What is adenovirus infection (Ad14)?

A report in the November 16, 2007, issue of the Morbidity and Mortality Weekly Report [MMWR 56(45):1181-1184] noted an unusual number of recent cases of severe pneumonia and deaths caused by adenovirus serotype 14 (Ad14) infection among civilian and military communities. Ad14 is one of the 51 serotypes of adenoviruses.

The MMWR report was based on investigations done by state and city health authorities, the U.S. Air Force, and CDC. The study showed that Ad14 is a rarely reported but emerging serotype of adenovirus that can cause severe and sometimes fatal respiratory disease in people of all ages, including healthy young adults. However, Ad 14 infections are uncommon. Most infections from Ad14 are not serious, and severe or fatal outcomes from Ad14 are rare. Thus, the public should not be concerned about the emergence of Ad14.

What are the symptoms of adenovirus infection?

The viruses are a common cause of infection in humans, but they rarely cause serious or fatal illness. Adenoviruses cause a wide range of illnesses and symptoms, including

• Colds
  
  

• Pharyngitis (sore throat)
  
  
• Bronchitis
  
  
• Pneumonia
  
  
• Diarrhea
  
  
• Conjunctivitis (eye infection)
  
  
• Fever
  
  
• Cystitis (bladder inflammation or infection)
  
  
• Rash illness
  
  
• Neurologic disease

Since Ad14 infections are not common and most Ad14 infections are not serious, the emergence of Ad14 should not be a concern to the general population. During the winter, many other common viral and bacterial infections, including influenza, can present with very similar symptoms. You should not change the criteria you use to decide when to consult your healthcare provider. As with any illness, you should check with your healthcare provider if you are concerned about the seriousness of your illness. For example, you may want to consult your doctor if you have an unusually high fever or fever that lasts more than a few days, have shortness of breath, or are feeling worse over time.

Who is most at risk for complications from adenovirus infection?

Everyone is at risk of adenovirus infection, but patients with weak immune systems or with underlying respiratory or cardiac disease are most at risk for severe complications from any respiratory infection, including adenovirus infections.

How is adenovirus infection spread?

Adenoviruses are spread like the common cold. The viruses can be spread from person to person via coughing or sneezing. People may also become infected by touching something with adenovirus on it and then touching their mouth, nose, or eyes. For example, adenoviruses can be transferred to a doorknob when an infected person sneezes into his/her hands and then touches the doorknob before washing. Germs can also be spread if an infected person sneezes or coughs onto tabletops or other items that might be touched by other people. To prevent the spread of disease, it is important to practice good health habits.

What steps can healthcare providers and people take to protect their health?

• People can protect themselves against all respiratory diseases by washing their hands, and they can protect others by covering their mouth when coughing or sneezing.
  
  
• People should, whenever possible, take steps to prevent respiratory infections. Such steps include vaccination and good health habits. At this time, Ad14 should not be considered a concern to the general public. Other respiratory infections, such as influenza, respiratory syncytial virus, and bacterial pneumonia, are other important causes of illness.
  
  
• Physicians should be aware that Ad14 can cause severe pneumonia and consider it in the differential diagnosis if the cause of infection is unknown.

State and local health departments and health care providers should consider Ad14 as a cause of outbreaks of pneumonia of unknown etiology.

• Clinicians and health officials should consider Ad14 as a possible cause of severe pneumonia and of outbreaks of pneumonia for which the cause cannot otherwise be determined.
  
  
• Clinicians should contact their state health departments for guidance on testing patients with a serious illness that they suspect may be an Ad14 infection. Testing for generic adenoviruses should precede any testing for specific serotypes, including Ad14.
  
  
• Health officials should be aware that Ad14 has been detected occasionally in military bases since 2005. Adenovirus infections in the military have been a concern for many years. Vaccines for the two adenoviruses most commonly causing disease in the military, Ad4 and Ad7, were used until 1996, and new versions of the vaccines are being studied in clinical trials for future use in the military.
  
  
• Health departments should report unusual clusters of severe adenoviral respiratory disease or cases of Ad14 to CDC.
  
  
• Clinicians and health officials should encourage people to follow good infection-control and hygiene practices to help control the spread all respiratory infections, including Ad14.

Adenovirus (AD14) At A Glance

• Recent cases of Ad14 have been identified in four locations across the country. The viruses isolated from each location were genetically identical, but no common source of infection was found between the locations.
  
  
• Ad14 was first identified in the 1950s, but until recently, has been detected only rarely. The newly re-emerged Ad14 strain was first identified in the United States in 2005 and has some genetic differences from the strain detected in the 1950s.
  
  
• This strain of Ad14 appears to have a higher rate of severe illness compared with other adenoviruses, but severe pneumonia and death from adenoviruses remain rare in otherwise healthy persons.
  
  
• A cluster of community-acquired Ad14-related pneumonia cases was reported from Oregon in early 2007. Such reports are unusual-adenovirus infections are usually detected as sporadic rather than grouped cases.
  
  
• A cluster of cases was also reported this year among new military recruits undergoing basic training at a Texas Air Force base. Early results from the outbreak investigation suggest that although some cases have been severe and required hospitalization, most have been mild or moderate, with cold-like symptoms.
  
  
• At this time, Ad14 should not be considered a special concern to the general public.

SOURCE: Centers for Disease Control