Molecular and serological prevalence of Babesia bovis and Babesia bigemina in cattle from central region of Syria

Detection and quantification of Babesia bovis and Babesia bigemina using different target genes

Molecular assays have been widely used for the detection and quantification of bovine babesiosis due to their high sensitivity and specificity. However, variations in the sensitivity of pathogen detection may occur depending on the selected target gene. Thus, this study aimed to compare the detection sensitivity (DS) of Babesia bovis and B. bigemina infection levels in artificially and naturally infected cattle using quantitative PCR (qPCR) and six target genes. For B. bovis, the merozoite surface antigen genes 2b and 2c (msa-2b and msa-2c), and the mitochondrial cytochrome b gene (cybmt) were used. For B. bigemina, the genes encoding the proteins associated with rhoptry 1c (rap-1c), rap-1a, and cybmt were used. Six bovines, free of babesiosis, were artificially infected with 1 × 10-8 red blood cells infected (iRBC) with B. bovis (n = 3) or 1 × 10-6B. bigemina iRBC (n = 3). The animals were evaluated daily until parasitemia was confirmed (≥ 2.0%). The quantity of iRBC present in each animal was determined by examining blood smears. Blood samples were then subjected to DNA extraction, serial dilution, and qPCR analysis to determine the DS of each target gene. In addition, 30 calves naturally infected by Babesia spp. were also evaluated using the same six target genes. Regarding the artificial infection, B. bovis cybmt showed 25-fold higher sensitivity than the msa-2b and msa-2c genes, while the B. bigemina cybmt exhibited 5-fold and 25-fold higher sensitivity than the rap-1a and rap-1c genes, respectively. The rap-1a gene was found to be 5 times more sensitive than the rap-1c gene, while the B. bovis msa-2b and msa-2c genes exhibited similar DS. The positive frequencies of naturally infected calves for the target cybmt, msa-2b, and msa-2c genes (B. bovis) were: 100%, 33.3% and 50%, while cybmt, rap-1a, and rap-1c genes (B. bigemina) were 90%, 83.3%, and 63.3%, respectively. This study may contribute to the selection of suitable genes for molecular monitoring of bovine babesiosis. Mitochondrial genes could be considered as an alternative to improve the sensitivity of B. bovis and B. bigemina detection using qPCR.

Molecular detection of Babesia and Theileria from crossbred cattle in Sirajganj and Rangpur districts of Bangladesh

BACKGROUND

Babesia and Theileria are potential threats to the livestock industry, causing considerable economic losses. These tick-borne blood parasites are more prevalent in crossbred cattle than local cattle in Bangladesh.

OBJECTIVES

To confirm the species of Babesia and Theileria in crossbred cattle from the northern part of Bangladesh using conventional and molecular tools.

METHODS

A total of 385 crossbred cattle blood samples were subjected to DNA extraction and PCR. For molecular detection, B. bigemina rhoptry-associated protein 1a, B. bovis spherical body protein-4, and Theileria spp. 18S rRNA were used as the marker genes.

RESULTS

Using PCR, only 72 (18.7%) samples were found piroplasm positive, of which 12.2% Theileria, 4.7% Babesia, and 1.8% mixed infections. Both Babesia (7.3%), Theileria (7.7%) and mixed (2.8%) infections were detected in Sirajganj, and only Theileria (20.4%) was detected in Rangpur district. By PCR and nPCR we detected B. bigemina and T. annulata in Sirajganj district, and Theileria sp. in Rangpur district. The target gene sequences of isolated pathogens confirmed B. bigemina and T. annulata, and Theileria sp from these samples. Blood smears of all samples were also examined microscopically for Babesia and/or Theileria spp. and 14.3% of samples were found positive, of which 5.9% Babesia and 8.3% Theileria. Generally, the pathogens detected in Sirajgang and Rangpur were genetically related to South Asia, particularly South East Asian isolates.

CONCLUSIONS

These findings provide information for a better understanding of the epidemiology of Babesia and Theileria as well as to improve the approaches for diagnosis and control of tick-borne diseases in Bangladesh.

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.

