Antibodies against Apicomplexa protozoa and absence sarcocysts in heart tissues from horses in southern Brazil.

The research article presents a study that investigates the prevalence of antibodies against protozoa — Sarcocystis spp., Neospora spp., and T. gondii — in horses from southern Brazil. It additionally explores the manifestation of these parasites within horses’ heart tissues. The findings reflect high antibody prevalence, but no direct evidence of parasites or damage in the heart tissue.

Research Methodology

• The researchers collected 197 matched serum and heart samples from horses slaughtered in southern Brazil.
• The chosen samples underwent serology (the study of serum or bodily fluids) and direct microscopic examination to detect antibodies against the three protozoa.
• Additionally, they conducted a histopathological analysis (examination of biological tissues to observe the appearance of disease) and PCR (polymerase chain reaction) analyses on a subset of 50 samples.

Findings

• They found antibodies against at least one of the protozoa present in 74.1% (146) of the serum samples. This high prevalence indicates these horses had been infected by one of these parasites during their lives.
• Breakdown of data shows 36% (71/197) of samples had antibodies against Sarcocystis spp., 39.1% (77/197) against Neospora spp., and 47.2% (93/197) against T. gondii.
• Despite the high frequency of antibodies indicating infection, none of the heart tissue samples showed presence of the protozoa themselves or any resultant tissue cysts, or DNA of Sarcocystis spp.
• The researchers also did not observe any histopathological indications associated with the parasites in the myocardial (heart muscle) tissue samples, implying that horses’ bodies had responded to the infections but were not Hosting the parasites.

Interpretations & Implications

• This high seropositivity against Sarcocystis spp., Neospora spp., and T. gondii implies these parasites commonly infect horses in southern Brazil.
• However, the lack of observed sarcocysts and absence of histopathological lesions in the horse tissues could suggest that horses might act as accidental or aberrant hosts. This means the horses get infected but do not contribute to the life cycle of the parasites by doing so — parasites possibly cannot reproduce or continue their development within horses.
• The findings of this research have validated the importance of studying parasite seroprevalence in livestock and how it may affect the animal health and the zoonotic potential.