Zoonotic Echinostome Infections in Free-Grazing Ducks in Thailand

Abstract

Free-grazing ducks play a major role in the rural economy of Eastern Asia in the form of egg and meat production. In Thailand, the geographical location, tropical climate conditions and wetland areas of the country are suitable for their husbandry. These environmental factors also favor growth, multiplication, development, survival, and spread of duck parasites. In this study, a total of 90 free-grazing ducks from northern, central, and northeastern regions of Thailand were examined for intestinal helminth parasites, with special emphasis on zoonotic echinostomes. Of these, 51 (56.7%) were infected by one or more species of zoonotic echinostomes, Echinostoma revolutum, Echinoparyphium recurvatum, and Hypoderaeum conoideum. Echinostomes found were identified using morphological criteria when possible. ITS2 sequences were used to identify juvenile and incomplete worms. The prevalence of infection was relatively high in each region, namely, north, central, and northeast region was 63.2%, 54.5%, and 55.3%, respectively. The intensity of infection ranged up to 49 worms/infected duck. Free-grazing ducks clearly play an important role in the life cycle maintenance, spread, and transmission of these medically important echinostomes in Thailand.

Morphological Characteristics and Phylogenetic Trends of Trematode Cercariae in Freshwater Snails from Nakhon Nayok Province, Thailand

“…[4,11]. Previous studies have revealed that the metacercarial and adult stages of these trematode species were frequently found in second intermediate hosts and definitive hosts in Thailand [37–39]. …”

Morphology and Molecular Identification of Echinostoma revolutum and Echinostoma macrorchis in Freshwater Snails and Experimental Hamsters in Upper Northern Thailand

“…E. revolutum has been shown to endemically infect humans in Southeast Asia [7,42]. In Thailand, it has been found in Northern, Northeastern, and Central parts, i.e., the metacercarial stage from freshwater snails and adult stage from poultry [9,10,17,20,21].…”

“…At least 23 species belonging to 10 genera are known to infect humans, i.e, Echinostoma , Echinochasmus , Acanthoparyphium , Artyfechinostomum , Echinoparyphium , Euparyphium , Episthmium , Himasthla , Hypoderaeum and Isthmiophora [ 6 , 7 ]. In Thailand, 4 echinostomes have been reported from humans, including Artyfechinostomum malayanum , Echinostoma revolutum , Echinostoma ilocanum , and Hypoderaeum conoideum [ 8 ], and 3 species have been recorded in poultry: Echinoparyphium recurvatum , E. revolutum , and H. conoideum [ 9 , 10 ]. Humans can be infected with echinostome metacercariae by eating raw snails, fish, or frogs [ 11 , 12 ].…”

Morphological Characterization of Emerging Cercariae among Lymnaeid Snails from Barangay Cawongan, Padre Garcia, Batangas, Philippines

“…are intestinal parasites of humans [ 51 ], and fork-tailed cercariae of avian origin can cause dermatitis. Echinostomes also are known to heavily infect domestic ducks, thus affecting greatly poultry business [ 52 ]. In the Philippines, two medically important echinostomes, Echinostoma ilocanum and Echinostoma malayanum , were recovered from infected humans that required freshwater gastropods belonging to the family Lymnaeidae as intermediate hosts [ 32 ].…”