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Common Cold

Common Cold. Faculty of Medicine University Of Jordan. Dr. M. El-Khateeb. Common Cold. Common Cold Syndrome is a general term of acute inflammatory disease of the upper respiratory tracts Syndrome includes rhinitis, tonsilitis, pharyngitis, laryngitis pharyngo-laryngitis etc.

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Common Cold

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  1. Common Cold Faculty of Medicine University Of Jordan Dr. M. El-Khateeb

  2. Common Cold • Common ColdSyndrome is a general term of acute inflammatory disease of the upper respiratory tracts • Syndrome includes rhinitis, tonsilitis, pharyngitis, laryngitis pharyngo-laryngitis etc. • SometimesInfluenza (the flu) and sinusitisare characterized as a common cold syndrome.

  3. Although many people are convinced that a cold results from: 1. Exposure to cold weather 2. From getting chilled or overheated 3. Fatigue, or sleep deprivation. These conditions have little or no effect on the development or severity of a cold.

  4. On the other hand, research suggests that : • Psychological stress • Allergic disorders affecting the nasal passages or throat • Menstrual cycles may have an impact on a person's susceptibility to colds.

  5. Common cold • Acute respiratory infections, predominantly rhinovirusinfections, are estimated to cause30-50%of time lost from work by adults and60-80%of time lost from school by children. • Up to 6common colds/year in adults and 8common colds/year for children acceptable. • Medications can help relieve cold symptoms, but only time can cure a cold.

  6. Common Cold • Common symptoms are sore throat, runny nose, nasal congestion, sneezing, • Sometimes accompanied by conjunctivitis, myalgias, fatigue • Sinusitis often present by CT scan; “rhinosinusitis” might be a better term • Seasonal variation • Rhinovirus early fall • Coronavirus- winter

  7. Viruses Associated with Respiratory Infection Syndrome Commonly Associated Less Commonly viruses Associated viruses Corza Rhino and Picrona Influenza, Parainfluenza Entero and Adeno Influenza Influenza Virus Parainfluenza, RSV, Adenovirus Croup Parainfluenza Influenza, RSV, Adenovirus Bronchiolitis RSV Influenza, Parainfluenza, Adenovirus Pronchopneumonia Parainfluenza, RSV, Parainfluenza, Measlse, Adenovirus VZV, CMV

  8. Common Cold Viruses • Common colds account for one-third to one-halfof all acute respiratory infections in humans. • Rhinoviruses are responsible for 30-50%of common colds, coronaviruses 10-30%. The rest are due to adenoviruses, enteroviruses, RSV, influenza, and parainfluenza viruses, which may cause symptoms indistinguishable to those of rhinoviruses and coronaviruses.

  9. Etiology Common viruses that usually cause common colds • Rhinoviruses • Parainfluenza or influenza viruses • Respiratory Syncytial Virus (RSV) • Coronaviruses • Adenovirus • Enteroviruses • Coxsackie Virus and ECHO Virus • Reoviruses

  10. Common Cold Viruses Viruses Serotype % C. cold • Rhinoviruses > 100 60 • Coronaviruses 2 15 • Influenza 3 <10 • Parainfluenza 4 <10 • R S V 2 <10 • Adenovirus 47 <10 • Entrovirus >40 <10

  11. Rhinovirus • Rhinovirus infections are chiefly limited to the upper respiratory tract but may include otitis media and sinusitis. • Rhinovirus plays a role inexacerbationsof asthma, cystic fibrosis, chronic bronchitis, and serious lower respiratory tract illness in infants, elderly persons, and patients who are immunocompromised. • Although infections occur year-round, the greatest incidence is in the fall and spring. • Of persons exposed to the virus, 70-80% have symptomatic disease.

