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

Serosurvey for equine piroplasms in horses and donkeys from North-Western Nigeria using IFAT and ELISA

Equine piroplasmosis is caused by apicomplexan parasites, namely, Babesia caballi and Theileria equi, which are transmitted to equids principally through ticks. To ascertain the exposure of equines to agents of equine piroplasms, we tested serum samples collected from horses (n = 272) and donkeys (n = 170) in North-Western Nigeria for the presence of antibodies against B. caballi and T. equi using IFAT and ELISA. The seroprevalence of T. equi in the horses determined using IFAT and ELISA was 48.89% and 45.96%, respectively, while for B. caballi, it was 6.3% and 0.4%, respectively. For T. equi, the seroprevalence based on IFAT and ELISA results in donkeys was 14.1% and 2.9%, respectively, while for B. caballi, the seroprevalence was 2.4% and 0.6%, respectively, for ELISA and IFAT. Mixed infection detected in the horses using IFAT and ELISA was 5.5% and 0.4%, respectively, while no mixed infection was observed in the donkeys. The seroprevalence of T. equi was significantly (P < .0001) higher than that of B. caballi in both horses and donkeys. Comparatively, the IFAT detected a greater number of piroplasm seropositive animals than ELISA, indicating a difference in their diagnostic accuracy. Findings from this study confirm the existence of equine piroplasms in both horses and donkeys in North-Western Nigeria and highlights the need for robust and effective control measures against the disease.

Imported Hyalomma ticks in the Netherlands 2018-2020

BACKGROUND

Ticks of the genus Hyalomma, which are vectors for several tick-borne diseases, are occasionally found in areas outside their endemic range including northern parts of Europe. The objective of this study was to analyse adult Hyalomma ticks that were recently found in the Netherlands.

METHODS

Hyalomma ticks were morphologically identified. Cluster analysis, based upon sequence data (cox1 barcoding) for molecular identification, and pathogen detection were performed. Additionally, a cross-sectional survey of horses was conducted to actively search for Hyalomma ticks in summer 2019. Analysis of temperature was done to assess the possibility of (i) introduced engorged nymphs moulting to adults and (ii) establishment of populations in the Netherlands.

RESULTS

Seventeen adult Hyalomma ticks (one in 2018, eleven in 2019, five in 2020) were found by citizens and reported. Fifteen ticks were detected on horses and two on humans. Twelve were identified as H. marginatum, one as H. rufipes and four, of which only photographic images were available, as Hyalomma sp. No Crimean-Congo haemorrhagic fever virus or Babesia/Theileria parasites were detected. One adult tick tested positive for Rickettsia aeschlimannii. In the cross-sectional horse survey, no Hyalomma ticks were found. Analysis of temperatures showed that engorged nymphs arriving on migratory birds in spring were able to moult to adults in 2019 and 2020, and that cumulative daily temperatures in the Netherlands were lower than in areas with established H. marginatum populations.

CONCLUSIONS

Our results show that Hyalomma ticks are regularly introduced in the Netherlands as nymphs. Under the Dutch weather conditions, these nymphs are able to develop to the adult stage, which can be sighted by vigilant citizens. Only one human pathogen, Rickettsia aeschlimannii, was found in one of the ticks. The risk of introduction of tick-borne diseases via Hyalomma ticks on migratory birds is considered to be low. Establishment of permanent Hyalomma populations is considered unlikely under the current Dutch climatic conditions.

Molecular and Serological Detection of Piroplasms in Horses from Nigeria

Equine piroplasmosis, an economically important disease of equids caused by the hemoprotozoan parasites Theileria equi, T. haneyi, and Babesia caballi, has a worldwide distribution. These parasites are transmitted by ixodid ticks. To improve the detection of horses in Nigeria exposed to piroplasm parasites, 72 horses with variable clinical signs of piroplasmosis were sampled from Northwest and Northcentral Nigeria and tested by nPCR and cELISA. Blood and serum samples were collected from each horse via jugular venesection. Individually, nPCR or cELISA failed to identify all horses exposed to piroplasms. A combination of species-specific nPCR and the OIE-approved T. equi and B. caballi cELISAs enhanced the detection of horses exposed to parasites. The results also demonstrated horses showing abnormal hematology were positive for only T. equi, except for one sample that was coinfected with T. equi and T. haneyi. We also identified ticks collected from some of the horses, with Rhipicephalus evertsi evertsi being the most prevalent. This study shows that a larger proportion of horses in the sample set were exposed to T. equi than B. caballi or T. haneyi. Additionally, ticks that have been previously reported as potential vectors for these parasites were found to have infested sampled horses. Further studies are needed to investigate which tick species are competent vectors for Theileria spp. and Babesia caballi in Nigeria.