Comparative Study of Indirect Fluorescent Antibody, ELISA, and Immunochromatography Tests for Serological Diagnosis of Bovine Babesiosis Caused by Babesia bovis

Simple Summary

Currently serological diagnosis of bovine babesiosis is based on the detection of Babesia-specific antibodies (immunoglobulin-G). Antibody detection is commonly used in seroepidemiological studies or in the assessment of antibabesial antibody titers after cattle vaccination. The indirect fluorescent antibody test (IFAT) and enzyme-linked immunosorbent assay (ELISA) are the most widely used diagnostic tests, although there their implementation has some drawbacks, principally due to the requirements for trained personnel, specific materials, and special laboratory equipment. This study compared a newly designed rapid immunochromatography test (ICT), which has been reported recently and used for Babesia bovis-specific antibody detection with promising results, with an in-house ELISA for the serological diagnosis of cattle exposed to B. bovis (Babesia bovis) in Mexico. Higher sensitivity and specificity values were found by ICT, proving its effectiveness over ELISA. ICT also had better concordance than ELISA when IFAT was used as the “gold standard”. The rapid ICT was shown to have diagnostic utility for the detection of antibodies against B. bovis and could be used as a field test in Mexico due to its practicality, as it does not need laboratory equipment for implementation and interpretation of results.

Abstract

The indirect fluorescent antibody test (IFAT) is the most frequently used test to conduct seroepidemiological studies so far, and it is regarded as the "gold standard" test for the serological diagnosis of bovine babesiosis. The aim of the present study was to compare the enzyme-linked immunosorbent assay (ELISA) and the rapid immunochromatography test (ICT) for use in the serological diagnosis of cattle exposed to B. bovis in Mexico. The evaluation of test performance was carried out with 30 positive and 30 negative reference sera. A total of 72 bovine sera samples collected from cattle in a region with endemic bovine babesiosis were analyzed by ELISA and ICT, and the results were compared with those of IFAT. Kappa value (k) was also calculated to determine the agreement between tests. The sensitivity and specificity of ELISA for detecting antibodies against B. bovis were 87% (26/30) and 80% (24/30), respectively. The sensitivity and specificity of ICT for detecting antibodies against B. bovis were 90% (27/30) and 83.3% (25/30), respectively. The overall concordance determined for ELISA and ICT was 94.4% (68/72) and 98.6% (71/72), respectively, when the results were compared with those of IFAT. ICT was more sensitive and specific in this comparative study, showing good strength of agreement (k = 0.79) with respect to IFAT. ICT combines a strip-based assay system that is fast, practical, and sensitive for detection of antibodies to B. bovis, which suggests that it could be applied in the field without requiring any laboratory equipment for its use and interpretation of test results.

Prevalence of camel babesiosis in southeast of Iran

Babesiosis is a globally distributed zoonotic parasitic disease in a broad range of vertebrates with great importance in the veterinary field. The standard diagnostic test for Babesiosis in animals is microscopic identification of the parasite in a venous blood smear stained with Giemsa combined with assessment of clinical manifestations throughout the acute phase of the disease. The present study was planned to determine the presence of Babesia species in camels from the southeastern regions of Iran. A total of 140 blood samples of camels were randomly collected in four selected cities including Qaen, Nehbandan, Iranshahr, and Zahedan from March to August 2019. Blood smears of each case were also examined by the Giemsa staining method and extracted DNA samples were subjected to internal transcribed spacers (ITS1) polymerase chain reaction (PCR) amplification. The prevalence rates using microscopically and molecular examinations were 10% and 19.28%, respectively. The prevalence rates significantly vary between the selected regions (p = 0.003). PCR technique showed higher sensitivity than microscopy. We found that all infected camels were positive for Babesia caballi. The rate of infection with Babesia among the camel in Zahedan is remarkable. Early diagnosis and early treatment can prevent further spread of the disease in this area.

Cross-sectional survey of cattle haemopathogens in Constantine, Northeast Algeria

This aim of the present study was to estimate the prevalence of haemopathogens in cattle in Beni Hamidene locality, district of Constantine (Νortheastern Algeria). Between June and October 2014, 169 bovines from 25 farms were included in this survey, 32 (18.9%) among them were suspected of piroplasmosis and/or anaplasmosis. Infection prevalences were estimated by microscopic examination of Giemsa‐stained blood smears and blood samples from all included cattle (n = 169). Animals were infected by Theileria annulata (65/169; 38.46%), Anaplasma marginale (22/169; 13%) and Babesia bovis (5/169; 3%). Two co‐infection patterns were found: Theileria annulata/Anaplasma marginale (7.69%) and Theileria annulata/Babesia bovis (1.18%). Only one farm had no cattle infected by any of the haemopathogens. There was a signification difference of T. annulata infection prevalence according to age category (p =.04). These results emphasised mainly the presence of bovine tropical theileriosis in northeastern, Beni Hamidene locality, province of Constantine, Algeria.

