Programme de bourses "Echanges Universitaires"

Morbidity of food and water borne fluke infections in Lao Peoples’ Democratic Republic

Abstract

Background
Fluke infections transmitted by food and water are neglected public health problems. Although currently world an estimates 40 million people are infected and 750 million more people at risk of infection with these parasites. Fluke infections are associated with serious morbidity of different tissue depending on their predominant habitat in humans. Adult and egg stages of blood flukes (Schistosoma spp.) and the liver fluke (Opisthorchis spp.) provoke divers liver pathologies including liver fibrosis, calcifications in portal venous systems and complications include portal hypertension, increased size of liver and spleen, rupture from oesophageal varices and others. Long-term infections may lead to death.

In Southeast Asia the most significant public health problem arises from an infection with the liver fluke Opisthorchis viverrini. In Lao People’s Democratic Republic (Lao PDR) it is estimated that at approximately 2.5 million people, corresponding to half of the population, are infected. The parasite is transmitted with the consumption of raw or insufficiently cooked fish. In areas where this behaviour is common and deeply culturally rooted, such as in several regions of central and southern Lao PDR, the infection prevalences are rampant. Furthermore, multiple infections with several food-borne fluke species are very common. Schistosoma mekongi is the endemic water-borne blood fluke affecting the liver and intestinal tract is particularly devastating in the most southern province Champasack.

Aim and objectives
The aim of this project is to describe and quantify the morbidity due to liver (O. viverrini)and blood fluke (S. mekongi) infection in individuals and communities and assess effectiveness of interventions. Thwo main objectives are pursued: (i) to assess and document the severity of morbidity due to blood fluke infections (S. mekongi) in endemic areas in Champasack province and to follow it after treatment, (ii) to assess liver morbidity due to liver flukes after treatment and describe and quantify the morbidity resolution dynamics.

Methods and activities
In the last two and a half years field work in relation to the above stated objectives were conducted in several provinces of Lao PDR: (i) Severe cases of schistosomiasis mekongi were identified, treated and yearly followed up in Champasack province. Nine patients with severe liver morbidity were identified on schistosomiasis endemic islands despite that the existence of a community interventions. Two patients died. Most alarming is the fact also children below five years are affected. (ii) In 2006 more than two hundred S. mekongi infected individuals were diagnosed, treated and followed-up yearly to assess the infection and liver morbidity resolution dynamics. The data of this cohort study has been computerized and the analysis is underway.
In the next working period data of these studies will be analyzed in detail. The results will be communicated to the Ministry of Health in Lao PDR and scientific publications will be compiled.

Funding
This project is funded by the Research Partnership Initiative of the Swiss National Science Foundation & the Swiss Development Cooperation, the World Health Organization (WHO) and the City of Basel.

Contacts
PhD Fellow
Dr. med. Phonepasong Soukhathammavong
Swiss Tropical and Public Health Institute, Department of Public Health and Epidemiology, P.O. Box, 4002 Basel, Switzerland, Tel.: +41 61 284-8614 and National Institute of Public Health, Vientiane, Lao PDR; Tel: +856-21-214 975 or +856-21-214 012; E-mail: phonepasong.soukhathammavong@unibas.ch

Supervisors

Dr. Peter Odermatt
Swiss Tropical and Public Health Institute, Department of Public Health and Epidemiology, P.O. Box, 4002 Basel, Switzerland, Tel.: +41 61 284-8214; Fax: +41 61 284-8105, E-mail: peter.odermatt@unibas.ch

Assoc. Professor Kongsap Akkhavong
Deputy Director, National Institute of Public Health, Vientiane, Lao PDR; Tel: +856-21-214 975 or +856-21-214 012; Email: kongsap@hotmail.com

Figure 1: Several traditional, widely consumed dishes cooked from insufficient cooked fish may transmit worm infection. Fermented fish (as shown above) is frequently contaminated with liver fluke infection

Figure 2: Fishermen in Mekong River (South of Lao PDR) at risk for infection with water-borne fluke (Schistosoma mekongi)

Figure 3: Adult liver flukeworms recovered from the stools of an infected patient