Mosquitoes cause diseases, such as malaria, dengue fever, and Japanese encephalitis. These diseases are caused by the pathogens listed in Table 1 [1]. When a mosquito bites a human or other animal infected with these pathogens, the pathogen is transferred to the mosquito and propagates inside the mosquito. When a mosquito that has propagated a pathogen in the body sucks blood from another person, the saliva of the mosquito is transferred to the human body and the human is infected with the pathogen (Figure).