Assessment of the Streptococcus equi infection in apparently healthy working horses of Urmia by indirect ELISA

Strangles is one of the most important infectious diseases of equids caused by Streptococcus equi subspecies equi. The disease is characterized by fever, anorexia, lethargy, purulent nasal discharge, and lymphadenopathy, particularly of the lymph nodes of the head and neck. The objective of this study was to determine the seroprevalence rate of S. equi infection in apparently healthy working horses of Urmia (northwest Iran).

Sera from 46 healthy horses were tested by enzyme linked immunosrobent assay (ELISA) kit (ID Screen S. equi Indirect) to detect IgG to S. equi M protein (SeM) antigen. Data were analyzed for effect of sex and age on seropositivity by chi-squared, fisher’s exact and logistic regression tests.

A total of 73.9% (95% CI: 61.2-86.6%) of samples were positive for S. equi antibodies. Seropositivity was not affected by age (p> 0.05) and sex (p> 0.05). In regression analysis only age was significant between predictor variables. Odds of infection between the age based on year and disease was 1.403 (95% CI: 1.006-1.958), and age explained 0.339% of infection’s fluctuations.

The final summary of results indicates that exposure to S. equi is very high in apparently healthy working horses of Urmia region.