At least two genetically distinct large Babesia species infective to sheep and goats in China

Prevalence and risk factors of Babesia species in domestic herbivores in China: A systematic review and meta-analysis

Babesia species are tick-transmitted hemoprotozoa that infect mammals, birds, and humans, posing a significant global threat to veterinary medicine threat. In this study, the authors systematically retrieved articles on the occurrence of Babesia species in domestic herbivores in China, including ovine, bovine, and equine species, through a search in the following six databases from their inception to 4 November 2024: PubMed, Web of Science, ScienceDirect, Chinese National Knowledge Infrastructure, Wanfang Data, and VIP Chinese Journal Database. A total of 94 studies (54 high-quality studies, 40 medium-quality studies) from 28 provinces were included. The pooled prevalence of Babesia infection was 11 % in ovines, 12 % in bovines, and 18 % in equines, with significant differences observed across subgroups, including, region, species, longitude, temperature, and season. Infection prevalence was higher in East and Central China, particularly in Hunan, Fujian, and Ningxia, as well as in regions characterized by lower altitude, higher temperature, and higher humidity. Longitude and season were significantly associated with Babesia infection in equines (p < 0.05), while temperature analysis indicated a significant difference (p < 0.05) in Babesia infection in bovines. In addition, infection rates were higher in female animals than in male animals; rates were also higher in 2013 or before in comparison to later sampling years. Moreover, the infection rates of different Babesia species varied significantly in bovines. These findings highlight key epidemiological patterns and potential risk factors, including regional and environmental influences associated with Babesia infection in domestic herbivores in China; thus, the findings of this study provide a solid foundation for developing targeted prevention and control strategies that can aim to mitigate the impact of babesiosis in domestic herbivores.

Diversity of piroplasma species in small rodents and ticks captured in suburbs of Gifu City, central Japan

Piroplasmas (Babesia and Theileria) are protozoa transmitted from ticks to warm-blooded animals. Some species of them, such as Babesia microti, can cause zoonotic infections. Although B. microti infections in wild rodents and ticks in Japan have been frequently reported in Hokkaido, there are only older reports of zoonotic babesiosis in other areas of Japan. In this study, we investigated prevalence of piroplasma species in wild rodents and ticks collected in near Gifu City, a central region in Japan, between 2021 and 2023 using nested-PCR to detect the 18S rRNA gene sequences of various piroplasma species. Among 87 wild rodents, piroplasma gene sequences detected in four large Japanese field mice (Apodemus speciosus) were 100% identical to B. microti Otsu/Hobetsu type. Notably, the gene detected in one pool of nymphal Haemaphysalis ticks was closely related to Babesia motasi-like isolates recently detected in human patients in South Korea. Additionally, the deer Theileria species, which has been widely detected throughout Asia, including Japan, was detected from Haemapyhsalis ticks. Our results indicate that a variety of piroplasmas, including piroplasmas that are potentially pathogenic to humans, such as B. microti Otsu/Hobetsu types and protozoa closely related to B. motasi, are distributed in the Gifu City area.

Experimental infection of purebred Saanen goats high pathogenicity and virulence of Babesia aktasi

Small ruminant babesiosis remains a neglected disease despite causing significant economic losses to sheep and goat herds in many regions around the world. The pathogenesis and clinical manifestations of ovine babesiosis are well-known, but there is a lack of information regarding caprine babesiosis. Since the discovery of the first Babesia spp. in 1888, several species/subspecies/genotypes, including Babesia aktasi, have been described. Our recent molecular survey revealed that the parasite is highly prevalent (22.5%) in indigenous goats from Mediterranean region of Türkiye. The aim of this experimental study was to determine the pathogenicity and virulence of B. aktasi in immunosuppressed (n = 5) and immunocompetent (n = 7) purebred Saanen goats. The goats were experimentally infected with fresh B. aktasi infected blood, and examined for clinical, parasitological, hematological, and serum biochemical findings throughout the infection. Following the parasite inoculation, intra-erythrocytic parasites were detected from the 1st day post-infection, followed by an increase in rectal temperature and parasitemia. The parasitemia was detected ranging from 4.3% to 33.5% in the immunosuppressed group, while it was 2.1% to 7.6% in the immunocompetent. Severe clinical symptoms characterized by anemia, jaundice, and hemoglobinuria developed in both groups. A statistically significant inverse correlation was observed between the increase in parasitemia and RBC, WBC, HCT, and Hb values in the goats compared to pre-infection levels. Values of AST, ALT, GGT, Total bilirubin, and Albumin showed a significant increase, with all the immunosuppressed goats dying on the 4th and 7th days post-infection, while four out of seven immunocompetent goats died on between 6-8th days. Severe edema in the lungs, frothy fluid in the trachea, jaundice in the subcutaneous and mesenteric fat, and dark red urine were detected in necropsy. The results obtained in this study demonstrated that B. aktasi was highly pathogenic to purebred Saanen goats. Current work assures valuable insights into the pathogenesis and virulence of B. aktasi and serves as a foundation for future studies to develop effective control strategies against caprine babesiosis.

Development and Evaluation of a Semi-Nested PCR Method Based on the 18S ribosomal RNA Gene for the Detection of Babesia aktasi Infections in Goats

We developed and evaluated a semi-nested PCR assay for the detection of Babesia aktasi infection in goats based on the sequence of the B. aktasi 18S ribosomal RNA gene. Following in silico screening, the specificity of the primers was assessed using reference DNA samples, including B. ovis, B. motasi, B. crassa, B. venatorum, B. divergens, B. capreoli, Theileria ovis, and T. annulata. To determine the sensitivity of the method, blood infected with 2% parasitemia of B. aktasi was diluted to 10-fold serial dilutions. The method specifically amplified a 438 bp fragment of B. aktasi DNA, but did not demonstrate cross-amplification with the other hemoparasites tested. The sensitivity assay indicated that this PCR method was able to detect infection at a dilution of 10-8 of 2% parasitemia (0.074 parasites/200 µL). Ninety-seven blood samples collected from goats were used to analyze for B. aktasi, and the infection was detected in 18.5% of the goats. Additionally, the method was also applied to 44 field DNA samples that were detected to be positive for B. aktasi by reverse line blotting (RLB), and showed 84.1% agreement. The findings revealed that newly developed semi-nested PCR can detect B. aktasi infections in goats with high sensitivity and specificity.

Molecular Detection of Theileria ovis, Anaplasma ovis, and Rickettsia spp. in Rhipicephalus turanicus and Hyalomma anatolicum Collected from Sheep in Southern Xinjiang, China

The Xinjiang Uygur Autonomous Region (Xinjiang) borders eight countries and has a complex geographic environment. There are almost 45.696 million herded sheep in Xinjiang, which occupies 13.80% of China's sheep farming industry. However, there is a scarcity of reports investigating the role of sheep or ticks in Xinjiang in transmitting tick-borne diseases (TBDs). A total of 894 ticks (298 tick pools) were collected from sheep in southern Xinjiang. Out of the 298 tick pools investigated in this study, Rhipicephalus turanicus (Rh. turanicus) and Hyalomma anatolicum (H. anatolicum) were identified through morphological and molecular sequencing. In the southern part of Xinjiang, 142 (47.65%), 86 (28.86%), and 60 (20.13%) tick pools were positive for Rickettsia spp., Theileria spp., and Anaplasma spp., respectively. Interestingly, the infection rate of Rickettsia spp. (73%, 35.10%, and 28.56-41.64%) was higher in Rh. turanicus pools than in H. anatolicum pools (4%, 4.44%, and 0.10-8.79%) in this study. Fifty-one tick pools were found to harbor two pathogens, while nineteen tick pools were detected to have the three pathogens. Our findings indicate the presence of Rickettsia spp., Theileria spp., and Anaplasma spp. potentially transmitted by H. anatolicum and Rh. turanicus in sheep in southern Xinjiang, China.

Sheep Displayed No Clinical and Parasitological Signs upon Experimental Infection with Babesia aktasi

Our survey in the Mediterranean region of Türkiye revealed high prevalence of Babesia aktasi in goats, while no molecular evidence of the parasite was found in sheep grazing in the same pasture. We hypothesized that the parasite may not be infectious to sheep. To test this hypothesis, the present study was designed to evaluate the susceptibility of Akkaraman sheep breed to B. aktasi infection. Fifteen mL of fresh blood infected with B. aktasi was injected into immune-suppressed lambs (n = 5). The recipient lambs were monitored daily for clinical signs of babesiosis over 30 days, and blood was collected for microscopic and molecular diagnostic evaluation. The lambs did not display clinical and parasitological signs of babesiosis. Two out of five recipient lambs were nested PCR-negative for B. aktasi over 30 days post infection. Out of the remaining three lambs, two were PCR positive on the first day, and one recipient was positive until the fourth day post infection. DNA sequencing confirmed that the PCR positivity in the recipient lambs originated from the inoculum. These findings revealed that immune-suppressed sheep do not appear to be susceptible to infection with B. aktasi that is lethal to immune-suppressed indigenous goats.

