Adenoviruses are a family of common viruses that most often cause respiratory illnesses resembling a cold or flu. There are more than 50 types that infect humans, and while most infections are mild and resolve on their own, certain types can cause pink eye, stomach bugs, bladder infections, and, rarely, serious complications like pneumonia or organ damage.
How Adenovirus Differs From Other Viruses
Adenoviruses belong to a distinct family of viruses built around double-stranded DNA, which makes them genetically more complex than many common respiratory viruses like influenza (which uses RNA). They also lack an outer fatty envelope, the membrane that surrounds viruses like the flu or COVID-19. This missing envelope is what makes adenoviruses remarkably tough outside the body. They can survive on hard surfaces like doorknobs, countertops, and medical equipment for anywhere from 7 days to 3 months at room temperature. They also persist for weeks in tap water, sewage, and seawater.
That environmental durability is a big reason adenoviruses spread so easily in places where people are in close quarters: daycare centers, schools, military barracks, and hospitals.
How It Spreads
Adenoviruses transmit through two main routes. The first is respiratory: inhaling aerosolized droplets when an infected person coughs, sneezes, or talks. The second is fecal-oral, which is especially relevant for the types that cause stomach illness in young children. You can also pick up the virus by touching a contaminated surface and then touching your eyes, nose, or mouth. Swimming pools that aren’t adequately chlorinated have been linked to outbreaks of adenovirus-related conjunctivitis.
People with adenovirus can shed the virus for days or even weeks after symptoms resolve, which makes containment tricky in group settings.
Symptoms by Type of Infection
The symptoms you experience depend largely on which type of adenovirus you’ve caught and where it takes hold in the body. The most common presentation is a respiratory infection with cold or flu-like symptoms: fever, sore throat, cough, runny nose, and sometimes bronchitis or pneumonia. Types 3, 4, and 7 are the ones most frequently behind acute respiratory illness.
Other common presentations include:
- Pink eye (conjunctivitis): Redness, watering, and irritation in one or both eyes. Some types cause a more severe form called epidemic keratoconjunctivitis, which can temporarily blur vision.
- Gastroenteritis: Diarrhea, vomiting, nausea, and stomach pain. Types 40 and 41 are the classic culprits for childhood stomach illness.
- Pharyngoconjunctival fever: A combination of sore throat, fever, and pink eye that often circulates among children in summer camps.
- Bladder inflammation: Less common, but certain types (especially type 11) can cause hemorrhagic cystitis, leading to blood in the urine.
Neurological illness involving the brain and spinal cord is rare but documented, particularly with types 3 and 7 in young children.
How Long It Lasts
Most adenovirus infections in otherwise healthy people are self-limiting, meaning your immune system clears the virus without medical intervention. Respiratory symptoms typically follow a course similar to a bad cold, lasting roughly 5 to 7 days, though coughing and fatigue can linger for a couple of weeks. Gastroenteritis episodes tend to be shorter, usually resolving within a few days. Conjunctivitis can take one to two weeks to fully clear.
Who Faces Serious Risk
For most healthy adults and older children, adenovirus is an unpleasant but temporary illness. The people at greatest risk for severe or life-threatening infections fall into a few specific groups: infants and young children (whose immune systems are still developing), people with weakened immune systems from organ transplants, chemotherapy, or HIV, and sometimes otherwise healthy adults who happen to encounter a particularly aggressive strain.
In severe cases, adenovirus can cause necrotizing pneumonia that progresses to acute respiratory failure. A case series of previously healthy adults with disseminated adenovirus disease documented rapid progression from mild upper respiratory symptoms to multi-organ failure within a week, with complications including pericardial effusion (fluid around the heart), cardiac arrest, brain hemorrhage, and gangrene of the limbs. These outcomes are rare, but they illustrate that adenovirus is not always a benign infection.
In 2021 and 2022, a cluster of acute hepatitis cases in children drew attention to adenovirus type 41. CDC investigators found adenovirus type 41 in all five specimens they sequenced from affected children in Alabama. Type 41 normally causes gastroenteritis, but evidence suggested it might be an underrecognized contributor to liver injury in otherwise healthy children. The investigation prompted enhanced surveillance, and clinicians were encouraged to consider adenovirus in unexplained pediatric hepatitis cases.
Diagnosis and Treatment
Most people with mild adenovirus illness never get a specific diagnosis, and they don’t need one. The infection looks and feels like a typical cold, so doctors generally treat it the same way: rest, fluids, and over-the-counter medications for fever and discomfort. There is no widely used antiviral drug for routine adenovirus infections. For immunocompromised patients with severe or disseminated disease, doctors may consider antiviral therapy in a hospital setting, but this is reserved for life-threatening situations.
When a specific diagnosis matters, such as during an outbreak investigation or for a hospitalized patient, PCR testing of respiratory, stool, or blood samples can confirm adenovirus and identify the specific type.
Prevention and the Military Vaccine
A vaccine against adenovirus types 4 and 7 exists, but it is only available to U.S. military personnel. The vaccine comes as two tablets swallowed whole (not chewed) and is approved for service members ages 17 through 50. The Department of Defense recommends it for recruits entering basic training, where crowded living conditions historically fueled large outbreaks. There is currently no adenovirus vaccine available to the general public.
For everyone else, prevention relies on the basics: frequent handwashing with soap and water, avoiding touching your face, disinfecting shared surfaces, and staying away from close contact with people who are visibly sick. Because the virus is so stable on surfaces, cleaning high-touch objects in homes, schools, and childcare settings matters more than it does for envelope-carrying viruses that die quickly outside the body.
Recent Activity Trends
CDC surveillance covering the 2024-25 respiratory season did not find a pattern of elevated adenovirus activity in the United States. Adenovirus circulates year-round, unlike influenza and RSV, which follow seasonal peaks. This means infections can pop up at any time of year, though small outbreaks tend to cluster in late winter, spring, and early summer, particularly among children in group settings.