Molecular prevalence of setaria digitata and its associated risk factors among horses in Kelantan

Setaria digitata is a filarial nematode primarily infecting cattle but capable of causing
ocular and neurological diseases in horses through aberrant migration. Despite Kelantan being a
major equine hub, molecular data on Setaria digitata in horses are limited in literature. This
study investigated its molecular prevalence and associated risk factors in 31 horses sampled
across three districts, using conventional PCR targeting mitochondrial 12S rDNA and COI
genes. The 12S assay produced faint or multiple bands, with three samples showing the expected
450 bp band leading to a suspected prevalence of 9.7%, while COI amplification yielded no
positive results. Several samples showed low A260/A230 ratios, indicating contamination that
may have impaired PCR outcomes. Fisher’s Exact Test showed no significant associations
between PCR results and sex, age, breed, water source, or cattle proximity. Small sample size,
limited site coverage, and DNA purity issues likely reduced detection sensitivity. These findings
indicate a low but detectable presence of Setaria DNA in horses in Kelantan, highlighting the
need for larger studies, improved DNA quality, and sequencing for definitive species
confirmation.