Multiplex PCR for detection of Trypanosoma evansi and Theileria equi in equids of Punjab, India

Comparison of direct and indirect methods to maximise the detection of Babesia caballi and Theileria equi infections in Central Southern Italy

Equine piroplasmosis is a disease of equids, caused by tick-borne apicomplexan protozoan pathogens Babesia caballi and Theileria equi, which, according to the World Organisation for Animal Health (OIE), can be diagnosed by enzyme-linked immunosorbent assay (ELISA), immunofluorescent antibody test (IFAT) and polymerase chain reaction (PCR). The present study was conducted to evaluate and compare the assays available for the diagnosis of equine piroplasmosis. Data employed were obtained from 1300 blood samples collected between 2012-2014 from asymptomatic and symptomatic equines (horses and donkeys) of central-southern regions of Italy and analyzed by ELISA, IFAT, PCR (one commercial and one from literature) and blood smear microscopic examination. Statistical differences of the proportions of positivity for each parasite and group (asymptomatic and symptomatic) among the methods were verified by the z test to identify the most sensitive. The concordance between each pair of methods - for each parasite and within the groups - and trends in detection of suspect samples of four hypothetical diagnostic algorithms using serological and biomolecular assays were evaluated to identify the most suitable laboratory diagnostic workflow. The results of this study highlighted a lower capacity to detect suspect samples of commercial ELISA for B. caballi in all groups when compared to biomolecular methods and IFAT; and of the commercial PCRs in asymptomatic animals, identifying a PCR from literature and IFAT as the best choice for a combined diagnosis. For T. equi, IFAT detected more suspect samples than ELISA, even if the latter showed good performance and some samples were positive only by the ELISA and PCR, indicating that their simultaneous employment is still advantageous. Host-parasite interaction, amino-acid/genetic diversity and differences in detection limits among the assays could be among the reasons in explaining the present results. In view of further studies, ELISA should be used in combination with PCR, that should regularly be included in the laboratory diagnosis to maximise the detection of early infections and support the evaluation of pharmacological treatment.

Occurrence and Genetic Diversity of Babesia caballi and Theileria equi in Chilean Thoroughbred Racing Horses

This study aimed to serologically and molecularly survey Babesia caballi and Theileria equi in thoroughbred horses from racecourses in Chile. Additionally, the genetic diversity of the positive samples was assessed. A total of 286 thoroughbred horses from the Santiago and Valparaíso racecourses had their serum samples submitted to an ELISA for B. caballi and T. equi, and 457 samples (from the Santiago, Valparaíso, and Concepción racecourses) were tested with nested PCRs for the B. caballi 48 KDa rhoptry protein (RAP-1) and T. equi 18S rRNA genes. Selected RAP-1 and 18S positive products were sequenced to perform phylogenetic and haplotype analyses. An overall seroprevalence of 35.6% was observed for these Chilean racecourses: 23.7% for T. equi, 8.4% for B. caballi, and 3.5% for both agents. Overall, a 53.6% occurrence by nPCR was detected for the three Chilean racecourses: 44.2% for T. equi, 5.4% for B. caballi, and 3.9% for both agents. Phylogenetic analysis of T. equi and B. caballi showed genetic proximity with sequences previously detected in other countries. Haplotype analysis revealed a low diversity among the Chilean sequences, which may have originated from those reported in Brazil, Israel, or Cuba. Babesia caballi and T. equi were detected for the first time in Chilean thoroughbred horses.

Molecular Identification of Trypanosoma evansi Isolated from Arabian Camels (Camelus dromedarius) in Riyadh and Al-Qassim, Saudi Arabia

We analyzed the blood from 400 one-humped camels, Camelus dromedarius (C. dromedarius), in Riyadh and Al-Qassim, Saudi Arabia to determine if they were infected with the parasite Trypanosoma spp. Polymerase chain reaction (PCR) targeting the internal transcribed spacer 1 (ITS1) gene was used to detect the prevalence of Trypanosoma spp. in the camels. Trypanosoma evansi (T. evansi) was detected in 79 of 200 camels in Riyadh, an infection rate of 39.5%, and in 92 of 200 camels in Al-Qassim, an infection rate of 46%. Sequence and phylogenetic analyses revealed that the isolated T. evansi was closely related to the T. evansi that was detected in C. dromedarius in Egypt and the T. evansi strain B15.1 18S ribosomal RNA gene identified from buffalo in Thailand. A BLAST search revealed that the sequences are also similar to those of T. evansi from beef cattle in Thailand and to T. brucei B8/18 18S ribosomal RNA from pigs in Nigeria.