Oxidative and local histopathological response on skin wound of horses due to Amblyomma sculptum tick parasitism

Amblyomma sculptum is frequently observed parasitizing horses, responsible for economic losses, damage to the host''s skin and transmission of pathogens. The oxidative stress profile and inflammatory mechanisms involved in this parasitism remain poorly studied. Thus, this study aimed to assess the histopathological changes and oxidative profile responses of horses in the attachment site of A. sculptum to find variations that indicate resistance and susceptibility between the breeds to this tick, based on the hypothesis that resistant animals have a greater inflammatory response and lesser number of attached ticks. We analyzed female horses of two breeds, Mangalarga Marchador and Breton Postier, naturally infested by Amblyomma sculptum. The ticks were counted and full-thickness excisional skin wounds of 10 mm were made on the perineal region on the attachment site of partially engorged females for histological and biochemical analyzes. The occurrence of the tick on the skin caused an increase in cellularity, inflammatory infiltrate, mast cells, pyknotic nuclei, and changes in the fibrous components of the matrix. The negative correlation observed between tick infestation and inflammatory response indicated that animals with greater inflammatory response tend to have less tick infestation. The oxidative stress markers, MDA, PCN and NO not present great variation; however, between the antioxidant enzymes levels, SOD was higher in tick attachment of Breton Postier skin, this may mean that these animals had higher oxidative enzymatic activity and consequently less tissue damage, while the GST dropped in the attachment sites compared to the control, which may indicate that animals were in a state of significant oxidative stress or raises the question of the possibility of enzymatic sequestration by ticks. No significant differences were found in the resistance of the two breeds since most of the analyzes varied due to the presence or absence of the tick attached to the skin. We draw attention to the importance of studying characteristics of the animal's antioxidant responses to the tick and the action of tick saliva on antioxidant enzymes and ROS because these characteristics are interdependent with the inflammatory response.

First Case of Autochthonous Equine Theileriosis in Austria

A 23-year-old pregnant warmblood mare from Güssing, Eastern Austria, presented with apathy, anemia, fever, tachycardia and tachypnoea, and a severely elevated serum amyloid A concentration. The horse had a poor body condition and showed thoracic and pericardial effusions, and later dependent edema and icteric mucous membranes. Blood smear and molecular analyses revealed an infection with Theileria equi. Upon treatment with imidocarb diproprionate, the mare improved clinically, parasites were undetectable in blood smears, and 19 days after hospitalization the horse was discharged from hospital. However, 89 days after first hospitalization, the mare again presented to the hospital with an abortion, and the spleen of the aborted fetus was also PCR-positive for T. equi. On the pasture, where the horse had grazed, different developmental stages of Dermacentor reticulatus ticks were collected and subjected to PCR, and one engorged specimen was positive for T. equi. All three amplicon sequences were identical (T. equi genotype E). It is suspected that T. equi may repeatedly be transmitted in the area where the infected mare had grazed, and it could be shown that transmission to the fetus had occurred. Due to the chronic nature of equine theileriosis and the possible health implications of infection, it is advised to include this disease in the panel of differential diagnoses in horses with relevant clinical signs, including horses without travel disease, and to be aware of iatrogenic transmission from inapparent carrier animals.

