What is a common disease caused by protozoa?

Malaria is a well-known disease caused by protozoa, specifically by Plasmodium species. These protozoa are single-celled organisms that enter the human body through the bite of an infected female Anopheles mosquito. Once in the bloodstream, the Plasmodium parasites invade red blood cells, leading to symptoms such as fever, chills, and flu-like illness, and if left untreated, it can result in severe complications or even death.

The other options refer to diseases caused by different pathogens. Staphylococcus is a type of bacteria that can cause a range of infections, Athlete's foot is a fungal infection that affects the skin on the feet, and chicken pox is a viral infection caused by the varicella-zoster virus. Understanding these distinctions is crucial in recognizing the various types of pathogens that can cause diseases and the specific illness each can lead to.