Improved molecular detection of Ehrlichia and Anaplasma species applied to Amblyomma ticks collected from cattle and sheep in Ethiopia

Tick-borne diseases (TBDs) cause significant losses among livestock and impact the livelihoods of resource-poor farming communities worldwide. In Ethiopia, detailed studies on the epidemiology of tick-borne pathogens (TBPs) in cattle using sensitive molecular detection methods are scarce. The objective of this study was to determine the prevalence and species composition of bovine TBPs of veterinary significance in local cattle populations. A comprehensive cross-sectional epidemiological study was conducted in cattle populations of Illubabor zone in Southwestern Ethiopia from June to August 2013. For this purpose, blood samples were collected from 392 cattle. A combination of polymerase chain reaction (PCR) and a Reverse Line Blot (RLB) hybridization assay was employed for the detection of TBPs in these samples. The PCR/RLB results of the 392 blood samples indicated a high overall prevalence of 96.9% for TBPs, including Theileria mutans (66.1%), Theileria orientalis (51.8%), Anaplasma sp. Omatjenne (25.5%), Anaplasma marginale (14.5%), Babesia bigemina (14.0%) and Theileria velifera (13.0%) and minor occurrences of Ehrlichia ruminantium (0.5%) and Ehrlichia minasensis (0.26%). Moreover, three novel Anaplasma genotypes were detected in bovine blood samples. A phylogenetic analysis revealed that they most likely represent three, but at least two, new species. The prevalence of the three novel Anaplasma species, preliminary designated as Anaplasma sp. Hadesa, Anaplasma sp. Saso and Anaplasma sp. Dedessa, was 12.5%, 14.3% and 5.6%, respectively. Overall, a total of 227 cattle (57.9%) were found to be co-infected with two or more TBPs simultaneously and 86 different species combinations were observed. The findings show a very high burden of infection of cattle with TBPs in Ethiopia. The high frequency of co-infections suggests that clinical manifestations might be complex. Further research is required to determine the pathogenicity, host cell types and vector of the three novel Anaplasma species identified in this study.

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“…DNA of E . ruminantium was previously also detected in Amblyomma ticks from Ethiopia [ 5 , 6 ]. The presence of pathogenic TBPs such as E .…”

Section: Discussionmentioning

confidence: 95%

“…variegatum and Am . lepidum ticks collected from two locations in Central Oromia and one in the Amhara Region of Ethiopia [ 5 ]. Its pathogenicity is still poorly understood.…”

Section: Discussionmentioning

confidence: 99%

Molecular detection of tick-borne pathogens in cattle from Southwestern Ethiopia

et al. 2017

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“…15 Volumes of whole blood utilized in published B. microti PCR protocols range from 200 mL to 2.0 mL, with corresponding analytical sensitivities ranging between 10 and 100 gene copies per PCR procedure. 7-10 …”

Section: Discussionmentioning

confidence: 99%

“…4 More recently, polymerase chain reaction (PCR) tests have been developed which detect B. microti DNA. 7-10 Individuals who are infected with B. microti also develop an immune response which is detectable by serologic assays such as immunofluorescent assay (IFA), enzyme-linked immunosorbent assay, and immu-noblot. 11-13 Antibody titers and direct markers of infectivity in asymptomatic blood donors, however, have only recently been evaluated.…”

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confidence: 99%

Serologic screening of United States blood donors for Babesia microti using an investigational enzyme immunoassay

Levin

Williamson²,

Bloch

et al. 2016

Transfusion

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BACKGROUND The tick-borne pathogen Babesia microti has become recognized as the leading infectious risk associated with blood transfusion in the United States, yet no Food and Drug Administration–licensed screening tests are currently available to mitigate this risk. The aim of this study was to evaluate the performance of an investigational enzyme immunoassay (EIA) for B. microti as a screening test applied to endemic and nonendemic blood donor populations. STUDY DESIGN AND METHODS The study aimed to test 20,000 blood donors from areas of the United States considered endemic for B. microti and 10,000 donors from a nonendemic area with the investigational B. microti EIA. Repeat-reactive samples were retested by polymerase chain reaction (PCR), blood smear, immunofluorescent assay (IFA), and immunoblot assay. In parallel, serum samples from symptomatic patients with confirmed babesiosis were tested by EIA, IFA, and immunoblot assays. RESULTS A total of 38 of 13,757 (0.28%) of the donors from New York, 7 of 4583 (0.15%) from Minnesota, and 11 of 8363 (0.13%) from New Mexico were found repeat reactive by EIA. Nine of the 56 EIA repeat-reactive donors (eight from New York and one from Minnesota) were positive by PCR. The specificity of the assay in a nonendemic population was 99.93%. Among IFA-positive clinical babesiosis patients, the sensitivity of the assay was 91.1%. CONCLUSION The B. microti EIA detected PCR-positive, potentially infectious blood donors in an endemic population and exhibited high specificity among uninfected and unexposed individuals. The EIA promises to provide an effective tool for blood donor screening for B. microti in a format amenable to high-throughput and cost-effective screening.

