Effect of niclosamide on the tegumental surface of Haplorchis taichui using scanning electron microscopy

Abstract

The effect of niclosamide on the tegument of adult Haplorchis taichui (Trematoda: Heterophyidae) exposed in vitro was observed by scanning electron microscope. Adult worms were incubated in Tyrode's solution containing 0.01, 0.1, 1.0, and 10 mg ml 21 of niclosamide for 30 min, 1, 6, 12 and 24 h. Control groups were incubated in Tyrode's solution without niclosamide and worms remained active until 24 h. In 0.01 mg ml 21 of niclosamide, worms showed slightly active movements up to 1 h after incubation, while in 0.1 mg ml 21 solution a few worms showed only slightly active movements after 30 min. Tegumental changes were determined by scanning electron microscopy. Swelling and blebbing of the tegument were observed on both ventral and dorsal sides. After longer periods, extensive swelling and blebbing of the tegument became more severe and there was a loss of the apical plasma membrane in some regions. Empty spine sockets occurred, and small perforations penetrated the basal lamina, followed by some lesions. Destruction of both surfaces was more pronounced on the posterior compared with the anterior regions.

Foodborne Intestinal Flukes in Southeast Asia

“…A single oral dose of 10-20 mg/kg praziquantel is satisfactory, with 95-100% cure rate for M. yokogawai infection [394,395]. Niclosamide was used in vitro to observe damage to H. taichui worms [396]. Irradiation of the sweetfish, Plecoglossus altivelis, by 200 Gy was highly effective in controlling infectivity of the M. yokogawai metacercariae [397].…”

Trematode metacercariae and adults in cyprinoid fish from Khun Thale Swamp in Surat Thani province, Thailand

“…The present investigation revealed 4 species of digenetic trematodes (3 in the metacercarial stage and 1 in the adult stage) and 1 species of aspidogastrean trematode (adult stage). Previous workers in Thailand reported 3 species of metacercariae, including C. formosanus, H. taichui, and H. mehrai, in cyprinoid fish [14,[23][24][25][26][27][28][29][30]. The metacercariae of H. taichui and C. formosanus can develop into adults in birds and mammals, including humans, and thus they are of zoonotic significance [21,[23][24][25][26][27][28][29][30][31][32].…”

“…Previous workers in Thailand reported 3 species of metacercariae, including C. formosanus, H. taichui, and H. mehrai, in cyprinoid fish [14,[23][24][25][26][27][28][29][30]. The metacercariae of H. taichui and C. formosanus can develop into adults in birds and mammals, including humans, and thus they are of zoonotic significance [21,[23][24][25][26][27][28][29][30][31][32]. These flukes can cause mild to severe gastrointestinal (abdominal pain, diarrhea, weight loss, and lethargy) or irritable bowel syndromelike symptoms [21,31].…”

General overview of the current status of human foodborne trematodiasis

“… Information obtained from Kumchoo et al . ( 2007 ), Fürst et al . ( 2012 b ), Chai ( 2013 a ), Garcia ( 2016 ) and Chai et al .…”