This deadly parasitic worm migrates to Europe – Edition du soir Ouest France



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Perhaps you have never heard of bilharziasis or schistosomiasis. Behind these two barbaric terms hides a single, deadly disease that affects more than 200 million people worldwide, also known as snail fever. Traditionally present in the southern hemisphere, it could very quickly adapt to the European climate. Since 2011, it is regularly detected in Corsica, and this could be just the beginning.

Countries affected by bilharziasis in the world, in 2016. In red, endemic areas. (Illustration: Percherie / CC)

According to the World Health Organization (WHO), at least 206.4 million people worldwide (in 2016, 92% in Africa), would require treatment for schistosomiasis . It is the world's second-largest parasite endemic, behind malaria

It is difficult to estimate that the number of deaths per year was estimated at 200 000 by WHO in 2000. But this figure has had to decrease considerably since then. following the prevention campaigns put in place. Bilharzia mainly affects poor farmers, children and fishermen infected with infected freshwater.

An 11-year-old Filipino boy with abdominal effusion as a result of schistosomiasis. (Photo: Flickr / CC)

Thousands of eggs a day

This parasitic disease is caused by a worm, the schistosome. Flat, it measures from 8 to 25 mm, according to its kind. The worms make their home in freshwater molluscs, where they multiply. The larval form of the schistosome infects the water, then penetrates the skin of humans who bathe there, or wash their clothes there.

Once in the body, the larva grows up to its adult size. There, the female worm colonizes the blood vessels, migrates to the bladder (for one of its species) and produces hundreds of thousands of eggs, which trigger immune reactions: diarrhea, blood in the stool, abdominal pain, fevers , bladder cancer or even lesions of the central nervous system … sometimes until death.

Present in France

In 2011, it is the stupefaction: the worm, absent from Europe since the 1970s, there rediscovered … in Corsica. In 2013, rebelote: people who have bathed in the Cavu River, a very touristy natural park in the south-east of the island, have disorders of the urinary system. 110 people are affected, according to the figures of the Regional Agency of Health (ARS) of Corsica, without developing a serious form of the disease. In 2014, the site is closed and then reopened in 2015. New people are then affected.

How to explain his arrival in Corsica? According to the ARS, the most likely hypothesis would be that a contaminated person, originating from an area affected by the disease (Senegal), would have urinated in the water, contaminating the bulines (molluscs) of the site, which have in turn contaminated bathers. The site is now closely followed by the prefecture and the health authorities, which have multiplied prevention actions to stop contamination.

But this could spread to other parts of Europe, for many Reasons: firstly, the parasites collected in the Cavu River have evolved into hybrid forms, compatible with contamination of cattle. They could eventually be modified to contaminate more and more European species.

A poster for the prevention of snail fever, in the United States, from 1945. (Illustration: National Library of Medicine / Flickr)

The researchers warn

Then, the different human migrations could help spread the disease, with the arrival of people from tropical or sub-Saharan Africa, in various countries of the European continent.

In an article published in June 2015 on the CNRS website, a European team of researchers specialized in pathogenic infections alerts the authorities. "Governments, research organizations and funding agencies need to consider the need to invest in research on shellfish-related diseases. It is no longer a risk of introduction into Europe due to climate and global changes. The introduction occurred.

In an article published on June 28 in The Conversation, Karl Hoffmann, professor of parasitology at the University of Aberystwyth (Wales), also draws the bell alarm. "The drug Praziquantel was developed in the 1970s. It is safe, cheap and easy to digest. But because of its qualities, no effort has been made in the search for new drugs (against flatworms, N.D.L.R.) for 20 or 30 years. This could be a real danger if schistosomes become resistant to Praziquantel. "

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