Aetiology and epidemiology of human cryptosporidiosis cases in Galicia (NW Spain), 2000–2008

Abstract

SUMMARYCryptosporidiuminfects millions of people worldwide causing acute gastroenteritis, but despite its remarkable epidemiological and economic impact, information on the epidemiological trends of human cryptosporidiosis is still scarce in most countries. Here we investigate a panel of 486 cases collected in Galicia (NW Iberian Peninsula) between 2000 and 2008, which sheds new light on the epidemiology in this region of the South Atlantic European façade. Incidence rates in Galicia are one order of magnitude higher than those reported in other regions of Spain, suggesting that this parasite remains largely underdiagnosed in this country, and are also larger than those typical of other European countries with available data. Two species dominate our dataset,Cryptosporidium hominis(65%) andC. parvum(34%). The sex ratio of patients infected by either species was 0·5, butC. hominiswas significantly more common in younger males.C. parvuminfections were more acute and required more specialized medical attention, which suggests a differential adaptation of each species to human hosts. The parasites display strong seasonal and geographical variation.C. parvumincidence peaked during summer and was mainly detected in rural areas whileC. hominisinfections were more frequent in autumn and exhibited a more even geographical distribution. Such differences probably reflect their distinct sources of infection – C. parvumis mainly zoonotic andC. hominisanthroponotic – and the effects of climatic variables, like temperature and rainfall.