Characterization of the Rhipicephalus (Boophilus) microplus Sialotranscriptome Profile in Response to Theileria equi Infection

This study intends to characterize the sialotranscriptome profile of Rhipicephalus (Boophilus) microplus in response to Theileria equi and identify genes of interest with differential genomic expression, indicating relevant targets in the tick–protozoan interactions. The experimental design consisted of RNA sequencing from uninfected and T. equi-infected R. microplus salivary glands (SGs) to obtain transcriptomic profiles for characterization and comparison. A total of 288,952 transcripts were obtained from both tick profiles, 3456 transcripts (p < 0.05) differentially expressed in response to T. equi infection. The uninfected SGs’ registered 231,179 transcripts, of which 155,359 were annotated. The most transcribed sequences were female-specific histamine binding protein and lipocalins. Regarding the T. equi-infected SGs, from the 238,964 assembled transcripts, 163,564 were annotated. The most transcribed sequences were histone demethylase JARID1 and Y-box-binding protein. Five transcripts (cystatin, arginase, nuclear factor κB kinase inhibitor subunit β (IκB), IκB delta, lysosomal-trafficking regulator, and reeler protein) presented the gene ontology (GO) category “response to protozoan” and were exclusively displayed in the T. equi-infected profile. The transcriptome of T. equi was also analyzed, registering 4728 hits. The study’s genetic and molecular information would be of great value for future studies and biotechnological applications envisaging disease control.

Apicomplexan Protozoa Responsible for Reproductive Disorders: Occurrence of DNA in Blood and Milk of Donkeys (Equus asinus) and Minireview of the Related Literature

Donkeys may be susceptible to many pathological agents and may act as carriers of pathogens for other animal species and humans. This study evaluated the occurrence of potentially abortifacient apicomplexan protozoa DNA in blood and milk samples collected at different time periods during lactation (1, 6, and 10 months) from 33 healthy dairy jennies. A total of 73 blood and 73 milk samples were used for DNA extraction and analysis. Blood specimens from 11/33 (33%) jennies scored positive for Theileria equi, while milk samples scored negative. Blood and milk of 3/33 jennies yielded DNA of Toxoplasma gondii at 6 months (n. 1) and 10 months (n. 2) after parturition. Neospora caninum DNA was found in four milk and in five blood samples only at one month after parturition. This study is the first report about the presence of N. caninum DNA in milk of naturally infected jennies. Moreover, the excretion of N. caninum DNA in some of these jennies at 30 days from the parturition may suggest a possible occurrence of an endogenous cycle, while the presence of T. gondii DNA in the milk collected at 6 and 10 months after parturition may be suggestive of a discontinuous excretion.

Challenges in Tick-Borne Pathogen Detection: The Case for Babesia spp. Identification in the Tick Vector

The causative agents of Babesiosis are intraerythrocytic protozoa of the genus Babesia. Babesia parasites are present around the world, affecting several mammals including humans, pets and livestock, hence its medical and veterinary relevance. Babesia spp. detection in its invertebrate host is a main point in understanding the biology of the parasite to acquire more knowledge on the host–Babesia–vector interactions, as increasing knowledge of the Babesia lifecycle and babesiosis epidemiology can help prevent babesiosis outbreaks in susceptible mammals. The aim of the present review is to highlight the newest findings in this field, based on a bibliographic compilation of research studies recently carried out for the detection of the main Babesia species found in tick vectors affecting mammalian hosts, including the different tick stages such as adult ticks, larvae, nymphs and eggs, as well as the detection method implemented: microscopic tools for parasite identification and molecular tools for parasite DNA detection by conventional PCR, nested-PCR, PCR-RFLP, PCR-RLB hybridization, real time-PCR, LAMP and RAP assays. Although molecular identification of Babesia parasites has been achieved in several tick species and tissue samples, it is still necessary to carry out transmission experiments through biological models to confirm the vectorial capacity of various tick species.

Endochin-like quinolone-300 and ELQ-316 inhibit Babesia bovis, B. bigemina, B. caballi and Theileria equi

Background

The most common apicomplexan parasites causing bovine babesiosis are Babesia bovis and B. bigemina, while B. caballi and Theileria equi are responsible for equine piroplasmosis. Treatment and control of these diseases are usually achieved using potentially toxic chemotherapeutics, such as imidocarb diproprionate, but drug-resistant parasites are emerging, and alternative effective and safer drugs are needed. The endochin-like quinolones (ELQ)-300 and ELQ-316 have been proven to be safe and efficacious against related apicomplexans, such as Plasmodium spp., with ELQ-316 also being effective against Babesia microti, without showing toxicity in mammals.

