference between samples, based on age or gender. The positivity percentage in the localities included in the study ranged from 8.33 to 100%. In the population under study, the seroprevalence rate was high, indicating a possible exposure risk in this area of Romania, which could have severe effects on equids in the case of clinical manifestations of the disease. EP represents a serious threat for equine health in Romania; therefore, close and continuous monitoring of the situation is required.

Babesiosis in Southeastern, Central and Northeastern Europe: An Emerging and Re-Emerging Tick-Borne Disease of Humans and Animals

There is now considerable evidence that in Europe, babesiosis is an emerging infectious disease, with some of the causative species spreading as a consequence of the increasing range of their tick vector hosts. In this review, we summarize both the historic records and recent findings on the occurrence and incidence of babesiosis in 20 European countries located in southeastern Europe (Bosnia and Herzegovina, Croatia, and Serbia), central Europe (Austria, the Czech Republic, Germany, Hungary, Luxembourg, Poland, Slovakia, Slovenia, and Switzerland), and northern and northeastern Europe (Lithuania, Latvia, Estonia, Iceland, Denmark, Finland, Sweden, and Norway), identified in humans and selected species of domesticated animals (cats, dogs, horses, and cattle). Recorded cases of human babesiosis are still rare, but their number is expected to rise in the coming years. This is because of the widespread and longer seasonal activity of Ixodes ricinus as a result of climate change and because of the more extensive use of better molecular diagnostic methods. Bovine babesiosis has a re-emerging potential because of the likely loss of herd immunity, while canine babesiosis is rapidly expanding in central and northeastern Europe, its occurrence correlating with the rapid, successful expansion of the ornate dog tick (Dermacentor reticulatus) populations in Europe. Taken together, our analysis of the available reports shows clear evidence of an increasing annual incidence of babesiosis across Europe in both humans and animals that is changing in line with similar increases in the incidence of other tick-borne diseases. This situation is of major concern, and we recommend more extensive and frequent, standardized monitoring using a "One Health" approach.

Effects of Competitive ELISA-Positive Results of Piroplasmosis on the Performance of Endurance Horses

Simple Summary

Equine piroplasmosis (EP) is a common infectious disease in southern Europe. To better understand the impact and influence of EP on the performance of endurance horses, we collected blood samples from national elite horses during different endurance competitions. The horses were tested against piroplasmosis, and several blood parameters related to performance were also evaluated. It seems that horses without clinical signs of piroplasmosis can participate without performance impairment in competitions of up to 80 km. Although it is recommended that longer distance competitions should be further evaluated, this is the first step for decision-making by organizers and participants in this sport.

Abstract

Endurance is an increasingly popular equestrian sport. However, in southern Europe, there is a high prevalence of horses that are asymptomatic carriers of equine piroplasmosis (EP), a tick-borne disease that could affect their performance. This study aimed to evaluate the impact and influence of EP on the performance of endurance horses. Blood samples were collected from 40 horses in Extremadura, Spain, before and after a race, in different national elite horse endurance competitions. Hematological and biochemical parameters and EP seroprevalence were analysed by competitive enzyme-linked immunosorbent assay. The global seroprevalence of EP was 70%, with 27 horses testing positive for Theileria equi (67.5%) and three (7.5%) for Babesia caballi, with two of these horses (5%) positive for both. Approximately 82.5% of the horses (33 of 40) completed the competition, with no influence on performance or position achieved in those with subclinical parasitosis. There were also no significant differences in hematological or biochemical values between seropositive and seronegative horses. The data suggest that horses without clinical signs of EP can participate without performance impairment in competitions of up to 80 km. Although it is recommended that longer distance competitions should be further evaluated, this is the first step for decision-making by organizers and participants in this sport.