Pentaplex PCR assay for rapid differential detection of Babesia bigemina, Theileria annulata, Anaplasma marginale and Trypanosoma evansi in cattle

A multiplex PCR (mPCR) assay for simultaneous detection and differentiation of four major haemoparasites in crossbred cattle was established using parasite specific genomic DNA and four sets of primer pairs targeting AMA-1, Tams1, MSP5 and VSG genes of Babesia bigemina, Theileria annulata, Anaplasma marginale and Trypanosoma evansi generating precise amplicons of 448, 156, 382 and 110 bp, respectively. An internal amplification control, 202 bp bovine β-casein gene fragment, was simultaneously amplified with four target genes to avoid false-negative results. The sensitivity of mPCR was 3.44 × 10², 5.9 × 10³, 2.88 × 10² and 3.3 × 10³ copies for B. bigemina, T. annulata, A. marginale and T. evansi, respectively. mPCR of cattle clinical samples (n = 516), suspected for haemoparasites, revealed single haemoparasitic infection in 279 (54.06%) cases, whereas mixed infection was recorded in 54 (10.46%) samples. In clinical samples, coinfection with T. annulata and A. marginale was the most common. The findings of mPCR were consistent with uniplex PCR under field conditions except for subtle variations in A. marginale infection. Overall, the mPCR assay represents an economical, reproducible and robust diagnostic tool for concurrent detection of cattle haemoparasites and large scale epidemiological studies.

Comparative haemato-biochemical alteration in theileriosis and babesiosis detected by duplex PCR in cattle

Blood samples from suspected crossbred cows (327) were examined microscopically as well as confirmed by in-house standardized duplex PCR assay. Out of 327 samples, 107 (32.72%) and 17 (5.19%) samples were positive for T. annulata and B. bigemina respectively by microscopy. When the samples were screened by duplex PCR, 130 (39.75%) and 27 (8.25%) animals had single infection with T. annulata (Group I) and B. bigemina (Group II), respectively. Duplex PCR was able to detect 11% of mixed infections (Group III) compared to 2.75% by microscopy. Haemato-biochemical profile of infected animals (30 for each group) were studied and compared with each other and normal healthy group (Group IV, n=10). The infected group showed significantly decreased levels of TEC, Hb and PCV, red blood cell indices than healthy control animals indicating microcytic hypochromic anaemia. Marked thrombocytopenia was also observed in affected animals. Serum biochemistry of infected cows revealed significantly higher values of AST and low levels of blood glucose, calcium, total protein, albumin as compared to healthy animals. Group I and Group II were further sub-divided into three sub-groups based on severity of infection as latent, subclinical and clinical. No significant difference among biochemical parameters was observed between subgroups of diseased animals but there was significant decline in hematological parameters, viz. haemaoglobin, PCV and TEC. Haemato-biochemical changes were more severe in B. bigemina infected group in contrast to other groups and anaemia is becoming more severe as the disease progress due to extensive intravascular haemolysis.

Direct PCR-RFLP based detection and differentiation of Anaplasma species in naturally infected goats of eastern Haryana, India

The present investigation was designed to develop a novel, rapid and cost effective direct PCR-RFLP assay, as a specific diagnostic tool for detection and differentiation of two Anaplasma species (A. ovis and A. marginale). Blood samples were collected randomly from 83 goats. A direct blood polymerase chain reaction (DT-PCR) for amplifying a fragment of the major surface protein 5 (msp5) gene of A. ovis/A. marginale from whole blood was developed and standardized. Blood smear examination revealed 24 samples (28.91%) positive for Anaplasma inclusion bodies. While, 39 (47%) samples were positive by DT-PCR. The results revealed that DT- PCR was 100% sensitive and 74.57% specific compared to microscopy based detection (k =0.62). Additionally DT-PCR showed 94.44% sensitivity and 100% specificity compared to conventional PCR results with suspected blood samples (k=0.94). All DT-PCR positive samples were confirmed to be A. ovis by restriction fragments length polymorphism (RFLP) analysis. The phylogenetic tree and sequence analysis revealed msp5 gene of Anaplasma species Indian isolate had maximum distance from A. phagocytophilum followed by A. centrale and A. marginale and 100% sequence identity with A. ovis isolates of Chinese origin which further confirmed the sequence identified in native goats to be of A. ovis. The simplified DT-PCR assay as a viable alternative to conventional PCR could be helpful for fast and accurate diagnosis of Anaplasma species and suitable for screening a large number of samples. Furthermore, results revealed that DT-PCR-RFLP of the msp5 gene might be a useful method for simultaneous detection and differentiation of A. ovis and A. marginale in goats.

