Emergence of zoonotic filariasis, Dirofilaria repens, in eastern Thailand 2019-2020: The impact of climate change

Abstract Dirofilaria repens is a zoonotic vector borne parasite in dogs and cats. It is not commonly found in every part of Thailand excepts Southern part. The aims of this study to investigate the prevalence and correlation of climate parameters in eastern Thailand during 2019–2020. A total of 15,552 blood samples were collected from private veterinary clinics and animal hospitals in eastern Thailand. Blood parasites were examined by using buffy coat thin blood smear with Wright-Giemsa stained. D. repens was morphologically identified and confirmed with acid phosphatase activity technique. Molecular analysis from randomly selected D. repens positive samples revealed they were grouped in D. repens group. The first emerging was found in March 2019. The prevalence of D. repens during March 2019 and January 2020 was 0.50 % (38/7,595) and increase rapidly to 1.76 % (140/7957) during February 2020 to October 2020. The correlation of climate parameters, for example rainfall, humidity and average temperature were tested with Pearson’s correlation. The results showed that the prevalence of D. repens related with rainfall with p ≤ 0.05. The Pearson’s coefficients of rainfall, humidity and average temperature were 0.80, 0.58 and − 0.36, respectively. The rainfall seems to affect the natural habitats for mosquitos as well as the rubber orchard and agricultural area which served as suitable habitat for Armigeres spp. like in Southern part of Thailand which plenty of rubber orchard. In this study, dog is considered as a reservoir host due to only one cat was positive. In conclusion, the prevalent data of D. repens in eastern Thailand should be informed as a zoonotic vector borne diseases. Strategic plan to control zoonotic transmission, preventive program should be emphasized and encouraged to pet owner and veterinarian.