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Biomedical subjects

P G Sergiev

Publications and source records attributed to P G Sergiev.

15 recordsLinked to original sources
PubMed1975

A strain of Plasmodium vivax characterized by prolonged incubation: morphological and biological characteristics.

Numerous strains of P. vivax, distinguishable chiefly by their biological characteristics, are known to exist. Two main varieties are recognized: the so-called temperate and tropical strains. The most extreme example of the former-designated by Nikolaev as P. vivax hibernans-constantly exhibited an extremely long incubation period. The strain is no longer in existence and no type material has been preserved. In its place, a North Korean strain with a generally long incubation period has been studied and compared with the well-known tropical Madagascar strain, which frequently but not constantly has a short incubation period. The data presented here concern the behaviour of various strains from the USSR and the morphological characteristics of the North Korean and Madagascar strains. Splenectomized chimpanzees were used as the host of these parasites, particularly in regard to exoerythrocytic schizogony. Attempts were also made, by late biopsies of the liver of the apes, to elucidate the prolonged latency of the North Korean strain. Although there was no evidence of specifically dormant forms, it is probable that certain sporozoites fail to develop in the normal time and that they are reactivated by an unknown factor a year or more after inoculation.

Animals↗
PubMed1968

Dates of onset of relapses and the duration of infection in induced tertian malaria with short and long incubation periods.

The course of induced tertian malaria has been studied in patients in psychoneurological hospitals in Moscow over a long period. Various strains of P. vivax were used to infect patients; the sporozoites were transmitted by Anopheles maculipennis atroparvus bred under laboratory conditions. There are marked differences between the dates of onset of relapses, reckoned from the primary manifestations of the disease, in patients developing malaria after long and short incubation periods. P. vivax strains which have a short incubation period are characterized by producing in patients a series of relapses following a long latent period; strains with a long incubation period are characterized by the occurrence of relapses during the first 3 months after the end of the primary series of attacks. However, some P. vivax strains give rise to both types of relapse, depending on the incubation period. In any event, the duration of the disease does not, as a rule, exceed 2 years, including the incubation period. The number of mosquitos (and hence the number of sporozoites) used to infect a patient does not have any noticeable effect on the number and frequency of relapses. In short-incubation tertian malaria, the use of quinocide during the period of treatment of the primary manifestations greatly reduced the number of relapses; in long-incubation tertian malaria similarly treated with quinocide, no relapses occurred.

Anopheles↗