Evaluation and correlation of oxidative stress and haemato-biochemical observations in horses with natural patent and latent trypanosomosis in Punjab state of India

The haemato-biochemical indices and oxidative stress markers in horses naturally infected with Trypanosoma evansi were evaluated by analyzing the level of these parameters between T. evansi infected (microscopically positive patent group and PCR positive latent group) and infection free horses. To compare the hemato-biochemical indices and oxidative stress indicators, horses were divided into three categories based on diagnostic test employed and positive results obtained. These included Romanowsky stained slide positive group (Group I; n = 6), PCR positive group (group II; n = 28) and negative control group (group III, n = 30), revealing parasitologically positive patent, molecular positive latent and disease free status of horses. A significant reductions in total erythrocytes count (TEC, P = 0.01), haemoglobin (Hb, P = 0.01) and packed cell volume (PCV, P = 0.04) was noticed both in group I and group II while significant neutrophilia and lymphocytopenia was observed in group I when compared to negative control group. Substantial increase in creatinine (CRTN, P = 0.032) and gamma glutamyl transferase (GGT, P = 0.012) in group I while significant decrease in glucose (GLU, P = 0.04) and iron (Fe, P = 0.01) were noticed in both group I and group II in comparison to group III. A significant difference in lipid peroxides (LPO, P = 0.01) with highest level in patent group I (15.33 ± 0.53) followed by PCR positive latent group (14.09 ± 1.66) indicates higher lipid peroxidation in erythrocytes and oxidative stress in decreasing order when compared with infection free control horses (9.83 ± 0.97). Catalase (CAT, P = 0.01) was significantly lower in parasitological (0.82 ± 0.14) and molecular positive cases (1.27 ± 0.35) in comparison to control group (3.43 ± 0.96). The levels of superoxide dismutase (SOD, P = 0.01), reduced glutathione (GSH, P = 0.01) and ferric reducing antioxidant power (FRAP, P = 0.01) were significantly lower in parasito-molecular positive cases as compared to infection free control horses. An inverse correlation of RBC count with LPO and GSH and a direct correlation with catalase, SOD and FRAP was revealed. Overall, the observed substantial decreases in the oxidative parameters like catalase CAT, SOD, GSH and FRAP activities with remarkably elevated levels of LPO indicate high exposure of erythrocytes to oxidative damage in T.evansi infected horses.

Detection of Theileria equi infection in ixodid ticks of equines using nested polymerase chain reaction from Punjab, India

The aim of this study was to perceive Theileria equi DNA in ticks by nested PCR and to list the risk factors associated with infection in equines from Punjab. A total of 84 ticks were obtained from 464 screened animals. The local tick variety was identified and verified on the basis of characters revealed in scanning electron microscopy. Amplicons of 665 bp obtained by nPCR specific for 18S rRNA of T. equi were detected in 13.1% of ticks, with higher risk of infection in western than in eastern Punjab. Incidence of parasite was higher in Hyalomma anatolicum anatolicum as compared to Rhipicephalus (Boophilus) microplus, particularly the female ticks. Phylogenetic analyses indicated closed homology with strain from Brazil. This is the first study of T. equi incidence in ixodid ticks in Punjab which is the most important vector for the spread of the infection to healthy equine in endemic areas.

