Observations on 43 patients infected with induced quartan malaria by three strains of parasites, are presented, and analyzed. A detailed summarization is impracticable. In five the attack was naturally induced, in 38 the inoculation was effected artificially. The incubation period subsequent to natural inoculation has varied from 4 to 5 weeks, with a lag of from three to 12 days between the first detection of parasites and the clinical onset. Subsequent to artificial inoculation it has usually been shorter, and but rarely has the clinical onset preceded the detection of parasites. The infections presented a mortality rate of 7.9 per cent and a case fatality ratio of 12.7:1. The attacks including recurrences subsequent to natural inoculation have in whites had a mean duration of 170 days and in negroes of 76 days. Subsequent to artificial inoculation the mean duration of uninterrupted attacks in whites has been 81.2 days and in negroes 53 days. The maximum duration observed, which may have been affected by therapeutic interference, was 303 days. Regardless of therapeutic interference or race, the mean duration of naturally induced attacks has been 132 days, and of artificially induced attacks 92 days. A majority of the patients born in Florida, Georgia, and Alabama have had attacks of less than the mean duration.
All of the naturally inoculated patients experienced remissions before the termination of clinical activity, and averaged two recurrences per patient. Twenty-eight of the artificially inoculated patients experienced remissions with 2.3 recurrences per patient. Their number has been greatest in the attacks of longest duration.
An onset with a remittent fever is unusual, and the early paroxysms invariably exhibit a simple quartan pattern. Double quartans and quotidians have not been observed until after the evolution of the attack is well advanced.
The clinical course following natural inoculation is of a much simpler pattern than that observed subsequent to artificial inoculation. The paroxysms are more commonly a simple quartan and show a high degree of constancy in the hours of their recurrence. On the other hand, those recurring subsequent to artificial inoculation show a much greater complexity and irregularity.
Characteristically the densities attained by the parasites are lower than those observed in infections by the other species of malaria parasites, and only rarely are exceptions noted.
The most common incident in the clinical course of the infection is the development of an albuminuria, which probably represents a nephrosis rather than a nephritis. This always has cleared up with the termination of the infection.
In only one instance has therapeutic interference failed to bring the infection under control. Reason for this failure is not apparent, although obviously the infection in this patient presented certain atypical features.