2014-06-23 14:51:30
Appearance of urogenital schistosomiasis in Corsica in 2014
Following the report of clustered cases of autochthonous schistosomiasis in southern Corsica, which took place before the 2014 bathing season, ANSES was asked to carry out an expert appraisal on the ecology of bulins (PDF). Its expert work led the Agency to recommend acquiring knowledge regarding these molluscs in order to draw up an inventory of their presence in bodies of water and streams conducive to their development. This knowledge is essential to establish a profile of water bodies and streams likely to meet the conditions favoring the possible installation of a source of transmission of S. haematobium.
Following the Agency’s opinion, management measures and environmental monitoring in Corsica have been implemented at several bathing sites and a prefectural decree dated June 16, 2014 had prohibited swimming during the summer period of 2014 in the Le Cavu river.
Following this ban, no case of urogenital schistosomiasis linked to swimming in the Cavu was recorded in 2014. The Directorate General for Health (DGS) then contacted the Agency in February 2015 to propose a list of criteria conditioning the lifting of the bathing ban in the Cavu for the 2015 summer period. These various measures are described in the ANSES opinion of 30 April 2015 (PDF).
In February 2016, two new cases of urogenital schistosomiasis were reported in connection with swimming in the Cavu during the summer of 2015. The Agency, once once more contacted, then proposed areas for development in order toimprove parasite detection in the water or the mollusc and a management strategy concerning the measures to be put in place in the event of the occurrence of new cases of bilharziasis in Corsica (opinion of 25 March 2016 (PDF))
In addition, autochthonous urogenital schistosomiasis has been on the list of notifiable diseases since June 2016.
Urogenital schistosomiasis: presentation and work of the Agency
What is urogenital schistosomiasis?
Second parasitic disease in the world following malaria, schistosomiasis is a infection due to trematodes (flatworms) of the genus Schistosoma. It is transmitted to humans during a simple skin contact with water in water bodies and streams where infested freshwater gastropod molluscs, bulins, live and release larvae into the water.
Infections due to Schistosoma haematobium touch 112 million people, 150,000 of whom die each year.
Following the report of grouped cases of autochthonous uro-genital schistosomiasis in southern Corsica in 2014, ANSES received a request from the Directorate General for Health (DGS) toassess the risk of human contamination by this parasite in mainland France. At the same time, the High Council for Public Health (HSCP) was also contacted by the DGS concerning the screening, treatment and prevention of infections due to S. haematobium.
The Agency’s work following the appearance of urogenital schistosomiasis in Corsica
Urogenital schistosomiasis is contracted by thetotal or partial immersion of the body in water containing the immature form of the parasite S. haematobium. This is hosted by the bulins. The environmental monitoring proposed by the Agency in its first opinion made it possible to search for bulins in 20 Corsican rivers. The population of bulins is mainly located in the Le Cavu river. None of the 3,500 bulins harvested during the summer of 2014 was infested.
At the same time, analyzes carried out by molecular biology on the eggs of schistosomes emitted in the urine of infected patients have shown the presence of a hybrid S. haematobium / S. bovis. Funding from ANSES made it possible to carry out epidemiological monitoring of S. bovis, a species of schistosomes infesting livestock, and more particularly sheep, goats and cattle. The objective was to determine whether S. bovis or a hybrid was found in ruminants in Corsica. The parallel search for the parasite undertaken in wildlife (rats) did not reveal any animal reservoir.
The Agency is continuing its commitment to acquiring knowledge and is currently funding a study on the ability of molluscs infected by the parasite S. haematobium and by the hybrid parasite S. haematobium x S. bovis withstand the winter conditions encountered in temperate latitudes. Pending the results of this study, the human reservoir seems to date the most probable hypothesis as the origin of the recontamination of the Corsican site.
Conclusions and final recommendations of the Agency
The Agency recalls that the recurrent presence of whelks in Corsican rivers, their receptivity to species of schistosomes introduced into the environment to date, the climatic conditions and the presence of nutrients favorable to their development, as well as a very large human population , create the necessary conditions to initiate a new cycle of transmission of urogenital schistosomiasis in Corsica.
In order to limit the resurgence of human cases during the summer periods, the Agency has proposed a management strategy concerning the measures to be put in place in the event of the occurrence of cases of bilharziasis in Corsica. ANSES therefore recommends:
- avoid the emission into water bodies of the eggs of Schistosoma haematobium, avoiding urinating in bodies of water and streams;
- continue the environmental monitoring initiated in 2014 and propose ways to improve the detection of the parasite both in earliness and sensitivity;
- inform Corsican health professionals the risk associated with urogenital schistosomiasis;
- inform the general population and workers likely to come into contact with water modes of transmission of genito-urinary schistosomiasis.
In the event of confirmed contamination of a water body or course, theThe Agency recommends informing the population and workers that any contact with water must be prohibited and taking all measures to avoid exposure. Wearing personal protection is also imperative for workers.
1693110204
#Urogenital #schistosomiasis #ANSES #National #Agency #Food #Environmental #Occupational #Health #Safety