Incompetence of Vector Capacity of Rhipicephalus bursa to Transmit Babesia aktasi following Feeding on Clinically Infected Goat with High Level of Parasitemia

A recent molecular survey revealed a high prevalence of Babesia aktasi in indigenous goats from the Mediterranean region of Türkiye, coinciding with heavy Rhipicephalus bursa infestations. This geographical overlap has raised the possibility that R. bursa may serve as a vector for the parasite. To evaluate the potential of R. bursa to serve as a vector for the parasite, an experimental study was conducted in indigenous goats. An immune-suppressed donor goat was intravenously injected with 15 mL of the cryopreserved B. aktasi stabilate, resulting in severe clinical babesiosis and parasitemia. Subsequently, R. bursa larvae and adults derived from Babesia-free laboratory colonies were allowed to feed on the infected donor goat. After oviposition, engorged female carcasses, representative engorged nymphs, unfed larvae, and adult pools were used for DNA extraction and PCR analysis. No PCR positivity was detected in any of the DNA samples, except for those with engorged female carcasses and nymphs. Three immune-suppressed recipient goats were infested with the unfed immature and mature ticks consuming the blood of a donor infected with B. aktasi. No clinical or parasitological findings were encountered in the recipient for 40 days post-infestation. These findings indicated that R. bursa was not a competent vector for B. aktasi.

Epidemiological and Molecular Characteristics of Piroplasmids and Anaplasma spp. in Tan Sheep, Ningxia, Northwest China

Piroplasmosis and anaplasmosis are important zoonotic diseases of animal origin, which can be transmitted by ticks to infect animals. However, there is limited information on the infection of piroplasmosis and anaplasmosis in Tan sheep in Ningxia, China. In order to understand the prevalence of piroplasmosis and anaplasmosis in Tan sheep in Ningxia, 150 blood samples of Tan sheep from farms in five urban areas of Ningxia were detected by PCR, and some positive samples were sequenced to establish a phylogenetic tree. PCR revealed that the prevalence of Anaplasma spp. in Tan sheep in Ningxia was 28.0%. The overall prevalence of Piroplasmids was 33.3%, of which Theileria spp. and Babesia spp. were 20.7% and 12.7%, respectively. Among the samples of different ages, the highest detection rates of Piroplasmids and Anaplasma spp. were found in Tan sheep aged 20-30 months, and the detection rate of Theileria spp., Babesia spp., and Anaplasma spp. were 25.4%, 23.6%, and 36.3%, respectively. In this study, one Theileria species was identified as Theileria uilenbergi, two Babesia species were identified as Babesia molasi and Babesia ovis, and two Anaplasma species were identified as Anaplasma ovis and Anaplasma phagocytophilum, and the dominant species were A. ovis and T. uilenbergi. To the best of our knowledge, this is the first report detailing the infection rate and genotype of Piroplasmids and Anaplasma spp. in Tan sheep in Ningxia, China. The results of this study provide valuable data for understanding the epidemiology of tick-borne disease in Tan sheep in Ningxia, China, and lay a theoretical foundation for the prevention and control of piroplasmosis and anaplasmosis in Tan sheep in Ningxia, northwest China.

First record of Babesia and Theileria parasites in ticks from Kassena-Nankana, Ghana

Ticks are efficient vectors for transmitting pathogens that negatively affect livestock production and pose a risk to public health. In this study, Babesia and Theileria species were identified in ticks collected from cattle, sheep and goats from the Kassena-Nankana Districts of Ghana between February and December 2020. A total of 1550 ticks were collected, morphologically identified, pooled and screened for pathogens using primers that amplify a 560 bp fragment of the ssrRNA gene and Sanger sequencing. Amblyomma variegatum (62.98%) was the predominant tick species. From the 491 tick pools screened, 12/15 (2.44%) positive pools were successfully sequenced. The pathogen DNA identified were Theileria ovis in eight (15.38%) pools of Rhipicephalus evertsi evertsi, Theileria velifera in two (0.78%) pools of A. variegatum and Babesia occultans and Babesia sp. Xinjiang in one (1.72%) pool each of Hyalomma truncatum. It was further observed that T. ovis occurred in ticks collected from only sheep (p < 0.001) which were females (p = 0.023) and < =1 year old (p = 0.040). This study reports the first identification of these pathogens in ticks within Kassena-Nankana. With the constant trade of livestock, there is a need for effective tick control measures to prevent infection spread.

Experimental infection of non-immunosuppressed and immunosuppressed goats reveals differential pathogenesis of Babesia aktasi n. sp

Babesiosis is an acute and persistent tick-borne disease caused by protozoan parasites of the genus Babesia. These hemoparasites affect vertebrates globally, resulting in symptoms such as high fever, anemia, jaundice, and even death. Advancements in molecular parasitology revealed new Babesia species/genotypes affecting sheep and goats, including Babesia aktasi n. sp., which is highly prevalent in goats from Turkiye's Mediterranean region. The objective of this study was to investigate the pathogenesis of B. aktasi infection in immunosuppressed (n=7) and non-immunosuppressed (n=6) goats. These animals were experimentally infected with fresh B. aktasi infected blood, and their clinical signs, hematological and serum biochemical parameters were monitored throughout the infection. The presence of parasites in the blood of immunosuppressed goats was detected by microscopic examination between 4 and 6 days after infection, accompanied by fever and increasing parasitemia. Goats that succumbed acute disease exhibited severe clinical signs, such as anemia, hemoglobinuria, and loss of appetite. However, the goats that survived showed milder clinical signs. In the non-immunosuppressed group, piroplasm forms of B. aktasi were observed in the blood within 2-5 days after inoculation, but with low (0.01-0.2%) parasitemia. Although these goats showed loss of appetite, typical signs of babesiosis were absent except for increased body temperature. Hematological analysis revealed significant decreases in the levels of red blood cells, leukocytes and platelet values post-infection in immunosuppressed goats, while no significant hematological changes were observed in non-immunosuppressed goats. In addition, serum biochemical analysis showed elevated transaminase liver enzymes levels, decreased glucose, and lower total protein values in the immunosuppressed group post-infection. Babesia aktasi, caused mild disease with minor clinical symptoms in non-immunosuppressed goats. However, in immunosuppressed goats, it exhibited remarkable pathogenicity, leading to severe clinical infections and death. In conclusion, this study provides valuable insights into the pathogenicity of the parasite and will serve as a foundation for future research aimed at developing effective prevention and control strategies against babesiosis in small ruminants. Further research is required to investigate the pathogenicity of B. aktasi in various goat breeds, other potential hosts, the vector ticks involved, and its presence in natural reservoirs.

Molecular Identification of Piroplasmids in Ticks from Infested Small Ruminants in Konya Province, Turkey

Ticks play a pivotal role in propagating a diverse spectrum of infectious agents that detrimentally affect the health of both humans and animals. In the present study, a molecular survey was executed of piroplasmids in ticks collected from small ruminants in four districts within Konya province, Turkey. Microscopic examination identified 1281 adult ticks, which were categorized into 357 pools based on their species, sexes, host animals, and collection site before DNA extraction. The infection rates were calculated by using a maximum likelihood estimate (MLE) with 95% confidence intervals (CI). Hyalomma detritum, H. excavatum, Rhipicephalus bursa, R. sanguineus, and R. turanicus were identified in this study. Among the five tick species identified here, R. turanicus exhibited the highest infestation rate in both goats and sheep. The presence of Babesia ovis and Theileria ovis based on 18S rRNA was confirmed using molecular assay. The overall MLE of infection rates for B. ovis and T. ovis was 2.49% (CI 1.72-3.46) and 1.46% (CI 0.87-2.23), respectively. The MLE of B. ovis and T. ovis infection rates in R. bursa was 10.80% (CI 7.43-14.90) and 0.33% (CI 0.02-1.42), respectively, while that in R. turanicus was 0.12% (CI 0.01-0.51) and 2.08% (CI 1.25-3.22). This study further confirms that R. turanicus and R. sanguineus can act as vectors for B. ovis, thus advancing our comprehension of tick-borne piroplasmids epidemiology and providing valuable insights for the development of effective control strategies for ticks and tick-borne diseases in Turkey.

