Write the name of toxic substance responsible for fever and chill in malaria.

Explanation

**Step-by-Step Solution:**

1. **Identify the Disease**: The question asks about a toxic substance related to a specific disease, which is malaria.

2. **Understand the Causative Agent**: Malaria is caused by a protozoan parasite known as Plasmodium. There are several species of Plasmodium that can cause malaria, such as Plasmodium falciparum, Plasmodium vivax, etc.

3. **Entry of the Parasite**: The Plasmodium enters the human body in the form of sporozoites, which are injected into the bloodstream by the bite of an infected Anopheles mosquito.

...