Serological detection and molecular characterization of piroplasmids in equids in Brazil.

This research article focuses on the study of equine piroplasmosis, a parasitic infection prevalent in horses, in the northwestern region of Rio Grande do Sul, Brazil. The study uses both serological surveys and molecular diagnostics to detect and characterize the presence of Babesia caballi and Theileria equi, the two organisms responsible for the disease.

Study Methodology

• The study involved the collection of blood samples from 90 horses in the city of Passo Fundo. These horses were employed in various activities such as sports, outdoor recreational riding, cattle herding, and mounted patrol.
• To detect anti-T. equi and anti-B. caballi IgG antibodies, the researchers used commercial ELISA kits. The presence of these antibodies in the blood serum indicates infection with the respective parasites.
• The molecular diagnosis included the amplification of the 18S rRNA gene using a technique called nested PCR, which was then followed by sequencing. This detected the gene fragments of T. equi and B. caballi in the samples.

Study Results

• Of the 90 serum samples tested, 17 (18.9%) and 5 (5.55%) were positive for T. equi and B. caballi antibodies, respectively, indicating prior exposure to these parasites.
• PCR detected piroplasmid 18S rRNA gene fragments in 24.4% (22/90) of the samples analysed which shared 99-100% gene sequence identity with T. equi when run through a BLASTn database, further confirming the presence of this organism.
• The samples were then assessed for their phylogenetic relationships, and were divided into 2 groups. Group A’s sequences were closely related to those reported on the US-Mexico border, in South Africa, and other regions of Brazil. Group B’s sequences had a close proximity to samples tested in the US and Spain.
• The variation of the 18S rRNA gene allowed the identification of 9 new T. equi genotypes in the geographical region studied, indicating genetic diversity within these organisms in the area.

Concluding Remarks

• This research highlights the presence and diversity of T. equi and B. caballi organisms in the northwestern region of Rio Grande do Sul, Brazil.
• The study contributes towards the better understanding of the genetic variations of T. equi, which is crucial in mapping out the disease’s spread and formulating efficient control and prevention strategies.
• The serological and molecular detection methods used in this study have proven to be reliable in detecting and characterizing these disease-causing organisms.