How this works

CycloTracker maps reported Cyclospora cayetanensis cases by U.S. state, covering roughly the last three months and updating once a week. Here's where the numbers come from and how far you should trust them.

What is counted

Counts come from the CDC's NNDSS weekly tables(nationally notifiable disease surveillance). They're provisionalreports, broken out by week and jurisdiction, and later weeks revise them. They count surveillance case reports, so they aren't limited to lab-confirmed cases, and they aren't outbreak counts either. Outbreaks are tracked separately in NORS and measured in a different unit.

The 3-month window

By default the map adds up each state's weekly counts over the 13 most recent MMWR weeks in the data. Pick a year from the dropdown instead and you get that year's running total. A state can turn up in one view and be absent from the other.

Zero vs. no data

A blank is not a zero, and the two are stored separately. Every state-week carries a status:

• reporting— there's a real count behind it. That count can be zero, in which case the state is left empty with no circle on it.
• no data — the disease is flagged not notifiable (N) or unavailable (U) in that jurisdiction. Those states get a hatched fillinstead of a circle with no size to it. Right now that's Idaho, Mississippi, and Pennsylvania.

Comparing states and years

Case definitions for cyclosporiasis have changed over the years (the CSTE position statements track the changes), and how completely a state reports varies by state and by season. That makes year-over-year and state-to-state comparisons rough. Weekly counts are provisional and get revised. Summer outbreaks, often traced back to fresh produce, cause big spikes that are entirely real. The Ohio and Michigan numbers right now are one of those.

When sources disagree

If two sources cover the same state and week, the value comes from whichever one ranks higher: state health departments first, then NNDSS annual, then NNDSS weekly. A source only wins if it actually has a number. When sources disagree the map flags it rather than splitting the difference. None of that fires today, since NNDSS weekly is the only case source turned on. The layer is there so the next source drops in without a rewrite.

Rates (per 100,000)

Per-capita rates use Census ACS 1-year population figures (variable B01001_001E). The original plan was the Census PEP API, but its population endpoint hasn't moved past Vintage 2021, and ACS 1-year is current through 2024. A state shows a rate only where the population is known.

Reading the circles

Circle area tracks the value, not radius. The radius scales with the square root, so a state with 4× the cases gets a circle twice as wide, not four times. NNDSS reports New York City on its own line and those cases are added back into New York State. Territories are in the database but not on the map, since the Albers USA projection covers the 50 states plus DC.

Rules the code holds to

• No fabricated or interpolated case data. If a number is missing, it stays missing.
• Every number on screen traces back to a source. They're in the table below and in each tooltip.
• Circles are never sized by radius, and no-data is never drawn as a zero.

Sources