Theileria equi and Babesia caballi in horses in the Czech Republic

Theileria equi and Babesia caballi are protozoan agents causing equine piroplasmosis, endemic in countries all over the world. The aim of this study was to detect antibodies to T. equi and B. caballi in horses in the Czech Republic and to investigate the origin of the infection. Blood sera from 711 horses were examined with competitive enzyme-linked immunosorbent assay; positive samples were verified with indirect fluorescence immunoassay. Antibodies to T. equi and B. caballi were detected in eight (1.1%) and three (0.4%) horses, respectively. Infection with T. equi was confirmed by PCR and sequencing in the blood of five serologically positive horses. An autochthonous origin of T. equi infection could not be excluded in two (0.3%) horses. Intensive movement of horses across European countries and the expanding occurrence of competent tick vector Dermacentor reticulatus in the Czech Republic create an increasing risk of establishing active foci of equine piroplasmosis in the country.

Eco-epidemiology of equine piroplasmosis and its associated tick vectors in Europe: A systematic literature review and a meta-analysis of prevalence

When studying a vector-borne disease, an eco-epidemiological approach is vital for a comprehensive understanding of how the pathogen circulates amongst populations. Equine piroplasmosis (EP), a tick-borne disease caused by the protozoans Babesia caballi and Theileria equi, is endemic in the Mediterranean basin of Europe and causes both animal health and economic issues for the equine sector. With no vaccine available, defining the episystem of the disease can help to identify which components of the host-pathogen-vector-environment system to target to improve preventive measures. In this systematic literature review, we collected relevant data on the eco-epidemiology of EP in Europe. The 62 studies remaining after the selection procedure explored potential vectors, indicators of parasite circulation and putative risk factors of EP. Eight hard tick species were identified as potential vectors of one or both piroplasm species. Meta-analyses were then conducted on prevalence and seroprevalence data in equids in European countries, demonstrating an estimated seroprevalence of 30% and 8% and prevalence of 25% and 2% for T. equi and B. caballi, respectively. Finally, herd management practices and environmental risk factors analysed in studies showed no real consensus between studies, but revealed a general trend highlighting age and exposure to ticks as risk factors, and vaccination as a protective factor. Through this study, we point out that only a few studies have focused on disease management practices and even fewer have studied the effect of environmental parameters on equid infections. Further investigation in these areas is required to better characterize the eco-epidemiology of EP and risk factors associated with this disease.

Twenty Years of Equine Piroplasmosis Research: Global Distribution, Molecular Diagnosis, and Phylogeny

Equine piroplasmosis (EP), caused by the hemoparasites Theileria equi, Theileria haneyi, and Babesia caballi, is an important tick-borne disease of equines that is prevalent in most parts of the world. Infection may affect animal welfare and has economic impacts related to limitations in horse transport between endemic and non-endemic regions, reduced performance of sport horses and treatment costs. Here, we analyzed the epidemiological, serological, and molecular diagnostic data published in the last 20 years, and all DNA sequences submitted to GenBank database, to describe the current global prevalence of these parasites. We demonstrate that EP is endemic in most parts of the world, and that it is spreading into more temperate climates. We emphasize the importance of using DNA sequencing and genotyping to monitor the spread of parasites, and point to the necessity of further studies to improve genotypic characterization of newly recognized parasite species and strains, and their linkage to virulence.

Equine piroplasmosis: an insight into global exposure of equids from 1990 to 2019 by systematic review and meta-analysis

Equine piroplasmosis (EP) is a tick-borne disease of economic importance, relevant in the international movement of equids. The causative agents are at least two apicomplexan protozoan parasites Babesia caballi and Theileria equi. To date, there is no study that estimates global and regional exposure of equids to EP. We therefore conducted a systematic review and meta-analysis to estimate the pooled prevalence and heterogeneity of EP using random-effects model. Six electronic databases were searched for publications on EP and assessed according to Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. A total of 66 eligible studies published between 1990 and 2019 and representing 24 041 equids were included. The overall pooled prevalence estimates (PPEs) of B. caballi was 22.3% (95% CI 21.7-22.8), while the overall PPE for T. equi was 29.4% (95% CI 28.7-30.0). The overall pooled prevalence due to co-infection with both parasites was 11.8% (95% CI 11.32-12.32). Also, subgroup analysis according to sex, age, diagnostic technique, equid species, region and publication years showed a substantial degree of heterogeneity across studies computed for both B. caballi and T. equi infections in equids. Awareness of the current status of EP globally will alert the relevant authorities and stakeholders where necessary on the need for better preventive and control strategies against the disease.