Molecular survey and characterization of Trypanosoma evansi in naturally infected camels with suspicion of a Trypanozoon infection in horses by molecular detection in Egypt

In Egypt, although the Trypanosoma evansi has been reported frequently among domestic animals, there is no published data on T. evansi in horses. Therefore, this study aimed to assess the prevalence and characterization of T. evansi in three governorates by examining blood samples from 40 local camels, 35 imported camels, 25 horses and 10 donkeys by PCR targeting the sequences of TBR and RoTat 1.2VSG. The overall prevalence of T. evansi was 54.5% and 21.8% by TBR PCR and RoTat 1.2VSG PCR, respectively. The TBR PCR detected T. evansi in 60% and 71.4%, respectively, of local and imported camels and in 10% and 40% of donkeys and horses, respectively. For RoTat 1.2VSG PCR, T. evansi was detected in 32.5% and 31.4 of local and imported camels, respectively. All horses and donkeys were negative by RoTat 1.2VSG PCR. TBR PCR was superior to RoTat 1.2VSG PCR in T. evansi infection detection. Statistically significant differences in the prevalence of the infection were observed on the basis of body condition and location. Sequencing and phylogenetic analysis, based on RoTat 1.2VSG, confirmed the presence of T. evansi, which was closely related to Egyptian and Indian isolates. In conclusion, TBR PCR is the best assay to monitor T. evansi infections in camels, horses, and donkeys. The presence of T. evansi in horses and donkeys possibly play a role in the transport of the infection to camels. This is the first report of T. evansi infection in horses in Egypt using TBR PCR.

Development of a duplex PCR assay for simultaneous detection of Babesia bigemina and Theileria annulata infections in cattle

Bovine babesiosis and theileriosis are fatal tick borne haemoparasites of vertebrates imposing serious constraints on health and productivity of livestock. Additionally, the recovered animals become persistent carriers and play a significant role in disease epidemiology. The present investigation describes the development and evaluation of duplex PCR assay for simultaneous detection of Babesia bigemina (B. bigemina) and Theileria annulata (T. annulata) in cattle. Following in silico analysis for candidate target genes representing each of the haemoparasites, an optimised duplex PCR assay was established using two sets of primers, ssurRNA and cytob1 for genomic DNA amplification of B. bigemina and T. annulata encoding product size of 689 and 312 bp, respectively. The results were compared with conventional microscopy and monoplex PCR assay. The sensitivity of each primer pair was checked using serial dilutions of parasite DNA, while specificity was determined by testing for amplification from DNA of different stocks of each pathogen. The duplex PCR detected each parasite species with the same level of sensitivity, irrespective of whether its DNA was amplified in isolation or with DNA mixture representing the other pathogens. Additionally, single and duplex PCRs could able to detect each species with equal sensitivity in serially diluted DNA representing mixtures of both the pathogen, and nonspecific amplification from non target species was not observed. The developed assay represents an economical, simple, sensitive, specific and reproducible diagnostic tool for simultaneous detection of tropical theileriosis and bovine babesiosis and boosting targeted selective control strategy in endemic areas.

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.

A new multiplex PCR assay to distinguish among three cryptic Galba species, intermediate hosts of Fasciola hepatica

A molecular tool described here allows in one step for specific discrimination among three cryptic freshwater snail species (genus Galba) involved in fasciolosis transmission, a worldwide infectious disease of humans and livestock. The multiplex PCR approach taken targets for each species a distinctive, known microsatellite locus which is amplified using specific primers designed to generate an amplicon of a distinctive size that can be readily separated from the amplicons of the other two species on an agarose gel. In this way, the three Galba species (G. cubensis, G. schirazensis, and G. truncatula) can be differentiated from one another, including even if DNA from all three were present in the same reaction. The accuracy of this new molecular tool was tested and validated by comparing multiplex PCR results with species identification based on sequences at mitochondrial and nuclear markers. This new method is accurate, inexpensive, simple, rapid, and can be adapted to handle large sample sizes. It will be helpful for monitoring invasion of Galba species and for developing strategies to limit the snail species involved in the emergence or re-emergence of fasciolosis.

