Molecular Survey and Genetic Diversity of Babesia spp. and Theileria spp. in Cattle in Gansu Province, China

Investigation of Babesia spp. and Theileria spp. in ticks from Western China and identification of a novel genotype of Babesia caballi

Babesia spp. and Theileria spp. are tick-borne protozoan parasites with veterinary importance. In China, epidemiological and genetic investigations on many Babesia and Theileria species were still absent in many areas and many tick species. From Aug 2021 to May 2023, 645 ticks were collected from the body surface of domestic animals (camels, goats, sheep, and cattle) using tweezers in seven counties in three provinces including Xinjiang (Qitai, Mulei, Hutubi, and Shihezi counties), Chongqing (Youyang and Yunyang counties), and Qinghai (Huangzhong county). Three tick species were morphologically and molecularly identified (334 Hyalomma asiaticum from Xinjiang, 245 Rhipicephalus microplus from Chongqing, and 66 Haemaphysalis qinghaiensis from Qinghai). A total of three Babesia species and two Theileria species were detected targeting the 18S gene. The COI and cytb sequences were also recovered from Babesia strains for further identification. In R. microplus from Chongqing, Babesia bigemina, the agent of bovine babesiosis, was detected. Notably, in H. asiaticum ticks from Xinjiang, a putative novel genotype of Babesia caballi was identified (0.90%, 3/334), whose COI and cytb genes have as low as 85.82% and 90.64-90.91% nucleotide identities to currently available sequences. It is noteworthy whether the sequence differences of its cytb contribute to the drug resistance of this variant due to the involvement of cytb in the drug resistance of Babesia. In addition, Theileria orientalis and Theileria annulata were detected in R. microplus from Chongqing (12.20%, 31/245) and H. asiaticum from Xinjiang (1.50%, 5/334), respectively. These results suggest that these protozoan parasites may be circulating in domestic animals in these areas. The pathogenicity of the novel genotype of B. caballi also warrants further investigation.

Molecular Identification of Babesia and Theileria Infections in Livestock in the Qinghai-Tibetan Plateau Area, China

The northwestern region of China, known as the Qinghai-Tibet Plateau Area (QTPA), is characterized by unique climate conditions that support the breeding of various highly-adapted livestock species. Tick vectors play a significant role in transmitting Babesia and Theileria species, posing serious risks to animal health as well as the economy of animal husbandry in QTPA. A total of 366 blood samples were collected from Tibetan sheep (n = 51), goats (n = 67), yaks (n = 43), cattle (n = 49), Bactrian camels (n = 50), horses (n = 65), and donkeys (n = 40). These samples were examined using conventional and nested PCR techniques to detect Theileria and Babesia species. The overall infection rates were 0.3% (1/366) for Babesia spp. and 38.2% (140/366) for Theileria spp. Notably, neither Babesia nor Theileria species were detected in donkeys and yaks. The infection rates of Babesia and Theileria species among animals in different prefectures were significantly different (p < 0.05). Furthermore, Babesia bovis, B. bigemina, B. caballi, and B. ovis were not detected in the current study. To our knowledge, this is the first documented detection of Theileria luwenshuni infection in Bactrian camels and goats, as well as T. sinesis in cattle and T. equi in horses on the Qinghai plateau. These novel findings shed light on the distribution of Babesia and Theileria species among livestock species in QTPA.

Differential microbial composition in parasitic vs. questing ticks based on 16S next-generation sequencing

Introduction

As tick-borne diseases rise to become the second most prevalent arthropod-transmitted disease globally, the increasing investigations focus on ticks correspondingly. Factors contributed to this increase include anthropogenic influences, changes in vertebrate faunal composition, social-recreational shifts, and climatic variation. Employing the 16S gene sequence method in next-generation sequencing (NGS) allows comprehensive pathogen identification in samples, facilitating the development of refined approaches to tick research omnidirectionally.

Methods

In our survey, we compared the microbial richness and biological diversity of ticks in Wuwei City, Gansu province, differentiating between questing ticks found in grass and parasitic ticks collected from sheep based on 16S NGS method.

