Adenovirus serotypes 40 & 41
Adenovirus (Ad) serotypes 40 & 41 (Group 7 Adenoviruses) are known as the enteric adenoviruses as they have been implicated in causing gastroenteritis. They have been found to be the second most common cause of diarrhea in studies of hospitalized children in developed countries, after rotaviruses. Studies have not been conducted in developing nations, so the prevalence and seriousness of Adenoviruses (Ads) are unknown. However, it is believed that enteric Ad infections would contribute to malnutrition because they can lead to chronic diarrhea.
In comparison with rotavirus, Ad 40 & 41do not have as strong of a seasonal pattern. Rotaviruses are more prevalent in winter months, while both Ad 40 & 41 show peaks in warmer months. Children under two years of age are the most susceptible for becoming infected with an enteric Ad. Ad 40 has a higher incidence in children younger than 12 months, and Ad 41 has the highest incidence in children around the age of 28 months.
There is a lot of viral shedding in fecal matter of infected individuals, and the virus is mainly transmitted by a fecal-oral route. Enteric Ads are most commonly transmitted in community or hospital settings. Most community-acquired enteric Ad infections occur in day-care centers where many children are in contact and have a change to swap viruses and in households where a young child passes the infection on to other family members. Infection is inapparent in many children infected in the day-care setting, and it is estimated that as many as 50% of children have antibodies to enteric adenoviruses by the age of 4 years. Once introduced into the pediatric ward of the hospital, enteric Ads can be passed between children, resulting in an outbreak that is dangerous for immunocompromised children.
The incubation period of enteric Ad infections is approximately 3 and 10 days. Usually, a mild case of gastroenteritis develops in symptomatic children that is characterized by persistent diarrhea accompanied by a fever and vomiting of short duration. In infections with Ad 41, the mean duration of diarrhea is 12 days and prolonged symptoms are not uncommon, while Ad 40 infection generally has a more intense onset with diarrhea lasting around 9 days. In infections with both serotypes, vomiting is mild, begins 1.5 days after diarrhea onset, and ceases after 2 days. Fevers also are mild in that they have a short duration of 2-3 days and only moderately-high temperatures. Respiratory infections associated with enteric Ad infections are uncommon and occur in only about 21% of patients with Ad gastroenteritis. Ad gastroenteritis is not a very serious disease as it rarely causes significant dehydration requiring parenteral or oral rehydration therapy. However, the diarrhea caused by Ad 41 can persist and threaten the survival of anyone who has malnutrition.
There is no vaccine available for enteric Ad viruses, nor is there a good treatment besides rehydration therapies, so prevention is the best option. As always, a little hand washing goes a long way to curb rates of fecal-oral transmission.
Kotloff KL et al. "Enteric Adenovirus Infection and Childhood Diarrhea: An Epidemiologic Study in Three Clinical Settings." Pediatrics. August, 1989. 84(2): 219-24.
Uhnoo I et al. "Importance of Enteric Adenoviruses 40 and 41 in Acute Gastroenteritis in Infants and Young Children." Journal of Clinical Microbiology. September, 1984. 20(3): 365-72.
Wood DJ et al. "One-Year Prospective Cross-Sectional Study to Assess the Importance of Group F Andenovirus Infections in Children Under 2 Years Admitted to Hospital." Journal of Medical Virology. 1988. 26:429-35.