Serological and molecular diagnostic surveys combined with examining hematological profiles suggests increased levels of infection and hematological response of cattle to babesiosis infections compared to native buffaloes in Egypt

In Egypt, bovine babesiosis is caused mainly by Babesia bovis and Babesia bigemina, with B. bovis parasites transmitted by Rhipicephalus microplus and B. bigemina transmitted by both R. microplus and Rhipicephalus annulatus. The disease has a significant economic impact on meat and milk production and livestock management, making it the most important endemic parasitic disease affecting cattle in Egypt. Babesiosis is caused by intraerythrocytic protozoan parasites of the genus Babesia that infect a wide range of domestic and wild animals and occasionally humans. The disease has the potential to cause large economic and sanitary disruptions, compromising the livestock industry worldwide. In Egypt, previous studies suggest that there are large numbers of cattle infected with subclinical babesiosis, and although clinical evidence suggests that buffaloes are likely more tolerant to Babesia infections, the hematological response of buffaloes to Babesia infection in Egypt remains poorly investigated. Accurate diagnosis of babesial infections plays an important role in monitoring, management, and control. A large diversity of diagnostic techniques exists, including blood smear examination, serological tests, and molecular (DNA-based) assays. However, each of these methods has limitations, and accurate diagnosis requires a combination of distinct approaches. Blood smear examination is often considered the standard technique for routine diagnosis of babesiosis, particularly in acute cases, but it is insufficient for accurate detection and identification of B. bovis and B. bigemina during mixed infections and in particular for the detection of carrier cases or subclinical infections with low parasitemia. Serological tests, including the indirect fluorescent antibody test (IFAT) and the enzyme-linked immunosorbent assay (ELISA), are capable of detecting antibodies in carrier animals and are often used for monitoring surveillance and export certification. However, specific and sensitive competitive ELISA (cELISA) methods have been developed for B. bovis and B. bigemina, and their use has been validated in several diagnostic laboratories around the world. DNA-based methods, including PCR techniques, have also been employed in the diagnosis of B. bovis and B. bigemina babesiosis, with appropriate targets for PCR assays including well-conserved and species-specific genes. The aim of the present study is to estimate the presence of bovine and buffaloes babesiosis in distinct populations in Egypt using blood smear examination, competitive inhibition ELISA, and novel PCR procedures based on the amplification of the recently identified and highly conserved rhoptry-associated protein (rap)-1c gene of B. bigemina and rap-1 related antigen (rra) gene of B. bovis. The study also compared Babesia-associated hematological alterations in cattle and buffaloes. A total of 253 and 81 blood samples from apparently healthy cattle and buffaloes, respectively, were randomly collected from diverse locations in Egypt and tested for Babesia bovis and B. bigemina infection using blood film examination, competitive ELISA, and PCR. The results of the study revealed that blood films examination revealed 13.8% and 7.4% Babesia infection rates in cattle and buffaloes, respectively. However, in cattle, the cELISA detected 32.8%, 21.3%, and 10.7% infection rates with B. bigemina, B. bovis, and mixed infection, respectively. In addition, cELISA identified 22.2%, 22.2%, and 6.2% infection rates with B. bigemina, B. bovis, and mixed infection, respectively in buffaloes. The semi-nested PCR assay showed that 15% of the tested samples were positive for B. bovis in cattle, but just 3% in buffaloes. Infections with B. bigemina were also found in cattle (32.4%), but not in buffaloes upon nested PCR analysis. Sequencing analysis confirmed the identity of the PCR amplicons and showed that Egyptian genotypes of B. bigemina and B. bovis highly resemble sequences previously deposited in GenBank. Hemograms performed on the sampled animals revealed macrocytic hypochromic anemia associated with reduced platelet counts in infected cattle with babesiosis. In addition, marked increases in total leukocyte and granulocytic counts and decreases in lymphocytic counts were found in infected cattle. In contrast, no such hematological anomalies were found in presumably Babesia-infected buffaloes. The study suggests that frequent occurrence of babesiosis among apparently healthy bovines in Egypt indicates the need for appropriately designed prevalence studies in this country. Infected bovine, but not buffalo, populations often present hemat