Parasitological and clinical investigations on infections with the VS Romanian strain of Plasmodium malariae transmitted by Anopheles labranchiae atroparvus.

In order to contribute to knowledge of the sporogonic cycle of malaria parasites, 3 batches of Anopheles labranchiae atroparvus were infected with the VS Romanian strain of Plasmodium malariae by feeding them on 2 patients undergoing malariotherapy in Romania. Of the 310 infected mosquitos 59 were dissected for ookinetes, oocysts and sporozoites, and the rest were used for further clinical trials in England. Mature ookinetes were observed 18 hours after infection, and sporozoites were first observed in the salivary glands 19 days after infection.One of the main characteristics of the VS strain of P. malariae observed in Romania was the relatively large number of gametocytes and subsequent heavy infections it could produce. However, gametocytes were found only in the heart blood of 1 of the 4 subjects infected in England (on autopsy after accidental death); post mortem examination of the liver of the same subject failed to show exo-erythrocytic schizonts. None of the other 3 subjects showed gametocytes or infected mosquitos. On the basis of clinical symptoms, the incubation period of P. malariae in these subjects was found to be 18-19 days.