Molecular detection of Babesia and Theileria species/genotypes in sheep and ixodid ticks in Erzurum, Northeastern Turkey: First report of Babesia canis in sheep

Piroplasmosis is a tick-borne protozoan disease caused by Babesia and Theileria species in ruminants. This study sought to determine the presence and prevalence of the agents causing piroplasmosis among sheep in Erzurum province, Turkey. It also sought to identify the tick species infesting the sheep and investigate the possible role of the ticks in the transmission of piroplasmosis. A total of 1621 blood samples and 1696 ixodid ticks from infested sheep were collected. Each blood sample and 115 tick pools were subjected to PCR assay. A total of 307 blood samples were found to be positive for Babesia spp. and Theileria spp. according to molecular analysis. The sequence analysis was revealed the presence of B. ovis (0.4%), B. crassa (0.4%), B. canis (0.4%), T. ovis (69.3%), Theileria sp. (26.6%), and Theileria sp. OT3 (2.9%) in 244 samples. The collected ticks were identified as D. marginatus (62.5%), Hae. parva (36.2%), Hae. punctata (1.1%), Rh. turanicus (0.1%), and H. marginatum (0.1%). The molecular analysis of the adult tick samples revealed T. ovis and T. annulata positivity in the D. marginatus pools, B. crassa and T. ovis positivity in the Hae. parva pools, and T. ovis positivity in the Hae. punctata pools. These results provide up-to-date data concerning tick-borne protozoan diseases of sheep and tick species infesting sheep in the region. The sheep breeding industry is an important livelihood for the region so it is essential to perform repeated studies on these pathogens in order to prevent disruptions to animal husbandry.

Small Ruminant Piroplasmosis: High Prevalence of Babesia aktasi n. sp. in Goats in Türkiye

Small ruminant piroplasmosis is the hemoparasitic infection of sheep and goats caused by Babesia and Theileria species responsible for clinical infections with high mortality outcomes. The disease is transmitted by ixodid ticks and prevalent in the tropical and subtropical regions of the world, including Türkiye. A prevalence survey, using molecular methods, is conducted in this study to determine the frequency of newly defined Babesia aktasi n. sp. and other tick-borne piroplasm species in small ruminants in Turkiye. A total of 640 blood samples from sheep (n = 137) and goats (n = 503) were analyzed by nested PCR-based reverse line blot (RLB) hybridization. The results show that 32.3% (207/640) of apparently healthy, small ruminants are infected with three Theileria and two Babesia species. Babesia aktasi n. sp. was the most prevalent species in goats, with 22.5% of samples being positive, followed by B. ovis (4%), T. ovis (2.8%), T. annulata (2.6%), and Theileria sp. (0.6%). None of the sheep samples were positive for Babesia aktasi n. sp.; however, 51.8% were infected with T. ovis. In conclusion, the findings reveal that B. aktasi n. sp. is highly prevalent in goats, but absent in sheep. In future studies, experimental infections will determine whether B. aktasi n. sp. is infectious to sheep, as well as its pathogenicity in small ruminants.

Comparative genomics reveals unique features of two Babesia motasi subspecies: Babesia motasi lintanensis and Babesia motasi hebeiensis

Parasites of the Babesia genus are prevalent worldwide and infect a wide diversity of domestic animals and humans. Herein, using Oxford Nanopore Technology and Illumina sequencing technologies, we sequenced two Babesia sub-species, Babesia motasi lintanensis and Babesia motasi hebeiensis. We identified 3,815 one-to-one ortholog genes that are specific to ovine Babesia spp. Phylogenetic analysis reveals that the two B. motasi subspecies form a distinct clade from other Piroplasma spp. Consistent with their phylogenetic position, comparative genomic analysis reveals that these two ovine Babesia spp. share higher colinearity with Babesia bovis than with Babesia microti. Concerning the speciation date, B. m. lintanensis split from B. m. hebeiensis approximately 17 million years ago. Genes correlated to transcription, translation, protein modification and degradation, as well as differential/specialized gene family expansions in these two subspecies may favor adaptation to vertebrate and tick hosts. The close relationship between B. m. lintanensis and B. m. hebeiensis is underlined by a high degree of genomic synteny. Compositions of most invasion, virulence, development, and gene transcript regulation-related multigene families, including spherical body protein, variant erythrocyte surface antigen, glycosylphosphatidylinositol anchored proteins, and transcription factor Apetala 2 genes, is largely conserved, but in contrast to this conserved situation, we observe major differences in species-specific genes that may be involved in multiple functions in parasite biology. For the first time in Babesia spp., we find abundant fragments of long terminal repeat-retrotransposons in these two species. We provide fundamental information to characterize the genomes of B. m. lintanensis and B. m. hebeiensis, providing insights into the evolution of B. motasi group parasites.

First molecular identification of multiple tick-borne pathogens in livestock within Kassena-Nankana, Ghana

The risk of pathogen transmission continues to increase significantly in the presence of tick vectors due to the trade of livestock across countries. In Ghana, there is a lack of data on the incidence of tick-borne pathogens that are of zoonotic and veterinary importance. This study, therefore, aimed to determine the prevalence of such pathogens in livestock using molecular approaches. A total of 276 dry blood spots were collected from cattle (100), sheep (95) and goats (81) in the Kassena-Nankana Districts. The samples were analyzed using Polymerase Chain Reaction (qPCR) and conventional assays and Sanger sequencing that targeted pathogens including Rickettsia, Coxiella, Babesia, Theileria, Ehrlichia and Anaplasma. An overall prevalence of 36.96% was recorded from the livestock DBS, with mixed infections seen in 7.97% samples. Furthermore, the prevalence of infections in livestock was recorded to be 19.21% in sheep, 14.13% in cattle, and 3.62% in goats. The pathogens identified were Rickettsia spp. (3.26%), Babesia sp. Lintan (8.70%), Theileria orientalis (2.17%), Theileria parva (0.36%), Anaplasma capra (18.48%), Anaplasma phagocytophilum (1.81%), Anaplasma marginale (3.26%) and Anaplasma ovis (7.25%). This study reports the first molecular identification of the above-mentioned pathogens in livestock in Ghana and highlights the use of dry blood spots in resource-limited settings. In addition, this research provides an update on tick-borne pathogens in Ghana, suggesting risks to livestock production and human health. Further studies will be essential to establish the distribution and epidemiology of these pathogens in Ghana.

Prevalence and phylogenetic analysis of Babesia parasites in reservoir host species in Fujian province, Southeast China

Babesiosis is a tick-borne disease that mainly affects small mammals and has been reported in at least five provinces in China. However, the host range and geographical distribution of the parasite in Fujian province are unclear. Therefore, we investigated the prevalence and genetic characteristics of Babesia in Fujian province, Southeast China, between 2015 and 2020. Rodent blood samples were collected from 26 different surveillance sites across Fujian province. Genomic DNA was extracted to screen for Babesia infection using polymerase chain reaction based on 18S rRNA. DNA samples from 316 domestic goats, 85 water buffalo, 56 domestic dogs and 18 domestic pigs were examined. The prevalence of Babesia was statistically analysed using the Chi-square test or Fisher's exact test. Babesia infections were detected in 3.96% (43/1,087; 95%CI: 2.80%, 5.12%) of rodents and 1.26% (6/475; 95%CI: 0.26%, 2.26%) of other mammals. Multivariate logistic regression analysis revealed that irrigated cropland, shrubs and forests were risk factors for Babesia microti infections. The infection rates among domestic pigs, dogs and goats were 5.56%, 1.79% and 1.27%, respectively, with no infection found in water buffalo. The 18S rRNA gene sequencing revealed that rodents were infected with Babesia (sensu lato), whereas other mammals were infected with Babesia (sensu stricto). The geographical distribution and phylogenetic relationship of Babesia was determined in Southeast China. Mammals, particularly wild rodents, maybe the main natural hosts of Babesia in Fujian. Our findings provide a foundation for public health officials to develop prevention and control measures for Babesia.

Anaemia in Sheep Caused by Babesia and Theileria Haemoparasites

Piroplasmoses in sheep are caused by vector-borne apicomplexan protozoa, Babesia and Theileria. Different species are responsible for the disease; some species are more pathogenic than others and have a worldwide distribution. In this sense, these causative agents can cause anaemia in flocks. In general, these vector-borne diseases infect small ruminants and cause host-mediated pathology. In the case of Babesia species, a combination of different mechanisms is involved: red blood cell lysis due to intracellular parasite multiplication, activation of biogenic amines and the coagulation system with the possibility of disseminated intravascular coagulation. By contrast, less information is available on the different immunopathogenic mechanisms involved in the development of anaemia in sheep with theileriosis. However, the mechanisms of pathogenic action in theileriosis are similar to those studied in babesiosis. Diagnosis is based on compatible clinical signs, laboratory findings, specific diagnostic tests and the presence of the tick vector. Some of these tests detect the causative agent itself, such as direct identification by light microscopy and molecular analysis. In contrast, other tests detect the sheep's immune response to the organism by serology. Both diseases pose a significant diagnostic challenge for veterinary practitioners around the world. This review presents the most frequent clinical signs, pathogenesis and clinicopathological findings, diagnosis.

