Description

Adenoviruses are ubiquitous, nonenveloped, double-stranded DNA viruses capable of causing respiratory tract disease, ocular disease, and gastroenteritis.

Epidemiology

• Primary infection usually occurs early in life (by age 5 years) and is, most often, characterized by upper respiratory symptoms.
• Peaks in the first 2 years of life
• Military trainees are especially susceptible to infection, probably due to crowded living conditions.
• Respiratory and enteric infections may occur at any time of year. In temperate climates, peaks tend to occur in winter months.
• Cause approximately 5% of all pediatric respiratory tract infections and 5–10% of pneumonias
• Transmission of respiratory disease occurs via infected droplets.
  • Transmission of enteric adenoviruses is via the fecal–oral route.
  • Transmission can less commonly occur via contact with infected conjunctiva.
• Outbreaks of pharyngoconjunctival fever have been associated with inadequately chlorinated swimming pools and shared towels.
• One of the most common causes of viral myocarditis in children and adults

Risk Factors

Exposure to adenovirus

General Prevention

• A live oral vaccine for prevention of acute respiratory tract disease is used in military personnel.
• For hospitalized patients:
  • Respiratory symptoms: contact/droplet precautions
  • Gastrointestinal symptoms: contact precautions
  • Conjunctivitis: contact precautions

Pathophysiology

• Adenoviruses may cause a lytic infection or a chronic/latent infection.
• In addition, they are capable of inducing oncogenic transformation of cells, although the clinical significance of this observation remains unclear.

Etiology

There are at least 67 identified human serotypes classified into seven species (species A to G).

Commonly Associated Conditions

• Respiratory infections
  • Upper respiratory tract infections: otitis media, common cold, pharyngitis
  • Lower respiratory tract infection: pneumonia, pertussis-like syndrome, croup, necrotizing bronchitis, bronchiolitis (serotypes 3, 7, and 21 predominant in pneumonia epidemics)
• Pharyngoconjunctival fever
  • Low-grade fever associated with conjunctivitis, pharyngitis, rhinitis, and cervical adenitis
  • 15% of patients may have meningismus.
  • Increased incidence in summer months
  • Common source outbreaks most often associated with type 3
• Epidemic keratoconjunctivitis
  • Bilateral conjunctivitis with preauricular adenopathy
  • May persist for up to 3 to 4 weeks
  • Corneal opacities may persist for several months.
  • Most commonly associated with types 8, 19, and 37
• Myocarditis preceding viral illness
  • Presents with cardiovascular collapse, congestive heart failure, respiratory distress, or ventricular tachycardia
  • Prognosis is poor.
  • High mortality; a large number require transplant, and a portion develop dilated cardiomyopathy.
• Hemorrhagic cystitis may cause microscopic or gross hematuria.
  • If present, gross hematuria persists on average for 3 days.
  • Often associated with dysuria and urinary frequency
  • More common in males than females
  • Associated with types 11 and 21
  • Can occur in both immunocompetent and immunocompromised hosts
• Infantile diarrhea
  • Watery diarrhea associated with fever
  • Symptoms may persist for 1 to 2 weeks.
  • Associated with types 40, 41, and less often 31
• CNS infection epidemics (associated with outbreaks of respiratory disease) and sporadic cases of encephalitis and meningitis have been observed; often associated with pneumonia
• Immunocompromised hosts
  • Can cause disseminated disease including pneumonia, hepatitis, and gastroenteritis
  • Frequently observed in transplanted patients; up to 40% of pediatric human stem cell transplant recipients and in 5–10% of solid organ transplant recipients
  • Fatality rates much higher, up to 30–75% in hematopoietic stem cell transplant patients
• Miscellaneous: associated with intussusception (isolated in up to 40% of cases) and fatal congenital infection