DNA detection of Trypanosoma evansi: Diagnostic validity of a new assay based on loop-mediated isothermal amplification (LAMP)

Trypanosoma evansi (T. evansi) is the most widely spread pathogenic trypanosome in the world. The control of trypanosomiasis depends on accurate diagnosis and effective treatment. Focusing on the presence of T. evansi in Asia, we developed a detection assay based on tracing phosphate ions (Pi) generated during LAMP targeting the variant surface glycoprotein (VSG) gene of Rode Trypanozoon antigenic type 1.2 (RoTat 1.2 VSG). The diagnostic potential as well as the use of the assay as a test-of-cure method after berenil treatment, was assessed in mice at different time points of infection. In addition, 67 buffalo blood collected from Tongling county, Anhui province, as well as 42 cattle sera from the Shanghai area, were used to evaluate the diagnostic validity of the test. The detection limit of the novel LAMP assay was determined to be as low as 1 fg of T. evansi DNA, while the reaction time for the test was only 30min. Hence it outperforms both microscopy and PCR. In the test-of-cure assessment, successful berenil mediated cure could be confirmed within 48h after treatment. This offers a tremendous advantage over conventional antibody-based diagnostic tools in which successful cure only can be confirmed after months. In the cattle and buffalo screening, the LAMP was able to detect a false-negative determined sample, wrongly classified in a conventional microscopy and PCR screening. Finally, no cross-reactivity was observed with other zoonotic parasites, such as T. evansi type B, T. congolense, T. brucei, Schistosoma japonicum, Plasmodium falciparum, Leishmania donovani, Toxoplasma gondii and Angiostrongylus cantonensis. We conclude that the novel LAMP assay is sensitive, specific and convenient for field use, particularly in areas where infection incidence has become extremely low. The LAMP assay could be used as a tool for trypanosomiasis control and elimination strategies in areas where T. evansi Type A infections are causing a threat to livestock farming.

Molecular survey in relation to risk factors and haemato-biochemical alteration in Theileria equi infection of equines in Punjab Province, India

Equine piroplasmosis caused by Theileria equi, an apicomplexan intracellular haemoprotozoan parasite effects equids throughout the world. Current investigation is the first detailed epidemiological survey report based on conventional (blood smear) and primary polymerase chain reaction (PCR) for the detection of T. equi on 464 equids (426 horses and 38 donkeys/mules) in Punjab province of India. PCR targeting 18S rRNA gene of T. equi produced high fidelity 709bp amplification products with 100% concordance with blood films. The prevalence of infection was proportional (P≤0.01) to temperature and aridness of the regions, which turned out to be the most important physical factor pertaining to T. equi infection. Spatial distribution analysis revealed an increasing trend of disease prevalence from north-eastern to south-western region of Punjab by both the techniques. Haemato-biochemical analysis revealed significant decrease in total erythrocyte count and haemoglobin; and increase in mean corpuscular haemoglobin, serum globulin, glucose, creatinine, aspartate aminotransferase and bilirubin levels (P≤0.05). This study divulges the endemicity of equine theileriosis in Punjab with the prominence of various odds of infection, emphasising the pathophysiological manifestation associated with latent infection of T. equi detectable by PCR.

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.

Theileria equi and Babesia caballi infection of equids in Punjab, India: a serological and molecular survey

A cross-sectional study was conducted in Submountain undulating, Undulating plain, Western and Western plain agro-climatic zones of Punjab province, India, to determine the prevalence, agreement between diagnostic tests and associated related risk factors of Theileria equi and Babesia caballi infection in equids (horses, donkey, mules). An overall prevalence of 14.14 and 0.0% of T. equi and B. caballi was recorded by multiplex polymerase chain reaction targeting 18S ribosomal RNA (rRNA) for both the parasites and 75 and 1.11% by competitive enzyme-linked immunosorbent assay in a representative sample of 180 animals. Only two animals with positive antibody titre from B. caballi and none with PCR indicated T. equi as the predominant haemoprotozoan responsible for equine piroplasmosis in the study area. Among the PCR-positive animals, presence of tick vectors in farm vicinity was the most influential associated with T. equi infection (P = 0.002; odds ratio (OR) 9.30; 95% confidence interval (CI) = 3.32-27.10). For animals with higher anti-T. equi antibody titres, strong association of sero-prevalence for T. equi was recorded with age, sex, usage, tick infestation and deworming/vaccination status of host animals and farm management strategies. The study has demonstrated the possible absence of B. caballi in both conducive and non-conducive areas of Punjab and demonstrated T. equi as the potential agent of equine piroplasmosis in Punjab.