What are the clinical features of an adenovirus infection?

Clinical Features of Adenovirus Infection

Adenovirus infections typically present with upper or lower respiratory tract symptoms, conjunctivitis, or gastrointestinal manifestations, with the clinical picture varying by serotype, patient age, and immune status. 1, 2, 3

Primary Clinical Manifestations

Respiratory Presentations

• Upper respiratory tract infection is the most common presentation, featuring fever (often >39°C), rhinorrhea, congestion, sore throat, sneezing, and cough 4, 1
• Lower respiratory tract involvement manifests as bronchiolitis, pneumonia, or croup (laryngotracheobronchitis), particularly in children 4, 1
• Cough and tachypnea occur in approximately 67% and 53% of cases respectively, with radiographic pneumonia evident in up to 80% of immunocompromised patients 5

Ocular Manifestations

• Viral conjunctivitis accounts for 5-20% of acute conjunctivitis cases and is highly contagious 6
• Follicular conjunctival reaction is characteristic, often with subconjunctival hemorrhage, chemosis, and watery discharge 4
• Epidemic keratoconjunctivitis (EKC) presents with marked lid swelling, chemosis, epithelial sloughing, or membranous conjunctivitis in severe cases 4
• Subepithelial infiltrates may develop later in the disease course, causing blurred vision and photophobia 7
• The virus can survive for weeks on surfaces, making transmission highly efficient 4, 7

Gastrointestinal Presentations

• Gastroenteritis caused by serotypes 40 and 41 accounts for 5-20% of hospitalizations for childhood diarrhea 6
• Systemic gastrointestinal symptoms including nausea, vomiting, and diarrhea occur in approximately 80% of immunocompromised patients 5

Dermatologic Manifestations

• Rash occurs in approximately one-third of children with adenovirus infection, though it is rare in adults 6
• Rash patterns vary considerably, presenting as petechial, maculopapular, diffuse erythema, or other morphologies 6
• Median onset is 5 days after symptom onset, with variable distribution involving extremities, trunk, face, or rarely palms and soles 6

Rare but Serious Manifestations

Organ-Specific Disease

• Hemorrhagic cystitis may occur, particularly in immunocompromised patients 1, 2, 3
• Hepatitis with moderate to severe elevation of liver enzymes (SGPT >450 IU/L) occurs in 45% of immunocompromised patients 5
• Hemorrhagic colitis, pancreatitis, nephritis, or meningoencephalitis are uncommon but recognized complications 1, 2, 3

Clinical Course and Severity Factors

Typical Disease Duration

• Illness typically lasts 7-10 days regardless of whether rash is present 6
• Patients remain infectious for 10-14 days from symptom onset in the last affected eye 4, 7

High-Risk Populations

• Young children are more commonly affected due to lack of humoral immunity 1, 2, 3
• Immunocompromised patients (organ transplant recipients, HIV infection, congenital immunodeficiency) experience more severe disease with higher dissemination risk 8, 1, 2
• Fatality rates may exceed 50% for untreated severe pneumonia or disseminated disease in immunocompromised hosts 1, 2, 3

Severe Disease Indicators in Immunocompromised Patients

• High fever (>39°C) is universally present 5
• Severe systemic symptoms including malaise, lethargy, fatigue, and night sweats occur in 80% 5
• Rapid downhill course may occur, with fulminant illness affecting multiple organs including lung and liver 5

Diagnostic Approach

Clinical Diagnosis

• Viral conjunctivitis in the presence of upper respiratory infection can often be diagnosed clinically without additional testing 4
• History of exposure, travel, and vaccination status should be obtained, particularly for less common viral causes 4

Laboratory Testing

• Rapid immunodiagnostic testing has 88-89% sensitivity and 91-94% specificity for adenovirus conjunctivitis 4, 6
• PCR testing provides highly sensitive and specific detection of adenovirus DNA when available 4, 6
• Nasopharyngeal swabs or respiratory secretions in viral transport medium are optimal specimens for respiratory disease 4
• Conjunctival swabs are appropriate for ocular disease 4

When to Test

• Testing may prevent misdiagnosis, disease spread, unnecessary antibiotic use, and increased healthcare costs 4
• Routine testing is not required for typical self-limited cases in immunocompetent patients 4
• Testing should be considered in immunocompromised patients, severe cases, or outbreak settings 4

Common Pitfalls

• Misdiagnosing as bacterial conjunctivitis leads to unnecessary antibiotic use and fails to implement appropriate infection control measures 6
• Failing to recognize severe disease in immunocompromised patients can result in delayed treatment and poor outcomes, given the >50% mortality rate for disseminated disease 1, 2, 3
• Underestimating contagiousness results in inadequate infection control, as the virus survives for weeks on surfaces 4, 7