Before 2000, no cases of P. falciparum had occurred in Chinese immigrants living in northern and central Italy, despite a large immigrant population. An initial cluster of 22 cases was described during summer 2000 in the Lombardy Region (3). A cluster of six cases was detected in Tuscany during the same period (4). In both outbreaks, the researchers described high rates of severe disease. All patients were exposed to malaria during a prolonged journey to Europe (3–9 months) through a number of Asian and African countries.

From 2000 to 2002, a total of 10 sporadic cases were reported to the Italian Ministry of Health in 2001 (L. Vellucci, Directorate for Prevention, Ministry of Health, Italy, pers. comm.). The 2003 cluster prompted us to examine hospital records from August 2002, where we identified an additional, previously undetected, cluster of 12 malaria cases in four of our study hospitals (data not included in the table). The Ministry of Health had 26 confirmed P. falciparum cases during 2002 (L. Vellucci, pers. comm.), suggesting an ongoing (and possibly increasing) influx of Chinese laborers. Some differences exist between the later cluster and the 2000 cluster. In the 2003 cluster, the proportion of severe cases was lower than in the previous reports, with a patient with a fatal case first admitted to a general hospital where diagnosis of malaria was not considered; in the others, awareness of the possibility of malaria had been raised by the earlier cluster (3,4) and led to prompt diagnosis and treatment, with favorable outcome. A single African country, Côte d’Ivoire, was the transit country for most of the patients. In previous cases, a number of other African countries were used for transit. Visa processing for entry to Europe was arranged by the courier organization in Côte d’Ivoire. The clustering of cases suggests that the illegal immigrants arrive in Europe in groups. Although Italy was the final destination, at least some immigrants entered through France, which also has had reports of P. falciparum cases in Chinese immigrants (F. Legros, Centre National de Référence de l’Epidémiologie du Paludisme, France, pers. comm.). As malaria is probably underreported in Europe, additional cases may well have occurred.

Use of clandestine travel by air to emigrate from China, where sudden acute respiratory syndrome (SARS) is present, poses a threat for the African countries, where the introduction of SARS virus could have devastating consequences on their health systems with a potential overlap with the HIV epidemic. Other diseases could be spread or acquired by the immigrants in the countries of transit. While curtailing the huge, illegal immigrant system to Europe is difficult, we cannot overemphasize the need for a sound surveillance on imported infectious diseases in this continent.

Both clusters of malaria were detected early through Salute Internazionale Regione Lombardia (SIRL), a network on imported diseases of the Lombardy Region, in conjunction with the European Network on Imported Infectious Disease Surveillance (TropNetEurop). Any physician in Europe who sees a Chinese patient with a history of recent travel and a high fever should exclude malaria, besides considering the possible diagnosis of SARS. Respiratory symptoms are also frequent in uncomplicated malaria (5,6), and acute respiratory distress syndrome has long been recognized as one of the main features of severe malaria (7,8).