Obesity is a major contributing factor to adult-onset diabetes. Infectious diseases or communicable diseases are caused by bacteria, viruses, and parasites that use our body as a host for reproduction.Tuberculosis, malaria, and AIDS are responsible for approximately half of all deaths caused by infectious diseases worldwide. Many viral, bacterial, and protozoan diseases are transmitted by insect bites from mosquitoes, flies, fleas, and ticks. 2  Diseases transmitted by mosquitoes include Dengue Fever, Malaria, Rift Valley Fever, Yellow Fever, and various types of viral encephalitis such as West Nile virus.