The person can also turn blue, due to the lack of oxygen, vomit, or go into convulsions. Influenza virus that infects people does not infect other hosts. Influenza is transmitted through air droplets expelled by coughing or sneezing. Measles is a highly contagious viral disease, which can enter the body through the eye or respiratory tract. Symptoms such as a rash, high fever, delirium, and eye pain can occur.
Mumps also occurs in the respiratory tract and later the infection can spread throughout the body.
Swelling of the glands can occur. Typhus is considered a vector-borne disease meaning an intermediate host is involved. Symptoms include fever, weakness, and hemorrhagic rash. Smallpox is a virus that enters the respiratory tract. The origin of disease in the New World and the Old World is very different.