The toxin responsible for the occurrence of malarial fever is:

Malaria

Read the following passage carefully and answer the given questions.

Plasmodium, a tiny protozoan is responsible for malaria. Different species of Plasmodium (P. vivax, P. malaria and P. falciparum) are responsible for different types of malaria. Plasmodium enters the human body as sporozoites through the bite of infected female Anopheles mosquito. The parasites initially multiply within the liver cells and then attack the RBCs resulting in their rupture. The rupture of RBCs is associated with release of a toxic substance, which is responsible for the chill and high fever recurring every three to four days. When a female Anopheles mosquito bites an infected person, these parasites enter the mosquito’s body and undergo further development. The parasites multiply within them to form sporozoites that are stored in their salivary glands. When these mosquitos bite a human, the sporozoites are introduced in the body, thereby initiating the life cycle of parasite. It is interesting to note that the malarial parasite requires two hosts to complete its life cycle.