Naturally acquired immunity to vivax malaria.

Sir Ernay Camargo and colleagues (April 24, p 1415) report that symptom-free carriers of Plasmodium vivax were found among native Amazonians living in an endemic area of vivax malaria. They state that these findings reflect a certain degree of premunition in the population, similar to that described for falciparum malaria, and that this has not been reported previously. In our study site on the western border of Thailand, vivax malaria is endemic, and symptomless carriage is not rare. In 1992, we followed two cohorts to describe the epidemiology of malaria in this area. Malaria cases were diagnosed by a combination of active and passive detection. Thus, we were able to identify symptom-free carriers and to follow them.

Full text article: https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(05)75295-8/fulltext