Norovirus, the leading cause of vomiting and diarrhea in the United States, is circulating at low levels nationally as fall begins, according to the most recent federal and academic surveillance data. For Florida, which has ranked among the states with the most confirmed outbreaks, that quiet stretch is unlikely to last through the coming months.
The CDC's NoroSTAT outbreak tracker, updated Sept. 17, counted 27 outbreaks from Aug. 1 through Sept. 4 in its participating states, compared with 29 during the same period last year. That is within the normal range for this point in the season. Florida is not one of the states that report to NoroSTAT, so the tracker does not reflect conditions there.
The reason to pay attention now is timing. Norovirus activity typically rises in the fall and peaks in winter. With schools in session, long-term care facilities heading into respiratory virus season, and Florida's winter cruise season approaching, the next few weeks are a practical window for families to prepare.
A Quiet Start in the Latest Surveillance Numbers
Wastewater testing offers the broadest early signal. In its latest nationwide wastewater monitoring update, published in early September, the WastewaterSCAN program, run by Stanford University and Emory University, reported that norovirus was detected in every sample it analyzed in August. Even so, median concentrations fell about 12% from July, and the program placed norovirus in its low category nationally with no clear trend over the prior three weeks. Its Southern region includes Florida, though the update did not break out Florida sites.
That is likely to change. In the 2024 to 2025 season, WastewaterSCAN saw norovirus levels start rising in early October and peak in early February. How high each winter peak climbs can vary from year to year.
These numbers have limits. Norovirus is not individually reportable to the CDC, most clinics do not test for it, and outbreak data arrive weeks after illnesses occur. The figures describe direction, not how many people in any Florida county are sick right now.
Florida's Track Record and Crowded Settings
Florida has ranked near the top for confirmed outbreaks. Between Sept. 1, 2023, and Oct. 31, 2024, the state reported 24 confirmed norovirus outbreaks, second only to California, according to CDC data reported by CBS News Miami. Cruise ships were hit hard that year, with 16 outbreaks reported in 2024, five of them in December.
Local signals can also differ from state trends. Last January, WUSF reported that Florida's wastewater levels were mostly steady statewide while Orange County saw a noticeable rise, a reminder that Orlando, Miami, Tampa and Jacksonville can move on different timelines.
Nationally, the CDC estimates norovirus causes 19 million to 21 million illnesses each year, according to its norovirus facts and statistics. The agency's outbreak overview says about 2,500 outbreaks are reported annually, and roughly half of all foodborne disease outbreaks are caused by norovirus, often when an infected food worker handles ready-to-eat food.
The virus spreads through tiny particles of vomit or stool, and people can shed it for two weeks or more after they feel better. Nursing homes, schools, child care centers, and cruise ships are among the places it spreads fastest.
Dehydration Signs, Home Care and When to Get Help
Symptoms usually start 12 to 48 hours after exposure and include sudden vomiting, diarrhea, nausea, and stomach cramps, sometimes with fever, headache, or body aches. Most healthy people recover in one to three days.
The main danger is dehydration. Young children account for many emergency visits, while most of the roughly 900 norovirus deaths each year in the United States occur in adults 65 and older, according to the CDC. Warning signs include urinating much less, a dry mouth and throat, and dizziness when standing. In children, crying with few or no tears and unusual sleepiness or fussiness are red flags. Severe dehydration may require IV fluids and needs prompt medical care.
Handwashing is the main defense, since no vaccine or specific antiviral treatment is available. "Like all viruses, the biggest thing is hand-washing," Dr. Carlos Abanses, medical director of the pediatric emergency department at St. Joseph's Children's Hospital in Tampa, told WUSF. Soap and water work better than alcohol-based hand sanitizer alone against this virus, a practical point for classrooms and cruise cabins alike.
Families can also clean contaminated hard surfaces with a chlorine bleach solution, wash soiled laundry on the longest cycle at the hottest setting, and keep sick people from preparing food for others until at least two days after symptoms stop. Oral rehydration solutions can help with mild dehydration, and antibiotics do not work against norovirus.
Residents without a regular doctor can contact their county health department or a community health center. MedicalDaily will report when the seasonal rise begins or if Florida officials issue local warnings.
There is no sign of a norovirus surge in current national data, but Florida is entering the months when outbreaks usually build, and older adults and young children carry the highest risk when they do.
Key Questions Answered
Is norovirus rising in Florida right now? Current national data show low levels, and the latest wastewater update found no clear upward trend. NoroSTAT does not include Florida, so local data are limited.
When does norovirus season usually start? Activity typically climbs in fall and peaks in winter. In the 2024 to 2025 season, wastewater levels began rising in early October and peaked in early February.
Who is most at risk? Young children, adults 65 and older, and people with weakened immune systems face the greatest risk of dehydration.
Does hand sanitizer work? Not well on its own. Washing with soap and water is more effective against norovirus.
When should someone seek medical care? For signs of dehydration such as little urination, dizziness when standing, or a child crying without tears or being unusually sleepy.
How long are people contagious? People can spread the virus while sick and for two weeks or more after they feel better.
