Evidence of autochthonous transmission of urinary schistosomiasis in Almeria (southeast Spain): An outbreak analysis

Background: Schistosomiasis is endemic in 78 countries belonging to tropical and subtropical areas. However, autochthonous transmission of urogenital schistosomiasis was reported in Corsica (France) in 2013. We present evidence of autochthonous transmission of urogenital schistosomiasis in Almeria (Spain) in 2003. Methods: Description of the outbreak in farmers and subsequent epidemiological studies aimed at searching for Bulinus snails and their genotypic characteristics. Results: The outbreak affected 4 farmers out of a group of 5 people who repeatedly bathed that summer in an irrigation pool in the area. Two of them presented macroscopic hematuria with bilharziomas, showing the presence of Schistosoma eggs in bladder biopsies. Two others were asymptomatic but the serology for schistosomiasis was positive. In 2015, the presence of the vector Bulinus truncatus was demonstrated in Almeria in water collections of appropriate characteristics. DNA sequencing proving that local B. truncatus species were base-tobase identical to B. truncatus from Senegal. Conclusions: We present a new outbreak of autochthonous transmission of urogenital schistosomiasis in Europe. Although no new cases of autochthonous transmission have been reported, some other cases may have occurred at that time or later on and be unnoticed as many cases of schistosomiasis are asymptomatic or present mild and unspecific symptoms.