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Comparison of Microscopy and PCR-RFLP for detection of Anaplasma marginale in carrier cattle.

ABSTRACT: BACKGROUND AND OBJECTIVES:In Iran, anaplasmosis is normally diagnosed with traditional Giemsa staining method. This is not applicable for identification of the carrier animals. The aim of this study was to compare the detection of Anaplasma marginale in two different numbers of microscopic fields (50 and 100) using conventional Giemsa staining method compared with the PCR-RFLP technique. MATERIALS AND METHODS:In this study, examinations were performed on 150 blood samples from cattle without clinical signs. Sensitivity and specificity of two microscopic fields (50 and 100 fields) were compared with A. marginale specific PCR-RFLP. The degree of agreement between PCR-RFLP and the two microscopic tests was determined by Kappa (?) values with 95% confidence intervals. RESULTS:PCR-RFLP showed that 58 samples were A. marginale, while routine microscopy showed erythrocytes harboring Anaplasma like structures in 16 and 75 blood samples determined in 50 and 100 microscopic fields respectively. Examination of 50 and 100 microscopic fields showed 25.8% and 91.4% sensitivity and 99% and 76.1% specificity compared to 100% sensitivity and specificity by PCR-RFLP. The Kappa coefficient between PCR-RFLP and Microscopy (50 fields) indicated a fair level of agreement (0.29). The Kappa coefficient between PCR-RFLP and Microscopy (100 fields) indicated a good level of agreement (0.64) CONCLUSION:Our results showed that the microscopic examination remains the convenient technique for day-to-day diagnosis of clinical cases in the laboratory but for the detection of carrier animal with low bacteremia, microscopy with 100 fields is preferable to Microscopy with 50 fields and molecular methods such as PCR-RFLP can be used as a safe method for identifying cattle persistently infected with A. marginale.

SUBMITTER: Noaman V

PROVIDER: S-EPMC3279773 | biostudies-literature | 2010 Jun

REPOSITORIES: biostudies-literature

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Comparison of Microscopy and PCR-RFLP for detection of Anaplasma marginale in carrier cattle.

Noaman V V Shayan P P

Iranian journal of microbiology 20100601 2

<h4>Background and objectives</h4>In Iran, anaplasmosis is normally diagnosed with traditional Giemsa staining method. This is not applicable for identification of the carrier animals. The aim of this study was to compare the detection of Anaplasma marginale in two different numbers of microscopic fields (50 and 100) using conventional Giemsa staining method compared with the PCR-RFLP technique.<h4>Materials and methods</h4>In this study, examinations were performed on 150 blood samples from cat ...[more]

PMID: 22347555

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Project description:Tropical theileriosis, bovine babesiosis and anaplasmosis are tick-borne protozoan diseases that impose serious constraints on the health and productivity of domestic cattle in tropical and sub-tropical regions of the world. A common feature of these diseases is that, following recovery from primary infection, animals become persistent carriers of the pathogen and continue to play a critical role in disease epidemiology, acting as reservoirs of infection. This study describes development and evaluation of multiplex and single PCR assays for simultaneous detection of Theileria annulata, Babesia bovis and Anaplasma marginale in cattle. Following in silico screening for candidate target genes representing each of the pathogens, an optimised multiplex PCR assay was established using three primer sets, cytob1, MAR1bB2 and bovar2A, for amplification of genomic DNA of T. annulata, A. marginale and B. bovis respectively. The designed primer sets were found to be species-specific, generating amplicons of 312, 265 and 166 base pairs, respectively and were deemed suitable for the development of a multiplex assay. The sensitivity of each primer pair was evaluated using serial dilutions of parasite DNA, while specificity was confirmed by testing for amplification from DNA of different stocks of each pathogen and other Theileria, Babesia and Anaplasma species. Additionally, DNA preparations derived from field samples were used to evaluate the utility of the single and multiplex PCRs for determination of infection status. The multiplex PCR was found to detect each pathogen species with the same level of sensitivity, irrespective of whether its DNA was amplified in isolation or together with DNA representing the other pathogens. Moreover, single and multiplex PCRs were able to detect each species with equal sensitivity in serially diluted DNA representing mixtures of T. annulata, B. bovis and A. marginale, and no evidence of non-specific amplification from non-target species was observed. Validation that the multiplex PCR efficiently detects single and mixed infections from field samples was demonstrated. The developed assay represents a simple and efficient diagnostic for co-detection of tropical theileriosis, bovine babesiosis and anaplasmosis, and may be a valuable tool for epidemiological studies aimed at assessing the burden of multiple infection with tick-borne pathogens and improving control of the associated diseases in endemic regions.

Project description:BackgroundOnly a few studies have examined the presence of Anaplasma marginale and Anaplasma centrale in South Africa, and no studies have comprehensively examined these species across the whole country. To undertake this country-wide study we adapted a duplex quantitative real-time PCR (qPCR) assay for use in South Africa but found that one of the genes on which the assay was based was variable. Therefore, we sequenced a variety of field samples and tested the assay on the variants detected. We used the assay to screen 517 cattle samples sourced from all nine provinces of South Africa, and subsequently examined A. marginale positive samples for msp1α genotype to gauge strain diversity.ResultsAlthough the A. marginale msp1β gene is variable, the qPCR functions at an acceptable efficiency. The A. centrale groEL gene was not variable within the qPCR assay region. Of the cattle samples screened using the assay, 57% and 17% were found to be positive for A. marginale and A. centrale, respectively. Approximately 15% of the cattle were co-infected. Msp1α genotyping revealed 36 novel repeat sequences. Together with data from previous studies, we analysed the Msp1a repeats from South Africa where a total of 99 repeats have been described that can be attributed to 190 msp1α genotypes. While 22% of these repeats are also found in other countries, only two South African genotypes are also found in other countries; otherwise, the genotypes are unique to South Africa.ConclusionsAnaplasma marginale was prevalent in the Western Cape, KwaZulu-Natal and Mpumalanga and absent in the Northern Cape. Anaplasma centrale was prevalent in the Western Cape and KwaZulu-Natal and absent in the Northern Cape and Eastern Cape. None of the cattle in the study were known to be vaccinated with A. centrale, so finding positive cattle indicates that this organism appears to be naturally circulating in cattle. A diverse population of A. marginale strains are found in South Africa, with some msp1α genotypes widely distributed across the country, and others appearing only once in one province. This diversity should be taken into account in future vaccine development studies.

Dataset Information

Comparison of Microscopy and PCR-RFLP for detection of Anaplasma marginale in carrier cattle.

Publications

Comparison of Microscopy and PCR-RFLP for detection of Anaplasma marginale in carrier cattle.

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