Which is an example of a disease transmitted by a vector?

Malaria is an example of a disease transmitted by a vector because it is spread by the bite of infected mosquitoes, specifically the Anopheles species. This transmission method is characteristic of vector-borne diseases, where a living organism (the vector) facilitates the spread of pathogens from one host to another. In the case of malaria, the Plasmodium parasite undergoes part of its life cycle within the mosquito before being transmitted to humans through their bites.

In contrast, the other diseases listed—influenza, tuberculosis, and pneumonia—are not transmitted through vectors. Influenza is primarily spread through respiratory droplets when an infected person coughs or sneezes. Tuberculosis is an airborne disease caused by bacteria that spread when an infected person coughs, sneezes, or talks, releasing the bacteria into the air. Pneumonia can be caused by various pathogens, including bacteria and viruses, and its transmission usually occurs through direct contact or inhalation of respiratory droplets, rather than through a vector. This distinction highlights why malaria is categorized as a vector-borne disease.