To these three, many would require a fourth criterion - demonstration of interruption of transmission for a prolonged period in a large geographic area.
Humans are critical to the maintenance of measles virus transmission.
Humans are the only reservoir for measles virus and virus survival in the environment is limited to several hours. Nonhuman primate populations are too small to sustain transmission. Thus, sensitive and specific serologic are available for the reliable diagnosis of measles. However, with two doses, these levels can be reached. All countries attempting to eliminate measles transmission have used some form of a two dose strategy.