Molecular Analysis and Risk Factors Associated With Theileria equi Infection in Domestic Donkeys and Mules of Punjab, Pakistan

Theileriosis is an important disease of economic significance which badly affects the equine husbandry of developing countries. The present study was planned to investigate the molecular prevalence of theileriosis, associated risk factors, and alterations in hematological parameters of donkeys and mules from district Mianwali, Punjab, Pakistan. Blood samples from 150 equids (n = 75 donkeys; n = 75 mules) were examined microscopically, and the genomic DNA from each sample was processed for the amplification of the 18S rRNA gene of Theileria. The polymerase chain reaction confirmed isolates were purified followed by sequencing. The data regarding the analysis of risk factors were collected in a predesigned questionnaire and statistically analyzed by logistic regression analysis. An overall prevalence of 17.33% was noted in this study. Donkeys showed more prevalence followed by mules being 20.0% and 14.7%, respectively. The study isolates showed high resemblance (99%) with isolates from the United States of America, Spain, Brazil, Israel, Cuba, France, South Africa, Korea, Turkey, Tunisia, India, E. Caribbean, and Nigeria. The potential risk factors found to be significantly associated (P < .05) with disease dynamics were tick infestation on study animals, previous tick history, and house hygiene. A significant (P < .05) decrease in the number of platelets, erythrocytes, hemoglobin level, and packed cell volume was observed in donkeys and mules suffering from theileriosis compared with the healthy ones. The study is the first report regarding the molecular characterization of theileriosis in donkeys and mules in Pakistan. The findings will be effectual in designing effective control strategies for this disease in Punjab, Pakistan.

A Review on Equine Piroplasmosis: Epidemiology, Vector Ecology, Risk Factors, Host Immunity, Diagnosis and Control

Equine Piroplasmosis (EP) is a tick-borne disease caused by apicomplexan protozoan parasites, Babesia caballi and Theileria equi. The disease is responsible for serious economic losses to the equine industry. It principally affects donkeys, horses, mules, and zebra but DNA of the parasites has also been detected in dogs and camels raising doubt about their host specificity. The disease is endemic in tropical and temperate regions of the world where the competent tick vectors are prevalent. Infected equids remain carrier for life with T. equi infection, whilst, infection with B. caballi is cleared within a few years. This review focuses on all aspects of the disease from the historical overview, biology of the parasite, epidemiology of the disease (specifically highlighting other non-equine hosts, such as dogs and camels), vector, clinical manifestations, risk factors, immunology, genetic diversity, diagnosis, treatment, and prevention.

Serological and molecular prevalence of equine piroplasmosis in Western Java, Indonesia

Equine piroplasmosis is an economically significant disease caused by Theileria equi and Babesia caballi, which are tick-borne hemoprotozoan parasites. Infections with these parasite species had never been reported in horses in Indonesia. The aim of the present study was to investigate the prevalence of T. equi and B. caballi in horses reared in parts of Western Java, Indonesia. Blood samples were collected randomly from 235 horses in four different districts (Bandung, Depok, Tangerang, and Bogor) in Western Java, Indonesia. Thin blood smears prepared from the sampled animals were stained by Giemsa and observed under a light microscope. Serum samples prepared from blood were screened by enzyme-linked immunosorbent assays (ELISAs) based on recombinant forms of EMA-2 and BC48 antigens to determine the seroprevalence of T. equi and B. caballi, respectively. DNA samples extracted from the same blood samples were screened by EMA-2 and BC48 gene-based nested polymerase chain reaction (nPCR) assays for T. equi and B. caballi infections, respectively. Of 235 surveyed animals, five (2.1%) and 15 (6.4%) were seropositive for T. equi and B. caballi, respectively, whereas one and four horses were nPCR-positive for T. equi and B. caballi, respectively. All of the surveyed animals were negative for T. equi and B. caballi by microscopy. The T. equi EMA-2 and B. caballi BC48 gene fragments amplified by the nPCR assays were cloned, sequenced, and subjected to bioinformatic and phylogenetic analyses. The T. equi EMA-2 gene sequence from an Indonesian horse was identical to sequences from Florida and Washington strains and clustered together with these sequences in phylogeny. On the other hand, four Indonesian BC48 gene sequences shared 99.8-100% identity scores. This present study is the first to report T. equi and B. caballi in horses in Indonesia. Our findings highlight the need for monitoring horses in Indonesia for clinical piroplasmosis caused by T. equi and B. caballi.

