(1973) n°3 - Royal Academy for Overseas Sciences

infected with the Moldavian strain. He returned with the
mosquitoes to England where we had a splenectomised chimpanzee
waiting to be inoculated with the sporozoites. The Romanian
workers and I ( G a r n h a m et al. 1968) had shown
in the meantime by blood inoculations on a « Fairley time
schedule » that the blood became infective, i.e. first contained
parasites, on the 15th day after injection of sporozoites. This
information provided the real guide line for the chimpanzee
experiment. Biopsies of the liver were made on days 12, 13, 14
and 15; mature schizonts {Fig- 6) were found on the 15th day
when parasites also appeared in the blood. P. malariae, the
agent of quartan malaria, was thus (L u p a s c u et al. 1967)
shown to be as slow in its exoerythrocytic cycle (15 days) as
it is in its sporogonie (15 days) and erythrocytic cycles (72
hours), as compared with the tertian species.
Much of my own research (see G a r n h a m 1966) in the
last 25 years has been devoted to the study of exoerythrocytic
schizogony in primate malaria, and the cycles of other parasites
have been successfully demonstrated. I will mention briefly
three species, because they have a special interest.
T h e tissu e sta ge o f P. knowlesi, th e q u otid ian parasite o f
orien tal m acaques, w a s fo u n d (G a r n h a m et al. 1957) to
m ature in 5 days and to ex h ib it an u n u su al m o rp h o lo g ica l
picture. T h is is the sh ortest tim e o f any p rim ate parasite.
P. brasilianum, the quartan parasite of New W orld monkeys
is known to be infective to man, and possesses exoerythrocytic
schizonts (G a r n h a m et al. 1963; C o a t n e y et al.
1971) which bear the closest resemblance to those of P. malariae:
they are totally different from those of P. inui, the quartan
parasite of Old W orld monkeys. For this reason and others,
many investigators believe that P. brasilianum arose from a
recent introduction of human quartan malaria into Latin America
and its spread into the monkey population in the forest —
a zoonosis in reverse.
P. vivax hibernans, the temperate strain of the parasite of
benign tertian malaria is a subspecies characterised by a greatly
prolonged prepatent period, which we (in press) have shown
extends up to 628 days. Over the past five years we have studied
this parasite in conjunction with our Russian and Romanian