Methods

The inhibitory effects of ELQ-300 and ELQ-316 were assessed on the growth of cultured B. bovis, B. bigemina, B. caballi and T. equi. The percentage of parasitized erythrocytes was measured by flow cytometry, and the effect of the ELQ compounds on the viability of horse and bovine peripheral blood mononuclear cells (PBMC) was assessed by monitoring cell metabolic activity using a colorimetric assay.

Results

We calculated the half maximal inhibitory concentration (IC₅₀) at 72 h, which ranged from 0.04 to 0.37 nM for ELQ-300, and from 0.002 to 0.1 nM for ELQ-316 among all cultured parasites tested at 72 h. None of the parasites tested were able to replicate in cultures in the presence of ELQ-300 and ELQ-316 at the maximal inhibitory concentration (IC₁₀₀), which ranged from 1.3 to 5.7 nM for ELQ-300 and from 1.0 to 6.0 nM for ELQ-316 at 72 h. Neither ELQ-300 nor ELQ-316 altered the viability of equine and bovine PBMC at their IC₁₀₀ in in vitro testing.

Conclusions

The compounds ELQ-300 and ELQ-316 showed significant inhibitory activity on the main parasites responsible for bovine babesiosis and equine piroplasmosis at doses that are tolerable to host cells. These ELQ drugs may be viable candidates for developing alternative protocols for the treatment of bovine babesiosis and equine piroplasmosis.

Parasitic diseases of equids in Iran (1931-2020): a literature review

Parasitic infections can cause many respiratory, digestive and other diseases and contribute to some performance conditions in equids. However, knowledge on the biodiversity of parasites of equids in Iran is still limited. The present review covers all the information about parasitic diseases of horses, donkeys, mules and wild asses in Iran published as articles in Iranian and international journals, dissertations and congress papers from 1931 to July 2020. Parasites so far described in Iranian equids include species of 9 genera of the Protozoa (Trypanosoma, Giardia, Eimeria, Klossiella, Cryptosporidium, Toxoplasma, Neospora, Theileria and Babesia), 50 helminth species from the digestive system (i.e., 2 trematodes, 3 cestodes and 37 nematodes) and from other organs (i.e., Schistosoma turkestanica, Echinococcus granulosus, Dictyocaulus arnfieldi, Parafilaria multipapillosa, Setaria equina and 3 Onchocerca spp.). Furthermore, 16 species of hard ticks, 3 mite species causing mange, 2 lice species, and larvae of 4 Gastrophilus species and Hippobosca equina have been reported from equids in Iran. Archeoparasitological findings in coprolites of equids include Fasciola hepatica, Oxyuris equi, Anoplocephala spp. and intestinal strongyles. Parasitic diseases are important issues in terms of animal welfare, economics and public health; however, parasites and parasitic diseases of equines have not received adequate attention compared with ruminants and camels in Iran. The present review highlights the knowledge gaps related to equines about the presence, species, genotypes and subtypes of Neospora hughesi, Sarcocystis spp., Trichinella spp., Cryptosporidium spp., Giardia duodenalis, Blastocystis and microsporidia. Identification of ticks vectoring pathogenic parasites, bacteria and viruses has received little attention, too. The efficacy of common horse wormers also needs to be evaluated systematically.

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.

Detecting antibodies to Leishmania infantum in horses from areas with different epizooticity levels of canine leishmaniosis and a retrospective revision of Italian data

Background

Leishmania infantum is a vector-borne pathogen endemic in countries in the Mediterranean basin, including Italy. Dogs act as the primary reservoir for this parasite, but other animal species may also be infected. Low-to-moderate seroprevalence levels of infection have been reported in apparent healthy equine populations in southern Europe, reinforcing the importance of exploring those species, including horses, that act as a food source for vectors and may thus participate in the epizoological scenario of canine leishmaniosis (CanL) and zoonotic visceral leishmaniosis (ZVL). Since little is known regarding the exposure to L. infantum in horses in Italy, we assessed the seroprevalence in healthy equine populations from different CanL endemic areas.