First Molecular Identification of Babesia, Theileria, and Anaplasma in Goats from the Philippines

Goats are key livestock animals and goat raising is an income-generating venture for smallholder farmers, supporting agricultural development in many parts of the world. However, goat production is often limited by various factors, such as tick-borne diseases. Goat piroplasmosis is a disease caused by apicomplexan parasites Babesia spp. and Theileria spp., while anaplasmosis is caused by bacterial Anaplasma spp. In the Philippines, the presence of Babesia, Theileria, and Anaplasma has not been reported in goats. In this study, DNA obtained from goats were molecularly screened for Babesia/Theileria and Anaplasma. Of 396, 77.02% (305/396) and 38.64% (153/396) were positive for piroplasma and Anaplasma using PCR assays targeting the 18S rRNA and 16S rRNA genes, respectively. Similarly, Babesia ovis was detected in six samples (1.52%). Representative Babesia/Theileria sequences shared 89.97–97.74% identity with each other and were most closely related to T. orientalis, T. annulata, and Theileria spp. Meanwhile, Anaplasma 16SrRNA sequences were related to A. odocoilei, A. platys, and A. phagocytophilum. This is the first molecular identification of B. ovis, Theileria spp., and Anaplasma spp. in goats from the Philippines.

Babesiosis as a potential threat for bovine production in China

Babesiosis is a tick-borne disease with global impact caused by parasites of the phylum Apicomplexa, genus Babesia. Typically, acute bovine babesiosis (BB) is characterized by fever, anemia, hemoglobinuria, and high mortality. Surviving animals remain persistently infected and become reservoirs for parasite transmission. Bovids in China can be infected by one or more Babesia species endemic to the country, including B. bovis, B. bigemina, B. orientalis, B. ovata, B. major, B. motasi, B. U sp. Kashi and B. venatorum. The latter may pose a zoonotic risk. Occurrence of this wide diversity of Babesia species in China may be due to a combination of favorable ecological factors, such as the presence of multiple tick vectors, including Rhipicephalus and Hyalomma, the coexistence of susceptible bovid species, such as domestic cattle, yaks, and water buffalo, and the lack of efficient measures of tick control. BB is currently widespread in several regions of the country and a limiting factor for cattle production. While some areas appear to have enzootic stability, others have considerable cattle mortality. Research is needed to devise solutions to the challenges posed by uncontrolled BB. Critical research gaps include risk assessment for cattle residing in endemic areas, understanding factors involved in endemic stability, evaluation of parasite diversity and pathogenicity of regional Babesia species, and estimation of whether and how BB should be controlled in China. Research should allow the design of comprehensive interventions to improve cattle production, diminish the risk of human infections, and increase the availability of affordable animal protein for human consumption in China and worldwide. In this review, we describe the current state of BB with reference to the diversity of hosts, vectors, and parasite species in China. We also discuss the unique risks and knowledge gaps that should be taken into consideration for future Babesia research and control strategies.

Primary Tick-Borne Protozoan and Rickettsial Infections of Animals in Turkey

Parasitic diseases caused by ticks constitute a barrier on global animal production, mainly in tropical and subtropical regions. As a country with a temperate and subtropical climate, Turkey has topography, climate, and pasture resources, and these resources are suitable for animal breeding and parasite–host–vector relationships throughout the country. This geography restricts the regulations on animal movements in the southeastern and eastern Anatolia because of the close contact with the neighboring states. The livestock resources in Turkey are regulated by strong foundations. Almost 30% of the agriculture-based gross domestic product is provided by the livestock industry. Parasitic diseases arising from ticks are endemic in Turkey, and they have a significant impact on the economy and animal health, particularly for ruminants. The main and economically-important tick-borne diseases (TBDs) suffered by animals include theileriosis, babesiosis, hepatozoonosis, and cytauxzoonosis caused by protozoa, and anaplasmosis and ehrlichiosis caused by rickettsiae. The most common hemoprotozoan and rickettsial agents are Anaplasma marginale, Anaplasma ovis, Anaplasma phagocytophilum, Anaplasma platys, Babesia bigemina, Babesia caballi, Babesia ovis, Cytauxzoon felis, Ehrlichia canis, Hepatozoon canis, Theileria annulata and Theileria equi. These diseases are basically controlled through treatment and measures for tick control. Vaccination can be performed for only tropical theileriosis caused in Turkey. We reviewed the studies published in domestic and international journals to gather epidemiological data regarding the major TBDs suffered by animals in Turkey.

Tick-Borne Hemoparasites of Sheep: A Molecular Research in Turkey

Tick-borne diseases (TBDs) indulge in severe economic losses in the livestock industry by adversely affecting the small ruminant breeding in tropical and subtropical zone countries, including Turkey. Turkey encompasses a wide land area representing diverse climatic conditions. The present study explored the presence and distribution of Babesia ovis, Theileria ovis, Theileria lestoquardi, Anaplasma ovis, Anaplasma phagocytophilum and the co-occurrence status of these pathogens. A total of 299 sheep blood samples were collected from fifteen provinces located in six different geographical regions in Turkey. PCR analyses were executed using species-specific primers based on Babesia ovis BoSSU rRNA, Theileria ovis ToSSU rRNA, Theileria lestoquardi 18S rRNA, Anaplasma ovis Major Surface Protein (AoMSP4), and Anaplasma phagocytophilum 16S rRNA genes. Overall, 219 (73.24%) sheep were found to be infected with at least one of the following protozoan and rickettsial pathogens; B. ovis, A. ovis,T. ovis, and A. phagocytophilum. Theileria lestoquardi was not detected in any blood sample. The global prevalence of B. ovis, A. ovis, T. ovis, and A. phagocytophilum was estimated to be 2.68%, 16.05%, 41.47%, and 57.19%, respectively. Besides this, dual (24.41%), triple (9.03%), and quadruple (0.67%) co-infections were detected in the study. Phylogenetic analysis revealed significant nucleotide sequence identities between the sequences obtained in this study and the sequences registered in the GenBank. This study provides relevant data regarding the predominance of ovine tick-borne protozoan and rickettsial agents in Turkey. A high molecular prevalence of tick-borne pathogens (TBPs) was identified in the study. This situation indicates that TBPs should be screened continuously, and necessary control measures should be taken to prevent diseases caused by tick-borne protozoan and rickettsial agents.

Protein regulation strategies of the mouse spleen in response to Babesia microti infection

BACKGROUND

Babesia is a protozoan parasite that infects red blood cells in some vertebrates. Some species of Babesia can induce zoonoses and cause considerable harm. As the largest immune organ in mammals, the spleen plays an important role in defending against Babesia infection. When infected with Babesia, the spleen is seriously injured but still actively initiates immunomodulatory responses.

METHODS

To explore the molecular mechanisms underlying the immune regulation and self-repair of the spleen in response to infection, this study used data-independent acquisition (DIA) quantitative proteomics to analyse changes in expression levels of global proteins and in phosphorylation modification in spleen tissue after Babesia microti infection in mice.

RESULTS

After mice were infected with B. microti, their spleens were seriously damaged. Using bioinformatics methods to analyse dynamic changes in a large number of proteins, we found that the spleen still initiated immune responses to combat the infection, with immune-related proteins playing an important role, including cathepsin D (CTSD), interferon-induced protein 44 (IFI44), interleukin-2 enhancer-binding factor 2 (ILF2), interleukin enhancer-binding factor 3 (ILF3) and signal transducer and activator of transcription 5A (STAT5A). In addition, some proteins related to iron metabolism were also involved in the repair of the spleen after B. microti infection, including serotransferrin, lactoferrin, transferrin receptor protein 1 (TfR1) and glutamate-cysteine ligase (GCL). At the same time, the expression and phosphorylation of proteins related to the growth and development of the spleen also changed, including protein kinase C-δ (PKC-δ), mitogen-activated protein kinase (MAPK) 3/1, growth factor receptor-bound protein 2 (Grb2) and P21-activated kinase 2 (PAK2).

CONCLUSIONS

Immune-related proteins, iron metabolism-related proteins and growth and development-related proteins play an important role in the regulation of spleen injury and maintenance of homeostasis. This study provides an important basis for the diagnosis and treatment of babesiosis.

