Historic Data (1999-2022)

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 (non-neuroinvasive disease) are more likely to be underreported compared to more severe disease (neuroinvasive) 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. Non-human surveillance is conducted variably across the country. Absence of non-human activity reported to CDC should not be interpreted as no risk.
5. There is a lag in case reporting to CDC and states and territories may publish surveillance data on different schedules than CDC.

The visuals on this dashboard display West Nile virus data from 1999 – 2022.

• The “Cumulative Data for 1999-2022” section displays combined data from this timeframe. This includes:
  • Disease cases by year
  • Disease cases by age and sex
  • Average annual incidence by county
• The “Explore Human Data for 1999-2022” section allows users to filter the data by year and type of case (all disease cases or neuroinvasive disease cases only) using the drop-down list of options. This includes:
  • Number of disease cases, hospitalizations, and deaths
  • Disease cases by month
  • Disease cases by state
• The “Explore County Level Data for 1999-2022” section allows users to filter the data by year using the drop-down list of options. This visualization includes:
  • Human and non-human activity by county
• The data for each visual can also be viewed in table form by clicking on its corresponding data table bar below the figure.

Please note – users may experience slow load times after selecting filters. Please allow the visualizations to fully load after selecting filters, which will be indicated by an updated visual title.