Methods

The survey was conducted on 660 apparently healthy horses distributed throughout central and northern regions of Italy between 2016 and 2019. Blood samples were collected and the presence of anti-Leishmania antibodies (IgG) was investigated by the immunofluorescence antibody test. Information on the location and altitude of the stables, along with the horses’ breed, age, sex, and reproductive status was obtained by filling in a questionnaire. This was then used for statistical analysis by generalized linear models to explore risk factors associated with seroreactivity to L. infantum.

Results

An average seroprevalence of 13.9% was detected for L. infantum in the equine populations investigated, with statistically significant associations between seroprevalence, geographical variables (northern vs central Italy, origin and altitude) and individual factors (i.e. age and breed morphotype).

Conclusions

Our results highlight that horses are frequently exposed to L. infantum. Further prevalence surveys in horses, also using direct methods (e.g. PCR), are warranted to clarify the role of these hosts in the epidemiology of Leishmania in Italy.

Survey of Zoonotic and Non-zoonotic Vector-Borne Pathogens in Military Horses in Lisbon, Portugal

Vector-borne diseases of zoonotic and/or veterinary relevance have been increasingly reported in horses globally, although data regarding working and military horses is lacking. Portuguese military horses may constitute a risk group for these pathogens, as they frequently work outdoors in various regions of the country. This study included 101 apparently healthy horses belonging to the Portuguese National Republican Guard. Blood samples were analyzed to determine the presence and prevalence of piroplasms, Anaplasmataceae, Rickettsia spp., and filarioid helminths. Overall 32.7% of the horses gave positive results for Theileria equi. Two genotypes of T. equi were verified. No positive results were recorded for Anaplasma spp., Rickettsia spp., filarioid helminthes, and Babesia caballi. As equine piroplasmosis is a severe infectious tick-borne disease responsible for significant losses in equine production and with numerous impacts in the international movement of horses, adequate treatment, and preventive measures are needed to reduce exposure to vectors and future infections.

Sero-molecular survey and risk factors of equine piroplasmosis in horses in Spain

BACKGROUND

Theileria equi and Babesia caballi cause equine piroplasmosis (EP), one of the most important tick-borne diseases of horses due to its high negative impact to the equine industry. Although infections with these parasites have been reported for decades in Spain, epidemiological studies have only been carried out in certain regions.

OBJECTIVES

To determine the (sero)prevalence of these parasites in asymptomatic horses nationwide in Spain and to identify potential individual and environmental factors associated with seropositivity to EP.

STUDY DESIGN

Sample size was calculated according to the horses registered in Spain in 2013 and by autonomous community using a random stratified sampling. A questionnaire was used to collect data on factors associated with EP seropositivity.

METHODS

Serological (cELISA and complement fixation test) and molecular (real-time PCR) analyses were carried out in 740 horses. Risk factors were identified computing two independent logistic regression models with the collated data.

RESULTS

Antibodies against EP were detected in 42.9% (95% CI 39.4-46.5) of horses, whereas 30.3% (95% CI 27.0-33.6) were EP positive by PCR. A substantial strength of agreement (k = 0.721) was estimated between serological tests. Exposure to T. equi was significantly higher than to B. caballi and the highest (sero)prevalence was detected in the northern communities. Increasing horse age, presence of ticks and contact with cows were factors related to EP seropositivity in the horses, whereas tetanus vaccination and fairs attendance were associated with lower seropositivity.

CONCLUSIONS

Almost half of the horses residing in Spain had antibodies against EP or circulating parasitaemia. Appropriate prevention measures and implementation of a EP surveillance programme should be considered in order to reduce and control the infection.

