Southwest Pacific vivax malaria; clinical features and observations concerning duration of clinical activity.

01 Mar 1949

The symptomatology, duration, relapse rate, and response to treatment of Southwest Pacific vivax malaria was evaluated in 328 veterans who were studied over a 33-month period. The infections were diagnosed by blood smear. Prodromal symptoms other than chills, fever and malaise were elicited in 46 per cent of the cases. Splenomegaly was noted in 37.6 per cent, and hepatomegaly in 15.1 per cent of the cases. In groups paired on the basis of average attack treated, the relapse rate following chloroquine was 56 per cent and atabrine 60 per cent. The relapses following chloroquine occurred much earlier. Chloroquine has no advantages over atabrine.

In the present series the relapse rate decreased with further attacks but the per cent of each relapse group recurring further was approximately the same from one attack to the next. Of a group of cases studied in the entirety of their clinical duration, 24.5 per cent were terminated in the first year, 52.9 per cent in the second year, and 18.3 per cent in the third year. Attacks were still occurring in 4.3 per cent in the fourth year of the disease. The frequency distribution of the duration of this group of cases is presented. Relapses of Pacific vivax malaria will be a rarity in the fifth year after infection. The earlier impression that few cases would last beyond two years is not borne out by this stidy. Patients with Pacific vivax malaria often harbor multiple strains. The duration of clinical activity of such a group of cases should not be interpreted as the behavior of a single strain infection.

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