What to know
These data are provisional and subject to change. Due to delays in reporting, state, territorial, and local health departments may have more up-to-date information than what is presented here. This page displays data regarding human cases only.
Limitations of ArboNET
Surveillance data have several limitations that should be considered when using and interpreting the data.
1. Under-reporting is a limitation common to all surveillance systems that rely on healthcare providers to consider the disease as a possible diagnosis in a patient, obtain the appropriate laboratory test, and report confirmed to public health authorities.
2. Cases of mild illness are more likely to be underreported compared to more severe disease cases. The degree of underreporting varies by disease awareness and healthcare-seeking behavior in any area. Surveillance data for non-neuroinvasive disease should not be used to make comparisons of disease activity between different locations or over time.
3. Surveillance data are reported by county of residence, not the location (county or state) of exposure.
4. There is a lag in case reporting to CDC and states and territories may publish surveillance data on different schedules than CDC.