Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2017 Sep 4;6(1):131.
doi: 10.1186/s40249-017-0343-x.

Transmission of Opisthorchis viverrini, Schistosoma mekongi and soil-transmitted helminthes on the Mekong Islands, Southern Lao PDR

Youthanavanh Vonghachack  1   2   3 , Peter Odermatt  1   2 , Keoka Taisayyavong  4 , Souphanh Phounsavath  5 , Kongsap Akkhavong  6 , Somphou Sayasone  7
Affiliations

Transmission of Opisthorchis viverrini, Schistosoma mekongi and soil-transmitted helminthes on the Mekong Islands, Southern Lao PDR

Youthanavanh Vonghachack et al. Infect Dis Poverty. .

Abstract

Background: Prevalence of Opisthorchis viverrini, Schistosoma mekongi and soil-transmitted helminths (STH) remains high in Lao People's Democratic Republic (Lao PDR), despite control efforts including mass-drug administration, education and communication campaigns. New approaches are required to advance helminth control.

Methods: An ecohealth study was conducted on two Mekong islands in Southern Laos. Demographic and behavioural data were collected by questionnaire. Human and animal reservoir stools were examined. Bithynia spp. and Neotricula aperta snails were examined using shedding. Fresh water fish were examined using digestion technique. Multivariate random-effects analysis was used to find risk factors associated with helminth infections.

Results: Human infection rates with O. viverrini, hookworm, S. mekongi, Trichuris trichiura, Ascaris lumbricoides and Taenia spp. were 60.7%, 44.1%, 22.2%, 4.1%, 0.6% and 0.1%, respectively. Heavy intensity infections were 4.2%, 3.6% and 1.8% for O. viverrini, S. mekongi and hookworm, respectively. O. viverrini and S. mekongi infection rates among dogs and cats were 25.0% and 14.7%, respectively. Of the cats tested, 53.1% were infected with O. viverrini. Prevalence of O. viverrini and S. mekongi in snails was 0.3% and 0.01%, respectively. Overall prevalence of O. viverrini infection in fresh water fish was 26.9%, with the highest infection rates occurring in Hampala dispa (87.1%), Cyclocheilichthys apogon (85.7%) and Puntius brevis (40.0%). Illiteracy and lower socioeconomic status increased the risk of O. viverrini infection, while those aged 10-16 years and possessing latrines at home were less likely to be infected. Household dogs and cats that consumed raw fish were significantly and positively associated with O. viverrini infection of the household members. For S. mekongi, children under 9 years old were exposed significantly to this infection, compared to older age groups.

Conclusions: There is a pressing need to design and implement an integrated helminth control intervention on the Mekong Islands in southern Lao PDR. Given the highly dynamic transmission of O. viverrini, S. mekongi, STH and extended multiparasitism, annual mass-drug administration is warranted along with environmental modifications, health education and improved access to clean water and adequate sanitation to consolidate morbidity control and move towards elimination.

Trail registration number: Our findings presented here are from a cross-sectional study, therefore, it has not been registered.

Keywords: Animal hosts; Bithynia species.; Cyprinidae fish; Laos; Neotricula aperta; Opisthorchis viverrini; Schistosoma mekongi; Southern Lao People's Democratic Republic.

PubMed Disclaimer

Conflict of interest statement

Ethics approval and consent to participate

This study was approved by the National Ethics Committee for Health Research, Ministry of Health (MOH), Vientiane, Lao PDR (reference no.043/NECR). Field activities were approved by the MOH steering committee. An inception meeting was organized at the study site prior to starting field work. Village and local health authorities and villagers were invited to participate in this meeting. Study participants were informed of the study aims and procedures, the benefits and risks of participating, as well as of their right to withdraw from the study at any time. Before enrolment, written informed consent was obtained from all study participants. For study participants under the age of 18, written informed consent was obtained from the parents or legal guardians. In addition, oral consent was obtained from each child participant between 12 and 17 years old. Permission to collect faecal samples from animals was obtained from their owners. All diagnosed infections were treated free of charge according to the Lao National guidelines [60]. Soil-transmitted helminths (STH) and/or trematode infections were treated with a single oral dose of 400 mg albendazole and praziquantel (40 mg/kg BW), respectively [–63].

Consent for publication

A written, informed consent to share and disseminate data was obtained from all study participants before enrolment. For children aged below 18 years, the consent was obtained from their parent or legal guardian.

Competing interests

The authors declare that they have no competing interests.

Figures

Fig. 1
Fig. 1
Study map: a Khong District with main Mekong islands; b Selected western shore of Done Som with human settlements and ecological features. (Source: Google Map)
Fig. 2
Fig. 2
Study diagram
Fig. 3
Fig. 3
Age distribution of major helminth infections by gender on Done Khon and Done Som islands. The figures represent the smoothed age distribution of male (solid line) and female (dotted line) study participants for an infection with (a): Opisthorchis viverrini, (b): hookworm, (c): Trichuris trichiura and (d): Schistosoma mekongi
See this image and copyright information in PMC

References

    1. Sripa B, Kaewkes S, Intapan PM, Maleewong W, Brindley PJ. Food-borne trematodiases in Southeast Asia epidemiology, pathology, clinical manifestation and control. Adv Parasitol 2010;72:305-50. - PubMed
    1. Utzinger J, Bergquist R, Olveda R, Zhou XN. Important helminth infections in Southeast Asia diversity, potential for control and prospects for elimination. Adv Parasitol. 2010;72:1–30. doi: 10.1016/S0065-308X(10)72001-7. - DOI - PubMed
    1. WHO . Prevention and control of schistosomiasis and soil-transmitted helminthiasis: first report of the joint WHO expert committees. Geneva: World Health Organization Technical Report Series No 912; 2002. p. 912. - PubMed
    1. Rim HJ, Chai JY, Min DY, Cho SY, Eom KS, Hong SJ, Sohn WM, Yong TS, Deodato G, Standgaard H, et al. Prevalence of intestinal parasite infections on a national scale among primary schoolchildren in Laos. Parasitol Res. 2003;91(4):267–272. doi: 10.1007/s00436-003-0963-x. - DOI - PubMed
    1. Sayasone S, Mak TK, Vanmany M, Rasphone O, Vounatsou P, Utzinger J, Akkhavong K, Odermatt P. Helminth and intestinal protozoa infections, multiparasitism and risk factors in Champasack province, Lao People's Democratic Republic. PLoS Negl Trop Dis. 2011;5(4):e1037. doi: 10.1371/journal.pntd.0001037. - DOI - PMC - PubMed

MeSH terms

LinkOut - more resources