What is rhinovirus?

What is Rhinovirus?

Rhinovirus is a non-enveloped RNA virus from the Picornaviridae family that represents the most common cause of the "common cold" and upper respiratory tract infections, accounting for approximately 50% of all viral upper respiratory infections in adults. 1

Viral Characteristics and Classification

Rhinovirus comprises three distinct species (A, B, and C) with over 160-170 known genotypes, which explains why individuals can experience repeated infections throughout their lifetime 2, 3. This extensive genetic diversity allows the virus to frequently evade the adaptive immune system and makes vaccine development extremely challenging 2.

Transmission and Epidemiology

• Highly infectious and transmitted through aerosols and direct contact 2
• Circulates year-round with peak incidence in autumn and spring in temperate climates 2
• Adults experience an average of 2-5 episodes per year; children may have 7-10 episodes annually 4
• Notably, rhinovirus transmission persisted even during the SARS-CoV-2 pandemic, demonstrating resistance to stringent public health measures 2

Pathophysiology and Mechanism of Infection

Rhinovirus enters through the nose or lacrimal duct and attaches to specific cellular receptors on respiratory epithelial cells 1:

• ICAM-1 receptors (used by majority of RV-A and all RV-B types)
• Low-density lipoprotein receptor family members (used by 12 RV-A types)
• CDHR3 (cadherin-related family member 3, used by RV-C) 3

The virus triggers upregulation of inflammatory mediators including histamine, bradykinin, and various cytokines (interleukin-1, -6, -8, tumor necrosis factor-α, and leukotriene C4) 1. Importantly, rhinovirus and coronavirus do not cause major epithelial damage, unlike influenza and adenovirus 1.

Immune Suppression Effects

Rhinoviruses have a substantial suppressive effect on immune function, including:

• Diminished neutrophil adherence, chemotaxis, phagocytosis, and bactericidal function
• Suppressed macrophage and lymphocyte function
• This makes patients more vulnerable to secondary bacterial overgrowth by pathogens like S. pneumoniae and H. influenzae 1

Clinical Manifestations

Upper Respiratory Tract Disease

Typical symptoms include: sneezing, rhinorrhea, nasal congestion, hyposmia/anosmia, facial pressure, postnasal drip, sore throat, cough, ear fullness, fever, and myalgia 1, 5.

Symptom progression follows three distinct patterns 1:

1. Fever and myalgia: Resolve after 5 days
2. Sneezing and sore throat: Resolve around day 5-7
3. Cough and rhinorrhea: Persist into the second and third week (10+ days)

Critical clinical point: Symptoms typically peak within 3 days, then gradually decline and resolve within 10-14 days 5. The mean duration ranges from 6.6 to 8.9 days, though symptoms may last >15 days in 7-13% of cases, particularly in children in daycare 1.

Lower Respiratory Tract Disease

Contrary to historical perception, rhinovirus causes significant lower respiratory disease 2:

• Bronchitis, bronchiolitis, and pneumonia
• Exacerbations of asthma and COPD (major clinical impact)
• Severe manifestations can occur even in immunocompetent individuals 2
• Some rhinoviruses replicate well at 37°C and can infect the lower airway 6

Important Clinical Distinction

Mucopurulent or discolored nasal discharge does NOT indicate bacterial infection—it reflects neutrophil influx and is a normal part of viral inflammation 1, 5. This is a common clinical pitfall.

Risk for Secondary Bacterial Infection

Only 0.5-2% of viral upper respiratory infections progress to acute bacterial rhinosinusitis (ABRS) 5, 4, 7, 4. Secondary bacterial invasion occurs through a combination of factors including nose blowing, local/systemic immunity, viral virulence, nasopharyngeal colonization with bacterial pathogens, and environmental factors 1.

Bacterial infection should be suspected when 4:

• Symptoms persist >10 days without improvement, OR
• Symptoms worsen after 5-7 days ("double sickening"), OR
• At least 3 of the following are present:
  • Discolored mucus
  • Severe unilateral pain
  • Fever >38°C
  • Elevated ESR/CRP
  • "Double sickening" pattern

Clinical Burden and Healthcare Impact

The impact of rhinovirus in adults rivals that of influenza and respiratory syncytial virus in terms of morbidity and healthcare utilization 2. The virus affects patients across all healthcare settings—from primary care to intensive care units 2.

Treatment and Prevention

No specific antiviral therapy or vaccine currently exists 2, 3, 8. Management is symptomatic only 5:

• Analgesics (acetaminophen, ibuprofen, NSAIDs)
• Topical intranasal steroids
• Nasal saline irrigation
• Oral decongestants (use <3-5 days to avoid rebound congestion)

Antibiotics are NOT indicated for uncomplicated rhinovirus infection and do not provide symptom relief 5. The risk of infection can be reduced through strict hygiene measures 8.