Upper respiratory tract infection &Pneumonia Lecture No.1
Dr Dhaher Jameel Salih Al-habbo FRCP London UK Professor of medicine Department of Medicine.The common cold Pharyngitis Epiglotitis Acute laryngitis Acute laryngotracheobronchitis Sinusitis Otitis externa, otitis media and mastoiditis
Typically, the incubation period of pertussis ranges from 3-12 days. Pertussis is a 6-week disease divided into catarrhal, paroxysmal, and convalescent stages, each lasting from 1-2 weeks. Stage 1 - Catarrhal phase:The initial (catarrhal) phase includes nasal congestion, rhinorrhea, and sneezing, variably accompanied by low-grade fever, tearing, and conjunctival suffusion. Pertussis is most infectious when patients are in the catarrhal phase, but pertussis may remain communicable for 3 or more weeks after the onset of cough.
Stage 2 - Paroxysmal phase Patients in the second (paroxysmal) phase present with paroxysms of intense coughing lasting up to several minutes. In older infants and toddlers, the paroxysms of coughing occasionally are followed by a loud whoop as inspired air goes through a still partially closed airway. Infants younger than 6 months do not have the characteristic whoop but may have apneic episodes and are at risk for exhaustion. Posttussive vomiting and turning red with coughing are common in affected children. Stage 3 - Convalescent phase Patients in the third (convalescent) stage have a chronic cough, which may last for weeks.
In patients with uncomplicated pertussis, physical examination findings contribute little to the diagnosis. In all patients with pertussis, fever is typically absent. Most patients do not have signs of lower respiratory tract disease. Conjunctival hemorrhages and facial petechiae are common and result from intense coughing.
The Orthomyxoviridae (influenza viruses) Three immunologic types are known: Type A; Type B Type C Etiology The standard nomenclature system for influenza virus isolates includes the following information: -type, -host of origin, -geographic origin, -strain number, year of isolation So far, 14 subtypes of HA (H1-H14) and nine subtypes of NA (N1-N9) in many different combinations have been recovered. Antigenic drift and antigenic shift . Minor antigenic changes are termed antigenic drift; Major antigenic changes in HA or NA, called antigenic shift
The three types of influenza vary in their epidemiologic patterns. Influenza C is least significant: it causes mild, sporadic respiratory disease, but not epidemic. Influenza B sometimes causes epidemics, Influenza type A can causes around the world massive epidemics called pandemics. Pathogenesis Influenza virus spreads from person to person by airborne droplets or by contact with contaminated hands or surfaces.
Uncomplicated Influenza Incubation period: 1-4 days. Symptoms usually appear abruptly and include: chills, headache, dry cough- respiratory symptoms typically last another 3-4 days. The cough and weakness may persist for 1-3 weeks. - high fever- lasts 3 days - generalised muscle aches, - malaise and anorexia Complications -Pneumonia Immunity to influenza is long-lived and subtype-specific.
Clinical findings
Diagnosis of influenza relies on: a-isolation of the virus; b-identification of viral antigen or viral nucleic acid in the patient’s cells, or c-demonstration of a specific immunologic response.Other tests are: ELISA and RIA. Paired acute and convalescent sera are necessary, because normal individuals usually have influenza antibodies. A fourfold or greater increased in titer must occur to indicate influenza infection.
1-Amantadine and rimantadine, 2-Zanamivir and Oseltamivir 3-All people at risk in whom influenza develops 4-Persons with severe influenza 5-For persons who wish to shorten the duration of illness.
A-Inactivated viral vaccines The vaccine is usually a cocktail containing two influenza A subtypes (H1N1, H3N2) and a type B virus of the strains isolated in the previous winter’s outbreaks. Annual influenza vaccination is recommended for high-risk groups.: • Persons >50 years old • those with either chronic heart or lung disease, • adult and children with asthma, or metabolic or renal disorders, immunossuppression, hemoglobinopathy •residents of nursing homes; • persons who might transmit influenza to high-risk groups : - medical personnel, - employees in chronic care facilities, - household members.
Community-acquired pneumonia (CAP)
UK figures suggest that an estimated 5-11/1000 adults suffer from CAP each year, accounting for around 5-12% of all lower respiratory tract infections. The incidence varies with age, being much higher in the very young and very old, in whom the mortality rates are also much higher. World-wide, CAP continues to kill more children than any other illness.Pneumonia usually presents as an acute illness in which systemic features such as fever, rigors, shivering and vomiting predominate . Pulmonary symptoms breathlessness and cough, painful and dry, but later accompanied by the expectoration of mucopurulent sputum. Proteinaceous fluid and inflammatory cells congest the airspaces, leading to consolidation of lung tissue. This improves the conductivity of sound to the chest wall (bronchial breathing and whispering pectoriloquy). Crackles are often also detected
The objectives are to exclude other conditions that mimic pneumonia ,assess the severity, and identify the development of complications. A chest X-ray usually provides confirmation of the diagnosis. In lobar pneumonia, a homogeneous opacity localised to the affected lobe or segment usually appears within 12-18 hours of the onset of the illness . Radiological examination is helpful if a complication such as parapneumonic effusion, intrapulmonary abscess formation or empyema is suspected.
This CXR demonstrates a lobar pneumonia
Oxygen: should be administered to all patients with tachypnoea, hypoxaemia, hypotension or acidosis with the aim of maintaining the PaO2 ≥ 8 kPa (60 mmHg) or SaO2 ≥ 92%. High concentrations (≥ 35%), preferably humidified, should be used in all patients who do not have hypercapnia associated with COPD. Assisted ventilation should be considered at an early stage in those who remain hypoxaemic despite adequate oxygen therapy.Noninvasive Ventilation (NIV ) may have a limited role but early recourse to mechanical ventilation is often more appropriate
Fluid balance: Intravenous fluids should be considered in those with severe illness, in older patients and in those with vomiting. Otherwise, an adequate oral intake of fluid should be encouraged. Inotropic support may be required in patients with circulatory shock.
Most patients respond promptly to antibiotic therapy. However, fever may persist for several days and the chest X-ray often takes several weeks or even months to resolve, especially in old age. Delayed recovery suggests either that a complication has occurred or that the diagnosis is incorrect . Alternatively, the pneumonia may be secondary to a proximal bronchial obstruction or recurrent aspiration. The mortality rate in adults managed at home is very low (< 1%); hospital death rates are typically between 5 and 10%, but may be as high as 50% in severe illness