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United States Department of Agriculture

Agricultural Research Service

Research Project: Pharmacological and Immunologic Interventions Against Vector-Borne Bovine and Equine Babesiosis

Location: Animal Diseases Research

Title: Diagnosis of theileria equi infections in horses in the Azores using cELISA and nested PCR

Authors
item Baptista, Cláudio -
item Lopes, Maria -
item Tavares, Ana -
item Rojer, Horst -
item Kappmeyer, Lowell
item Mendonça, Duarte -
item Da Câmara Machado, Artur -

Submitted to: Ticks and Tick Borne Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 4, 2013
Publication Date: January 19, 2013
Citation: Baptista, C., Lopes, M.S., Tavares, A.C., Rojer, H., Kappmeyer, L.S., Mendonça, D., Da Câmara Machado, A. 2013. Diagnosis of theileria equi infections in horses in the Azores using cELISA and nested PCR. Ticks and Tick Borne Diseases. 4(3):242-245.

Interpretive Summary: Tick-transmitted single-cell parasites of the group Apicomplexa cause disease and result in death or persistent infection and represent a major challenge to global human and animal health. One member of the group, the horse parasite Theileria equi is monitored in horses, and those found positive for infection are restricted in movement to prevent exposure to other animals. Monitoring in horses typically checks for antibodies to the parasite in horse blood using a test called the cELISA. A DNA-based test to check for parasite DNA in the blood of horses is also used in some cases. These two tests were compared in a survey of horses for Theileria equi in the Azores Islands and the Portugal mainland. The two tests had a high degree of agreement in comparing results from a group of 162 samples from mainland Portugal and 143 samples from the Azores. Importantly, the tests were used to determine that a rare population of ponies called the Terceira pony with only 38 individuals was all negative for Theileria equi. The authors propose careful testing of horses before import to the islands to protect this rare breed of horses from exposure and further threat to their existence.

Technical Abstract: Equine piroplasmosis is a tick-borne disease of equids that is often caused by the parasite Theileria equi. We applied competitive ELISA (cELISA) and nested PCR diagnostic methods to detect this parasite in horses by screening 162 samples from mainland Portugal where the parasite is endemic, and 143 from the Azores representing both native and imported horse populations. We found that 2.8% of the Azorean samples tested positive exclusively by cELISA, 1.4% tested positive only by nested PCR, and 9.1% tested positive using both tests. Samples from the native Terceira Pony population were negative for both tests. The parasite was more prevalent in samples from mainland Portugal when both test methods were considered (9.3% positive exclusively by cELISA, 1.9% positive exclusively by nested PCR, and 16.7% positive for both tests). To our knowledge, this is the first time that molecular techniques have been used to detect T. equi in the Azores and the first report of this parasite in the archipelago. Based on this study, it is clear that the import of horses into the Azores and the movement of horses between the islands must be controlled to reduce the risk of new infections, contributing to the protection of native horse populations such as the Terceira Pony population.

Last Modified: 4/19/2014
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