Sero-prevalence and risk factor analysis of Theileria equi infection in equids from different agro-climatic zones of Punjab (India) by Indirect Immunofluorescence Antibody test

In the Indian sub-continent, equine piroplasmosis (EP) is an imperative tick-borne disease of equids predominately caused by obligatory intra-erythrocytic protozoa Theileria equi. Present exploration is the first epidemiological survey report based on Indirect Immunofluorescence Antibody test (IFAT). A total of 120 equines (98 horses and 22 donkeys/mules) from five districts of two main agro-climatic zones of Punjab were screened. The overall prevalence was 58.33%, with western plane zone at higher infection risk for T. equi (74.50%, OR = 7.45, 95% CI = 62.24-85.76); followed by western zone (46.38%, OR = 4.63, 95% CI = 34-57.7). District wise highest and lowest prevalence was recorded in district Fazilka (80.76%) and Bathinda (35.29%) respectively. IFAT revealed elevated risk of infection of T. equi in the farms with inappropriate management structure. The risk factor connected with the type of host species had an odds ratio of 1.67 for donkeys/mules versus horses for T. equi infection. Followed by presence/absence of tick on animal. This study reveals the endemicity of EP in Punjab with prominence of various odds of infection, associated with latent infection of T. equi detectable by serological techniques as it was noticed that western plane zone and western zone are more prone to EP infection.

Risk factor analysis associated with Theileria equi infected equines in semi-arid and sub-humid ecological enzootic zones of India

Equine piroplasmosis is a haemoprtozoan disease of equines and enzootic in tropical and subtropical countries. A cross-sectional study on sero-prevalence of Theileria equi, the causative agent of EP, was performed in semi-arid and sub-humid ecological endemic zones of India including Rajasthan, Haryana and Gujarat states, in order to evaluate the enzootic status/level of exposure to equine population due to this infection and addressed associated risk factors. Serum samples were collected from a total of 1021 equids that comprised of 792 horses, 168 donkeys and 61 mules and evaluated for T. equi specific antibodies in equine merozoite antigen-2 (EMA-2) based on indirect ELISA. The state with high sero-prevalence rate was Rajasthan (71.40%), followed by Haryana (60.39%) and Gujarat (48.92%). Overall T. equi sero-positivity in equines was 64.44%. Species-wise T. equi sero-prevalence was 66.29%, 51.19% and 91.80% in horses, donkeys and mules respectively. The association and risk factor among age, gender and species in relation with T. equi infection was statistically analyzed at 95% level of significance (p<0.05). A very high T. equi sero-positivity was recorded in 0-1year age group of equines (60%), indicating that this naïve age group contacts with T. equi infected ticks and remains infected throughout its lifetime. The sero-prevalence rate was significantly associated with the species of animal (p<0.05). The risk factor analysis kept mules at higher risk (Odd's ratio; 5.696; 95% confidence interval: 2.25-14.38) of getting infection as compared to horses and donkeys. This study has demonstrated high enzootic nature of T. equi infection in semi-arid and sub-humid ecological zones of India. Mules, in comparison to horses and donkeys were found at higher risk of getting T. equi infection, indicating that disease prevalence is associated with species of the infected host.

Seroprevalence of Theileria equi and Babesia caballi in horses in Spain

Equine piroplasmoses are enzootic parasitic diseases distributed worldwide with high incidence in tropical and subtropical regions. In Spain, there is insufficient epidemiological data about equine piroplasmoses. The main aim of the present study was therefore to estimate the prevalence of Theileria equi and Babesia caballi in five regions and obtain information about the risk factors. This study was conducted in the central and south-western regions of Spain, using indirect fluorescence antibody testing (IFAT) in 3,100 sera samples from apparently healthy horses of different ages, breeds, coat colours, genders and geographical locations. The overall seroprevalence was 52%, consisting of 44% seropositive for T. equi and 21% for B. caballi. There was a significant association between age (p < 0.0001), breed (p < 0.004), geographical location (p < 0.0001) and the seroprevalence, but neither the coat colour nor the gender was significantly associated with prevalence. In addition, it was proved that most of the geographic areas showed a moderate to high prevalence. The statistical κ value was used to compare the results obtained by the IFAT and the competitive enzyme-linked immunosorbent assay (cELISA) utilised to test some samples (n = 108) and showed a higher concordance for T. equi (κ = 0.68) than for B. caballi (κ = 0.22). Consequently, this revealed the importance of developing an appropriate technique to detect each haemoparasite.

