The status of infection was studied on 29 patients with malaria. The 29 patients included 28 patients with imported malaria, consisting of 22 with Plasmodium vivax, five with P. falciparum, and 1 with vivaxfalciparum mixed infection. Besides these 28 patients, there was one vivax malaria patient with domestic infection.
The cases with falciparum malaria all developed as early as within 21 days after the repartriation of the patients to Japan from the areas where it was prevailing. On the other hand, only about half of the cases with vivax malaria evolved within one month after the return of the patients to Japan, and the other half developed not less than 2 months after the repatriation of the patients: thus, there was an apparent difference between these cases and the cases of falciparum malaria.
Seventeen with 28 patients with imported malaria had not received chemoprophylaxis in the respective malaria-prevailing areas. Out of the people who had received the chemoprophylaxis, on the other hand, there were 9 patients with P. vivax (40.9%) and two with P. falciparum (40.0%); however, chemoprophylaxis in all of these patients had been insufficient both in dosage and medication period.
Both the patients with P. vivax and those with P. falciparum were, in principle, treated with chloroquine to control the pyretic attack. Then, the patients with P. vivax and the one with mixed infection were medicated with primaquine 15 mg base/day, for 14 days as radical treatment to prevent relapse. Despite this treatment, the vivax malaria relapsed in 55 and 88 days in two of the patients with this infection, and both of the two had been infected in New Guinea. Attention should be called to the report that there is a primaquine-resistant P. vivax (Chesson strain) infection, the relapse of which cannot be completely prevented with the usual doses of this drug, in the vivax malaria prevailing in New Guinea. Therefore, a particular care is necessary in prescribing the dosage of primaquine for the treatment of the patients infected by P. vivax in New Guinea.