Adenoviruses primarily infect children. Adults are also infected. Certain serotypes of adenovirus are associated with specific syndromes. Respiratory infections are caused by low-numbered serotypes (1, 2, 3, 5, and 7) and gastrointestinal infection by high-numbered serotypes (40, 41, 42) (Table 58-2). Incubation period varies from 5 to 8 days. Major clinical syndromes caused by the human adenoviruses are as follows:
Acute respiratory disease: This disease is caused by adeno-virus serotypes 4 and 7. Fever, rhinorrhea, cough, and sore throat are the typical symptoms, which last for 3–5 days. This syndrome most often affects military recruits living in crowded conditions.
Pharyngoconjunctival fever: This syndrome occurs primarilyin school-going children. Fever, sore throat, coryza, and red eye are the classic presentations of the condition. These symptoms may precede ocular findings, or they may not be present. Acute conjunctivitis may occur as a separate entity with or without pharyngitis. The condition is usually self-limiting. This condi-tion is caused predominantly by serotypes 3, 4, and 7.
Other respiratory tract diseases: Bronchiolitis, croup, lar-yngitis, and cold-like symptoms are the other respiratory tract diseases caused by adenoviruses.
This is a highly contagious condition and has an insidious onset of unilateral red eye. Subsequently, both the eyes are involved. Patients complain of photophobia, tearing, and pain. Fever and lymphadenopathy may be present in some children. Inflammation of the conjunctiva may persist for a week, accom-panied with residual scarring and visual impairment. The con-dition may occur as an epidemic, which is usually caused by serotype 8 and less often by serotypes 19 and 37.
These conditions are most commonly associated with serotypes 40 and 41, but other serotypes may also be involved. The enteric adenovirus infection is a common cause of infantile diarrhea in day-care centers. The condition manifests as fever and watery diarrhea, which resolves within 1–2 weeks.
Adenoviruses have also been associated with acute hemor-rhagic cystitis caused by serotypes 11 and 21, intussusception in young children, pertussis-like illness, musculoskeletal disor-ders, and genital and skin infections.
These infections are caused by multiple serotypes of adeno- viruses. These serotypes cause disease during the posttrans-plant period in the patients who have received hematopoietic stem cell transplant. Patients receiving stem cell transplanta-tion and with T-cell deletion and lymphopenia are at risk for serious adenovirus infections. Infections in these patients may cause variable manifestations, but include hemorrhagic cystitis, pneumonia, nephritis, and gastroenteritis. Infection occurs either by reactivation of old infection or by exogenous transmission from other infected hosts. Adenovirus serotypes associated with various human illnesses are summarized in Table 58-2.