Senter for internasjonal helse


There has not been added a translated version of this content. You can either try searching or go to the "area" home page to see if you can find the information there
Research publication

Warning: think before you get wet!!

There were over 300 exchange students from Norway in Africa between 2003-2018. A group of Norwegian doctors have now studied how many became infected with Schistosomiasis after being exposed to fresh water.

schistosoma life cycle
Wikimedia Commons, the free media repository


While exchange programmes are inarguably enriching experiences, there are some experiences that might be better avoided. A study by researchers from the Norwegian National Advisory Unit on Tropical Infectious Diseases at Haukeland University Hospital in Bergen and the Regional Competency Centre for Imported and Tropical Diseases at Oslo University Hospital, and others, has shown that “off-the-beaten-track” tourist experiences, such as river rafting, may result in Schistosomiasis infections, and hence potentially long-term, serious illness.

Around half of 2003-2018 exchange student group participated in the study. Around 30% of the study participants were shown to have antibodies to Schistosomiasis, indicating to the parasite. About 55% of those who reported exposure to fresh water, stated that this exposure occurred during a rafting experience. There is a belief that the risk of contracting Schistosomiasis is greater in stagnant water, but the Norwegian exchange student evidence shows that there is also significant risk in moving fresh water, and limited exposures.


According to WHO, Schistosomiasis is an acute and chronic disease caused by parasitic worms. Infection by the worms can last many years. The WHO website states: “The economic and health effects of schistosomiasis are considerable and the disease disables more than it kills.” Their website further states: “The WHO strategy for schistosomiasis control focuses on reducing disease through periodic, targeted treatment with praziquantel through the large-scale treatment (preventive chemotherapy) of affected populations.” Read more.

In an informal discussion with CIH researchers who work in the affected areas of Africa, some shared their experience that researchers who work regularly in areas of Africa, where transmission is common, recommend that praziquantel be purchased in Africa, as it is not easily available in Norway. Some researchers also recommend taking the drug regularly when staying for extended periods of several years in Africa – at least every year. However, the drug only works against adult worms, and not against the egg or larval phases, which may be present for many weeks after exposure.

The authors of the above-mentioned paper, in fact, specifically do not advise people to take praziquantel immediately after exposure, because it will not be effective at that time. One needs to wait at least 6 weeks or longer.


Read the article published in Tidsskriftet Den norske legeforening (in Norwegian)