In brief
- Human adenoviruses are divided into 7 species, A through G, and more than 100 genotypes [1].
- Different types tend to cause different illnesses: respiratory infections, conjunctivitis (pink eye), gastroenteritis or cystitis [2].
- In the US in 2003–2016, types 1, 2, 3, 4, 7 and 14 accounted for 85.5% of all cases in which the type was identified [3].
- A child can have adenovirus infection several times, gradually building immunity [4].
Species, type, serotype: how adenoviruses are classified
Adenoviruses make up the family Adenoviridae. It is divided into six genera and infects vertebrates, from fish to humans [2]. Human adenoviruses belong to the genus Mastadenovirus, whose members infect only mammals [2].
Within the genus, human adenoviruses are divided into 7 species, traditionally labeled with the letters A through G [1]. Each species includes several numbered types: adenovirus type 3, type 7, type 40 and so on.
Types used to be told apart by how antibodies react to the virus, and were called serotypes [2]. Reference sources now speak of genotypes [1]. That is why the numbers differ between sources: the Russian Ministry of Health clinical guidelines say "more than 80 serotypes" [4], the MSD Manual says more than 100 genotypes [1], and in the registry of the Human Adenovirus Working Group the latest assigned number is 118 (August 2026 update) [5].
Which types cause which diseases
Most adenovirus infections cause no symptoms [2]. But some types are linked to specific diseases:
| Disease | Types | Source |
|---|---|---|
| Acute respiratory infections | 1–5, 7, 14, 21 | [2] |
| Pharyngoconjunctival fever: sore throat, eyes, fever | 3, 4, 7, 14 | [2] |
| Epidemic keratoconjunctivitis | 8, 19, 37, 53, 54, 56 | [2] |
| Acute gastroenteritis in young children | 40, 41 | [2] |
| Kidney disease and hemorrhagic cystitis, most often after transplantation | 11, 34, 35 | [2] |
| Severe infections in people with weakened immunity | 31, 1, 2, 5 | [2] |
| Post-infectious bronchiolitis obliterans in children | 3, 7, 21 | [6] |
Types 40 and 41 are the second most common cause of diarrhea in children after rotavirus [2]. Read more in our articles on the intestinal form and conjunctivitis.
“Because there are so many serotypes, the clinical picture of the disease can vary a lot”
Izvestia (in Russian), May 24, 2023
Which types are most common
According to the US laboratory surveillance system, the types identified most often in 2003–2016 were 1, 2, 3, 4, 7 and 14: together they made up 85.5% of reports that specified the type [3].
In the US, type 7 is recognized as an important cause of severe respiratory infections in adults [3]. In 2006–2007, type 14 caused cases of severe illness in four states. Of 140 confirmed cases in Oregon, Washington and Texas, 53 people (38%) were hospitalized, 24 (17%) were admitted to intensive care, and 9 died. Healthy young adults got sick too [7].
Type 4 is well known for respiratory outbreaks among military recruits [3]. The US has a vaccine against types 4 and 7, but only for the military; see the article on prevention.
Adenovirus type 2
Human adenovirus type 2 is one of the six most common types in the US [3]. It causes acute respiratory infections, and in people with weakened immunity, together with types 1 and 5, severe infections [2].
People searching for "adenovirus type 2" are often looking for something else: canine adenovirus type 2. It is a separate virus, covered in the article adenovirus in dogs.
Can you get it again
Yes. Babies under 6 months are protected by their mother's antibodies. After that, a child may have adenovirus infection several times, gradually building immunity, and the chance of getting sick drops with age [4].
Does the type need to be identified
Not for routine treatment. Clinical guidelines for respiratory viral infections suggest detecting adenovirus itself with a rapid test or PCR when needed, more often in the hospital; the virus type is not part of the workup [4]. Typing is used in public health surveillance to track outbreaks [3]. Read more about testing in the article adenovirus test.
Frequently asked questions
How many types of adenovirus are there?
Human adenoviruses are divided into 7 species (A–G) and more than 100 genotypes [1]. In the registry of the Human Adenovirus Working Group, the latest assigned number is 118 [5].
Which adenovirus type causes conjunctivitis?
Epidemic keratoconjunctivitis is most often caused by types 8, 19, 37, 53, 54 and 56; pharyngoconjunctival fever by types 3, 4, 7 and 14 [2].
Which adenovirus types cause stomach infections?
Types 40 and 41: they are the second most common cause of diarrhea in children after rotavirus [2].
Can you get adenovirus more than once?
Yes. A child can get adenovirus infection several times, gradually building immunity [4].
How adenovirus is built
Explore a 3D model of the virion: capsid, hexons, pentons, fibers and DNA.
Sources
- MSD Manual Professional Version. Katz S. Adenovirus Infections (fully revised July 2026). Accessed October 10, 2026.
- ICTV (International Committee on Taxonomy of Viruses). ICTV Report: Family Adenoviridae (Benkő M. et al., updated 2026). Accessed October 10, 2026.
- CDC, MMWR. Human Adenovirus Surveillance — United States, 2003–2016. Accessed October 7, 2026.
- Russian Ministry of Health, Union of Pediatricians of Russia. Clinical guidelines “Acute respiratory viral infection (ARVI)”, children, ID 25_3, published in the guidelines database on September 2, 2026 (in Russian). Accessed October 8, 2026.
- Human Adenovirus Working Group. Registry of human adenovirus types. Accessed October 7, 2026.
- Russian Ministry of Health. Clinical guidelines “Acute bronchiolitis”, children, ID 360_3, published in the guidelines database on January 14, 2025 (in Russian). Accessed October 10, 2026.
- CDC, MMWR. Acute Respiratory Disease Associated with Adenovirus Serotype 14 — Four States, 2006–2007. MMWR 2007;56(45):1181–1184. Accessed October 10, 2026.
This article was prepared by our editorial team from official sources and does not replace a doctor’s advice. Found an error? Write to us.