Prevalence and risk factors of human trichostrongylosis in Satun, southern Thailand.

Abstract

Trichostrongylus spp., zoonotic soil-transmitted nematodes, affect both livestock and humans globally. In Thailand, human trichostrongylosis has been reported, but no systematic study examining livestock and humans in the same locality has been conducted. This study aimed to address this gap in Satun Province, southern Thailand by characterizing the disease's epidemiologic status among livestock, farmers, and the environment using both microscopic and molecular techniques. Human risk factors were assessed via questionnaires. Stool samples were collected from livestock farmers, their families, and herbivores in Nongkhai, Ratchaburi, and Satun Provinces. Vegetable samples were also obtained from households and local markets. Human and livestock feces were examined using the modified Kato-Katz method and a Mini Parasep^® solvent-free fecal parasite concentrator. Total DNA was then extracted from fecal and vegetable sediments, and a 211 bp fragment of the ribosomal internal transcribed spacer 2 (ITS2) gene was amplified using a polymerase chain reaction (PCR). PCR products were digested with HinfI and analyzed via electrophoresis to identify Trichostrongylus species. In Satun, Trichostrongylus colubriformis monoinfection was found in 12 of 221 (5.4%) residents, while co-infection with T. colubriformis and T. axei occurred in 3 (1.4%). Herbivore feces and vegetable sediments from Satun also tested positive. No human cases were found in Nongkhai or Ratchaburi. Risk factors included education level, occupation, and outdoor toilet use. Most infected individuals in Satun were asymptomatic. Despite this, public health interventions should be implemented, targeting the human-livestock-environment interface to control the disease effectively.