Abstract
BackgroundAnaplasma marginale is an obligate intracellular bacterium and the main cause of bovine anaplasmosis in tropical and subtropical regions. In Egypt, data regarding the prevalence of A. marginale in ruminant hosts and of the circulating genotypes is lacking. This study therefore aimed to (i) investigate the presence, epidemiology and genotypes of A. marginale in cattle and buffaloes in Egypt, (ii) to evaluate suitable diagnostic tools and (iii) to identify co-infections of A. marginale with other selected tick-borne pathogens.MethodsBlood samples were collected from 394 animals (309 cattle and 85 buffaloes) from three different areas in Egypt. For the detection of A. marginale infection, several tests were compared for their sensitivity and specificity: blood smear analysis, enzyme-linked immunosorbent assay (ELISA), PCR, real-time PCR and reverse line blot (RLB) assay. Co-infections with A. marginale, piroplasms and other Anaplasmataceae were surveyed by RLB while A. marginale genotypes were identified by amplifying and sequencing the partial msp1α gene.ResultsAnaplasma marginale DNA was amplified by qPCR in 68.3% of cattle and 29.4% of buffaloes. RLB showed infection with A. marginale in 50.2% of cattle and 42.5% of buffaloes. Blood smear analysis detected this agent in 16.2% of cattle and 2.4% of buffaloes. ELISA showed specific antibodies against A. marginale in 54.9% of cattle. Anaplasma marginale was associated, in cattle and buffaloes, with several tick-borne pathogens (Theileria annulata, Babesia bovis, Babesia bigemina, Babesia occultans and Anaplasma platys). A significant difference of A. marginale infection level was noticed in cattle, where animals between 3–5-years-old had a higher prevalence (79.2%) compared to those older than 5 years (36.4%) and younger than 3 years (59.7%) and one year (64.5%), respectively (P = 0.002281). Microsatellite analysis identified 15 different genotypes.ConclusionsThe epidemiological findings revealed high prevalence of A. marginale in cattle and buffaloes in all the investigated areas. The circulation of diverse genotypes was observed, most of these A. marginale genotypes being specific for Egypt. The qPCR assay was confirmed to be the most sensitive tool for detection of A. marginale in cattle and buffaloes even in the carrier state, highlighting the importance of using suitable diagnostic tests.
Highlights
Anaplasma marginale is an obligate intracellular bacterium and the main cause of bovine anaplasmo‐ sis in tropical and subtropical regions
Animals originated from three different localities: Middle Egypt (119 cattle and 23 buffaloes), Upper Egypt (111 cattle and 62 buffaloes) and Egyptian Oases (79 cattle)
Buffaloes tested positive for co-infections with A. marginale and T. annulata (n = 1; 1.18%), B. bigemina (n = 2; 2.35%) and A. platys (n = 4; 4.71%)
Summary
Anaplasma marginale is an obligate intracellular bacterium and the main cause of bovine anaplasmo‐ sis in tropical and subtropical regions. Bovine anaplasmosis is characterized by mild to severe hemolysis and anemia that adversely affects animal health, production and reproduction [9, 10] It is caused by Anaplasma marginale, an intraerythrocytic rickettsia mainly transmitted by Rhipicephalus microplus ticks, but other tick species have been incriminated as vectors worldwide [11, 12]. Mechanical transmission through contaminated needles or surgical instruments under poor hygienic conditions or through biting flies may occur Both tick and animal hosts are considered reservoirs for this pathogen and can become persistently infected with A. marginale. Coinfections with A. marginale and other tick-borne pathogens such as Theileria, Babesia and other Anaplasma species are common in cattle [4, 13,14,15]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
