Risk factors associated with the frequency of antibodies against Babesia bovis and Babesia bigemina in cattle in southern Mozambique

Genetic diversity in Babesia bovis from southern Africa and estimation of B. bovis infection levels in cattle using an optimised quantitative PCR assay

Babesia bovis is a causal agent of bovine babesiosis, a disease which leads to mortality and morbidity and impacts the cattle industry worldwide. We amplified, cloned and sequenced the B. bovis merozoite surface antigen-2b (msa-2b) gene (_∼940 bp) and the near full-length 18S rRNA gene (_∼1600 bp) from cattle samples from South Africa and Mozambique to determine sequence variation between B. bovis parasites in the region. A TaqMan quantitative real-time PCR (qPCR) assay (18S rRNA gene) was optimised for the detection of B. bovis and estimation of parasitaemia in field samples from cattle from southern Africa. Phylogenetic analysis grouped the Msa-2b sequences in six clades and these were 59.7 to 99.6% identical to reference sequences. Sequence variation amongst B. bovis 18S rRNA sequences was found at 2 to 36 positions, and the sequences were 97 to 99% identical to published sequences. Mismatches between the B. bovis 18S rRNA sequences and a previously published qPCR forward primer (BoF) were observed; therefore, we developed a new forward primer (BoF2), and optimised the qPCR assay. Six 10-fold dilution series of B. bovis infected erythrocytes (2 × 10⁸ to 2 × 10³ infected red blood cells [iRBC]/ml) were analysed in triplicate in each of six separate qPCR runs, to determine the efficiency of the assay. The qPCR assay amplified the B. bovis 18S rRNA gene with 92.0 to 94.9% efficiency. The detection limit of the qPCR assay was approximately 6 iRBCs/μl. The performance of the optimised assay to diagnose B. bovis in field samples was assessed by testing DNA from 222 field samples of cattle from South Africa and Mozambique using three methods: the optimised qPCR assay, the reverse line blot (RLB) hybridisation assay, and the previously published qPCR assay. The detection rate of B. bovis using the optimised qPCR assay (31.1%, 69/222) was significantly higher (p<0.001) than both that using RLB (20.7%, 46/222) and the previously published qPCR assay (5.4%; 12/222). The B. bovis parasitaemia in samples from infected cattle ranged from 6 iRBCs/μl to 101,852 iRBCs/μl of blood. Our study revealed marked sequence variation between B. bovis parasites from southern Africa. The optimised qPCR assay will be useful in epidemiological studies and clinical diagnosis of B. bovis in southern Africa, and can be used to determine parasitaemia and potential carrier status in cattle populations, which is essential in the control of babesiosis.

Molecular Epidemiological Investigation of Piroplasms and Anaplasmataceae Bacteria in Egyptian Domestic Animals and Associated Ticks

Piroplasmosis and anaplasmosis are serious tick-borne diseases (TBDs) that are concerning for the public and animal health. This study aimed to detect the molecular prevalence and epidemiological risk factors of Piroplasma and Anaplasma species in animal hosts and their associated ticks in Egypt. A total of 234 blood samples and 95 adult ticks were collected from animal hosts (112 cattle, 38 sheep, 28 goats, 26 buffaloes, 22 donkeys, and 8 horses) from six provinces of Egypt (AL-Faiyum, AL-Giza, Beni-Suef, Al-Minufia, Al-Beheira, and Matruh). Blood and tick samples were investigated by polymerase chain reaction coupled with sequencing targeting 18S and 16S RNA genes for Piroplasma and anaplasmataceae, respectively. Statistical analysis was conducted on the potential epidemiological factors. Of the 234 animals examined, 54 (23.08%) were positive for pathogens DNA distributed among the six provinces, where 10 (4.27%) were positive for Piroplasma, 44 (18.80%) for anaplasmataceae, and 5 (2.14%) were co-infected. Co-infections were observed only in cattle as Theileria annulata and Anaplasma marginale plus Babesia bigemina, A. marginale plus B. bigemina, and T. annulata plus B. bigemina. Piroplasmosis was recorded in cattle, with significant differences between their prevalence in their tick infestation factors. Animal species, age, and tick infestation were the potential risk factors for anaplasmosis. All ticks were free from piroplasms, but they revealed high prevalence rates of 72.63% (69/95) with anaplasmataceae. We identified T. annulata, B. bigemina, and A. marginale in cattle; A. platys in buffaloes; A. marginale and A. ovis in sheep; for the first time, A. ovis in goats; and Ehrlichia sp. in Rhipicephalus annulatus ticks. Our findings confirm the significant prevalence of piroplasmosis and anaplasmosis among subclinical and carrier animals in Egypt, highlighting the importance of the government developing policies to improve animal and public health security.

