Molecular detection and genetic characterization of hemotropic mycoplasmas in goats and fleas from Thailand

Arthropod vectors play a crucial role in the transmission of hemotropic mycoplasmas, small bacteria that infect red blood cells in a wide range of animals and humans globally, leading to intravascular infections. Traditional Giemsa-stained thin blood smears, used for diagnosing hemotropic mycoplasmas through microscopic examination, have low sensitivity and are effective only when bacteremia levels are high. This study aimed to employ molecular methods to detect and genetically characterize hemotropic mycoplasmas in goats as well as investigate the potential role of fleas as vectors. Blood and flea samples were collected concurrently from goats on 16 farms across seven provinces in Thailand from January 2017 to October 2023. The 16 S rRNA, 23 S rRNA, and rnpB genes of hemoplasmas were amplified and sequenced. All fleas were identified morphologically and molecularly through DNA barcoding of the cytochrome oxidase I gene. A total of 78 out of 500 goats (15.6%), three pooled flea samples (3/6, 50%), and one individual flea (1/49, 2.04%) tested positive for hemoplasmas and all fleas were identified as Ctenocephalides orientis. BLASTN searches utilizing the three genetic markers revealed that the hemoplasmas detected in this study showed 97.81-100% similarity to Mycoplasma ovis and Candidatus Mycoplasma haemovis, which have been previously reported in sheep, goats, and humans, suggesting their zoonotic potential. The sequences were grouped into 28 unique nucleotide sequence types (ntSTs) based on minor variations in the 16 S rRNA gene. Hemotropic mycoplasma infection was significantly associated with farm locations and seasonality of sample collection (p < 0.0001), indicating that farm management practices or environmental conditions may play a critical role in the epidemiology of these infections. This study represents the first report of hemotropic mycoplasmas in goats in Thailand, confirms their presence in fleas, and provides valuable insights for farm management, such as guiding the rational use of insecticides and antibiotics.