High Prevalence of Haplorchis taichui, Phaneropsolus molenkampi, and Other Helminth Infections among People in Khammouane Province, Lao PDR

Abstract

The prevalence of liver and intestinal helminth infections, including Opisthorchis, Haplorchis, Phaneropsolus, hookworms, Enterobius, and Taenia, was surveyed in Khammouane province, Lao PDR. Fecal specimens were collected from 1,242 people (590 men and 652 women) in 3 Mekong riverside villages and were examined by the Kato-Katz thick smear technique. The overall helminth egg positive rate was 81.1%. The positive rate for small trematode eggs, including Opisthorchis viverrini, heterophyids, and lecithodendriids, was 81.1% and the positive rate for hookworms was 6.7%. To obtain adult worms, 35 people who were positive for small trematode eggs were treated with 20-30 mg/kg praziquantel and 10-15 mg/kg pyrantel pamoate, and then purged. Diarrheic stools were collected from 33 of these people and searched for helminth parasites using a stereomicroscope. Mixed infections with various helminths (Haplorchis taichui, Haplorchis yokogawai, Prosthodendrium molenkampi, Phaneropsolus bonnei, echinostomes, hookworms, Trichostrongylus spp., Trichuris trichiura, Enterobius vermicularis, and/or Taenia saginata) were found. The total number of helminth specimens collected was 20,907 (approximately 634 per person). The most common species was H. taichui, followed by P. molenkampi, O. viverrini, P. bonnei, E. vermicularis, hookworms, and Trichostrongylus spp. These results show that diverse species of intestinal nematodes, trematodes, and cestodes are infecting humans in Khammouane province, Lao PDR.

Perceived illness drives participation in mass deworming campaigns in Laos

“…Communities believed that after squeezing hundreds of weaver ants -this ant contains a sour juice -over the fish meat this would turn to white colour which was comparable to a well-cooked dish and therefore safe for eating (Xayaseng et al, 2013). In Lao PDR, freshwater fish are infected in high prevalence rates with O. viverrini, H. taichui and other minute intestinal flukes Chai et al, 2007;Chai et al, 2009). Thus local conceptions on preparation technique of raw fish dish will keep up a high infection prevalence with H. taichui and O. viverrini in the communities.…”

Foodborne Intestinal Flukes in Southeast Asia

“…Subsequently, high prevalences of this fluke infection were found in noreastern provinces of Thailand [14]. Also in Lao PDR, a total of 1,303 adult specimens were recovered from 27 people residing in Mekong riverside areas of Savannakhet, Khammouane, and Saravane Provinces [62,171,176]. The egg morphology is very similar to that of heterophyid fluke or Opisthorchis viverrini [242,243].…”

“…Later, high prevalences were reported in different areas of northeast Thailand [14]. In Lao PDR, a total of 8,899 adult specimens were recovered from 52 infected people residing along the Mekong riverside areas of Vientian Municipality, Savannakhet, Khammoune, and Saravane Provinces [62,171,176]. Metacercariae were discovered in naiads and adult dragon-and damselflies in Thailand [244].…”

“…Metacercariae were discovered in naiads and adult dragon-and damselflies in Thailand [244]. Local people in northeast Thailand and Laos sometimes eat naiads of these insects [171,176,244]. This lecithodendriid species was described as a new species from a human infection case in northeast Thailand [245].…”

“…An experimental human infection with this fluke was successful by Katsuda [180], but natural human infections have been known after reports in the Philippines [175]. Now this fluke is known to occur in the Philippines, South China, Malaysia, Indonesia, Thailand, Laos, Vietnam, India, Australia, and Egypt as human or animal infections [6,170,172,176]. Freshwater snails, Melanoides tuberculata or Stenomelania newcombi, shed the cercariae [170].…”