  12. Rhinovirus • Belong to the picornavirus family the smallest (pico) RNA viruses (24-30 nm) • ssRNA virus • Acid-labile • Rhinovirus Capsid consists of 4 proteins VP1, VP2, VP3& VP4 • At least 100 serotypes are known • Intercellular Adhesion Protein-1 (ICAM-1) • Receptor for most human rhinovirus serotypes Antibodies bonded to a rhinovirus Rhinovirus bonded to a CAM 1 receptor

  13. Functions of Viral RNA • RNA genome is mRNA Positive strand. • A viral-coded peptide (VPg) is attached to the 5’ end. • When introduced into cells, viral RNA can produce infectious virus. • Viral RNA serves as a template for its replication • Optimum growth occurs between 33 and 34 oC • Viruses replicate rapidly in the cytoplasm • do not require DNA for reproduction

  14. Functions of Viral Proteins • Derived from one polyprotein precursor • Processed by post-translational cleaving • Structural proteins • Responsible for host tropisms • Protection of genome • Antigenicity • Non-structural proteins • Proteases • RNA polymerase • Inhibitors of normal host cell functions

  15. Virus Replication Cycle Internal ribosome entry segment (IRES)

  16. Coronavirus • ssRNA Virus • Enveloped, pleomorphic morphology • 2 serogroups: OC43 and 229E

  17. Transmission Routes Cold viruses may be transmitted by three routes: • Large-particle droplets, which can travel a short distance to directly inoculate another person • Small-particle aerosols, which can travel longer distances and deposit directly in alveoli of other individuals • Secretion, which are transmitted by direct physical contact

  18. How does it spread? • Very contagious • Spread from person to person • Usually from nasal secretions and from fingers of the affected person • Most contagious in the first 3 days after symptoms begin • Viruses can last up to 5 hours on the skin and hard surfaces

  19. Rhinovirus Higher rates occur in humid, crowdedconditions, as found in nurseries, day care centers, and schools, especially during cooler months in temperate regions and rainy season in tropical regions.

  20. Pathogenesis • The offending virus invades the epithelial cells of URT. • Inflammatory mediators are released. • They alter the vascular permeability and cause tissue edema and stuffiness. • Stimulation of cholinergic nerves in the nose and URT leads to increased mucus production (rhinorrhea) and occasionally to bronchocontriction • Injury to cilia in the nasal epithelial cells may decrease ciliary function and impair clearance of nasal secretions.

  21. Pathophysiology • Rhinoviruses are transmitted to susceptible individuals by : • Direct contact • Aerosol particles infecting both ciliated areas of the nose and nonciliated areas of the nasopharynx through receptors, most frequently ICAM-1 (found in high quantities in the posterior nasopharynx). • Few cells are actually infected by the virus, and the infection involves only a small portionof the epithelium.

  22. Pathophysiology • Symptoms develop 1-2 days after viral infection, peaking 2-4 days after inoculation, although reports have described symptoms as early as 2 hours after inoculation with primary symptoms 8-16 hours later.

  23. Pathophysiology • Detectablehistopathologycausing the associated nasal obstruction, rhinorrhea, and sneezing is lacking: which leads to the hypothesis that the host immune response plays a major role in rhinovirus pathogenesis. • Infected cells release interleukin-8 (IL-8),which is a potent polymorphonuclear (PMN) chemoattractant. • Concentrations of IL-8 in secretions correlate proportionally with the severityof common cold symptoms. • Inflammatory mediators, such as kinins and prostaglandins, may cause vasodilatation, increased vascular permeability, and exocrine gland secretion. • These, together with local parasympathetic nerve-ending stimulation, lead to cold symptoms

  24. Pathophysiology • Viral clearance is associated with the host response and is due, in part, to the local production of nitric oxide. • Serotype-specific neutralizing antibodiesare found 7-21 days after infection in 80% of patients. • Although these antibodies persist for years, providing long-lasting immunity, recovery from illness is more likely related to cell-mediated immunity. • Persistent protectionfrom repeat infection by that serotype appears to be partially attributable to immunoglobulin A (IgA) antibodies in nasal secretions, serum immunoglobulin G (IgG), and, possibly, serum immunoglobulin M (IgM).

  25. Pathophysiology • The virus has a limited temperature range in which it can grow (33-35°C) and cannot tolerate an acidic environment. Thus, finding the virus outside of the nasopharynx is unlikely because of the acidic environment of the stomach and the temperature elevation in both the lower respiratory and gastrointestinal tracts.

