Info

Fasciolopsis buski

Asymptomatic or mild GI symptoms. Can be severe, more often in children

50x15

135x80

Praziquantel*

Echinostoma spp. Heterophyes heterophyes

Asymptomatic or mild GI symptoms Asymptomatic or mild GI symptoms. Occasional disseminated disease

10x1 1.4x0.4

110x70 29x16

Praziquantel* Praziquantel*

Metagonimus yokogawai

Asymptomatic or mild GI symptoms. Occasional disseminated disease

1.5x0.6

29x15

Praziquantel*

GI, gastrointestinal; ^considered investigational for this use.

GI, gastrointestinal; ^considered investigational for this use.

discovered by Busk in 1843 at an autopsy where the worms were found in the duodenum, and was originally named Distomum buski. The adult worm varies in length from 20 to 75 mm, with a width of 8-20 mm and a thickness of 2 mm (Figure 24.2). It contains testes which are highly branched, ovaries, a ventral sucker, an intestinal cecum and an excretory bladder. An average of 10 worms infect each human host and excrete approximately 10000-20000 eggs/day (Malek, 1980; Rahman et al., 1981). The eggs are ovoid, operculated, have a thin shell and average 130140 pm in length and 80-85 ^ in width (Figure 24.3). They are excreted in the feces of humans or pigs, where they mature into miracidia over 3-7 weeks in freshwater. The miracidia hatch from the egg and infect the snail intermediate host (Segmentina hemisphaerula and Hippeutis cantori) where sporocyst, rediae and then cer-cariae develop after approximately 7 weeks. The cercariae encyst and form metacercariae on various water plants, including water caltrop, chestnut, morning glory, lotus and water hyacinth (Manning et al., 1971). The metacercariae, which are visible with an average size of 2-4 mm, are ingested by the definitive host and excyst in the duodenum, where they mature over 3 months into adult flukes (Malek, 1980).

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