Seroprevalence of Streptococcus equi subspecies equi in Croatia – Short communication

Abstract

Clinical cases resembling strangles are regularly seen in some areas of Croatia. However, there are no data on the prevalence of infection and the clinical forms or geographic distribution of the disease. The aim of this study was to determine the seroprevalence of Streptococcus equi subspecies equi in horses resident in Croatia, in order to estimate the geographic distribution of infection. The study included 291 horse sera from the eight counties where the majority of Croatian horses are kept. Sera were tested by indirect ELISA (iELISA) for the presence of serum antibodies against S. equi protein A (SEQ_2190) and protein C (SeM). Positive horses were detected in all counties. Overall seroprevalence was 16.5 per cent (48/291), ranging from 7.1 to 29.6 per cent. A positive association was observed between the population size of the horses in the counties and the seropositivity rates: the larger the population, the higher the seropositivity. The results of this study suggest that S. equi infection is widespread in Croatia. Further investigation of the clinical manifestations, circulating strains and other characteristics of the disease in Croatia and raising awareness of the disease among horse owners are now required.

The persistence of equine strangles

“…The international transmission of S. equi , as demonstrated by Mitchell et al (2021), is in accordance with the first criterion of the World Organisation of Animal Health listing of terrestrial animal diseases. The other three criteria are demonstrated elsewhere (Björnsdóttir et al, 2017, Boyle et al, 2018; therefore, it was recommended strangles be added to this listing (Mitchell et al, 2021).…”

“…Equids are widely used and transported between geographic regions and strangles continues to spread as rapidly as ever (Mitchell et al, 2021, Leadon et al, 2008. Strangles is endemic worldwide, with only Iceland remaining free from the disease, due to a self-imposed import ban of equids and geographical isolation (Björnsdóttir et al, 2017).…”

“…Strangles is endemic worldwide, with only Iceland remaining free from the disease, due to a self-imposed import ban of equids and geographical isolation (Björnsdóttir et al, 2017). Population analysis of 670 isolates from 19 countries (Mitchell et al, 2021) revealed the extent of the international transmission that results in the endemicity of strangles across the world. The international transmission of S. equi , as demonstrated by Mitchell et al (2021), is in accordance with the first criterion of the World Organisation of Animal Health listing of terrestrial animal diseases.…”

“…Population analysis of 670 isolates from 19 countries (Mitchell et al, 2021) revealed the extent of the international transmission that results in the endemicity of strangles across the world. The international transmission of S. equi , as demonstrated by Mitchell et al (2021), is in accordance with the first criterion of the World Organisation of Animal Health listing of terrestrial animal diseases. The other three criteria are demonstrated elsewhere (Björnsdóttir et al, 2017, Boyle et al, 2018; therefore, it was recommended strangles be added to this listing (Mitchell et al, 2021).…”

“…The dual-target ELISA is reported to have similar sensitivity but greater specificity than the single target SeM-based ELISA (Robinson et al, 2013). It can be used to identify recent exposure, from as little as two weeks post-infection, and has been used to determine exposure in populations across the globe (Ling et al, 2011, Štritof et al, 2021, Ivens et al, 2011.…”