A comparison of the course of natural infection of P.vivax and P. falciparum in man:
Comparison # P. Vivax:
1. Pre-erythrocytic schizogony:
It consists of one cycle, lasts 7-8 days. Number of merozoites produced by each schizont is about 12,000.
2. Erythrocytic schizogony:
Duration of erythrocytic schizogony is about 48 hours. Appearance of parasites in the peripheral blood on 12th day of infection.
First rise of temperature on 16th day of infection. Primary attack lasts 3-4 weeks.
3. Gametogony:
Appearance of gametocytes in peripheral blood is on 16th day of infection (First day of fever: 4 days after the appearance of asexual parasites in peripheral blood).
4. Exoerythrocytic schizogony:
Present, may continue for a period of about 3 yrs. Relapses often occur.
5. Single infection:
Lasts upto 3 years.
Comparison # P. Falciparum:
1. Pre-erythrocytic schizogony:
It consists of one cycle and this phase lasts for 6 days. Each matured schizont produces about 40,000 merozoites.
2. Erythrocytic schizogony:
Each cycle lasts 36-48 hours. Appearance of parasites in the peripheral blood on 10th day of infection.
First rise of temperature on 12th day of infection.
Primary attack lasts 10-14 days.
3. Gametogony:
Appearance of gametocytes in peripheral blood is on 21st day of infection (after 9 days of fever: about 10 days after the appearance of asexual parasites in peripheral blood).
4. Exoerythrocytic schizogony:
Absent, relapses do not take place.
5. Single infection:
Generally lasts for about one month but may last upto a maximum of one year.