Fly dermatitis, also known as swimmer’s itch or clam itch, is caused by bloodsucking larvae that are parasites of birds or mammals. When these larvae, called cercariae, penetrate human skin, they trigger an allergic reaction within 10-15 hours that takes about a week to heal. Unable to mature into adulthood, then the larvae die on the skin. The severity of an outbreak depends on how humans, birds or mammals come into contact with the aquatic environment, but people who engage in aquatic activities, such as farmers, fishermen and agricultural workers, are more likely to be affected.
Between August and October 2020, chin dermatitis spread with 359 confirmed cases in Chana District, Songkhla Province, southern Thailand. It mostly affected the rice farmers of the area, who were busy with farming during the rainy season. After a short investigation, three cases of patients were confirmed surgically infected by skin biopsy (Office of Epidemiology, Department of Disease Control, Ministry of Public Health, Thailand).
“The study of the intermediate host and the definitive host in the outbreak area is important for the snail-borne disease control program,” the researchers say in their paper, published in the open-access scientific journal. Evolutionary systematic theology.
After studying six species of snails in the area, they discovered that two were infected, each with three different types of flatworms. The outbreak of chin dermatitis was caused by parasites of ruminants, such as blood fluke Schistosomiasis indicawhich often use pets as their host.
“Nematodes that infect ruminants, which are S. indica And the S. spindale, It causes hepato-intestinal schistosomiasis resulting in decreased milk production.” S. indica And the S. Spindel Means the spread of the cattle roundworm cercariae in aquatic environments.”
In addition, these types of S. indica The combination primarily causes chin dermatitis in humans, which has become an important public health issue for people living in endemic areas.”
“In South India and Southeast Asia, where S. indica And the S. Spindel It was reported to have spread widely, and caused serious diseases and livestock deaths, leading to social and economic problems, especially among poor subsistence farmers and their families.”
Some of the other types of worms they found parasitized the intestines of fish, mammals, or birds, while others caused anemia and even death in ruminants.
“The results of this study will provide insight into the types of parasites that cause chin dermatitis and may improve our understanding of public health problems in outbreaks and adjacent agricultural areas,” the study authors say. “In addition, the sequencing data generated here is the first S. indica DNA sequencing from Thailand, which will be useful for further genetic study of other blood trematodes in this region.”