Discrimination between Theileria lestoquardi and Theileria annulata in their vectors and hosts by RFLP based on the 18S rRNA gene

Development of a duplex PCR assay for detecting Theileria luwenshuni and Anaplasma phagocytophilum in sheep and goats

Coinfections with the tick-borne pathogens Theileria luwenshuni and Anaplasma phagocytophilum can cause significant economic losses in sheep and goat farming. The difficulty in detecting these two pathogens by microscopic examination warrants the development of a rapid detection test to discriminate them. In this study, a duplex polymerase chain reaction (PCR) assay was developed to simultaneously detect T. luwenshuni and A. phagocytophilum. Alignment of the sequences from related pathogens allowed us to design a primer pair targeting the 18S ribosomal RNA gene in T. luwenshuni and generate a target product of 962 bp, whereas a previously reported species-specific primer (SSAP2f/SSAP2r) for A. phagocytophilum was used in the same reaction to generate a product of 641 bp. Genomic DNA from T. luwenshuni and A. phagocytophilum was 10-fold serially diluted for testing PCR sensitivity. Under the optimal PCR conditions we established, the lower limit of detection of the assay was 29.13 fg/μL for T. luwenshuni and 1.53 fg/μL for A. phagocytophilum, and PCR primers used in this study were confirmed to be 100% species-specific using other hemoparasites previously identified by other methods. No significant difference was found between conventional and duplex PCR protocols used to detect the two species. Our study provides an effective, sensitive, specific, and accurate tool for the diagnosis and epidemiological surveillance of mixed infections of the two pathogens in sheep and goats.

Molecular surveillance of Theileria ovis, Theileria lestoquardi and Theileria annulata infection in sheep and ixodid ticks in Iran

A molecular study was undertaken to detect Theileria ovis, Theileria lestoquardi and Theileria annulata in sheep and tick vectors. Investigation was conducted from 2010 to 2011 in the south of Khorasan Razavi Province, Iran. A total of 150 blood samples were collected from 30 different sheep flocks. In addition, ixodid ticks were sampled from the same flocks. The stained blood smears were microscopically examined for the presence of piroplasms and a semi-nested polymerase chain reaction-restriction (PCR) was used for subsequent molecular speciation. Salivary glands were isolated from the ticks and subsequently analysed by semi-nested PCR. polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) was used to differentiate between T. lestoquardi and T. annulata from PCR-positive samples. Theileria species infection was microscopically detected in 18.6% of blood smears. The presence of T. ovis and T. lestoquardi or T. annulata was detected by semi-nested PCR in 58.6% and 6.6% of blood samples respectively. In total, 169 ixodid ticks were collected from different areas of the province. The most prevalent ticks were Rhipicephalus turanicus (n = 155; 91.7% of the total), followed by Hyalomma anatolicum anatolicum (n = 8; 4.7%) and Hyalomma marginatum turanicum (n = 6; 3.5%). From an organ pooling of 33 ticks, three pools of salivary glands from R. turanicus were positive for Theileria species by semi-nested PCR. Of the three R. turanicus samples testing positive for Theileria species, two (6.1%) were positive for T. ovis and one (3.0%) for T. lestoquardi or T.annulata. Amongst the 11 PCR-positive samples for T. lestoquardi or T. annulata, 10 were positive for T. lestoquardi and one sample was positive for both T. lestoquardi and T. annulata using PCR-RFLP. The results also demonstrated that PCR-RFLP could be used for the detection of T. ovis. Based on the results, it can be concluded that T. ovis has a higher prevalence than T. lestoquardi, and that R. turanicus could be a possible vector for T. ovis and T. lestoquardi. Finally, the PCR-RFLP based on Msp1 restriction enzyme is a simple method for differentiation of Theileria species in sheep and ixodid ticks.

High Prevalence of Anaplasma spp. in Small Ruminants in Morocco

The prevalence of infection by Anaplasma spp. (including Anaplasma phagocytophilum) was determined using blood smear microscopy and PCR through screening of small ruminant blood samples collected from seven regions of Morocco. Co-infections of Anaplasma spp., Babesia spp, Theileria spp. and Mycoplasma spp. were investigated and risk factors for Anaplasma spp. infection assessed. A total of 422 small ruminant blood samples were randomly collected from 70 flocks. Individual animal (breed, age, tick burden and previous treatment) and flock data (GPS coordinate of farm, size of flock and livestock production system) were collected. Upon examination of blood smears, 375 blood samples (88.9%) were found to contain Anaplasma-like erythrocytic inclusion bodies. Upon screening with a large spectrum PCR targeting the Anaplasma 16S rRNA region, 303 (71%) samples were found to be positive. All 303 samples screened with the A. phagocytophilum-specific PCR, which targets the msp2 region, were found to be negative. Differences in prevalence were found to be statistically significant with regard to region, altitude, flock size, livestock production system, grazing system, presence of clinical cases and application of tick and tick-borne diseases prophylactic measures. Kappa analysis revealed a poor concordance between microscopy and PCR (k = 0.14). Agreement with PCR is improved by considering microscopy and packed cell volume (PCV) in parallel. The prevalence of double infections was found to be 1.7, 2.5 and 24% for Anaplasma-Babesia, Anaplasma-Mycoplasma and Anaplasma-Theileria, respectively. Co-infection with three or more haemoparasites was found in 1.6% of animals examined. In conclusion, we demonstrate the high burden of anaplasmosis in small ruminants in Morocco and the high prevalence of co-infections of tick-borne diseases. There is an urgent need to improve the control of this neglected group of diseases.

