Part 1 — Data guide

Frozen raw snapshot

raw/cdc_nndss_wnv_weekly_2022_2026.csv is a filtered snapshot of the CDC NNDSS Weekly Data table (x9gk-5huc), downloaded on 27 September 2026.

Filter:

label = "Arboviral diseases, West Nile virus disease"

The snapshot contains 17,220 data rows covering 2022 through MMWR week 37 of 2026. It includes states, territories, census regions and totals. advanced/R/01-data.R retains the 50 states, District of Columbia and New York City, then combines New York State and New York City.

The CDC metadata does not provide a licence identifier. The dataset is publicly readable and attributed to the CDC Office of Public Health Data, Surveillance, and Technology. Preserve that attribution and review CDC reuse policies before redistributing the raw file outside this teaching repository.

Flag handling

• Numeric m1: reported current-week cases.
• m1_flag = "-": no reported cases, converted to zero.
• m1_flag = "U": unavailable, retained as missing.
• Other non-numeric flags are also retained as missing.

Do not convert unavailable reporting to zero.

Processed data

processed/wnv_state_week.csv is the prepared teaching dataset read directly by R/workshop.R. Do not edit it by hand during the live workshop.

The optional advanced data-preparation code is preserved in advanced/R/01-data.R.

Source: https://data.cdc.gov/NNDSS/NNDSS-Weekly-Data/x9gk-5huc