Which set of disease is spread mainly by insect vectors?

The set of diseases that is spread mainly by insect vectors is "Malaria, cholera and river blindness". Insect vectors are organisms like mosquitoes, ticks, and flies that can carry and transmit disease-causing pathogens like bacteria and viruses. Malaria is spread by the Anopheles mosquito, cholera by the Vibrio cholerae bacteria which can contaminate water sources, and river blindness by the black fly which carries the parasite Onchocerca volvulus. The other options do not have diseases that are primarily spread by insect vectors.