Results

The results show Rickettsia, Coxiella, and Francisella were detected in all 50 Dermacentor nuttalli samples, suggesting that the co-infection may be linked to specific symbiotic bacteria in ticks. Our findings reveal significant differences in the composition and diversity of microorganisms, with the Friedmanniella and Bordetella genera existing more prevalent in parasitic ticks than in questing ticks (p < 0.05). Additionally, the network analysis demonstrates that the interactions among bacterial genera can be either promotive or inhibitive in ticks exhibiting different lifestyles with the correlation index |r| > 0.6. For instance, Francisella restrains the development of 10 other bacteria in parasitic ticks, whereas Phyllobacterium and Arthrobacter enhance colonization across all tick species.

Discussion

By leveraging NGS techniques, our study reveals a high degree of species and phylogenetic diversity within the tick microbiome. It further highlights the potential to investigate the interplay between bacterial genera in both parasitic and questing ticks residing in identical habitat environments.

Cattle co-infection patterns by hemopathogens and their phylogenetic analysis during the tick season in Constantine and Mila, Northeast Algeria

Tropical theileriosis, babesiosis, and anaplasmosis are the most dominant tick-borne infections in North Africa where they cause significant economic losses in ruminants' industry. The aim of the present work was to study infections and co-infection patterns in 66 cattle with clinical signs of piroplasmosis and/or anaplasmosis in two localities, Beni Hamidene and Grarem Gouga, districts of Constantine and Mila (Northeast of Algeria), respectively. This study was conducted between early May and late September during four years 2017, 2018, 2020, and 2021. PCR showed that the most frequent pathogen in cattle with clinical signs of piroplasmosis and/or anaplasmosis was Theileria annulata (66/66; 100%) followed by Babesia bovis (21/66; 31.8%), Anaplasma marginale (15/66; 22.7%), and Babesia bigemina (3/66; 4.5%) (p < 0.001). Giemsa-stained blood smears examinations revealed that 66.7% (44/66); 10.6% (7/66); and 9.1% (6/66) of cattle were infected by T. annulata, Babesia spp., and A. marginale, respectively (p < 0.001). PCR revealed seven co-infection patterns: T. annulata/A. marginale (15/66; 22.7%), T. annulata/B. bovis (21/66; 31.8%), T. annulata/B. bigemina (3/66; 4.5%), T. annulata/A. marginale/B. bovis (7/66; 10.6%), T. annulata/B. bovis/B. bigemina (2/66; 3%), T. annulata/A. marginale/B. bigemina (1/66; 1.5%), and T. annulata/A. marginale/B. bigemina/B. bovis (1/66; 1.5%). Phylogenetic analyses showed that T. annulata Tams1 and B. bigemina gp45 sequences were identical to isolates from Mauritania and South Africa, respectively. The three A. marginale amplicons obtained herein had 99.63 to 99.88% similarity between them. This study provides data that can be used to improve control programs targeting these cattle hemopathogens.

Surveillance and Risk Analysis for Bovine Babesiosis in England and Wales to Inform Disease Distribution

Babesia divergens is a zoonotic piroplasm that infects both cattle and humans in Europe. Disease transmission occurs through Ixodes ricinus tick bites, a species that is increasing in abundance and distribution across Europe in response to climate and land-use changes. Developments in agri-environment policy and changing consumer demands may also have unintended consequences on tick-borne disease rates. Currently, B. divergens surveillance in British cattle is limited, rendering temporal trend analysis and the detection of potential zoonotic hotspots impossible. The objective of this study was to assess syndromic surveillance as a means of determining babesiosis distribution in British cattle, and to evaluate the intrinsic disease risk factors in order to respond to disease threats posed by changing environments. Samples from 95 clinically affected cattle on 70 unique holdings were screened for Babesia spp., using established blood smear examination techniques and a B. divergens-specific PCR method, between April and December 2021. B. divergens was detected in 45/95 animals (47.4%), with PCR offering the advantage of identification at species level. Infection with Anaplasma phagocytophilum was detected in 19/95 animals (20%). Co-infection was detected in five animals. The cases were recorded across multiple geographic regions and throughout the sampling period. Univariate logistic regression analysis failed to identify any statistically significant risk factors for B. divergens presence. This study demonstrates that bovine babesiosis is geographically widespread throughout England and Wales, placing a large proportion of the cattle population at risk of infection, with the potential for zoonotic transmission to humans.

