Federal health officials on Tuesday announced a second measles death in the United States as an outbreak continued across 47 states. The CDC disclosure arrived amid an ongoing conflict over which fatalities are appearing in the national count.

As of 24 September, the CDC had confirmed 3,659 measles cases nationwide. The agency said two deaths had been confirmed on Tuesday, but its announcement did not identify the states where those deaths occurred.

Pennsylvania has reported more than 900 cases, making it the state with the largest reported burden. State officials have also recorded four measles deaths, none of which the CDC includes in its national figures.

The mismatch has become part of an ongoing dispute between Pennsylvania governor Josh Shapiro and US health secretary Robert F Kennedy Jr. Their clash centers on the gap between federal measles death figures and the numbers published by Pennsylvania’s department of health.

The CDC previously collected information from states for its count. It has shifted to mortality data from the National Center for Health Statistics, known as NCHS, when calculating the national measles death total.

Pennsylvania’s outbreak data also showed 114 new measles cases during the previous seven days. A third of those cases involved children younger than 18, adding a stark age breakdown to the state’s latest report.

The state has reported 176 hospitalizations involving people with measles. Fewer than 1% of all cases involved people who had been fully vaccinated against the disease, according to Pennsylvania’s figures.

Pennsylvania’s health department said: “While daily numbers fluctuate, tracking these trends provides Pennsylvanians and health care providers with visibility into community transmission across the [state] and helps inform the department’s ongoing response.”

Across the country, the case count has reached a level not seen in decades. The United States has now recorded more measles cases this year than in any other year since 1991.

The surge follows a major public health milestone that had stood for years. In 2000, the US government declared measles eliminated in the United States.

Measles is a highly contagious virus and can lead to serious health complications. Death is rare, but it occurs in approximately one to three patients for every 1,000 measles cases.

Symptoms generally begin seven to 14 days after infection, according to the CDC. Early signs can include high fever, cough, runny nose, and red, watery eyes before a rash develops and spreads down the body.

Federal guidance also emphasizes vaccination against the virus. The CDC advises that two doses of the MMR vaccine “provide the best protection against measles”.

The measles announcement comes as the CDC faces a dramatic contraction in its work force. The Trump administration has laid off 18% of the agency’s staff during 2025.

The American Federation of Government Employees, the largest federal employee union and a representative of 82,000 workers, said the CDC has 3,810 fewer civil service employees than it did in the past year. The union described that loss as a total reduction of a third.