Molecular identification and genetic characterization of tick-borne pathogens in sheep and goats at two farms in the central and southern regions of Malawi

Tick-borne diseases (TBDs) caused by pathogens belonging to the genera Anaplasma, Ehrlichia, Babesia and Theileria in small ruminants are widespread in the tropical and sub-tropical countries. The epidemiology of tick-borne pathogens (TBPs) in small ruminants is less understood compared to those infecting cattle in general. This study was carried out to investigate and characterize TBPs in sheep and goats using molecular tools. A total of 107 blood samples from sheep (n = 8) and goats (n = 99) were collected from animals that were apparently healthy from two farms in the central and the southern regions of Malawi. The V4 hypervariable region of the 18S ribosomal RNA gene (rDNA) and the V1 hypervariable region of the 16S rDNA polymerase chain reaction (PCR) assays were used for detection of tick-borne piroplasms and Anaplasmataceae, respectively. Almost the full-length 18S rDNA and the heat shock protein (groEL) gene sequences were used for genetic characterization of the piroplasms and Anaplasmataceae, respectively. The results showed that 76.6 % of the examined animals (n = 107) were positive for at least one TBP. The overall co-infection with at least two TBPs was observed in forty-eight animals (45 %). The detected TBPs were Anaplasma ovis (65 %), Ehrlichia ruminantium (4%), Ehrlichia canis (2%), Babesia strain closely related to Babesia gibsoni (1%), Theileria ovis (52 %), Theileria mutans (3%), Theileria separata (2%), Anaplasma sp. (1%) and Theileria sp. strain MSD-like (17 %). To the authors knowledge this is the first molecular study of TBPs in sheep and goats in Malawi. These results have therefore provided a significant milestone in the knowledge of occurrence of TBPs in sheep and goats in Malawi, which is prerequisite to proper diagnosis and control.

Quantitative proteomics and phosphoproteomic analyses of mouse livers after tick-borne Babesia microti infection

Babesia microti is a tick-borne protozoan parasite that infects the red blood cells of mice, humans, and other mammals. The liver tissues of BALB/c mice infected with B. microti exhibit severe injury. To further investigate the molecular mechanisms underlying liver injury and liver self-repair after B. microti infection, data-independent acquisition (DIA) quantitative proteomics was used to analyse changes in the expression and phosphorylation of proteins in liver tissues of BALB/c mice during a B. microti infection period and a recovery period. The expression of FABP1 and ACBP, which are related to fatty acid transport in the liver, was downregulated after infection with B. microti, as was the expression of Acox1, Ehhadh and Acaa1a, which are crucial rate-limiting enzymes in the process of fatty acid β oxidation. The phosphorylation levels of AMP-activated protein kinase (AMPK) and Hormone-sensitive lipase (HSL) were also downregulated. In addition, the expression of PSMB9, CTSC, and other immune-related proteins was increased, reflecting an active immune regulation mechanism in the mice. The weights of mice infected with B. microti were significantly reduced, and the phosphorylation levels of IRS-1, c-Raf, mTOR, and other proteins related to growth and development were downregulated.

Genetic Diversity and Coexistence of Babesia in Ticks (Acari: Ixodidae) from Northeastern China

Background: Human babesiosis is an emerging zoonotic disease transmitted by ticks in China. A few systematic reports on Babesia spp. was involved with ticks, especially in the human babesiosis endemic areas in Northeastern China. Materials and Methods: Ticks were collected from 30 individual waypoints along 2.0 km transects in two recreational forests. Babesia spp. infection in ticks was screened by amplifying the partial 18s rRNA gene with subsequent sequencing. Multivariate logistic regression analysis was used to determine the association between tick infection and related environmental risk factors. Cluster analyses were performed using SaTScan v6.0 software to identify any geographical cluster of infected ticks. Results: A total of 2380 Ixodes persulcatus and 461 Haemaphysalis concinna ticks were collected. Of the 0.97% of I. persulcatus ticks that tested positive, five Babesia species were identified, including B. bigemina (n = 6), B. divergens (n = 2), B. microti (n = 3), B. venatorum (n = 11), and one novel strain HLJ-8. Thirteen (2.92%) H. concinna ticks tested positive for B. bigemina (n = 1), B. divergens (n = 1), three genetic variants of Babesia represented by HLJ-874, which was closely related to Babesia sp.MA#361-1, and eight other Babesia variants represented by HLJ242, which were similar to B. crassa. Each study site had 5-6 different Babesia spp. One waypoint was more likely to yield B. venatorum (relative risk = 15.36, p = 0.045) than all other waypoints. Conclusions: There exists a high genetic diversity of Babesia spp. across a relatively small sampled region. Further study is needed to understand the risks these variants pose to human health.

Rapid detection of Babesia motasi responsible for human babesiosis by cross-priming amplification combined with a vertical flow

Background

Babesia motasi is known as an etiological agent of human and ovine babesiosis. Diagnosis of babesiosis is traditionally performed by microscopy, examining Giemsa-stained thin peripheral blood smears. Rapid detection and accurate identification of species are desirable for clinical care and epidemiological studies.

Methods

An easy to operate molecular method, which requires less capital equipment and incorporates cross-priming amplification combined with a vertical flow (CPA-VF) visualization strip for rapid detection and identification of B. motasi.

Results

The CPA-VF targets the 18S rRNA gene and has a detection limit of 50 fg per reaction; no cross reaction was observed with other piroplasms infective to sheep or Babesia infective to humans. CPA-VF and real-time (RT)-PCR had sensitivities of 95.2% (95% confidence interval, CI 78.1–99.4%) and 90.5% (95% CI 72–97.6%) and specificities of 95.8 (95% CI 80.5–99.5%) and 97.9 (95% CI 83.5–99.9%), respectively, versus microscopy and nested (n) PCR combined with gene sequencing. The clinical performance of the CPA-VF assay was evaluated with field blood samples from sheep (n = 340) in Jintai county, Gansu Province, and clinical specimens (n = 492) obtained from patients bitten by ticks.

Conclusions

Our results indicate that the CPA-VF is a rapid, accurate, nearly instrument-free molecular diagnostic approach for identification of B. motasi. Therefore, it could be an alternative technique for epidemiological investigations and diagnoses of ovine and/or human babesiosis caused by B. motasi, especially in resource-limited regions.

Insights into the phylogenetic relationships and drug targets of Babesia isolates infective to small ruminants from the mitochondrial genomes

Background

Babesiosis, a tick-borne disease caused by protozoans of the genus Babesia, is widespread in subtropical and tropical countries. Mitochondria are essential organelles that are responsible for energy transduction and metabolism, calcium homeostasis and cell signaling. Mitochondrial genomes could provide new insights to help elucidate and investigate the biological features, genetic evolution and classification of the protozoans. Nevertheless, there are limited data on the mitochondrial genomes of ovine Babesia spp. in China.

Methods

Herein, we sequenced, assembled and annotated the mitochondrial genomes of six ovine Babesia isolates; analyzed the genome size, gene content, genome structure and cytochrome b (cytb) amino acid sequences and performed comparative mitochondrial genomics and phylogenomic analyses among apicomplexan parasites.

Results

The mitochondrial genomes range from 5767 to 5946 bp in length with a linear form and contain three protein-encoding genes, cytochrome c oxidase subunit 1 (cox1), cytochrome c oxidase subunit 3 (cox3) and cytb, six large subunit rRNA genes (LSU) and two terminal inverted repeats (TIR) on both ends. The cytb gene sequence analysis indicated the binding site of anti-Babesia drugs that targeted the cytochrome bc1 complex. Babesia microti and Babesia rodhaini have a dual flip-flop inversion of 184–1082 bp, whereas other Babesia spp. and Theileria spp. have one pair of TIRs, 25–1563 bp. Phylogenetic analysis indicated that the six ovine Babesia isolates were divided into two clades, Babesia sp. and Babesia motasi. Babesia motasi isolates were further separated into two small clades (B. motasi Hebei/Ningxian and B. motasi Tianzhu/Lintan).

Conclusions

The data provided new insights into the taxonomic relationships and drug targets of apicomplexan parasites.

Detection and characterization of an emerging type of Babesia sp. similar to Babesia motasi for the first case of human babesiosis and ticks in Korea

Babesiosis is a tick-transmitted intraerythrocytic zoonosis. In Korea, the first mortalities were reported in 2005 due to Babesia sp. detection in sheep; herein we report epidemiological and genetic characteristics of a second case of babesiosis. Microscopic analysis of patient blood revealed polymorphic merozoites. To detect Babesia spp., PCR was performed using Babesia specific primers for β-tubulin, 18S rDNA, COB, and COX3 gene fragments. 18S rDNA analysis for Babesia sp., showed 98% homology with ovine Babesia sp. and with Babesia infections in Korea in 2005. Moreover, phylogenetic analysis of 18S rDNA, COB, and COX3 revealed close associations with B. motasi. For identifying the infectious agent, Haemaphysalis longicornis (296) and Haemaphysalis flava (301) were collected around the previous residence of the babesiosis patient. Babesia genes were identified in three H. longicornis: one sample was identified as B. microti and two samples were 98% homologous to B. motasi. Our study is the first direct confirmation of the infectious agent for human babesiosis. This case most likely resulted from tick bites from ticks near the patient house of the babesiosis patient. H. longicornis has been implicated as a vector of B. microti and other Babesia sp. infections.