Ticks and Tick-Borne Diseases of Livestock in the Middle East and North Africa: A Review

Ticks are important vectors of an array of viral, bacterial and protozoan pathogens resulting in a wide range of animal and human diseases. There is limited information in the literature about tick species in the Middle East and North Africa (MENA) countries, even though they have suitable climate and vegetation for ticks and their hosts. We reviewed the occurrence of tick species and the pathogens they transmit from the MENA on published papers from 1901-2020. We found taxonomic records of 55 tick species infesting livestock representing the following eight genera: Ornithodoros, Otobius, Amblyomma, Dermacentor, Haemaphysalis, Hyalomma, Ixodes, and Rhipicephalus. In addition, 15 pathogens were recorded causing diseases of significance, with Crimean-Congo hemorrhagic fever, theileriosis, babesiosis and anaplasmosis being widely distributed diseases in the region. In recent decades, there has been increasing trends in disease occurrence and movement associated with global movement of humans and global trade of animals. We suggest that disease control and prevention could be achieved effectively through good integration between public health, veterinary medicine and animal management, and ecological approaches. We recommend further research in the areas of tick ecology and tick born-disease transmission. Furthermore, we suggest evaluation and improvement of disease control policies in the region.

Diagnostic Tools for the Identification of Babesia sp. in Persistently Infected Cattle

Bovine babesiosis is a tick-borne disease of cattle caused by the protozoan parasites of the genus Babesia. Babesia bovis, Babesia bigemina and Babesia divergens are considered by International health authorities (OIE) as the principal species of Babesia that cause bovine babesiosis. Animals that recover from a babesial primo infection may remain as persistent carriers with no clinical signs of disease and can be the source of infection for ticks that are able to acquire Babesia parasites from infected cattle and to transmit Babesia parasites to susceptible cattle. Several procedures that have been developed for parasite detection and diagnosis of this infectious carrier state constitute the basis for this review: A brief description of the direct microscopic detection of Babesia-infected erytrocytes; PCR-based diagnostic assays, which are very sensitive particularly in detecting Babesia in carrier cattle; in-vitro culture methods, used to demonstrate presence of carrier infections of Babesia sp.; animal inoculation, particularly for B. divergens isolation are discussed. Alternatively, persistently infected animals can be tested for specific antibabesial antibodies by using indirect serological assays. Serological procedures are not necessarily consistent in identifying persistently infected animals and have the disadvantage of presenting with cross reactions between antibodies to Babesia sp.

Molecular and serological detection of bovine babesiosis in Indonesia

BACKGROUND

Bovine babesiosis, mainly caused by Babesia bovis and B. bigemina, is a huge threat to the livestock industry. In Indonesia, the current distribution of the disease is unknown due to a lack of scientific study.

METHODS

In the present study, 487 blood samples were collected from cattle with different breeding and age groups in a broad geographical area across the archipelago. The presence of antibodies and current infections of B. bovis and B. bigemina were determined using enzyme-linked immunosorbent assay (ELISA), immunochromatographic test (ICT), and nested PCR (nPCR) targeting B. bovis SBP-4 and B. bigemina RAP-1a genes. Sequence analysis was performed to the amplicon of B. bovis SBP-4, B. bigemina RAP-1a, and internal transcribed spacer (ITS) region of ribosomal RNA of both Babesia species.

RESULTS

In total, B. bovis positives were detected by ELISA, single-ICT, dual-ICT and nPCR in 340 (69.8%), 317 (65.1%), 307 (63.0%) and 247 (50.7%) samples, respectively. For B. bigemina, the positive samples were detected in 134 (27.5%), 130 (26.7%), 127 (26.1%) and 93 (19.1%), respectively. Furthermore, mixed infections were found in 125 (25.7%), 113 (23.2%), 109 (22.4%) and 52 (10.7%) samples, respectively, which occurred only by chance and were not influenced by additional factors. The obtained nucleotide sequences of B. bovis SBP-4 and B. bigemina RAP-1a genes showed a high homology with other isolates from different countries. Further nucleotide sequence analysis using ITS region showed a great genetic diversity of B. bovis isolates among sampling locations; a lower diversity was found in B. bigemina ITS isolates.