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“…Ehrlichia sp. (Omatjenne), which is apparently apathogenic has also been detected in several ruminants in South Africa including Boer goats [28], in Uganda [18] and in Ethiopia [29,30].The observed epizootiological picture with respect to Ehrlichia spp [E. sp. (Omatjenne)] and E.ruminantium from all the cited studies and ours suggests that other rickettsia or pathogens may be causing pathological or clinical signs similar to those of heartwater in the region since both show crossreactivity [18].…”

Section: Discussionmentioning

confidence: 86%

Molecular detection of concurrent infections of Anaplasma sp Omatjenne, Theileria mutans, Babesia bigemina and Anaplasma marginale in calves and yearlings in a tick endemic Guinea savannah ecosystem in Cameroon

Achukwi¹,

Sali²,

Madder³

et al. 2020

Preprint

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Background Ticks infesting animals constitute one of the most important factors limiting profitable livestock production in sub-Saharan Africa and the region is beleaguered by a paucity of data on diseases implicated in high morbidity and mortality in most of its livestock production systems. Methods In a tick endemic Guinea savannah ecosystem, ticks infesting calves and yearlings during their first eighteen months of life were collected weekly and morphologically identified. PCR, Restriction Fragment Length Polymorphism (RFLP) and sequencing were applied on DNA of tick-borne pathogens in animal blood buffy coat to amplify and characterize the 16S rRNA genes of Anaplasma, Ehrlichia and 18S rRNA gene for Babesia spp. Results Of 31 364 adult ticks, nymphs and larvae collected from the 20 experimental animals, 6525 (20.1%), 7399 (23.6%), 990 (3.2%), 16450 (52.4%) were Amblyomma variegatum, Rhipicephalus spp., other genera, and tick larvae respectively. Tick infestation rates during the rainy season for A.variegatum, Rhipicephalus spp. and larvae were 50.3, 12.4 and 28.3, respectively, while in the dry season the proportions were one, 26.2 and 72.8 respectively. A. variegatum had no effect on haematocrit (P > 0.05) but high Rhipicephalus spp. (Boophilus) infestation rates significantly reduced haematocrit (P < 0.01). All animals had mixed infections of haemoparasites. The effect of season on haematocrit was not significant (P > 0.05). The presence of Anaplasma marginale and Anaplasma sp. Omatjenne in the blood significantly reduced haematocrit (p < 0.0001) while Babesia bigemina and Theileria mutans had no effect (P > 0.05). No E. ruminantium was detected. We report for the first time in Cameroon, the detection of Anaplasma sp. Omatjenne and T.mutans infecting all and four of the animals, respectively. Babesia bigemina, and Anaplasma sp.Omatjenne concurrently occurred in all 20 experimental animals, A.marginale in 15 and T.mutans in four. The mean first-time contact periods (in weeks) for B.bigemina, T.mutans, Anaplasma sp.Omatjenne and A.marginale were 15(3–37), 30(9–43), 21(5–55) and 25(7–55) respectively; and they were not significantly different (P > 0.05). Conclusion The absence of clinical cases of the four pathogens detected during the study demonstrates an endemically stable situation in the region for these infections. With no clinical data on A.sp. Omatjenne and T.mutans infections in this area, further insights into their epizootiology should be of interest.

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Improved molecular detection of Ehrlichia and Anaplasma species applied to Amblyomma ticks collected from cattle and sheep in Ethiopia

Cited by 35 publications

References 27 publications

Molecular detection of tick-borne pathogens in cattle from Southwestern Ethiopia

Molecular detection of tick-borne pathogens in cattle from Southwestern Ethiopia

Serologic screening of United States blood donors for Babesia microti using an investigational enzyme immunoassay

Molecular detection of concurrent infections of Anaplasma sp Omatjenne, Theileria mutans, Babesia bigemina and Anaplasma marginale in calves and yearlings in a tick endemic Guinea savannah ecosystem in Cameroon

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