Prevalence and molecular characterization of Theileria equi and Babesia caballi in jereed horses in Erzurum, Turkey

Equine piroplasmosis (EP) is a hemoprotozoan tick-borne disease with worldwide distribution that is caused by Theileria equi and Babesia caballi. There are studies reporting the presence of equine piroplasmosis in Turkey but the situation in Erzurum is unknown. The aim of the current study was to determine the situation of equine piroplasmosis in jeered horses in Erzurum. Between April and August 2015, a total of 125 Arabian horse were examined and blood samples were collected. At the time of sampling, animals were also examined for tick infestations and clinical signs. Besides microscopic examination of Giemsastained blood smears, multiplex PCR performed with species specific primers partially amplifying the 18S rRNA gene of B. caballi and T. equi. During the microscopic examination of blood smears, T. equi piroplasms were found in 6 (4.8%) samples. In total, 11 (8.8%) T. equi DNA were detected with multiplex PCR. B. caballi piroplasms or DNA were not obtained. BLAST analysis of the sequenced T. equi samples (GenBank: KU921661-KU921667) indicated 98.8-100% identity to each other, and 100% similarity to T. equi isolates in South Africa, Iran, China, Sudan, India, Mongolia, Trinidad, Kenya, Spain, Serbia, Bosnia and Herzegovina and Turkey (Bursa). The results of our study indicate that T. equi occurs more frequently than B. caballi in the study area. To the authors' knowledge, this is the first report of the molecular detection of equine piroplasmosis in jeered horses in Erzurum, Turkey.

Sequence heterogeneity in the 18S rRNA gene in Theileria equi from horses presented in Switzerland

A reverse line blot (RLB) hybridization assay was adapted and applied for equine blood samples collected at the animal hospital of the University of Zurich to determine the presence of piroplasms in horses in Switzerland. A total of 100 equine blood samples were included in the study. The V4 hypervariable region of the 18S rRNA gene was amplified by polymerase chain reaction and analyzed using the RLB assay. Samples from seven horses hybridized to a Theileria/Babesia genus-specific and a Theileria genus-specific probe. Of these, two hybridized also to the Theileria equi-specific probe. The other five positive samples did not hybridize to any of the species-specific probes, suggesting the presence of unrecognized Theileria variants or genotypes. The 18S rRNA gene of the latter five samples were sequenced and found to be closely related to T. equi isolated from horses in Spain (AY534822) and China (KF559357) (≥98.4% identity). Four of the seven horses that tested positive had a documented travel history (France, Italy, and Spain) or lived abroad (Hungary). The present study adds new insight into the presence and sequence heterogeneity of T. equi in Switzerland. The results prompt that species-specific probes must be designed in regions of the gene unique to T. equi. Of note, none of the seven positive horses were suspected of having Theileria infection at the time of presentation to the clinic. Clinicians should be aware of the possibility of equine piroplasma infections outside of endemic areas and in horses without signs of piroplasmosis.

Molecular detection and prevalence of Theileria equi and Babesia caballi in horses of central Balkan

Equine piroplasmosis is significant tick-borne disease with wide distribution. The prevalence of equine piroplasmosis in Serbia, Montenegro and Bosnia and Herzegovina is unknown. In aim to obtain a first insight into the prevalence we performed molecular epidemiological study which included 142 horses, on seven locations in these three countries. We first performed PCR for the detection of a 450bp long section of the 18S rRNA of piroplasma-specific region. For all positive samples we have done multiplex PCR for the species detection. Species determination was further confirmed by sequencing PCR products of 10 randomly selected Theileria equi and all Babesia caballi samples. The overall prevalence rates in analysed region for T. equi and B. caballi were 22.5% and 2.1%, respectively. Possible risk factors (such as location, age, sex and activity) associated with PCR positivity were evaluated. Marked differences were found in prevalence between geographic areas. There was no significant association between positivity and age group. T. equi was more prevalent in females and farming horses. This is the first report on the molecular survey of T. equi and B. caballi in central Balkan. Further prevalence studies on definitive host and vectors in this region are necessary.