CONCLUSIONS

These data revealed the current distribution of B. bovis and B. bigemina infection in cattle in Indonesia. The rate of infection varied among sampling locations, cattle breeds and age groups. Furthermore, B. bovis ITS isolates from Indonesia were found to be more genetically diverse than B. bigemina ITS isolates. The data presented in this study are necessary to develop an effective strategy for controlling the disease in the country.

An Evaluation of Quantitative PCR Assays (TaqMan® and SYBR Green) for the Detection of Babesia bigemina and Babesia bovis, and a Novel Fluorescent-ITS1-PCR Capillary Electrophoresis Method for Genotyping B. bovis Isolates

Babesia spp. are tick-transmitted haemoparasites causing tick fever in cattle. In Australia, economic losses to the cattle industry from tick fever are estimated at AUD$26 Million per annum. If animals recover from these infections, they become immune carriers. Here we describe a novel multiplex TaqMan qPCR targeting cytochrome b genes for the identification of Babesia spp. The assay shows high sensitivity, specificity and reproducibility, and allows quantification of parasite DNA from Babesia bovis and B. bigemina compared to standard PCR assays. A previously published cytochrome b SYBR Green qPCR was also tested in this study, showing slightly higher sensitivity than the Taqman qPCRs but requires melting curve analysis post-PCR to confirm specificity. The SYBR Green assays were further evaluated using both diagnostic submissions and vaccinated cattle (at 7, 9, 11 and 14 days post-inoculation) showed that B. bigemina can be detected more frequently than B. bovis. Due to fewer circulating parasites, B. bovis detection in carrier animals requires higher DNA input. Preliminary data for a novel fluorescent PCR genotyping based on the Internal Transcribed Spacer 1 region to detect vaccine and field alleles of B. bovis are described. This assay is capable of detecting vaccine and novel field isolate alleles in a single sample.

What's in your next-generation sequence data? An exploration of unmapped DNA and RNA sequence reads from the bovine reference individual

BACKGROUND

Next-generation sequencing projects commonly commence by aligning reads to a reference genome assembly. While improvements in alignment algorithms and computational hardware have greatly enhanced the efficiency and accuracy of alignments, a significant percentage of reads often remain unmapped.

RESULTS

We generated de novo assemblies of unmapped reads from the DNA and RNA sequencing of the Bos taurus reference individual and identified the closest matching sequence to each contig by alignment to the NCBI non-redundant nucleotide database using BLAST. As expected, many of these contigs represent vertebrate sequence that is absent, incomplete, or misassembled in the UMD3.1 reference assembly. However, numerous additional contigs represent invertebrate species. Most prominent were several species of Spirurid nematodes and a blood-borne parasite, Babesia bigemina. These species are either not present in the US or are not known to infect taurine cattle and the reference animal appears to have been host to unsequenced sister species.

CONCLUSIONS

We demonstrate the importance of exploring unmapped reads to ascertain sequences that are either absent or misassembled in the reference assembly and for detecting sequences indicative of parasitic or commensal organisms.

Molecular characterization of the Israeli B. bigemina vaccine strain and field isolates

The present study demonstrated the genetic character of the Israeli Babesia bigemina vaccine strain and field isolates, based on rap-1a and rap-1c gene sequences. The RAP-1a of blood-derived Israeli B. bigemina field isolates shared 100% amino acid sequence identity. However, comparison of RAP-1c from various Israeli B. bigemina field isolates revealed that the total sequence identity among the field isolates ranged from 98.2 to 100%. High identity was observed when RAP-1a sequences from the Israeli vaccine strain and field isolates were compared with RAP-1a from Egypt, Syria, Mexico and South Africa, while, the Israeli RAP-1c sequences showed the highest identity to the Mexican isolate JG-29 and to the PR isolate from Puerto-Rico. Based on sequence variations between the rap-1a of the vaccine strain and that of the field isolate, and between the rap-1c of the vaccine strain and that of the field isolates, nPCR-RFLP procedures were developed that enable, for the first time differentiation between the Israeli B. bigemina vaccine strain and field-infection isolates. These assays could serve as fast and sensitive methods for detection and differentiation between Israeli B. bigemina vaccine strains and field isolates, as well as for epidemiological investigations.