A molecular survey of Anaplasma, Ehrlichia, Bartonella and Theileria in ticks collected from southeastern China

To investigate the prevalence of Anaplasma, Ehrlichia, Bartonella and Theileria, we collected ticks from small mammals in six counties of Zhejiang Province in southeastern China. Polymerase chain reaction (PCR) amplification was performed to test Anaplasma, Ehrlichia, Bartonella and Theileria in tick samples. Positive PCR products were sequenced and then compared with previously published sequences deposited in GenBank using BLAST. About 292 adult ticks were captured and the dominant tick species were Ixodes sinensis and Haemaphysalis longicornis. Overall, 34 ticks (11.6%) were tested positive for at least one pathogen of Anaplasma, Ehrlichia, Bartonella and Theileria. Rates of PCR-positivity to Anaplasma, Ehrlichia, Bartonella and Theileria were 5.5, 1.7, 2.4 and 2.4%, respectively. Positive rates of Anaplasma, Bartonella and Theileria were significantly different among ticks of different species. Prevalence of Anaplasma and Theileria varied significantly among ticks of different counties. Anaplasma, Ehrlichia, Bartonella and Theileria were widely prevalent in ticks in Zhejiang Province suggesting other tick-borne pathogens should also be suspected if patients had history of tick bites.

Comparative analysis of apicoplast genomes of Babesia infective to small ruminants in China

Background

Babesiosis is an economically important disease caused by tick-borne apicomplexan protists of the genus Babesia. Most apicomplexan parasites, including Babesia, have a plastid-derived organelle termed an apicoplast, which is involved in critical metabolic pathways such as fatty acid, iron-sulphur, haem and isoprenoid biosynthesis. Apicoplast genomic data can provide significant information for understanding and exploring the biological features, taxonomic and evolutionary relationships of apicomplexan parasites, and identify targets for anti-parasitic drugs. However, there are limited data on the apicoplast genomes of Babesia species infective to small ruminants.

Methods

PCR primers were designed based on the previously reported apicoplast genome sequences of Babesia motasi Lintan and Babesia sp. Xinjiang using Illumina technology. The overlapped apicoplast genomic fragments of six ovine Babesia isolates were amplified and sequenced using the Sanger dideoxy chain-termination method. The full-length sequences of the apicoplast genomes were assembled and annotated using bioinformatics software. The gene contents and order of apicoplast genomes obtained in this study were defined and compared with those of other apicomplexan parasites. Phylogenetic trees were constructed on the concatenated amino acid sequences of 13 gene products using MEGA v.6.06.

Results

The results showed that the six ovine Babesia apicoplast genomes consisted of circular DNA. The genome sizes were 29,916–30,846 bp with 78.7–81.0% A + T content, 29–31 open reading frames (ORF) and 23–24 transport RNAs. The ORFs encoded four DNA-directed RNA polymerase subunits (rpoB, rpoCl, rpoC2a and rpoC2b), 13 ribosomal proteins, one elongation factor TU (tufA), two ATP-dependent Clp proteases (ClpC) and 7–11 hypothetical proteins. Babesia sp. has three more genes than Babesia motasi (rpl5, rps8 and rpoB). Phylogenetic analysis showed that Babesia sp. is located in a separate clade. Babesia motasi Lintan/Tianzhu and B. motasi Ningxian/Hebei were divided into two subclades.

Conclusions

To our knowledge, this study is the first to elucidate the whole apicoplast genomic structural features of six Babesia isolates infective to small ruminants in China using Sanger sequencing. The data provide useful information confirming the taxonomic relationships of these parasites and identifying targets for anti-apicomplexan parasite drugs.

Electronic supplementary material

The online version of this article (10.1186/s13071-019-3581-x) contains supplementary material, which is available to authorized users.

First molecular evidence of Babesia occultans and Theileria separata infection in ticks and sheep in China

Protozoan parasites of the genus Babesia and Theileria are significant tick-borne pathogens of domestic animals and cause economic losses to the livestock industry in tropical and subtropical regions worldwide. In this study, 274 blood samples and 32 tick samples were collected from four counties of Wuwei City in northwestern China in June and July in 2018. The DNA from the field samples was analyzed for Babesia or Theileria infection using specific PCR and sequencing based on 18S rRNA gene fragments. The total infection rates were 0.4% for B. motasi and T. separata (both 1/274) in sheep, 3.1% for T. annulata (1/32), 6.2% for B. occultans (2/32) and 9.4% for B. bigemina (3/32) in ticks, respectively. In particular, T. separata has been for the first time detected in sheep in China and B. occultans in Hyalomma asiaticum from Gansu Province of China.

Detection of Babesia spp., Theileria spp. and Anaplasma ovis in Border Regions, northwestern China

Babesia spp., Theileria spp. and Anaplasma ovis are important intracellular agents that are transmitted by tick bites. However, Babesia spp., Theileria spp. and A. ovis in ticks have not been systematically reported along the border of northwestern China. In this study, a total of 1,084 adult ticks, including 134 Haemaphysalis punctata, 337 Hyalomma asiaticum, 233 Dermacentor nuttalli, 69 Rhipicephalus turanicus and 265 Dermacentor marginatus were collected from 11 counties or cities of Xinjiang Uygur Autonomous Region. The ticks were identified from morphological and molecular characteristics. Two fragments of 18S rRNA gene were used to determine the species level of Babesia and Theileria. Msp4 gene encoding major surface protein 4 was used to determine A. ovis. Of the 1,084 samples, five species of Babesia (B. occultans, B. caballi, B. motasi, B. major and Babesia sp. detected in this study), two kinds of Theileria (Theileria ovis and Theileria sp. detected in this study) and A. ovis with six phylogenic branches were detected in the border of northwestern China. Babesia occultans, first found in China, was first molecularly detected in D. nuttalli. Babesia caballi and Babesia sp. detected in this study were first molecularly detected in Hy. asiaticum. Genotype III of A. ovis was predominant in the border regions of northwestern China.

Genetic characterization and molecular survey of Babesia sp. Xinjiang infection in small ruminants and ixodid ticks in China

Babesia sp. Xinjiang is a large ovine Babesia species that was recently isolated in China. Compared with other ovine Babesia species, it has different morphological features, pathogenicity and vector tick species. The known transmitting vector is Hyalomma anatolicum. In this study, the distribution and the presence of Babesia sp. Xinjiang in small ruminants and ixodid ticks in China were assessed by specific nested-PCR assay based on the rap-1a gene. A total of 978 blood samples from sheep or goats from 15 provinces and 797 tick specimens from vegetation from 10 provinces were collected and analysed for the presence of the Babesia sp. Xinjiang. Full-length and partial rap-1a of Babesia sp. Xinjiang were amplified from field samples. The PCR results were further confirmed by DNA sequencing. Overall, 38 (3.89%) blood samples and 51 (6.4%) tick samples were positive for Babesia sp. Xinjiang infection. The highest presence (26.92%) was found in blood samples from Yunnan province, while H. qinghaiensis ticks with the highest presence of infection (21.3%) were from Gansu province. This study identified for the first time Babesia sp. Xinjiang infection in H. longicornis tick species. The rap-1a sequences of Babesia sp. Xinjiang from field blood and tick samples indicated 100% identity. The presence of Babesia sp. Xinjiang infection may increase in China. Novel potential transmitting vectors might be more extensive than previously thought.

Molecular evidence of a new Babesia sp. in goats

In this study, a novel Babesia sp. infecting goats was detected and its phylogenetic relationship to related species was determined. A total of 200 blood samples collected from sheep (n=78) and goats (n=122) were examined in the study. The V4 hypervariable region of the 18S rRNA gene of the novel Babesia sp. was amplified by PCR and analysed using a reverse line blot hybridization assay adapted for small ruminants. Samples from seven goats hybridized to Theileria/Babesia catch-all and Babesia catch-all probes and did not hybridize to any species-specific probe tested, suggesting the presence of an unrecognized Babesia species or genotype. Sequencing results showed the isolate to clearly differ from ovine Babesia species and genotypes currently available in the GenBank database. The isolate showed 90.9%, 93.5%, and 93.4% identity to B. ovis, B. motasi, and B. crassa, respectively and 91-93% similarity to Babesia genotypes recently described in small ruminants. The highest homology (∼96-97%) observed was with Babesia odocoilei, Babesia sp. EU1, and Babesia divergens. The new isolate was provisionally designated Babesia sp. The study contributes to better insight into the distribution and phylogenetic diversity of piroplasms in small ruminants. The survey indicated a high prevalence of piroplasms in small ruminants (21.5%). Of those detected, T. ovis was the most prevalent (17%), followed by Babesia sp. (3.5%), and B. ovis (2%).

