US measles cases surpass 4,500 as Pennsylvania and national outbreaks expand
Is it spreading to new areas?
Spread confirmed
As of 21 October 2026, DuPage County health officials reported the county's first measles case of 2026 following exposure at Chicago O'Hare International Airport, alongside spreading cases in Chester County, Pennsylvania.
Sources: CBS NewsThe Philadelphia InquirerKey figures
| Figure | Value | Basis | As of | Sources |
|---|---|---|---|---|
| Total US Measles Cases Stated by US CDC; US health authorities subsequently reported 178 additional cases on 24 October 2026. | 4,588 | Official | Sources: ReutersCIDRAPThe Guardian | |
| Pennsylvania Measles Cases Stated by Pennsylvania Department of Health. | 1,317 | Press reports | Sources: ReutersU.S. News & World Report | |
| US Measles Deaths (CDC Count) Stated by CDC; local media and state authorities in Pennsylvania report 5 to 6 deaths in that state. | 3 | Official | Sources: Fox NewsThe Philadelphia InquirerFOX 29 Philadelphia | |
| Lancaster County Measles Cases Reported by LNP as Lancaster County's total following a weekly increase. | 452 | Press reports | Sources: LNP | LancasterOnline |
Who says what
| Who | Says | Date | Sources |
|---|---|---|---|
| Pennsylvania Department of Health | Reported 1,317 measles cases in the state, issued health alerts regarding risks to pregnant women and congenital measles, and criticized the CDC for excluding state-confirmed deaths from federal counts. | Sources: Reuters6abc PhiladelphiaThe Philadelphia Inquirer | |
| US Centers for Disease Control and Prevention (CDC) | Confirmed 4,588 national cases and 3 deaths, and dispatched disease investigators to assist Pennsylvania health authorities. | Sources: ReutersFox NewsCBS News | |
| State Health Officials and Public Health Experts | Expressed concern regarding reduced transparency at the CDC and delays or denials in approving faster, high-volume testing for measles. | Sources: The GuardianU.S. News & World ReportThe Guardian 2The New York Times |
Summary
As of 24 October 2026, the United States is experiencing its largest measles outbreak year since 1991, with total national cases reaching 4,588 as reported by the CDC on 23 October 2026, and an additional 178 cases reported on 24 October 2026.
The ongoing expansion is driven primarily by an outbreak in Pennsylvania that began in Lebanon County in late April 2026—where Lancaster County has recorded the highest local total—and an outbreak in under-immunized rural communities in New York State, where a state disaster emergency was declared on 5 October 2026.
The CDC has dispatched disease investigators to Pennsylvania to assist local response efforts, while state officials have warned of risks including congenital measles and raised concerns over discrepancies between state and federal death tallies.
Timeline
- Pennsylvania health officials report over 1,200 cases and five deaths, criticizing the CDC for excluding state deaths from national counts.Sources: The Philadelphia Inquirer
- FOX 29 reports a sixth measles death in Pennsylvania, and state health officials warn of rising congenital measles risks.Sources: FOX 29 PhiladelphiaNBC News
- Pennsylvania health officials report cases reached 1,317, the CDC confirms a third national death, and DuPage County, Illinois reports its first case of 2026.Sources: ReutersFox NewsCBS News
- The CDC sends an investigator to Pennsylvania while the state issues a health alert for pregnant women.Sources: CBS News6abc Philadelphia
- The CDC reports total US measles cases have reached 4,588.Sources: Reuters
- US health authorities report an additional 178 cases of measles.Sources: The Guardian
Still unknown
- Why the CDC's official national death count differs from state health reporting in Pennsylvania.
- When high-volume or faster diagnostic measles tests will receive federal validation and approval for state laboratory use.
- Whether newly reported clusters in states like Illinois and Minnesota will develop into larger community outbreaks.