This page answers one question every week: what is actually going around in the United States right now, according to the surveillance data, not the headlines. It is rewritten each week from the same feeds Vira reads. Where the data is thin or late, it says so.
The short version
Rising this week: West Nile virus (5 cases, up from an average of 4.0).
Falling: Cryptosporidiosis, Hepatitis A, Mumps.
Reportable diseases, CDC week ending September 21, 2026
Counts are what state health departments reported to the CDC's National Notifiable Diseases Surveillance System for the week. They run about three weeks behind the calendar and are revised for months, so read the direction more than the number. The trend compares the week with the average of the four weeks before it.
| Disease | This week | 4-week avg | Trend | Most cases |
|---|---|---|---|---|
| West Nile virus | 5 | 4.0 | rising | Nebraska (1), Arkansas (1), Arizona (1) |
| Campylobacter | 1,015 | 1,012 | steady | Florida (134), California (120), Ohio (84) |
| Salmonella | 867 | 895 | steady | Florida (255), South Carolina (57), New York (50) |
| E. coli (STEC) | 209 | 198 | steady | Ohio (40), Florida (30), New York City (22) |
| Giardiasis | 187 | 208 | steady | New York City (31), New York (27), Florida (24) |
| Shigella | 165 | 196 | steady | New York City (29), Florida (28), New York (17) |
| Measles | 140 | 132 | steady | Pennsylvania (88), Wisconsin (20), New York (18) |
| Cryptosporidiosis | 117 | 198 | falling | Ohio (27), Florida (15), California (11) |
| Legionnaires' disease | 101 | 124 | steady | Florida (18), New York (15), Wisconsin (13) |
| Invasive pneumococcal disease | 93 | 86 | steady | New York City (12), Ohio (12), Maryland (9) |
| Whooping cough (pertussis) | 76 | 64 | steady | Ohio (17), Arizona (10), Florida (9) |
| Tuberculosis | 75 | 69 | steady | North Carolina (11), New York City (11), California (8) |
| Chickenpox (varicella) | 45 | 45 | steady | Florida (16), Ohio (5), South Carolina (4) |
| Hepatitis A | 4 | 7.0 | falling | Nebraska (1), New York City (1), Ohio (1) |
| Mumps | 1 | 1.5 | falling | California (1) |
Flu-like illness, week ending September 6, 2026
The share of doctor visits for influenza-like illness, by CDC region. The national baseline that marks the start of flu season is about 3 percent; anything under 2 is a quiet week.
National: 1.5% of visits, from 1.4% the week before.
| Region | ILI visits |
|---|---|
| Southwest and Pacific | 2.3% |
| Southeast | 1.8% |
| South Central | 1.8% |
| NY, NJ, PR, VI | 1.4% |
| Mid-Atlantic | 1.4% |
| Northwest | 1.1% |
| Mountain | 1.1% |
| New England | 0.9% |
| Central Plains | 0.9% |
| Great Lakes | 0.8% |
Season posts: Flu season 2026 to 2027 and RSV season 2026 to 2027.
Stomach bugs
Norovirus is the most searched illness on this site and one the CDC does not count case by case: it is not a reportable disease. What we can see is CDC wastewater monitoring, which tracks norovirus in sewage across about 40 states, the reportable gastrointestinal diseases in the table above (Salmonella, E. coli, Shigella, Campylobacter), and the outbreak reports in the news. The wastewater table by state is on the norovirus fall 2026 page.
In the news this week
US outbreak reporting picked up by our feeds in the last seven days. A headline is a signal of attention, not a case count.
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Food Poisoning (Tennessee): Dozens of Tennessee Walmart employees hospitalized for 'possible' food illness (Oct 14)
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Measles (Texas): 🚨 Anti-vaxxers target Texas measles doctors to cast doubt on deaths amid outbreak (Oct 13)
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Measles (Bangladesh): Measles Outbreak In Bangladesh Claims Eight More Lives, 2026 Death Toll Reaches 1155 (Oct 11)
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Measles: Chester County high school closed Friday due to confirmed measles case (Oct 10)
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Measles: US Measles Cases Rise to 4,080, CDC Says (Oct 10)
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Measles (Pennsylvania): Measles cases surpass 1,000 in Pennsylvania amid the state's largest outbreak in decades (Oct 10)
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Cyclosporiasis (Mexico): Exclusive | Taylor Farms to Curb Lettuce Sales From Mexico After Massive Cyclospora Outbreak (Oct 9)
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Rabies, Human (Georgia): USDA to airdrop rabies vaccine baits across Northwest Georgia in effort to stop virus's spread (Oct 8)
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Lyme disease, Total (Maine): Maine CDC encourages tick bite prevention this fall (Oct 8)
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Avian Influenza (H5N1): Highly Pathogenic Avian Influenza Confirmed in Racine County (Oct 8)
How to use this
A rising line in the table is a reason to pay attention where you live, not a reason to worry. The counts are statewide; your county can be quiet while the state number climbs. If you want to know when something changes in your own city rather than checking back here, that is what Vira does: she watches the same feeds for the places you name and texts you only when something moves. Join the early access list.
Data: CDC NNDSS weekly tables (week ending September 21, 2026), CDC ILINet, and Virus Watcher outbreak feeds. Updated weekly. Past weeks are archived in Virus Watcher Weekly.