Fatal cases of Theileria annulata infection in calves in Portugal associated with neoplastic-like lymphoid cell proliferation

This study was carried out to investigate fifteen cases of acute lethal infection of calves (<or= 4 months of age) by the protozoan parasite Theileria (T.) annulata in the south of Portugal. Calves developed multifocal to coalescent nodular skin lesions, similar to multicentric malignant lymphoma. Infestation with ticks (genus Hyalomma) was intense. Theileria was seen in blood and lymph node smears, and T. annulata infection was confirmed by isolation of schizont-transformed cells and sequencing of hypervariable region 4 of the 18S rRNA gene. At necropsy, hemorrhagic nodules or nodules with a hemorrhagic halo were seen, particularly in the skin, subcutaneous tissue, skeletal and cardiac muscles, pharynx, trachea and intestinal serosa. Histologically, nodules were formed by large, round, lymphoblastoid neoplastic-like cells. Immunohistochemistry (IHC) identified these cells as mostly CD3 positive T lymphocytes and MAC387 positive macrophages. A marker for B lymphocytes (CD79alphacy) labeled very few cells. T. annulata infected cells in these nodules were also identified by IHC through the use of two monoclonal antibodies (1C7 and 1C12) which are diagnostic for the parasite. It was concluded that the pathological changes observed in the different organs and tissues were caused by proliferation of schizont-infected macrophages, which subsequently stimulate a severe uncontrolled proliferation of uninfected T lymphocytes.

Molecular identification of ovine Theileria species by a new PCR-RFLP method

Theileria spp. infect wild and domestic ruminants in the tropical and subtropical regions of the world. Two species, T. lestoquardi and T. ovis, are suspected to cause ovine theileriosis in Iran. The epidemiological aspects of ovine theileriosis in Iran are poorly understood, and further investigations by sensitive and precise techniques are required. In this study, the use of a nested PCR for amplification of a fragment of the 18S ribosomal DNA from virtually all species of Theileria is described. For differentiation of various Theileria spp. a RFLP assay was developed as a diagnostic tool enabling direct, concurrent, highly specific and sensitive identification of Theileria spp. The sensitivity of the nested PCR for Theileria species was 10(-5)% parasitemia. Restriction fragment length polymorphism (RFLP) of the PCR products allowed differentiation between three different Theileria species (T. annulata, T. lestoquardi and T. ovis) and seems to be useful for differentiation of other species such as T. separata and Theileria spp. china. From 100 field blood samples obtained from sheep in East and South-East Iran, 56% were positive for Theileria spp. by nested-PCR compared with 21% by microscopic examination. Out of 56 positive samples, 12.5% (7/56) were positive for T. ovis and 87/5% (49/56) were positive for T. lestoquardi. This is the first report in which T. ovis has been detected in Iran using molecular identification techniques.

Phylogenetics of Theileria species in small ruminants

Our study is based on the collection of blood and ticks from sheep in Iran and Italy. Polymerase chain reaction (PCR) testing was performed to target the 18S rRNA gene and RLB was performed using previously published probes. In Italy and Iran 78.7% and 76.0% of the sheep were PCR positive, which after sequencing and RLB showed that they were Theileria ovis and Theileria lestoquardi, respectively. Phylogenetic analysis was performed using the Clustal W multiple sequence alignment program and our sequences were compared with more than 50 others already published in the EMBL database. Our T. lestoquardi sequences linked with other T. lestoquardi sequences from Iran, Tanzania, and Sudan and Theileria annulata showed the importance of having species-specific probes between these two species. However, distinctive clades were found between T. lestoquardi ticks and those found in sheep blood. Italian T. ovis seemed to be closer to Theileria spp. from Namibia and Iran than with other T. ovis from Spain, Turkey, Tanzania, and Sudan adding some information to the controversy about this species. However, some confusion was found on the existing database where the location of pathogens, years, and species names was inaccurate and when available sequences were not always appropriately used. This article will discuss our results and some comparisons with other phylogenetic approaches.

Ticks (Ixodidae) from passerine birds in the Carpathian region

Birds have been found to be a reservoir host of borrelia. In order to assess the situation in Slovakia ticks were collected from a total of 3057 mist-netted, ringed and released passerine birds in two locations at 500 m (in 2001) and 1000 m (in 2003) above sea level in the Bukovské Vrchy Hills, part of the Carpathian region in the north-east of Slovakia. A total of 75 birds of 16 species were infested with subadult ticks of Ixodes ricinus species (prevalence of parasitization 5%). Sixty-two larvae from 31 birds of 9 species and 80 nymphs from 52 birds of 15 species were found. The highest intensity of parasitization was observed on blackbirds Turdus merula, song thrushes T. philomelos and dunnocks Prunella modularis. Six Ixodes ricinus adult ticks were found on humans working with birds, and one I. ricinus female tick on their dog. In ticks, the presence of Rickettsia sp., Coxiella burnetii, Borrelia burgdorferi sensu lato and members of the Anaplasmataceae and Piroplasmidae, were investigated by polymerase chain reaction, followed by sequence analysis. Rickettsia sp. was found in 1 nymph from the European robin Erithacus rubecula, in 3 adult ticks (1 male, 2 females) from humans and in the tick from the dog. The closely related Ehrlichia- like species "Schotti variant" was detected in 1 nymph from the song thrush. Borrelia afzelii was identified in 1 male and B. garinii in 1 female tick collected on humans. Ixodes ricinus was found to be the vector of a wide spectrum of tick-borne pathogens in a mountainous area of the Carpathians. Because of the low yield of ticks and pathogens the importance of birds as reservoir hosts is still poorly understood.