Prevalence of Theileria in cattle in China: A systematic review and meta-analysis

Theileria, one of the causative agents of blood protozoan, has brought a huge economic loss to the cattle industry worldwide. However, the epidemiology of Theileria in Chinese cattle has not been systematically investigated. This comprehensive review aimed at investigating the prevalence of Theileria infection in cattle in China. A total of 48 published papers on Theileria infection in cattle in China (including data from 21,366 animals) from inception to October 8, 2021 met the inclusion standard after searching in five databases (Technology Periodical Database, Wan Fang Database, China National Knowledge Infrastructure, PubMed, and ScienceDirect). The pooled prevalence of Theileria in cattle in China was 32.4% identified by using a random effects model. The prevalence in Northeastern China (45.3%) was higher than that in other regions. In the sex subgroup, the prevalence of Theileria was higher in females (48.9%) than that in males (45.8%). The prevalence of Theileria was higher in cattle of free range (34.4%) compared with that of intensive farming (22.3%). The prevalence prior to 2013 (36.1%) was higher than that after 2013 (33.6%). Among three cattle species, dairy cows had the lowest prevalence (21.5%). The prevalence of Theileria (T.) annulata (22.2%) and T. sergenti (26.2%) was higher than other species of Theileria (T. buffeli: 17.5%, T. luwenshuni: 0.9%, T. orientalis: 15.5%, T. ovis: 0.21%, T. sinensis: 20.2%, T. uilenbergi: 6.2%, Others: 0.9%). We also analyzed the impact of different geographic factor subgroups (longitude, latitude, precipitation, temperature, humidity, and altitude) on the prevalence of Theileria in cattle. Among them, climatic factors of longitude, latitude, precipitation, humidity, temperature were associated with the prevalence of Theileria. These analyses suggested that Theileria was common in cattle in China. Targeted prevention programs based on geographic and climatic conditions in different areas may play an important role in reducing Theileria infection among cattle.

Ticks and Tick-Borne Pathogens Abound in the Cattle Population of the Rabat-Sale Kenitra Region, Morocco

Tick-borne pathogens cause the majority of diseases in the cattle population in Morocco. In this study, ticks were collected from cattle in the Rabat-Sale-Kenitra region of Morocco and identified morphologically, while tick-borne pathogens were detected in cattle blood samples via polymerase chain reaction assay and sequencing. A total of 3394 adult ixodid ticks were collected from cattle and identified as eight different tick species representing two genera, Hyalomma and Rhipicephalus. The collected ticks consisted of Hyalomma marginatum, Hyalomma anatolicum excavatum, Rhipicephalus sanguineus sensu lato, Rhipicephalus bursa, Hyalomma detritum, Hyalomma lusitanicum, Hyalomma dromedarii, and Hyalomma impeltatum. The overall prevalence of tick-borne pathogens in blood samples was 63.8%, with 29.3% positive for Babesia/Theileria spp., 51.2% for Anaplasma/Ehrlichia spp., and none of the samples positive for Rickettsia spp. Sequencing results revealed the presence of Theileria annulata, Babesia bovis, Anaplasma marginale, Theileria buffeli, Theileria orientalis, Babesia occultans, Anaplasma phagocytophilum, Anaplasma capra, Anaplasma platys, Anaplasma bovis, Ehrlichia minasensis, and one isolate of an unknown bovine Anaplasma sp. Crossbreeds, females, older age, and high tick infestation were the most important risk factors for the abundance of tick-borne pathogens, which occurred most frequently in Jorf El Melha, Sidi Yahya Zaer, Ait Ichou, and Arbaoua locations.

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.