Spatial distribution, risk factors and haemato-biochemical alterations associated with Theileria equi infected equids of Punjab (India) diagnosed by indirect ELISA and nested PCR

Equine piroplasmosis is a febrile, tick-borne disease of equids predominately caused by obligatory intra-erythrocytic protozoa Theileria equi in the Indian sub-continent. A cross-sectional study was carried out on 464 equids (426 horses and 38 donkeys/mules) in Punjab, India to assess the level of exposure to equine piroplasmosis by 18S rRNA gene nested polymerase chain reaction (nPCR) and equine merozoite antigen-2 (EMA2) indirect-ELISA (enzyme linked immunosorbent assay), to investigate risk factors and haemato-biochemical alterations associated with the infection. The endemicity of the disease was confirmed by positive PCR amplification in 21.77% and positive antibody titers in 49.78% equid samples. There was a fair agreement between these two diagnostic techniques (Kappa coefficient=0.326). The spatial distribution analysis revealed an increasing trend of T. equi prevalence from north-eastern to south-western region of Punjab by both the techniques correspondingly, which proffered a direct relation with temperature and inverse with humidity variables. The relatively prominent risk factor associated with sero-positivity was the presence of other domestic animals in the herd, while the propensity of finding a positive PCR amplification was higher in donkeys/mules, animal kept at unorganised farm or those used for commercial purposes as compared to their counterparts. There was a significant increase in globulins, gamma glutamyl-transferase, total bilirubin, direct bilirubin, indirect bilirubin, glucose levels and decrease in total erythrocyte count, haemoglobin, packed cell volume by animals, which were revealed positive by nPCR (may or may not positive by indirect-ELISA) and increase in creatinine, total bilirubin, direct bilirubin, glucose and decrease in total erythrocytes count by animals, which were revealed positive by indirect-ELISA (alone). To our knowledge, this study, for the first time, brings out a comprehensive report on the status on spatial distribution of T. equi in Punjab (India) state, thoroughly investigated by molecular and serological techniques, evaluating various environmental and demographic risk factors along with the haemato-biochemical alterations in the exposed animals.

Quantitative PCR detection of Theileria equi using laboratory workflows to detect asymptomatic persistently infected horses

Equine piroplasmosis is the most important tick-borne disease of horses. Regulations on movement of horses into disease-free countries are in place to preserve international trade. Introduction of infectious disease, such as equine piroplasmosis, into non-endemic countries remains a substantial risk owing to the wide-spread distribution of vectors. Identification and restriction of movement of Theileria equi persistently infected horses is an integral part of control strategies, because persistently infected horses with low parasitaemia are an important reservoir. We used real-time PCR for diagnosis of T. equi DNA in clinically healthy horses in an equine piroplasmosis endemic area. The sensitivity was assessed using a synthetic plasmid DNA and a laboratory workflow was developed to maximise detection of persistently infected horses. The detection limit was 10 rDNA copies of the plasmid DNA. Assuming that each red blood cell contains a single T. equi genome the detection limit corresponded to 2.5 T. equi/μl of total blood and parasitaemia as low as 2-3.8 × 10(-5)%. A laboratory workflow was developed and assessed on samples from Saudi Arabia. The laboratory workflow focused on samples returning no or single positive result in duplicate PCR. In total, we obtained 42% (59/141; 95% confidence interval: 33.85-50.15) T. equi positive samples, 26% (37/141) negative for T. equi samples. The remaining 45 samples were judged as suspect with no definitive diagnosis made. The Saudi Arabia's T. equi small subunit ribosomal DNA (SSU rDNA) sequencing (n=16) demonstrated A clade (n=15) as the dominant T. equi clade. Clade B was sequenced in a single case. We present an approach for diagnostic workflow to detect T. equi in clinically healthy but persistently infected horses. Results from Saudi Arabia confirm that T. equi is widespread in the Middle East region. High proportion of horses with low parasitaemia calls for caution with results based on a single blood sample. Understating of the fluctuation of the parasitaema in persistently infected horses in endemic areas is needed to establish the required sample numbers for reliable detection of T. equi.

