Stress conditions do not affect Theileria equi parasitemia levels in sub-clinically infected horses.

The study investigates the effect of stress on Theileria equi blood parasite levels in horses that are sub-clinically infected. The researchers found that stress did not have a significant impact on the parasite levels in the examined horses.

Research Objective

The research aimed to examine whether stress triggers a significant increase in the levels of Theileria equi parasitemia – a condition where parasites are present in the patient’s blood – in horses that are sub-clinically infected.

Methodology

• The study comprised two separate settings: a veterinary teaching hospital and an endurance farm.
• At the hospital, blood samples were collected from 32 horses when they were admitted and when they got discharged. The goal was to compare the horses that had undergone surgery – the stress group – with other hospitalized horses – the control group – in terms of their T. equi parasite load.
• At the endurance farm, blood samples were collected from 20 horses six weeks prior to and two days post an 80-km endurance event. The intent was to compare the parasite loads of horses that participated in the event (stress group) with horses that didn’t (control group).
• At both settings, the researchers utilized qPCR to evaluate T. equi parasite loads, and subsequently computed each horse’s parasite load ratio for the two time points, T1/T0.

Results

• The mean parasite load across both time points did not show significant statistical variation between the control group and the stress group for both settings. This demonstrates that stress had no evident impact on the levels of T. equi in the sampled horses.
• Using the 18S rRNA gene for identification, they determined the genotype of the T. equi parasites when feasible. The parasite genotypes were found to be similar to strains previously characterized in the region, and were classified as genotypes A and D.

Conclusion

These findings challenge the widely held belief that stress can lead to an increased parasite load in horses with a subclinical T. equi infection. The stress conditions applied in the study apparently had no effect on the level of T. equi parasitemia in sub-clinically infected horses.