Investigation of Fasciola gigantica in freshwater snail Radix (Lymnaea) spp. In the highly parasite-prevalent area of Nakhon Ratchasima Province, Thailand.

This study investigates the distribution of the Lymnaea (Radix) spp. in Pak Chong district, Nakhon Ratchasima province, northeast Thailand, where a vast cattle farming area is located and has a high prevalence of Fasciola spp. in the cattle. By random selection, 1,414 snails were collected from the natural and man-made ponds. The snails were recorded for morphology and processed for DNA isolation. The snail species were investigated by conventional PCR using a 16S rDNA-specific primer. The result demonstrated that all collected snails were R. (L.) rubiginosa. Moreover, the infection of Fasciola gigantica in the snails was investigated by PCR using a cytochrome c oxidase I (COX1)-specific primer. The results illustrated that the overall prevalence was 22.5% (318/1414), with the highest prevalence in the Nong Sa Rai subdistrict at 73.6% (81/110), which is the highest prevalence of Fasciola gigantica in the snail host that has ever been reported. The lowest prevalence existed in the Pong Ta Long subdistrict at 3.7% (4/109). Our results corresponded to the previous report on the Fasciola spp. infection in the cattle from this area, and the geographical analysis revealed that the most suspected factor would be the earth dam located in these subdistricts, where many animals live freely during the day. Our findings could be helpful for further parasite control and could trigger the study of the biology and associated factors in the future.

Coproprevalence, seroprevalence, and geographic distribution of Fasciola spp. infection in beef and dairy cattle in Pak Chong highland, Nakhon-Ratchasima Province, Northeast Thailand.

Fasciola spp. is a major livestock parasite, especially in cattle, water buffalo, sheep, and goats. Infection reduces animal productivity, e.g., meat, dairy, wool and might cause death. In Thailand, reports of Fasciola spp. infection in livestock, especially dairy and beef cattle, are sparse. Pakchong district in Nakhon Ratchasima province is one of Thailand's largest farming areas for dairy and beef cattle, but the prevalence of Fasciola spp. infection has never been reported in this district. The landscape of this area is mainly a hilltop plateau with many water sources suitable for the development of lymnaeid snails, the intermediate host of Fasciola spp., which are essential for the parasite life cycle. This study surveyed the copro- and seroprevalence of Fasciola spp. infection in dairy and beef cattle farmed in Pakchong district by microscope-based examination, PCR, and indirect ELISA. Associated risk factors and geographic information data were collected and analyzed. Paired stool and serum samples were collected from 102 dairy cattle and 99 beef cattle from April to November 2021. Sample analyses demonstrated a high prevalence of Fasciola spp. infection, especially in beef cattle. The overall copro-prevalence was 5.97%, with 0.99% in dairy cattle and 11.11% in beef cattle. The overall seroprevalence was 23.88%, with 2.94% in dairy cattle and 45.45% in beef cattle. Moreover, the data indicated that infection status was not correlated with animal sex and age whereas consumption of natural grasses, water resources, housing floor, and farming system were significant risk factors. Data analysis by a geographic information system (GIS) demonstrated that an associated risk could be farmed in lowering areas, especially in Chan Thuck, Nong Sa Rai, and Khlong Muang subdistricts. In conclusion, this study reports the prevalence of Fasciola spp. infection in cattle in a major farming area of Thailand which could be beneficial for designing parasite control policies in this region as well as adapting this knowledge to other Fasciola spp. endemic areas.