Seroprevalence and risk factors associated with Babesia caballi and Theileria equi infections in donkeys from Southern Italy

Equine piroplasmosis (EP) has been frequently described in donkeys in subtropical and tropical regions, but published data reflecting large scale surveys are very limited in Europe. The seroprevalence of Babesia caballi and Theileria equi was determined in a donkey population from Campania Region in Southern Italy using a commercial indirect fluorescent antibody test (IFAT), and the risk factors associated with the occurrence of the infection were assessed. Of 203 samples, the overall seroprevalence for EP was 57.1% (116/203), with 35.5% (72/203) for B. caballi and 44.3% (90/203) for T. equi. Co-infection was detected in 46 donkeys (22.6%). The distribution of IFAT antibody titres to B. caballi was: 1:80 (n= 67), 1:160 (n= 2), 1:320 (n= 3); while the distribution of IFAT antibody titres to T. equi was: 1:80 (n= 25), 1:160 (n= 42), 1:320 (n= 12), 1:640 (n= 8), 1:1280 (n= 3). All examined donkeys were asymptomatic, except one adult male (with a titre of 1:640 against T. equi) that showed clinical signs corresponding to the acute stage of EP, reported for the first time in Italy. The unique risk factor associated with a higher B. caballi seroprevalence was the presence of horses in the farms, while risk factors associated with a higher T. equi seroprevalence were poor body condition, presence of ruminants in the farms and milk production. The results indicate a high level of exposure in donkeys living in Southern Italy and suggest that donkeys may be an important reservoir of EP.

Molecular and serological detection of Theileria equi and Babesia caballi infection in horses and ixodid ticks in Iran

Equine piroplasmosis is a hemoprotozoan tick-borne disease with worldwide distribution that is caused by Theileria equi and Babesia caballi. However, the geographical distribution of equine piroplasmosis in Iran is unknown. The aim of the current study was to determine the causative agents and vector ticks of equine piroplasmosis in horses in the North Khorasan Province. In the year 2011, 100 horses were randomly selected from 14 villages. Blood samples and ixodid ticks were collected and examined using microscopical, molecular, and serological methods. Theileria equi infection was microscopically detected in 5 (5%) of the blood smears with low parasitemia, while serum samples were tested by the indirect immunofluorescent antibody test (IFAT). Antibodies against T. equi, B. caballi, and a mixed infection were detected in 48 (48%), 2 (2%), and 3 (3%) of the serum samples, respectively. A multiplex PCR was used to detect T. equi and B. caballi DNA in blood samples. No B. caballi infections could be found, but Theileria equi DNA was detected in 45 (45%) of the blood samples, and a BLAST analysis of the sequenced samples indicated a 99% similarity with T. equi 18S rRNA gene sequences in GenBank. Both molecular and serological results did not identify any significant association between T. equi infection and risk factors. A comparision of the results of 3 diagnostic methods demonstrated a poor agreement between microscopical examination with IFAT and PCR and a moderate agreement between IFAT and PCR. Thirty-seven adult ticks (20 females and 17 males) were collected from 15 horses. The most common tick was Hyalomma marginatum marginatum (n=19), followed by Hyalomma anatolicum excavatum (n=10), Rhipicephalus bursa (n=4), Hyalomma marginatum turanicum (n=3), and Hyalomma anatolicum anatolicum (n=1). The salivary glands and ovaries were also examined using PCR. The genomic DNA samples of the salivary glands of 3 ticks, H. a. excavatum (n=2) and R. bursa (n=1), had a positive reaction for T. equi, but no tick contained B. caballi DNA. Thus, our results indicate that T. equi occurs more frequently than B. caballi in the investigated geographical region.

