There are five risk factors that contribute to the overall risk of arbovirus transmission in an area.

1. Environmental conditions (rainfall and temperature)
2. Adult vector mosquito abundance
3. Virus isolation rates from mosquitoes
4. Infection rates in wild or domestic animals
5. Human cases of mosquito-borne viruses

Each of these factors is rated on a scale of 1 to 5, with 5 representing conditions indicative of a high risk of human infection with a mosquito-borne virus. An average rating is determined for the five factors and is correlated with the response level as follows:

Level 1: Normal Season (1.0 to 2.5)

Level 2: Emergency Planning (2.6 to 4.0)

Level 3: Epidemic Conditions (4.1 to 5.0)

To learn more information on the risk factors and how they are scored, view the video above or view our Mosquito-Borne Virus Surveillance and Emergency Response Plan.