The Exoerythrocytic Cycle of Plasmodium Cynomolgi and P. Cynomolgi Bastianellii in the Rhesus Monkey

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  • Laboratory of Parasite Chemotherapy, National Institute of Allergy and Infectious Diseases


Three experiments were performed in which large numbers of dissected, uninfected salivary glands of Anopheles mosquitoes were injected intravenously into normal rhesus monkeys. No artefacts resembling exoerythrocytic parasites of Plasmodium cynomolgi were seen when liver taken at biopsy 8 days later was examined.

The same three monkeys were subsequently injected with smaller numbers of glands infected with sporozoites. Liver biopsy revealed many P. cynomolgi schizonts 8 days later.

When monkeys were injected intravenously with infected glands, exoerythrocytic parasites were invariably seen, even when as few as eight pairs of glands were used. Exoerythrocytic parasites have been seen in 24 different monkeys.

Exoerythrocytic parasites are described from 5 to 120 days after inoculation of the monkeys. The findings in all essential details confirm those of Shortt and Garnham and their associates. Small differences between typical P. cynomolgi and subspecies bastianellii are described.

Two plates, made from color photomicrographs, depicting the cycle in the monkey are presented.

Author Notes

From the Section on Cytology located at the Medical School of the University of Tennessee, 874 Union Avenue, Memphis 3, Tennessee.