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Title: Assessment of theileria equi and babesia caballi infections in equine populations in Egypt by molecular, serological and hematological approaches

Author
item MAHMOUD, M - National Research Centre
item ABU EL-EZZ, N - National Research Centre
item ABDEL-SHAFY, S - National Research Centre
item NASSAR, S - National Research Centre
item EL NAMAKY, A - National Research Centre
item KHALIL, WK - National Research Centre
item Knowles Jr, Donald
item Kappmeyer, Lowell
item SILVA, M - Washington State University
item Suarez, Carlos

Submitted to: Parasites & Vectors
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/26/2016
Publication Date: 5/4/2016
Citation: Mahmoud, M.S., Abu El-Ezz, N.T., Abdel-Shafy, S., Nassar, S.A., El Namaky, A.H., Khalil, W.B., Knowles Jr, D.P., Kappmeyer, L.S., Silva, M.G., Suarez, C.E. 2016. Assessment of theileria equi and babesia caballi infections in equine populations in Egypt by molecular, serological and hematological approaches. Parasites & Vectors. doi: 10.1186/s13071-016-1539-9.

Interpretive Summary: Equine piroplasmosis caused by Theileria equi, Babesia caballi, or both, cause significant economic losses in the equine industry and remains uncontrolled in Egypt. The main objectives of this study were estimating the prevalence of equine pirolasmosis in distinct populations in Egypt, and examining hematological alterations present in this group of animals including horses and donkeys. Blood field samples were tested for Babesia caballi and Theileria equi infection using blood film examination, indirect immunofluorescent antibody test (IFAT), cELISA and PCR assays with species-specific primers. Overall, the data confirms relatively high levels of infection with either T. equi and/or B. caballi, likely causing hematological abnormalities in horses in Egypt. Yet, the cELISA test used for the serological diagnosis failed completely in identifying infected equids, despite the identification of B. caballi infected animals using PCR and IFAT. The failure of the test could be due to sequence polymorphism found in the rap-1 genes of the Egyptian strains of B. caballi. This finding suggests the need for developing improved serological test for the diagnosis of B. caballi infection in Egypt.

Technical Abstract: Background: Equine piroplasmosis caused by Theileria equi, Babesia caballi, or both, cause significant economic losses in the equine industry and remains uncontrolled in Egypt. Methods: T. equi and B. caballi infections were assessed in blood from 88 horses and 51 donkeys from different localities of Egypt using microscopic examinations, indirect immunofluorescent antibody test (IFAT), nested PCR (nPCR), and competitive-ELISA (cELISA) assays. PCR products were examined by DNA sequencing. Hematological alterations were evaluated using a standard cell counter. Results: Microscopic analysis revealed EP infection in 11.4% and 17.8% for horses and donkeys respectively. IFAT detected 23.9% and 17.0% infection for T. equi and B. caballi respectively in horses, and 31.4% for T. equi and B. caballi in donkeys. The T. equi cELISA detected 14.8 % and 23.5 % positive horses and donkeys respectively, but the B. caballi RAP-1-based cELISA failed in detecting positive samples, which could be due to sequence polymorphism found in the rap-1 genes. nPCR analysis identified 36.4% and 43.1% positive horses and donkeys, respectively for T. equi and it also identified 19.3% and 15.7% positive horses and donkeys, respectively for B. caballi. Hematologic analysis revealed macrocytic hypochromic anemia, and thrombocytopenia in all piroplasma-infected horses. Conclusions: The data confirms relatively high levels of infection with either T. equi and/or B. caballi, likely causing hematological abnormalities in horses in Egypt and suggests the need for improved serological test for the diagnosis of B. caballi infection in this country.