Babesiosis in cattle and ixodid tick distribution in Dasenech and Salamago Districts, southern Ethiopia

Babesiosis, caused by protozoan parasites of the genus Babesia, and ixodid ticks are considered to be one of the most important causes that result in significant economic losses in cattle production worldwide, including in Ethiopia. A cross-sectional study was undertaken in the Dasenech and Salamago Districts of South Omo zone Ethiopia to determine the prevalence and associated risk factors of babesia infection and ixodid ticks of cattle using Giemsa-stained thin and thick film techniques and morphological identification keys for babesia species and tick identification, respectively. Out of 470 examined cattle, 102 (21.7%) were infected by Babesiosis (15.53% Babesia bigemina and 6.17% Babesia bovis). A statistically significant association (p < 0.05) was observed between babesia infection and season and tick infestation. However, cattle that were infected with the Babesia parasite revealed a lower mean PCV value (21.49%) than noninfected cattle (28.29%) and showed a statistically significant (p < 0.05) difference with the occurrence of Babesia infection. The overall prevalence of ixodid ticks was 53.8% (253/470) and revealed a statistically significant association (p < 0.05) between the season and origin of the animal. However, no statistically significant association (p > 0.05) was observed between sex, age, and body condition score of the animal with the occurrence of ixodid tick. A total of 8040 adult ticks belonging to four tick genera, Amblyomma, Rhipicephalus (Boophilus), Hyalomma, and Rhipicephalus, were collected from various body parts and identified. The high prevalence of Babesia infection and ixodid ticks in cattle at the study sites requires seroprevalence and molecular studies to identify the predominant Babesia species and to detect Babesia in tick hemolymph for the identification of tick genera responsible for the occurrence of Babesia infection. Additionally, tailoring suitable and coordinated tick management methods using chemotherapy as well as strategic treatment to overt clinical cases of bovine babesiosis is critical.

Serological Survey of Babesia bigemina and Babesia bovis in Cattle and Water Buffaloes from Menoufia Province, Egypt

PURPOSE

Bovine babesiosis causes morbidity in tropical and subtropical countries worldwide. The present study aimed to determine the seroprevalence of Babesia bigemina and B. bovis in cattle and water buffaloes in Menoufia province, where the second-highest population of bovines in Lower Egypt are raised.

MATERIALS AND METHODS

A total of 506 blood samples were collected from cattle (N = 262) and water buffaloes (N = 244) in Menoufia province, Egypt. Seroprevalences of B. bigemina and B. bovis in the samples were determined using recombinant Babesia antigen-specific enzyme-linked immunosorbent assays (ELISA).

RESULTS

In cattle, the seroprevalences of B. bigemina and B. bovis were 41.60 and 38.17% (37.40 and 35.88% for IgM and 9.54 and 6.11% for IgG), respectively, whereas those of water buffaloes were 35.66 and 31.97% (27.87 and 21.72% for IgM and 15.16 and 15.16% for IgG), respectively. Statistically significant changes in the seroprevalences of the two infective agents were recorded on the basis of region and season of sample collection.

CONCLUSION

In conclusion, babesiosis is frequent and presents a threat of an epidemic among bovines in Menoufia province. In turn, control of bovine babesiosis is required because of its potential to detrimentally affect milk and meat production in Menoufia province.

The molecular prevalence, distribution and risk factors associated with Babesia bigemina infection in Peninsular Malaysia

Babesia bigemina is a tick-borne protozoan that affects cattle in almost all regions of the world. Despite its importance, there is no report of its prevalence in cattle using molecular detection methods in Peninsular Malaysia. This study describes the prevalence, distribution, and risk factors associated with B. bigemina infection using molecular diagnostic methods. Also, the species of ticks infesting cattle and the attitude of cattle farmers towards tick control in Peninsular Malaysia were studied. Blood samples were collected from 1045 cattle from 43 herds throughout the country, and were subjected to molecular studies to detect B. bigemina. Tick samples for entomological studies were also collected and identified. Epidemiological information of each cattle and farm were obtained using a well-structured questionnaire containing open-ended and closed-ended questions. Data were statistically analyzed using Univariate and Multivariate models. The 211-base pair of AMA-1 gene of B. bigemina was amplified and confirmed in 30.5 % (319/1045; 95 % CI = 27.8-33.4) of the sampled population, with the haemoprotozoan detected in all the sampled herds. Breed, age, physiological status, management type, rate of de-ticking, and closeness to human settlement were the risk factors significantly (p < 0.05) associated with the prevalence of B. bigemina in cattle. Rhipicephalus (Boophilus) microplus and Haemaphysalis bispinosa were the species of ticks collected from cattle, with the former been more prevalent. A large number of cattle farmers (12/43; 28 %) do not control ticks in their herds. The findings of this study will create baseline data on the epidemiology of the haemoprotozoan and control patterns of its tick vectors that will guide the government in enacting policies that will improve food security and the economy of the nation.