Bovine babesiosis and anaplasmosis complex: diagnosis and evaluation of the risk factors from Bahia, Brazil

Direct diagnoses were made by using - blood smears and nested PCR (nPCR) tests on 309 blood samples from crossbred dairy cattle in the municipality of Ibicaraí, Bahia. From diagnostic blood smear slides, the observed parasitic frequencies were 31.1% for Anaplasma marginale and 20.4% for Babesia sp. From nPCR diagnoses, they were 63% for A. marginale, 34% for Babesia bigemina and 20.4% for Babesia bovis. There were significant differences (P <0.01) between the two diagnostic methods (nPCR and blood smear slides). The compliance obtained from the kappa test was 0.41 and 0.48 for A. marginale and Babesia sp., respectively. The tick samples from the six farms analyzed using nPCR were only positive for A. marginale. Evaluation of the risk factors relating to the presence of ticks and the age of the animals showed that there was a significant association (P <0.01) with the frequency of animals infected with both pathogens. Therefore, under the conditions studied, nPCR proved to be a good tool for diagnosing the agents of the bovine babesiosis and anaplasmosis complex because of its sensitivity and specificity in comparison with blood smears. The municipality of Ibicaraí is an area with endemic prevalence of bovine babesiosis and anaplasmosis confirmed by nPCR and A. marginale is the main agent of the disease.

Molecular and serological prevalence of Babesia bigemina and Babesia bovis in cattle and water buffalos under small-scale dairy farming in Beheira and Faiyum Provinces, Egypt

In order to determine the molecular and serological prevalence of Babesia bigemina and Babesia bovis, a total of 247 blood samples were collected from cattle and water buffalos in Beheira and Faiyum Provinces in Egypt and examined by nested polymerase chain reaction (nPCR) and enzyme-linked immunosorbent assay (ELISA). In cattle, the prevalence of B. bigemina and B. bovis was 5.30% and 3.97% by nPCR and 10.60% and 9.27% by ELISA, respectively, whereas those of water buffalos were 10.42% and 4.17% by nPCR and 15.63% and 11.46% by ELISA, respectively. Statistically significant differences in the prevalence of the two infections were observed on the basis of age and health status. Sequencing analysis revealed two genotypes for B. bovis spherical body protein-4. In conclusion, the current data provide valuable information regarding the epidemiology of B. bigemina and B. bovis infections in cattle and water buffalos from Egypt, which can be employed in developing future strategies for disease management and control.

Epidemiological survey of Babesia bovis and Babesia bigemina infections of cattle in Philippines

A total of 250 blood samples were collected from clinically healthy cattle in five provinces of Philippines. DNA was extracted from the samples and analyzed by nested PCR assays for an epidemiological survey of Babesia bovis and Babesia bigemina infections. Out of the 250 samples, 27 (10.8%) and 16 (6.4%) were positive for B. bovis infection and B. bigemina infection, respectively. Mixed infections were detected in a total of 4 samples (1.6%). Our data provide baseline information regarding the epidemiology of B. bovis and B. bigemina infections in cattle in Philippines, which can be utilized in developing proper strategies for disease control and management.

The use of different diagnostic tools for Babesia and Theileria parasites in cattle in Menofia, Egypt

Bovine piroplasmosis is caused by tick-borne hemoprotozoans of the genera Babesia and Theileria and is the most prevalent in tropical and subtropical countries, causing a major economic impact worldwide. In the current study, a total of 405 cattle of different ages, sexes, and breeds were randomly sampled for surveying and diagnosis of babesiosis and theileriosis using three methods: direct microscopy (blood smears), indirect fluorescent antibody test (IFAT) and polymerase chain reaction (PCR). Giemsa-stained blood smears revealed that, out of 405 examined cattle, 33 (8.15 %) were infected with Babesia sp. and 65 (16.05 %) with Theileria sp. (total number of infected cattle was 98). Mixed infection was seen in 11 (2.72 %) animals. Moreover, application of the three diagnostic assays on 158 randomly sampled cattle indicated that 17 (10.76 %) and 33 (20.89 %) were positive for Babesia and Theileria spp. by the direct smear technique, 25 (15.82 %) and 33 (20.89 %) by IFAT (fluorescence was greenish yellow for Babesia and yellowish for Theileria), and 20 (12.66 %) and 38 (24.05 %) by PCR. Using primers specific for Babesia and Theileria spp., we found that diagnostic bands appeared at ~350 and ~370 bp, respectively indicating the presence of these piroplasms. Statistically, there was a non-significant difference of the positivity in response to the three techniques; thus, any of these methods can be described as useful for diagnosing blood parasites in both domesticated animals and birds. On the basis of the obtained results, it could be concluded that direct microscopy can be used in acute infections, whereas IFAT and PCR are useful in chronicity.