Occurrence of Trypanosoma spp. and piroplasm infections of horses at Obollo-Afor southeastern Nigeria and resistance profiles of trypanosomes to isometamidium and diminazene salts

Epidemiological data on trypanosomosis and piroplasmosis of horses are lacking in southeastern Nigeria. The prevalence of trypanosome and piroplasm infections in horses and resistance profile of isolated trypanosomes to diminazene and isometamidium salts were investigated. For the cross-sectional study of horses billed for slaughter, 304 horses were randomly sampled. Approximately 2 ml of blood was collected into anticoagulant-treated bottles for haematocrit (HCT) determination, direct microscopic examinations, and rat inoculation. Gender, body condition scores (BCS), age groups, and body weights of sampled horses were noted. Two isolates of Trypanosoma brucei recovered from the cross-sectional study were profiled for resistance to isometamidium hydrochloride and diminazene diaceturate in 36 BALB/c mice. Standardized protocols were used (Eisler et al., Veterinary Parasitology 97:171-182, 2001). 19.1% of horses (95% confidence interval 14.7-23.5%) were positive for haemoparasite infections including Theileria equi (16.1%) and Babesia caballi (3.9%). Only two (0.66%) Trypanosoma brucei infections were seen, being from active cases. Associations between age or gender, and presence of haemoparasites were only random. Haemoparasite-infected horses had significantly (p < 0.05) lower mean HCT and body weights and poorer BCS. From resistance profiling, for each isolate, all mice in control groups were parasitaemic by day 6 post-inoculation, while mice in test groups remained aparasitaemic over 60-day observation period. The study showed the endemicity and weights of Trypanososma spp. and piroplasm infections and among horses within the area. Furthermore, circulating strains of Trypanosoma brucei in the area are still susceptible to isometamidium and diminazene salts in mice. The pharmacoepidemiological significances of these findings were discussed.

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.

Ticks and Tick-Borne Diseases in Cuba, Half a Century of Scientific Research

Ticks and the vast array of pathogens they transmit, including bacteria, viruses, protozoa, and helminths, constitute a growing burden for human and animal health worldwide. In Cuba, the major tropical island in the Caribbean, ticks are an important cause of vector-borne diseases affecting livestock production, pet animal health and, to a lesser extent, human health. The higher number of tick species in the country belong to the Argasidae family and, probably less known, is the presence of an autochthonous tick species in the island, Ixodes capromydis. Herein, we provide a comprehensive review of the ticks and tick-borne pathogens (TBPs) affecting animal and human health in Cuba. The review covers research results including ecophysiology of ticks, the epidemiology of TBPs, and the diagnostic tools used currently in the country for the surveillance of TBPs. We also introduce the programs implemented in the country for tick control and the biotechnology research applied to the development of anti-tick vaccines.

Inhibitory effects of novel ciprofloxacin derivatives on the growth of four Babesia species and Theileria equi

The problems of parasite resistance, as well as the toxic residues to most of the commercially available antipiroplasmic drugs severely weaken their effective, curative, and environmental safe employment. Therefore, it is clear that the development of treatment options for piroplasmosis is vital for improving disease treatment and control. Ciprofloxacin is a broad-spectrum antibiotic that targets mainly the DNA replication machinery by inhibiting DNA gyrase and topoisomerase enzymes. As a result, ciprofloxacin is used for treating several bacterial and parasitic infections. In this study, the efficacy of 15 novel ciprofloxacin derivatives (NCD) that had been developed against drug-resistant Mycobacterium tuberculosis was evaluated against piroplasm parasite multiplication in vitro. The half-maximal inhibitory concentration (IC₅₀) values of the most effective five compounds of NCD (No. 3, 5, 10, 14, 15) on Babesia bovis, Babesia bigemina, Babesia caballi, and Theileria equi were 32.9, 13.7, 14.9, and 30.9; 14.9, 25.8, 13.6, and 27.5; 34.9, 33.9, 21.1, and 22.3; 26.7, 28.3, 34.5, and 29.1; and 4.7, 26.6, 33.9, and 29.1 μM, respectively. Possible detrimental effects of tested NCD on host cells were assessed using mouse embryonic fibroblast (NIH/3T3) and Madin-Darby bovine kidney (MDBK) cell lines. Tested NCD did not suppress NIH/3T3 and MDBK cell viability, even at the highest concentration used (500 μM). Combination treatments of the identified most effective compounds of NCD/diminazene aceturate (DA), /atovaquone (AQ), and /clofazimine (CF) showed mainly synergistic and additive effects. The IC₅₀ values of NCD showed that they are promising future candidates against piroplasmosis. Further in vivo trials are required to evaluate the therapeutic potential of NCD.