Improved detection of Babesia bigemina from various geographical areas in Africa using quantitative PCR and reverse line blot hybridisation

Babesia bigemina is one of the aetiological agents of bovine babesiosis, which causes economic losses through mortality, loss of production and control costs. Effective means of detecting and quantifying B. bigemina in cattle populations is therefore important to inform control approaches. In order to examine the parasite genetic diversity in African countries, B. bigemina 18S rRNA genes from cattle from South Africa, Uganda and Angola were sequenced. The 25 distinct B. bigemina 18S rRNA gene sequences obtained in this study showed 99 to 100% identity with previously published sequences of strains from African and other continents. The sequences of the previously published B. bigemina 18S rRNA gene-specific quantitative PCR (qPCR) primers and probe, developed based on American and Asian strains, were conserved in the African B. bigemina sequences. The qPCR assay was evaluated using 10-fold and 2-fold serial dilutions of B. bigemina-infected erythrocytes to determine the efficiency and analytical sensitivity. The qPCR assay had an efficiency of 98.14 ± 1.71%, and the limit of detection was approximately 1.5 infected red blood cells (iRBCs) per microlitre (μl) of blood. The detection rate of B. bigemina from duplicates of field-collected blood samples from cattle from South Africa, Mozambique and Angola was 37% (30/81), 12% (6/49) and 50% (38/76), respectively. Reverse line blot hybridisation (RLB) results obtained from the same samples in previous studies, using a previously published B. bigemina-specific probe, detected the parasite DNA in only 1.5% (3/206) of the samples. A new B. bigemina-specific RLB oligonucleotide probe was designed in the hypervariable V4 region of the 18S rRNA gene. Screening of field blood samples from cattle showed that the new probe was specific, and its frequency of detection of B. bigemina was three times higher than the previously published probe. The qPCR assay and the newly developed B. bigemina-specific RLB probe provide good tools for epidemiological studies, which are essential in the control of bovine babesiosis.

Serosurvey of Babesia bovis and Babesia bigemina in cattle in Mongolia

Mongolia is an agriculturally rich country with large livestock populations that contribute significantly to its national economy. However, the export market for live animals and livestock products is often constrained for various reasons including infectious diseases. Babesia bovis and B. bigemina, which are bovine hemoprotozoan parasites, cause severe forms of clinical babesiosis, in cattle. However, a country-wide survey to determine the exposure rates in various provinces in Mongolia was not conducted to determine the risk for infections with these parasite species. Therefore, we investigated the frequency of antibodies to B. bovis and B. bigemina in cattle reared throughout Mongolia. B. bovis-and B. bigemina-specific enzyme-linked immunosorbent assays (ELISAs) were used to screen the serum samples sourced from 1946 cattle in 19 of 21 provinces and a provincial municipality (Ulaanbaatar) in Mongolia. We found 351 (18.0%) samples positive for B. bovis and 435 (22.4%) samples positive for B. bigemina infections. The B. bovis- and B. bigemina-positive rates ranged from 0.8 to 61.5% and 4.0 to 50.6%, respectively, among the surveyed provinces. The positive rates of B. bovis and B. bigemina infections were relatively higher in the provinces located in northernmost, northern, eastern, southeastern, and southern Mongolia. Additionally, the B. bovis- and B. bigemina-positive rates were not significantly different between females (18.2 and 22.2%, respectively) and males (17.2 and 18.8%, respectively) or between the 1-3-year-old (16.2 and 19.4%, respectively) and >3-year-old (17.1 and 20.9%, respectively) age groups. The differential seropositivity for B. bovis and B. bigemina infections among the provinces may reflect the variations in the risk of cattle being infected with these parasite species. The findings of the present study highlight the need for country-wide control measures, including tick control programs, to minimize the rates of B. bovis and B. bigemina infections in Mongolian cattle.