Adenoviruses

They are extremely rare in the central nervous system. There are several types of adenoviruses – 49 adenovirus types have been isolated in humans. Acute diarrhoeal diseases are caused by adenoviruses types 40 and 41. It has been found that adenoviruses cause 4% of diarrhoeal diseases in outpatients and 2–22% in hospitalised children. Adenoviral diarrhoea affects mainly children up to two years of age, but older children and adults can also get sick. Adenoviruses also cause outbreaks in hospital settings.

The course of the infection

Incubation lasts from 1 to 10 days. Symptoms and signs include fever, runny nose, sore throat, cough, headache and malaise. Problems resolve more quickly if the adenovirus has caused an upper respiratory tract infection and take longer if the patient has adenoviral pneumonia. In adenoviral infection of the gastrointestinal tract, the leading clinical signs are watery diarrhoea and vomiting. Sometimes sufferers have a slight fever and cold symptoms. If dehydration (drying out) occurs, it is usually mild. The disease does not usually have serious health consequences.

Mode of transmission of the micro-organism

Adenoviruses that cause conjunctivitis or acute respiratory infection are transmitted via infected droplets at a distance of up to 1 metre, or via objects contaminated with respiratory secretions. Adenoviral diarrhoeal diseases are transmitted by faecal-oral routes. The main source of infection is the faeces of affected people. Infected persons excrete the virus in their faeces for 10 to 14 days; on average 2 days before the onset of diarrhoea and for 5 days after the diarrhoea has stopped. Unhygienic handling and conditions (especially poor hand-washing) can lead to the virus being introduced into food and drinking water. Humans become infected by ingesting contaminated food and drinking water contaminated with faeces from affected people.

Prevention of infections

Adenoviral infections are common, especially in the colder months (winter, early spring), and their spread is difficult to prevent. Because they are spread by droplets and contaminated objects, they are prevented by frequent hand washing. Patients with a respiratory infection should wash their hands frequently to avoid contaminating their surroundings, and cough into their sleeve to prevent infectious droplets from spreading around the room. There is no effective vaccine against adenoviruses.