Molecular detection of Theileria species and Babesia caballi from horses in Nigeria

Equine piroplasmosis (EP) is an infectious, tick-borne disease caused by the hemoprotozoan parasites, Theileria equi, Babesia caballi, and a recently reported new species, T. haneyi. Infections by these apicomplexan parasites limit performance and cause economic losses for the horse industry. Equine piroplasmosis is widespread in the northern regions of Nigeria, where an increasing portion of the animal population is composed of horses. This disease has remained epidemiologically challenging, especially as the movement of horses increases across Nigeria. In this study, blood samples from 300 horses were collected in three states of northwestern Nigeria. The presence of piroplasms was screened by nested PCR targeting 18S rDNA and positive samples were analyzed using species-specific-nested PCR-targeting genes including ema1 (T. equi), rap1 (B. caballi), and a gene coding a protein of unknown function (T. haneyi). Species-specific-nPCR results demonstrated that the prevalence of T. equi was 13.0% (39/300), B. caballi was 3.3% (10/300) and T. haneyi was 2.7% (8/300). Mixed infections with T. equi and B. caballi was 2.7% (8/300) while T. equi, B. caballi, and T. haneyi multiple infection prevalence was 0.6% (2/300). We used 18S rDNA sequences to determine close relationships between T. equi by phylogenetic analysis and demonstrated that among 57 sequences of Theileria parasites, 28 samples belonged to clade A (49%), 13 samples were found to be clade C (22%), and 16 were clade D (28%). These results demonstrate the genetic diversity of T. equi circulating in horses from Nigeria.

Molecular evidence of Babesia caballi and Theileria equi in equines and ticks in Nigeria: prevalence and risk factors analysis

Babesia caballi and Theileria equi are biological agents responsible for equine piroplasmosis (EP). We conducted a robust and extensive epidemiological study in Nigeria on the prevalence and risk factors of EP. Blood (468, both horses and donkeys) and ticks (201 pools) were screened using polymerase chain reaction (PCR). DNA of equine piroplasms was observed in tick pools with B. caballi amplified in Rhipicephalus evertsi evertsi only [minimum infection rate (MIR) of 7.6%] while T. equi was observed in R. e. evertsi (MIR, 61.6%), Hyalomma dromedarii (MIR, 23.7%) and H. truncatum (MIR, 50.0%). Overall results showed that 196/468 (41.9%) animals were positive for equine piroplasms (both B. caballi and T. equi). The prevalence for T. equi was 189/468 (40.4%) compared to 7/468 (1.5%) for B. caballi. In the horses and donkeys, respectively, the prevalence for T. equi was (39.9%; 112/281) and (41.2%; 77/187) compared with (1.4%; 4/281) and (1.6%; 3/187) due to B. caballi. Our analysis showed that location (Jigawa state), Talon breed, horses used for work and reproduction, unsatisfactory husbandry practices, contact with other mammals are risk factors that associated positivity to T. equi infection in horses, whilst horses kept on intensive management appeared to be less prone to infection. On the other hand, Jangora breed of donkeys and location (Jigawa state) are risk factors to infection with T. equi in donkeys. Findings suggest the persistence of EP in equids and ticks in Nigeria.

Evaluation of cytokines and sialic acids contents in horses naturally infected with Theileria equi

This study was undertaken to assess the effects of T. equi infection on serum concentrations of some important cytokines including interferon-γ (IFN-γ), tumor necrosis factor-α (TNF-α), and interleukin-1 beta (IL-1β), IL-1α, IL-4, IL-6, IL-8, IL-10, IL-12α, IL-12β, IL-18, as well as total, protein and lipid binding sialic acids (TSA, PBSA and LBSA). Furthermore, any probable relation among the parasitemia, cytokines and sialic acids (SAs) were calculated using Pearson correlation and simple linear regression. Almost 300 draft horses (Kurdish-breed) with age of 3-4 years old from north-west of Iran were examined and an infected group comprised of 28 mares, naturally infected with T. equi, was identified and divided into 3 subgroups according to their parasitemia rates (low <1 %, moderate 1-3 % and high 3-5 %). Twenty healthy horses were considered as a control. Characterization and differentiation of piroplasmosis were conducted using routine hematological procedures and specific PCR assay. The results revealed a significant increase (P < 0.05) in all of the cytokines and SAs in a parasitic burden-dependent fashion. Additionally, a strong and positive relation was detected among the parasitemia, cytokines and SAs. Conclusively, T. equi infection is associated with induction of severe inflammatory processes in horses and SA plays a pivotal role in pathophysiology of the disease as it is tightly correlated with the parasitemia rate.

