[Plasmodium ovale malaria in France. Probability of of genetic control of the incubation period (author's transl)].

Plasmodium ovale as the causative parasite in attacks of malaria is rare. Nevertheless, the number of cases seen in France would seem to be on the increase. In 137 attacks of malaria collected between 1967 and 1978, Plasmodium ovale was found on 13 occasions. The main characteristics of this form of malaria are, apart from its benign nature, the usual absence of any recurrence and a very variable incubation period, ranging from fifteen days to several months or even a year (with an average of 3.2 months). It is thus important to bear this diagnosis in mind, even if a long period elapsed since return from an endemic area, and it will be realised that adequate chemoprophylaxis using a schizonticide does not offer protection from forms with a long incubation period. Genetic control of the duration of the period of maturation of exo-erythrocytic forms, i.e. the incubation period, is suggested, identical to that recently advanced in the case of Plasmodium vivax. This would account for the variability and possible long duration of incubation periods. A usual monoclonal character of these infections could explain the virtual absence of recurrences.