Welcome to the thirty-first edition of FOI Clinical. Each week, we'll send you a briefing on outbreak news. When something urgent breaks, you'll get an alert the same day.
In this edition
Measles – Cyclosporiasis – Sprouts recall expanded – Covid-19 – National surveillance, week 34 – West Nile virus – Ebola: DRC
National interest
Measles — U.S. tops 3,000 cases
CDC reported 3,134 confirmed cases on September 3, up 231 cases in one week. There have been 38 outbreaks this year, 95% of cases are outbreak-associated (2,969 of 3,134), and 8% of cases (248 of 3,134) have been hospitalized. The last year with more measles cases than 2026 was 1991, when 9,643 were reported; 1992 saw 2,126 cases, and no year since has come close until now. Active outbreaks are running concurrently in at least four states.
CDC has changed its stated reason for leaving Pennsylvania's two measles-associated deaths out of the national tally. Last week's footnote said the agency was reviewing the circumstances and causes of death. The current footnote says the National Center for Health Statistics "does not currently have any death records from 2026 that indicate measles is the underlying cause," and that CDC is working with the Council of State and Territorial Epidemiologists "to develop a standardized case definition for deaths due to measles." U.S. deaths for 2026 remain listed as an asterisk rather than a number; the 2025 column still shows three.
State updates:
- Pennsylvania: The state has reported 624 cases as of September 9, including 91 new cases in one week. 109 people have been hospitalized, up from 87 two weeks ago; 32% of cases are under 18, and no cases were in people recorded as fully vaccinated. The dashboard continues to list two measles-associated deaths.
- Wisconsin: The state has reported 151 confirmed and six probable cases in an outbreak across Grant, Iowa and Lafayette counties as of September 8, the state's highest annual count since 1990. The outbreak roughly doubled in the last week of August and has grown by about half again since. Wisconsin's kindergarten two-dose MMR coverage was 85.1% in 2025-2026, nearly ten points below the herd-immunity threshold of 95%. The state department of health also reports that wastewater samples from treatment facilities in Lafayette and Iowa counties during the week of August 24 were positive for measles virus. A Grant County sample from August 26 was negative on retest and has been withdrawn, though a sample from August 19 was positive.
- Texas: The state has reported 191 cases as of September 4, unchanged in a week, with 136 in Hudspeth County. The state department of health notes that some confirmed cases are among people housed in federal detention facilities.