After entering the human body through mosquito bite, the malarial parasite (Plasmodium) shows initial multiplication in

After a female Anopheles mosquito bites a human, it injects Plasmodium parasites in the form of sporozoites into the bloodstream [1]. These sporozoites quickly travel to the liver, where they invade hepatocytes [2]. This phase, known as the pre-erythrocytic or exo-erythrocytic stage, represents the initial site of multiplication within the human body [1]. Inside the liver cells, the parasites undergo asexual reproduction (schizogony), transforming into schizonts that eventually rupture to release thousands of merozoites [2]. It is only after this massive initial amplification in the liver that the parasites enter the bloodstream to infect red blood cells (erythrocytes), leading to the clinical symptoms of malaria [4]. While the spleen may enlarge during infection due to the clearance of infected red cells, it is not the site of initial multiplication [3].

Sources

1. [1] https://www.cdc.gov/dpdx/malaria/index.html
2. [2] https://pmc.ncbi.nlm.nih.gov/articles/PMC5453383/
3. [4] https://www.nature.com/articles/nrmicro3111
4. [3] Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 8: Natural Hazards and Disaster Management > Malaria > p. 79