Mitochondrial genomes of two Babesia taxa from sheep in China as a foundation for population genetic and epidemiological investigations

Here, we sequenced, assembled and annotated the mitochondrial (mt) genomes of two operational taxonomic units of Babesia from sheep from China using a deep sequencing-coupled approach. Then, we defined and compared the gene order of these mt genomes (~5.8 to 6.2kb in size), assessed sequence differences in mt genes among Babesia taxa and evaluated genetic relationships among these taxa and related apicomplexans (Theileria) for which mt genomic data sets were available. We also identified mt genetic regions that might be useful as markers for future population genetic and molecular epidemiological studies of Babesia from small ruminants. We propose that the sequencing-bioinformatic approach used here should be applicable to a wide range of protists of veterinary importance.

The apicoplast genomes of two taxonomic units of Babesia from sheep

The apicoplast (ap) is a unique, non-photosynthetic organelle found in most apicomplexan parasites. Due to the essential roles that this organelle has, it has been widely considered as target for drugs against diseases caused by apicomplexans. Exploring the ap genomes of such parasites would provide a better understanding of their systematics and their basic molecular biology for therapeutics. However, there is limited information available on the ap genomes of apicomplexan parasites. In the present study, the ap genomes of two operational taxonomic units of Babesia (known as Babesia sp. Lintan [Bl] and Babesia sp. Xinjiang [Bx]) from sheep were sequenced, assembled and annotated using a massive parallel sequencing-based approach. Then, the gene content and gene order in these ap genomes (∼30.7kb in size) were defined and compared, and the genetic differences were assessed. In addition, a phylogenetic analysis of ap genomic data sets was carried out to assess the relationships of these taxonomic units with other apicomplexan parasites for which complete ap genomic data sets were publicly available. The results showed that the ap genomes of Bl and Bx encode 59 and 57 genes, respectively, including 2 ribosomal RNA genes, 25 transfer RNA genes and 30-32 protein-encoding genes, being similar in content to those of Babesia bovis and B. orientalis. Ap gene regions that might serve as markers for future epidemiological and population genetic studies of Babesia species were identified. Using sequence data for a subset of six protein-encoding genes, a close relationship of Bl and Bx with Babesia bovis from cattle and B. orientalis from water buffalo was inferred. Although the focus of the present study was on Babesia, we propose that the present sequencing-bioinformatic approach should be applicable to organellar genomes of a wide range of apicomplexans of veterinary importance.

Expression of sheep pathogen Babesia sp. Xinjiang rhoptry-associated protein 1 and evaluation of its diagnostic potential by enzyme-linked immunosorbent assay

Ovine babesiosis is one of the most important tick-borne haemoparasitic diseases of small ruminants. The ovine parasite Babesia sp. Xinjiang is widespread in China. In this study, recombinant full-length XJrRAP-1aα2 (rhoptry-associated protein 1aα2) and C-terminal XJrRAP-1aα2 CT of Babesia sp. Xinjiang were expressed and used to evaluate their diagnostic potential for Babesia sp. Xinjiang infections by indirect enzyme-linked immunosorbent assay (ELISA). Purified XJrRAP-1aα2 was tested for reactivity with sera from animals experimentally infected with Babesia sp. Xinjiang and other haemoparasites using Western blotting and ELISA. The results showed no cross-reactivities between XJrRAP-1aα2 CT and sera from animals infected by other pathogens. High level of antibodies against RAP-1a usually lasted 10 weeks post-infection (wpi). A total of 3690 serum samples from small ruminants in 23 provinces located in 59 different regions of China were tested by ELISA. The results indicated that the average positive rate was 30·43%, and the infections were found in all of the investigated provinces. This is the first report on the expression and potential use of a recombinant XJrRAP-1aα2 CT antigen for the development of serological assays for the diagnosis of ovine babesiosis, caused by Babesia sp. Xinjiang.

Expression analysis and biological characterization of Babesia sp. BQ1 (Lintan) (Babesia motasi-like) rhoptry-associated protein 1 and its potential use in serodiagnosis via ELISA

Background

In China, ovine babesiosis is one of the most important tick-borne haemoparasitic diseases of small ruminants. It has a significant economic impact, and several Babesia motasi-like isolates have been recently shown to be responsible for ovine babesiosis in this country.

Methods

Full-length and C-terminal-truncated forms of the rap-1a61-1 gene of Babesia sp. BQ1 (Lintan) were cloned into the pET-30a plasmid and subsequently expressed as His-fusion proteins. The resulting recombinant RAP-1a proteins (rRAP-1a61-1 and rRAP-1a61-1/CT) were purified and evaluated as diagnostic antigens using Western blot analysis and ELISA. The native Babesia sp. BQ1 (Lintan) RAP-1 protein was recognized using Western blots and IFAT by antibodies that were raised in rabbits against rRAP-1a61-1/CT. The specificity, sensitivity and positive threshold values for rRAP-1a61-1/CT in ELISA were evaluated.

Results

Cross-reactivity was observed between rRAP-1a61-1/CT and positive sera for Babesia sp. BQ1 (Lintan), Babesia sp. BQ1 (Ningxian) and Babesia sp. Tianzhu isolates obtained from infected sheep. At one week post-inoculation, a significant increase was observed in the amount of antibodies produced against RAP-1a, and high levels of antibodies against RAP-1a were observed for 3 months (at 84 days p.i.). A total of 3198 serum samples were collected from small ruminants in 54 different regions in 23 provinces of China. These samples were tested using ELISA based on the rRAP-1a61-1/CT protein. The results indicated that the average positive rate was 36.02 %.

Conclusions

The present study suggests that rRAP-1a61-1/CT might be a potential diagnostic antigen for detecting several isolates of B. motasi-like parasites infection.

Prevalence of Theileria and Babesia species in Tunisian sheep

In this study, the prevalence of Theileria and Babesia species in sheep was assessed with Giemsa-stained blood smear examination and polymerase chain reaction to identify the different piroplasms in 270 sheep from three Tunisian bioclimatic zones (north, centre, and south). The overall infection prevalence by Babesia spp. and Theileria spp. in Giemsa-stained blood smears was 2.9% (8/270) and 4.8% (13/270) respectively. The molecular results showed that sheep were more often infected by Theileria ovis than Babesia ovis with an overall prevalence of 16.3% (44/270) and 7.8% (21/270) respectively (p = 0.01). The molecular prevalence by Babesia ovis was significantly higher in females than in males (p < 0.05). According to localities B. ovis was found exclusively in sheep from the centre of Tunisia (Kairouan) whereas Theileria ovis was found in all regions. Infections with T. ovis and B. ovis were confirmed by sequencing. The sequence of T. ovis in this study (accession numbers KM924442) falls into the same clade as T. ovis deposited in GenBank. The T. ovis amplicons (KM924442) showed 99%–100% identities with GenBank sequences. Moreover, comparison of the partial sequences of 18S rRNA gene of B. ovis described in this study (KP670199) revealed 99.4% similarity with B. ovis recently reported in northern Tunisia from sheep and goats. Three nucleotides were different at positions 73 (A/T), 417 (A/T), and 420 (G/T). It also had 99% identity with B. ovis from Spain, Turkey and Iraq. The results suggest a high T. ovis prevalence in Tunisia with a decreasing north-south gradient. This could be correlated to the vector tick distribution.

Genetic diversity and molecular characterization of Babesia motasi-like in small ruminants and ixodid ticks from China

Ovine babesioses, an important tick-borne disease of sheep and goats in China, is caused by the reproduction of intraerythrocytic protozoa of the Babesia genus. Babesia motasi-like is a Babesia parasite that infects small ruminant in China, and two sub-groups of B. motasi-like can be subdivided based on differences in the rhoptry-associated-protein-1 gene. This study aimed to characterize the distribution, epidemiology and genetics of B. motasi-like in animals and ticks. A molecular investigation was carried out from 2009 to 2015 in 16 provinces in China. In total, 1081 blood samples were collected from sheep and goats originating from 27 different regions, and 778 ixodid tick samples were collected from 8 regions; the samples were tested for the presence of B. motasi-like using a specific nested PCR assay based on the rap-1b gene. The results indicated that 139 (12.9%), 91 (8.4%), 48 (4.4%) and 6 (0.7%) of the blood samples were positive for general B. motasi-like, Babesia sp. BQ1 (Lintan and Ningxian), Babesia sp. Tianzhu and Babesia sp. Hebei sub-groups, mixed infections, respectively. Among the collected 778 ixodid ticks (including Haemaphysalis longicornis, Haemaphysalis qinghaiensis, Dermacentor silvarum, Ixodes persulcatus, Rhipicephalus sanguineus and Rhipicephalus (Boophilus) microplus), the most frequently infected with Babesia were D. silvarum and I. persulcatus (35.7%), followed by H. longicornis (26.8%), H. qinghaiensis (24.8%) and R. sanguineus (9.3%). The PCR results were confirmed by DNA sequencing. The positive rates of B. motasi-like infection in ticks were found to be higher in China, compared with previous studies in other countries. B. motasi-like infections have not previously been reported in D. silvarum, I. persulcatus or R. sanguineus. The findings obtained in this study could be used for planning effective control strategies against babesiosis in China.

