Validation of a competitive enzyme-linked immunosorbent assay for diagnosing Babesia equi infections of Moroccan origin and its use in determining the seroprevalence of B. equi in Morocco.

This research is about the validation of a test (competitive enzyme-linked immunosorbent assay) used to diagnose a specific parasitic infection (Babesia equi) in Moroccan horses and donkeys, and its subsequent application to evaluate the prevalence of infections in donkeys and horses across the country.

Validation of the Diagnostic Test

The researchers developed and validated a highly specific and sensitive diagnostic test, a competitive enzyme-linked immunosorbent assay (cELISA). This type of test is used to detect specific antibodies in animal serum, in this case, those that target the Babesia equi, a parasite which mainly infect horses and donkeys. The assay is designed around the principle of a specific monoclonal antibody binding to a conserved epitope found within a recombinant peptide of the B. equi parasite. The test measures how much of this binding is inhibited by serum from infected animals.

• The test was compared to an established indirect immunofluorescence assay and showed a high level of agreement (91%), thus demonstrating that the cELISA performs well as a diagnostic tool.

Defining Prevalence of B. equi in Morocco

Utilizing the validated assay, the research continued to determine the seroprevalence (the measure of the presence of specific antibodies in the population) of B. equi in horses and donkeys across Morocco. To do this, the researchers collected and tested serum from 578 animals (163 horses and 415 donkeys) from six different bioclimatic regions across the country.

• Results of their tests revealed that donkeys were significantly more likely than horses to be seropositive for B. equi.
• The location from where animals were sampled did not significantly impact the test results according to an analysis of variance, suggesting that infection occurs ubiquitously across different bioclimatic regions of Morocco.
• It was proposed that management conditions, which might contribute to a greater exposure to ticks (the primary vector for B. equi), could explain the higher susceptibility of donkeys to infection.

This research not only validated a new diagnostic tool for a prevalent equine parasite, but it also provided valuable epidemiological data about the presence and distribution of this parasitic infection in Morocco.