Prevalence of intestinal parasite infections on a national scale among primary schoolchildren in Laos

Abstract

In order to investigate the epidemiological situation of intestinal parasite infections in Laos, parasitological surveys were carried out on a national scale including 17 provinces and the Vientiane Municipality. A total of 29,846 stool specimens were collected from primary schoolchildren from May 2000 to June 2002 and examined once with the cellophane thick smear technique. The cumulative egg positive rate for intestinal helminths was 61.9%. By species, the rate for Ascaris lumbricoides was 34.9%, hookworm 19.1%, Trichuris trichiura 25.8%, Opisthorchis viverrini 10.9%, Taenia spp. 0.6% and Hymenolepis spp. 0.2%. The northern mountainous regions such as Phongsaly, Huaphan or Saysomboune Province showed a higher prevalence (over 70%) of soil- transmitted helminths. The regions along the Mekong River such as Khammuane, Saravane or Savannakhet Province showed a higher prevalence (over 20%) of fish-borne parasites. On the other hand, Schistosoma mansoni eggs were detected in 1.7% of schoolchildren only in Champassak Province, a previously endemic area. The highest prevalence was noted in Phongsaly Province (96.0%) and the lowest in Bolikhamxay Province (27.5%). An additional small-scale survey by cellophane anal swab detected Enterobius vermicularis eggs in 35.7% of 451 schoolchildren aged 6-8 years in Khammuane, Vientiane, Champassak Province and the Vientiane Municipality. Meanwhile, the mean blood haemoglobin level of hookworm-infected children was not lower than that of children not infected with hookworm, suggesting that nutritional factors are more important than parasite infection per se. Nevertheless, the above results indicate that a nationwide parasite control project is necessary to reduce possible morbidity due to parasitic diseases in the country.

Epidemiology of Opisthorchis viverrini in a rural district of southern Lao PDR

“…This finding confirms the previous reports by Rim et al (2003) in the same province and by Kobayashi et al (2000), who showed high infection rates in the neighbouring Khammouane province. In addition, our study is most likely to underestimate infection rates.…”

“…The survey was conducted in the Saravane district, province of Saravane, southern Lao PDR (Figure 1), where recently a high prevalence of O. viverrini was found among schoolchildren (Rim et al, 2003). The province has a population of approximately 318 100; 20% are children under 5 years of age.…”

“…Today, the prevalence is still very high. Rim et al (2003) recently completed a nationwide survey among schoolchildren and found infection rates often exceeding 50% in the southern provinces. Recently, Thakek still had a prevalence rate of approximately 60% (Kobayashi et al, 2000).…”

Diversity of human intestinal helminthiasis in Lao PDR

“…Previous studies have shown that O. viverrini is endemic in all provinces of Lao PDR. 7 The highest prevalence rates were found in central and southern parts, reaching levels of up to 60%. 8 However, in these studies only 'Opisthorchis-like' eggs were reported.…”

Raw fish consumption in liver fluke endemic areas in rural southern Laos

“…viverrini infection is endemic in several countries in Southeast Asia and in all provinces of Laos (Rim et al, 2003). It is highly prevalent in central and southern Laos, reaching infection rates of more than 90% in adult populations (Forrer et al, 2012;Sayasone et al, 2007;Sayasone et al, 2011).…”