Active infection and morphometric study of Trypanosoma evansi among horses in Peninsula Malaysia.

The research article reports on a study that examined the prevalence of Trypanosoma evansi infection in horses in Peninsula Malaysia, using various diagnostic tools. The study further investigated parasite size and correlation with levels of anaemia in the affected horses.

Objective of the Study

The researchers sought to fill the information gap about Trypanosoma evansi (a protozoan parasite) in horses in Peninsula Malaysia, given the limited reports on the disease in this region. This parasite causes ‘surra’, a disease known to affect various mammals including horses, causing symptoms like fever, anaemia and even death in severe conditions.

Methodology

• A total of 527 blood samples were collected from horses across eight states in Peninsula Malaysia.
• These samples were tested using the haematocrit centrifugation technique (HCT), Giemsa-stained thin blood smear (GSS), morphometric measurements, polymerase chain reaction (PCR), and cloning of PCR products.

Results

• The parasitological prevalence was 0.57% amongst the sample, identified through both HCT and GSS techniques.
• Morphometric study showed the average total length of the parasites, including the free flagellum, was about 28 μm.
• PCR, a more sensitive diagnostic tool, identified the parasite in 1.14% of samples, confirmed by nucleotide sequences.
• The mean packed cell volume (PCV, a measure of anaemia) for the positive cases detected by HCT was lower in comparison to the cases detected by PCR in the state of Terengganu. This implies that PCR was able to detect infections even in the absence of pronounced anaemia.

Conclusions

Even though the frequency of T. evansi infection in horses in Peninsula Malaysia appears to be low, the study emphasizes the need to further investigate, given the possible presence of a more virulent strain indicated by the slightly lengthier parasites and the presence of anaemia in infected horses. The use of PCR as a sensitive diagnostic tool was highlighted, especially when parasitaemia is undetectable. The researchers recommend further studies to enhance understanding of the host-parasite relationship and its epidemiological implications.