Seroprevalence of Babesia caballi and Theileria equi in five draught equine populated metropolises of Punjab, Pakistan

Equine piroplasmosis (EP) caused by intraerythrocytic parasites (Theileria equi and Babesia caballi) is an emerging equine disease of world-wide distribution. In Pakistan, the prevalence and incidence of EP are unknown. In order to obtain the first insights into the prevalence of the disease, a total of 430 equids, including 33 mules, 65 horses and 332 donkeys, aging from ≤ 5 to ≥ 10 years of either sex, from five metropolises of Punjab, Pakistan, were serologically tested for the presence of antibodies directed against B. caballi and T. equi, using a competitive enzyme-linked immunosorbent assay (cELISA). Out of 430 equid serum samples tested, 226 (52.6%, 95% CI 47.7-57.4) were found cELISA positive for EP (T. equi and/or B. caballi infections). The overall seroprevalence of EP was 41.2% (95% CI 36.5-46.0) for T. equi and 21.6% (95% CI 17.8-25.8) for B. caballi. A small proportion of equids (10.2%, 95% CI 7.5-13.5) was seropositive for both T. equi and B. caballi. Seroprevalence of T. equi was significantly higher (P<0.01) in equines from the metropolis of Lahore (66.7%, 95% CI 54.3-77.6) and in horses (56.9%, 95% CI 44.0-69.2). Multivariable logistic regression model analysis indicated that factors associated with prevalence of EP were being an equine species kept in metropolis Lahore (OR=4.24, 95% CI 2.28-7.90), horse (OR=2.82, 95% CI 1.53-5.20) and male equids (OR=1.81, 95% CI 1.15-2.86).

Equine piroplasmosis treatment protocols: specific effect on orocaecal transit time as measured by the lactose 13C-ureide breath test

REASONS FOR PERFORMING STUDY

Imidocarb dipropionate is the drug of choice for equine piroplasmosis but its administration causes severe colic and diarrhoea. An imidocarb protocol that reduces these effects is needed.

OBJECTIVES

1) Quantification of the effects of imidocarb dipropionate on equine orocaecal transit time (OCTT), with and without atropine or glycopyrrolate premedication and 2) investigation of an improved pretreatment regimen for imidocarb administration.

HYPOTHESIS

Treatment with imidocarb dipropionate will result in colic and reduced OCTT as demonstrated by the lactose 13C-ureide breath test which will be ameliorated by premedication with either atropine or glycopyrrolate.

METHODS

The effects of 3 drug therapies on OCTT were compared in 6 healthy horses in a randomised double-blind study vs. a saline control: 1) imidocarb dipropionate 2.4 mg/kg bwt administered intramuscularly (i.m.) with saline administered intravenously (i.v.; imidocarb/saline); 2) imidocarb dipropionate 2.4 mg/kg bwt administered i.m. with atropine 0.035 mg/kg bwt administered i.v. (imidocarb/atropine) and 3) imidocarb dipropionate 2.4 mg/kg bwt administered i.m. with glycopyrrolate 0.0025 mg/kg bwt administered i.v. (imidocarb/glycopyrrolate). The lactose 13C-ureide breath test was used to measure OCTT in each case and significance of treatment effect determined by a linear model analysis of variance.

RESULTS

Imidocarb/atropine treatment caused an increase in OCTT (P < 0.05) whereas imidocarb/saline produced a nonsignificant decrease in OCTT. Imidocarb/saline caused colic and diarrhoea in 4 of 6 horses, which were not seen in any of the horses treated with imidocarb/atropine or imidocarb/glycopyrrolate or administered the saline control. Intestinal borborygmi were increased in imidocarb/saline and decreased in imidocarb/atropine treated horses, respectively.

CONCLUSIONS

Imidocarb/saline treatment induced colic signs and a potential reduction in OCTT while imidocarb/atropine treatment increased OCTT significantly when compared with imidocarb/saline. Both atropine and glycopyrrolate premedication ameliorated the clinical gastrointestinal effects of imidocarb but atropine produced significant inhibition of gastric and/or small intestinal motility not detected with glycopyrrolate. Premedication with glycopyrrolate is recommended when using imidocarb for treatment of equine piroplasmosis.