Echinostoma revolutum: Metacercariae inFilopaludinaSnails from Nam Dinh Province, Vietnam, and Adults from Experimental Hamsters

Abstract

We detected metacercariae of Echinostoma revolutum in Filopaludina sp. snails purchased from a local market in Nam Dinh Province for the first time in Vietnam. Adult flukes were harvested from experimentally infected hamsters at days 14 and 17 post-infection. The metacercariae were round, 170-190 µm (n=15) in diameter, with a cyst wall thickness of about 12 µm. A total of 37 collar spines were arranged around the head collar, and large excretory granules were seen in 2 canals of the excretory bladder. The 14-day old adult flukes were elongated, ventrally curved, and 5.0-7.2×0.8-1.3 mm (n=20). The head collar had a total of 37 collar spines arranged in 2 alternating rows, including 5 corner spines on each side. The cirrus sac contained a saccular seminal vesicle, a prostatic gland, and an unarmed cirrus. Two tandem testes were smooth or slightly lobed. Eggs were ovoid to elliptical, 110-118×70-75 µm. These morphological characters were similar to those of E. revolutum and E. jurini. We tentatively identified it as E. revolutum because the validity of E. jurini remains to be elucidated. The taxonomic relationship of E. revolutum and E. jurini is discussed.

Echinostoma revolutum: Freshwater Snails as the Second Intermediate Hosts in Chiang Mai, Thailand

“…For bithyniid snails, B. funiculata and B. siamensis siamensis are important intermediate hosts of Opisthorchis viverrini [14,33], while in this study they were found to harbor E. revolutum metacercariae. With regard to C. helena , they appeared to be infected with E. revolutum metacercariae in this study, although they had never been considered to be of medical importance previously [11,14,15,19,28,33]. Hence, detection of E. revolutum metacercariae in C. helena is for the first time so far as the literature are concerned.…”

“…Ten species of Echinostoma were listed as valid within the revolutum group by Fried and Graczyk [18]; E. caproni Richard, 1964, E. trivolvis (Cort, 1914), E. paraensei Lie and Basch, 1967, E. revolutum (Frölich, 1802), E. friedi Toledo et al, 2000, E. miyagawai Ishii, 1932, E. echinatum (Zeder, 1803), E. parvocirrus Nassy and Dupouy, 1988, E. luisreyi Maldonado et al, 2003, and E. jurini (Skvortzov, 1924). Review of the Echinostoma species in the revolutum group in terms of morphological features, morphometrics, host-parasite relationships, and geographic distribution [3,18-28] revealed that our specimens resembled most closely E. revolutum and E. jurini . Of these, our specimens were more compatible to E. revolutum .…”

High prevalence of large trematode eggs in schoolchildren in Cambodia

“…in Southeast Asia is well known (Chai et al, 2009). Different Echinostoma species have been reported in Cambodia's neighboring countries: Lao PDR (Chai et al, 2012;Sohn et al, 2013), Thailand (Radomyos et al, 1998;Tungtrongchitr et al, 2007;Waree et al, 2001) and Vietnam (Chai et al, 2011). At the beginning of the 2000s, the first Echinostoma spp.…”

Epidemiology of cercarial stage of trematodes in freshwater snails from Chiang Mai province, Thailand

“…and Lymnaea spp. were reported to act as the first and second most common intermediate hosts of trematodes in the family Echinostomatidae [9] . Furthermore, the planorbis snails are intermediate hosts of blood fluke in family Schistosomatidae [10,11] .…”