Influence of progesterone and estrogen administration on the recrudescence patterns of Plasmodium knowlesi infection in female rhesus monkeys (Macaca mulatta) following initial subcurative chloroquine therapy
Dutta, G.P.; Kamboj, K.K.
Indian Journal of Malariology 21(2): 79-88
1984
ISSN/ISBN: 0367-8326 PMID: 6536543 Document Number: 222688
The effect of short-term treatment of female rhesus monkeys (Macaca mulatta) with high doses of progesterone or estrogen, on the pattern of recrudescence of Plasmodium knowlesi, after initial subcurative chloroquine therapy has been studied. Progesterone (1 mg/kg/day) or estrogen (estradiol dipropionate, 10 .mu.g/kg/day) was administered to groups of nine monkeys by i/m route for 25 days prior to malaria infection and the treatment was continued during the rest of the study. Nine monkeys which served as control, were administered only the vehicle (sterile olive oil, 0.5 ml, i/m) for 25 days. In order to suppress primary infection, chloroquine (9-10 mg base) was administered in 2-4 divided doses between 12-25th day of P. knowlesi inoculation, and the patterns of recrudescence were studied. All the monkeys with progesterone or estrogen showed recrudescence 7-8 days after subcurative therapy with peak parasitaemia levels of 8.50 .+-. 7.70% and 5.13 .+-. 3.51% respectively, which were significantly higher than the controls (peak 1.81 .+-. 0.88%). The total parasitaemia load during recrudescence was 5.10-fold higher in progesterone treated group and 3.46-fold higher in estrogen treated group, as compared to the controls. The duration of major peaks of parasitaemia in both the steroid treated groups was significantly longer. These studies suggest that high doses of steroids tend to slightly delay the development of protective immune responses against P. knowlesi in rhesus monkeys.