What parasite can cause "black fever"?

"Black fever" is a term commonly associated with the disease visceral leishmaniasis, which is primarily caused by the protozoan parasite Leishmania donovani. This parasite is transmitted through the bite of infected sandflies, and it predominantly affects internal organs, leading to symptoms such as prolonged fever, substantial weight loss, and anemia. The term "black fever" is used because the illness can cause the skin to darken, particularly in advanced cases of the disease.

The other options refer to different parasites associated with distinct diseases. Toxoplasma gondii is known for causing toxoplasmosis, which often presents with flu-like symptoms and is particularly concerning for immunocompromised individuals. Plasmodium falciparum is the most severe human malaria parasite, causing episodes of fever, chills, and can lead to serious complications but is not associated with the term "black fever." Trypanosoma brucei is the causative agent of African sleeping sickness, which primarily affects the central nervous system and presents with different sets of symptoms. Thus, Leishmania donovani is specifically linked to the term "black fever" due to the nature of the illness it causes.