Genetic Characterization of Piroplasms in Donkeys and Horses from Nigeria

Simple Summary

Theileria equi and Babesia caballi are blood-parasites of horses and donkeys that are transmitted by ticks and may cause severe clinical illness. Many infected animals are carriers of parasites without showing signs of disease and, thus, pose a risk of transmission. Nigeria is a major passageway in animal import, export and transport within Africa. This movement of animals may play a key role in the spread of parasites. The aim of this study was to characterize these parasites that infect both horses and donkeys in Nigeria. Blood was collected from horses and draught-donkeys at two separately-owned farms in northern Nigeria. Infection with T. equi was detected in both donkeys and horses, with four of the five known genotypes present in Africa. Infection with a single genotype of B. caballi was detected in donkeys. Our results suggest that donkeys may be an important reservoir of these parasites. The high diversity of T. equi supports the hypothesis that animal transport through Nigeria may contribute to the spread of parasites to and from other countries in the region.

Abstract

Equine piroplasmosis (EP) is a tick-borne disease of equids, caused by the two haemoprotozoal parasites: Theileria equi and Babesia caballi. Nigeria constitutes a major crossroads of animal transport in West Africa and may serve as a factor in EP dissemination in the region. The study aim was to characterize EP parasites in donkeys and horses in northern Nigeria using a molecular approach. Blood was collected from 57 donkeys and 47 horses. EP infection was detected and characterized by polymerase chain reaction (PCR). Twenty five donkeys (43.8%) were infected with T. equi, five (8.8%) with B. caballi, three (5.3%) with dual infections. Four horses (8.5%) were infected by T. equi and none by B. caballi. Four of the five known T. equi 18S rRNA genotypes (A, B, C and D) were identified. Theileria equi ema-1 and ema-2 genes were amplified in only 2 and 10 samples, respectively, showing no genetic variation. All B. caballi isolates were classified as rap-1 genotype A1. Twenty-two (42.3%) of the donkeys were positive for anti-T. equi antibodies and 29 (55.8%) were positive for anti-B. caballi antibodies, using immunofluorescence antibody test (IFAT). The study results demonstrate high genetic variation within T. equi parasites, suggesting that donkeys may be reservoirs of EP parasites in West Africa.

Serological and molecular detection of selected hemoprotozoan parasites in donkeys in West Omdurman, Khartoum State, Sudan

In Sudan, donkeys are important animals, providing transportation and income possibilities. However, the prevalence of parasites in donkeys in Sudan has not been thoroughly characterized. Accordingly, in this study, we aimed to detect selected hemoprotozoan parasites in donkeys in West Omdurman, Khartoum State, Sudan, wherein people depend mainly on donkeys for their daily life. In total, 198 blood samples collected from donkeys in a local market in West Omdurman, were screened using serological and molecular diagnostic techniques. Serologically, 52 (26.3%), 56 (28.3%), and 19 (9.6%) samples were positive for trypanosomosis using Card Agglutination Test for Trypanosoma evansi, Trypanosoma evansi crude antigen -based enzyme-linked immuno sorbent assay (ELISA) and recombinant Trypanosoma evansi GM6-4r-based ELISA, respectively. ELISA for equine piroplasmosis revealed 156 (78.8%) and 10 (5.1%)Theileria equi- and Babesia caballi-positive samples, respectively. PCR detected Trypanosoma congolense, subgenus Trypanozoon, Theileria equi, and Babesia caballi in 18 (9.1%), 77 (38.9%), 18 (9.1%), and 8 (4%) samples, respectively. Of the 77 Trypanozoon-positive samples, 35 (45.5%) were confirmed as Trypanosoma evansi type A. To our knowledge, this is the first report of detection of Trypanosoma congolense in donkeys outside of tsetse-infested areas in Sudan.