Identification of piroplasm infection in questing ticks by RLB: a broad range extension of tick-borne piroplasm in China?

Sensitive and specific diagnostic method for rapid and simultaneous detection and discrimination of the different species is needed for an effective control of piroplasmosis. Here, a reverse line blot (RLB) assay was developed for piroplasm detection. A general pair of primer based on 18S ribosomal RNA (rRNA) gene was used to amplify V4 region of 18S rRNA gene. General and specific probes for 13 piroplasm species were cited from previous publications or designed according to the alignment of 18S rRNA gene sequences. For sensitivity test of RLB assay, serially diluted plasmids of the different species were used to access the sensitivity of the RLB. Four hundred and fifty tick samples collected from grass from different provinces of China were then detected. The result indicated that the RLB assay is highly specific and sensitive, detecting up to 10(2) copies/μl of recombinant plasmid DNA. Multiple piroplasms were detected as single or mixed infection from tick species. Eight piroplasm species, most of which were Theileria annulata (33/450, 7.3 %) or Babesia sp. Xinjiang (30/450, 6.7 %), were found to infect with 89 tick samples in four tick species; no infections with Babesia major, Babesia ovata, Babesia bigemina, Theileria sergenti, or Theileria equi were detected. The piroplasms species-specific RLB assay may have potential clinical application in the simultaneous detection and differentiation of Babesia and Theileria species.

Emerging tick-borne infections in mainland China: an increasing public health threat

Since the beginning of the 1980s, 33 emerging tick-borne agents have been identified in mainland China, including eight species of spotted fever group rickettsiae, seven species in the family Anaplasmataceae, six genospecies in the complex Borrelia burgdorferi sensu lato, 11 species of Babesia, and the virus causing severe fever with thrombocytopenia syndrome. In this Review we have mapped the geographical distributions of human cases of infection. 15 of the 33 emerging tick-borne agents have been reported to cause human disease, and their clinical characteristics have been described. The non-specific clinical manifestations caused by tick-borne pathogens present a major diagnostic challenge and most physicians are unfamiliar with the many tick-borne diseases that present with non-specific symptoms in the early stages of the illness. Advances in and application of modern molecular techniques should help with identification of emerging tick-borne pathogens and improve laboratory diagnosis of human infections. We expect that more novel tick-borne infections in ticks and animals will be identified and additional emerging tick-borne diseases in human beings will be discovered.

Transmission of Babesia ovis by different Rhipicephalus bursa developmental stages and infected blood injection

In this report, the transmission efficacy of Babesia ovis, the principal causative agent of ovine babesiosis, was studied by infestation of lambs with different Rhipicephalus bursa stages or by injection of infected blood. Infected blood injection induced acute babesiosis in splenectomized lambs, while only mild clinical signs were observed in intact animals. Both splenectomized and intact lambs developed high antibody titer, detectable for at least 180 days post infection. Infestation of splenectomized and intact lambs with infected tick larvae did not induce clinical babesiosis or specific serum response in any of the examined animals. Similarly, infestation of one splenectomized lamb with partially-fed infected R. bursa males did not induce any clinical response or seroconversion. Nymph infestation caused a mild clinical response followed by specific seroconversion, in one out of five lambs. All animals infested with infected unfed adults (males and females) showed mild-to-severe clinical signs 8 to 12 days post infestation. The acute phase was followed by a marked seroconversion. Our results indicate that the principal transmission of B. ovis is performed by adult R. bursa ticks, and that the host reaction can last as long as 6 months following the acute infection.

A member of the HSP90 family from ovine Babesia in China: molecular characterization, phylogenetic analysis and antigenicity

Heat shock protein 90 (HSP90) is a key component of the molecular chaperone complex essential for activating many signalling proteins involved in the development and progression of pathogenic cellular transformation. A Hsp90 gene (BQHsp90) was cloned and characterized from Babesia sp. BQ1 (Lintan), an ovine Babesia isolate belonging to Babesia motasi-like group, by screening a cDNA expression library and performing rapid amplification of cDNA ends. The full-length cDNA of BQHsp90 is 2399 bp with an open reading frame of 2154 bp encoding a predicted 83 kDa polypeptide with 717 amino acid residues. It shows significant homology and similar structural characteristics to Hsp90 of other apicomplex organisms. Phylogenetic analysis, based on the HSP90 amino acid sequences, showed that the Babesia genus is clearly separated from other apicomplexa genera. Five Chinese ovine Babesia isolates were divided into 2 phylogenetic clusters, namely Babesia sp. Xinjiang (previously designated a new species) cluster and B. motasi-like cluster which could be further divided into 2 subclusters (Babesia sp. BQ1 (Lintan)/Babesia sp. Tianzhu and Babesia sp. BQ1 (Ningxian)/Babesia sp. Hebei). Finally, the antigenicity of rBQHSP90 protein from prokaryotic expression was also evaluated using western blot and enzyme-linked immunosorbent assay (ELISA).

Rhoptry-associated protein (rap-1) genes in the sheep pathogen Babesia sp. Xinjiang: Multiple transcribed copies differing by 3' end repeated sequences

Sheep babesiosis occurs mainly in tropical and subtropical areas. The sheep parasite Babesia sp. Xinjiang is widespread in China, and our goal is to characterize rap-1 (rhoptry-associated protein 1) gene diversity and expression as a first step of a long term goal aiming at developing a recombinant subunit vaccine. Seven different rap-1a genes were amplified in Babesia sp. Xinjiang, using degenerate primers designed from conserved motifs. Rap-1b and rap-1c gene types could not be identified. In all seven rap-1a genes, the 5' regions exhibited identical sequences over 936 nt, and the 3' regions differed at 28 positions over 147 nt, defining two types of genes designated α and β. The remaining 3' part varied from 72 to 360 nt in length, depending on the gene. This region consists of a succession of two to ten 36 nt repeats, which explains the size differences. Even if the nucleotide sequences varied, 6 repeats encoded the same stretch of amino acids. Transcription of at least four α and two β genes was demonstrated by standard RT-PCR.

Genetic variability of Babesia parasites in Haemaphysalis spp. and Ixodes persulcatus ticks in the Baikal region and Far East of Russia

To study Babesia diversity in Ixodid ticks in Russia, Ixodes persulcatus, Haemaphysalis japonica, Haemaphysalisconcinna, Dermacentor silvarum, and Dermacentor nuttalli ticks collected in the Far East and Baikal region were assayed for the presence of Babesia spp. using nested PCR. In total, Babesia DNA was detected in 30 of the 1125 (2.7%) I. persulcatus, 17 of the 573 (3.0%) H. concinna, and 12 of the 543 (2.2%) H. japonica but was undetectable in any of the 294 analyzed Dermacentor spp. Partial 18S rRNA gene sequences were determined for all of the positive samples. Among the positive ticks, nine I. persulcatus were infected by Babesia microti 'US'-type, five I. persulcatus were infected by Babesia divergens-like parasites, and 11 I. persulcatus were infected by Babesia venatorum. For all three of these species, the determined 18S rRNA gene sequences were identical to those of the Babesia genetic variants found previously in I. persulcatus in Russia. In addition, five I. persulcatus from the Baikal region and all of the positive Haemaphysalis spp. ticks carried 13 different sequence variants of Babesia sensu stricto belonging to distinct phylogenetic clusters. Babesia spp. from 29 ticks of different species collected in distinct locations belonged to the cluster of cattle and ovine parasites (Babesia crassa, Babesiamajor, Babesiamotasi, Babesiabigemina, etc.). Babesia spp. from four H. japonica ticks in the Far East belonged to the cluster formed by parasites of carnivores. One more Babesia sequence variant detected in an I. persulcatus tick from the Baikal region belonged to the cluster formed by parasites of cattle and wild cervids (B. divergens, Babesiacapreoli, B. venatorum, Babesiaodocoilei, etc.).