A Cluster of Cryptic Plasmodium falciparum Malaria in African Migrants in Southern Italy, October 2017

Background: Italy was declared malaria free by the World Health Organization in 1970. Despite this, nonimport malaria cases are on the increase in Italy and throughout the Mediterranean area. In Italy, in the period between 2011 and 2015, seven cases of locally acquired malaria have been reported, including one introduced case of Plasmodium vivax; moreover, the last certain case of introduced malaria (by P. vivax) has been reported in Tuscany in 1997. No case of introduced malaria from Plasmodium falciparum has been reported in Italy since 1970. Case Presentation: A cluster of four cryptic P. falciparum malaria cases were ascertained in migrant farm workers (three from Morocco and one from Sudan) in Apulia (southern Italy) with clinical onset between September 20 and 27, 2017. None of the patients reported a history of a recent trip to malaria-endemic areas or hospitalization or other risk factors. Typing of malaria was also confirmed using molecular biology methods in two different laboratories. There were no cases of severe malaria in our four patients, and only one in need of transfusion. All patients were discharged cured after being treated with mefloquine due to the unavailability of other antimalarials. Conclusions: In recent years, numerous reports of locally acquired malaria have been made in southern Europe. The cases described in this article represent the first cluster of malaria caused by P. falciparum in Europe. Today, clinical presentation in the diagnosis of malaria is more important than ever, since epidemiological criterion cannot be considered unfailing. The mode of transmission has not been proven and further biological and entomological studies are necessary to define our case as cryptic or confirm the presence of mosquitoes capable of transmitting P. falciparum and/or the capacity of Anopheles labranchiae, An. superpictus, or An. plumbeus to transmit it on Italian territory.