  26. The Common Cold Chemical Mediators of Inflammation Vascular Dilatation NASAL OBSTRACTION Tissue Edema Increased Vascular Permeability VIRAL INFECTION OF NAZAL CELLS SNEEZING SORE THROAT Serum Transduction Increased Mucus Production RHINORRHEA Sensitization of Irritated of Airways Receptors Cholinergic Stimulation Bronchoconstriction COUGH

  27. Physical examination • Red nose with dripping nasal discharge may be present. • Nasal mucous membranes have a glistening, glassyappearance without obvious erythema and edema. • Yellow or green nasal dischargedoes not indicate bacterial infection because a large number of white blood cells migrate to the site of viral infection.

  28. Physical Examination • If marked: 1. erythema, edema, exudates, or small vesicles are observed in the oropharynx 2. conjunctivitis 3. polyps in the nasal mucosa occur, consider other etiologies, including: adenovirus, herpes simplex virus, mononucleosis, diphtheria, Coxsackie A virus, or group A streptococcus (GAS).

  29. Clinical characteristics • Incubation period 12-72 hours • Nasal obstruction, drainage, sneezing, scratchy throat • Median duration 1 week but 25% can last 2 weeks • Pharyngeal erythema is commoner with adenovirus than with rhino or coronavirus

  30. Symptoms • Begins with a feeling of dryness and stuffiness in the nasopharynx (nose) • Nasal secretions (usually clear and watery) • Watery eyes • Red and swollen nasal mucous membranes • Headache • Generalized tiredness • Chills (in severe cases) • Fever (in severe cases) • Exhaustion (in severe cases) If the pharynx and larynx (throat) becomes involved: Sore throat Hoarseness

  31. ICEBERG CONCEPT INFECTION Sever Symptoms Mild Symptoms Infection but no Symptoms Exposure but no Symptoms

  32. RISK FACTOR FOR MORE SEVER COMMON COLD • LOW NEUTRALIZING Ab • CHRONIC LUNG DISEASE • EXTREMES AGE • ASTHMA • ALLERGY • Ig E • CYTOKINE PRODUCTION • I F N -gamma • I L-5

  33. Complications • Acute otitis media • Paranasal sinusitis • Neck lymphonoditis • Retropharyngeal abscess • Laryngitis • Lower respiratory tract disease • Acute glomerulonephritis and rheumatic fever

  34. Laboratory Test • White cell count • The viral infections is normal to low. • The bacterial infections or viral-bacterial infection is high. • Laboratory diagnosis of viral infections • Antigen or nucleic acid detection • Serologic testing • Isolation of viruses by culture of the throat or nasopharynx • Use of monoclonal antibodies • Polymerase chain reaction (PCR)

  35. TREATMENT

  36. Treatment of common cold • Antihistamines • Decongestants • Pain Relievers • Cough suppressants • Nasal Strips • Antibiotics are ineffective!!!

  37. MEDICATION • Drugs used in the symptomatic treatment include: • Nonsteroidal anti-inflammatory drugs (NSAIDs) • Antihistamines • Anticholinergic nasal solutions • These agents have no preventive activity and appear to have no impact on complications.

  38. TREATMENT • Rhinovirus infections are predominately mild and self-limited: thus, treatment is generally focused on symptomatic relief and prevention of person-to-person spread and complications. The mainstays of therapy include: • Rest, • Hydration, • Antihistamines, • Nasal decongestants • Antibacterial agents are not effective unless bacterial superinfection occurs.

  39. TREATMENT • Development of effective antiviral medications has been hampered by the short courseof these infections. • Because peak symptom severity occurs at 24-36 hours after inoculation, only a narrow window of timeexists in which antivirals could positively impact upon this infection. • In addition, the cause of the common cold is not alwaysrhinovirus. • Therefore, rapid and accurate diagnostic tests would be needed if a specific antiviral therapy were developed.

  40. VACCINATION Because of the large number of rhinovirus immunotypes and the inaccessibility of the conserved region of the viral capsid(the most likely effective site for targeting a vaccine), no rhinovirus vaccine is on the horizon.

  41. PREVENTION • Because infection is spread by: hand-to-hand contact, autoinoculation, possibly, aerosol particles, emphasize appropriate hand washing, avoidance of finger-to-eyes or finger-to-nose contact, and use of nasal tissue. Cough and sneeze into arm or tissue, not into your hand

  42. SUMMARY

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