Usefulness of seminested multiplex PCR in surveillance of imported malariain Spain

The use of a new PCR-based method for the diagnosis of malaria in the Spani sh Malaria Reference Laboratory has promoted an increase in confirmed cases of malaria. From August 1997 to July 1998, a total of 192 whole-blood samp les and 71 serum samples from 168 patients were received from the hospitals of the Spanish National Health System. Most of the patients came from west -central African countries (85%), This molecular method show ed more sensit ivity and specificity than microscopy, detecting 12.4% more positive sample s than microscopy and 13% of mixed infections undetectable by Giemsa stain. Plasmodium falciparum was the main species detected, with 68% of the total positive malaria cases, follow ed by Plasmodium malariae (29%), Plasmodium vivax (14%), and Plasmodium ovale (7%), including mixed infections in all cases. This report consists of the first wide, centralized survey of malari a surveillance in Spain. The reference laboratory conducted the analysis of all imported cases in order to detect trends in acquisition. The use of a seminested multiplex PCR permitted confirmation of the origins of the infec tions and the Plasmodium species involved and confirmation of the effective ness of drug treatments. This PCR also allowed the detection of the presenc e in Spain of primaquine-tolerant P. vivax strains from west-central Africa , as well as the detection of a P, falciparum infection induced by transfus ion.