Seasonal Variations in the Characteristics of Vivax Malaria

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  • Station for Malaria Research, Tallahassee, Florida


The observations recorded indicate that inoculations made with P. vivax during the first or winter quarter result in a lower proportion of takes. It would also appear that the successful inoculations present longer incubation periods, have shorter clinical courses, and, if renewed clinical activity is experienced, are likely to be confined to a period of eight weeks following cessation of the primary attack. Inoculations made during the second, third, and fourth quarters present a marked contrast in all these characteristics. This contrast is most evident in the case of the third or summer quarter, in which have been secured the largest proportion of successful inoculations and in which the incubation periods are shortest, the clinical attacks the longest, and the likelihood of renewed activity twenty-four weeks after cessation of the primary attack appears greatest.