Measles outbreaks continue to expand across parts of the United States as health officials respond to growing clusters in Pennsylvania, Wisconsin and Georgia.
The outbreaks come during the nation's worst measles year in more than three decades. The Centers for Disease Control and Prevention says more than 2,700 cases have been reported nationwide in 2026, already surpassing last year's total. Nearly all U.S. cases this year have been linked to outbreaks, highlighting the continued spread of the highly contagious virus. The agency also notes that its national case totals are updated weekly and may lag behind state reporting. The CDC's website said a data update on cases scheduled for Aug. 28 was delayed.
Pennsylvania has reported the largest outbreak
among the three states that have identified growing cases in recent weeks. On Aug. 25, Pennsylvania announced the nation's first measles-associated deaths of 2026. Wisconsin is experiencing its largest outbreak in decades, while Georgia health officials are working to contain a cluster tied to a metro Atlanta daycare.
Here's what to know.
Pennsylvania outbreak: Cases climb as related deaths reported
Pennsylvania reported 460 confirmed measles cases as of Aug. 28, including 86 new cases over the previous week, according to the state Department of Health.
Lancaster County remains the center of the outbreak with 210 cases. State health officials announced two measles-associated deaths on Aug. 25, including a newborn infant, however Health and Human Services Secretary Robert F. Kennedy Jr. has disputed whether the deaths were caused by the contagion. Both people were unvaccinated.
Pennsylvania officials say a death may be classified as measles-associated when laboratory or epidemiological evidence links the disease to the infection, even if measles is not listed as the immediate cause of death. Community transmission has been identified in 10 counties, while Butler and Westmoreland counties recently reported their first confirmed cases.
Wisconsin outbreak: Largest since 1990
Wisconsin health officials say 98 cases are tied to an outbreak in the state's southwest region, more than doubling from the previous week's total, USA TODAY network partner Milwaukee Journal Sentinel reported.
The outbreak includes 52 cases in Iowa County, 43 in Lafayette County and three in Grant County. Including two unrelated infections reported earlier this year, Wisconsin has recorded 100 measles cases in 2026, the state's highest annual total since 1990.
The CDC has deployed two public health workers to assist local investigators with contact tracing and case identification. State officials say nearly every person infected during the outbreak had not received the measles, mumps and rubella (MMR) vaccine.
Georgia outbreak: Daycare cluster grows
Georgia health officials have confirmed four new measles cases in an outbreak linked to a metro Atlanta daycare.
Officials said the newly infected children were close contacts of an earlier confirmed case and were either unvaccinated or not fully vaccinated. Health investigators are working to identify additional people who may have been exposed.
Georgia has now reported 11 measles cases this year, making 2026 the state's second-highest annual total in the past decade.
Why health officials are concerned
The CDC says 94% of measles cases reported in 2026 are associated with outbreaks, illustrating how quickly the virus can spread once it reaches communities with lower vaccination coverage. Measles spreads through the air and can remain in a room for up to two hours after an infected person leaves.
Symptoms typically begin with a high fever, cough, runny nose and red, watery eyes. A rash usually develops three to five days later, starting on the face before spreading to the rest of the body.
Health officials recommend that anyone who believes they have measles call a healthcare provider before seeking medical care in person to help prevent exposing others. The CDC continues to recommend the MMR vaccine as the most effective protection against measles.
Reporter Anthony Thompson can be reached at ajthompson@usatodayco.com, or on X @athompsonUSAT
This article originally appeared on USA TODAY: 3 states battling new measles outbreaks. What to know
