Presentation on theme: "Respiratory infection - 1"— Presentation transcript:
1Respiratory infection - 1 Dr Paul McIntyreThis is a big subject and requires some background reading.TAKE NPA EQUIPMENT FROM BOTTOM DRAWER.
2Influenza - clinical presentation Fever: high, abrupt onsetMalaiseMyalgiaHeadacheCoughProstrationUp to 40CGenerally feeling unwellMuscle pain is markedHeadache marked, may early in epidemic be mistaken for meningitis.Cough initially dry and painful, becomes productive but painlessLaryngo- tracheo - bronchitisInterferon cause systemic symptoms, virus restricted to resp epithelium
3‘Flu - aetiology Classical flu ‘Flu- like illnesses influenza A virusesinfluenza B viruses‘Flu- like illnessesparainfluenza virusesmany othersHaemophilus influenzaebacteriumnot a primary cause of ‘flumay be a secondary invaderMore than 1 subtype of flu A circulating.Flu - like illnesses occur outside of the major epidemics
4‘Flu - complications Primary influenzal pneumonia seen most during pandemic yearscan be disease of young adultshigh mortalitySecondary bacterial pneumoniamore common in elderly and debilitated, pre-existing diseasecause of mortality in all influenza epidemicsPandemics: multi continent epidemicsIn 1918/19 pandemic mortality most common in young adults eg 60k of 110k US troops in trenches.20 million dead in 1918/19
5‘Flu - therapy Symptomatic Antivirals bed rest, fluids, paracetamolAntiviralsoseltamivirzanamivirsee NICE guidelines‘flu circulatingrisk of complicationsuse in prophylaxis (additional to vaccine)Nice says that only given in patients at risk of complications and when flu circulating and early in disease.
6Epidemiology of ‘flu Winter epidemics Epidemics seen in association with minor mutations in the surface proteins of the virusantigenic driftPandemics: rare, unpredictable, influenza Aantigenic shiftsegmented genomeanimal reservoir/mixing vesselDrift classical Darwinian selection
7Current pandemic planning assumption the combination of “reasonable worst case” 30% Clinical Attack Rate and 0.1% Case Fatality Ratio would result in a total number of deaths of about 20,000, or about 1/30th of the total expected each year from all causes (about 600,000).These are planning assumptions for forthcoming winter, not predictions
9Comparison of H1N1 Swine Genotypes in Early Cases in the United States Figure 3. Comparison of H1N1 Swine Genotypes in Recent Cases in the United States. The triple-reassortant strain was identified in specimens from patients with infection with triple-reassortant swine influenza viruses before the current epidemic of human infection with S-OIV. HA denotes the hemagglutinin gene, M the M protein gene, NA the neuraminidase gene, NP the nucleoprotein gene, NS the nonstructural protein gene, PA the polymerase PA gene, PB1 the polymerase PB1 gene, and PB2 the polymerase PB2 gene.Novel Swine-Origin Influenza A (H1N1) Virus Investigation Team. N Engl J Med 2009;360:
10Future threats Highly pathogenic avian flu is influenza A H5N1 bird to human transmission seenHigh mortalitynot readily transmitted human to human
11Egon Schiele,The Family,1918.Oesterreichische Galerie, Vienna Egon Schiele,The Family,1918.Oesterreichische Galerie, Vienna
12Lab confirmation of influenza Direct detection of virusPCRThroat swabs in virus transport mediumPernasal swabs in virus transport mediumother respiratory samplesOther labs may use immunofluorescence, antigen detection (near patient), virus culture
13Lab confirmation of influenza Direct detection of virusPCRAntibody detectionmay need paired acute and convalescent bloodsoften retrospective
14PCR for Influenza A Virus Influenza A RNApositive samplesInfluenza A RNAnegative samples
15Prevention of ‘flu Vaccine killed vaccine given annually to patients at risk of complicationsgiven to health care workers
16Antiviral as prophylaxis antivirals after a contact with ‘fluNICE guidelinesrarely usedDuring “containment phase” of first wave of pandemic.
17Other causes of community acquired pneumonia Microbiological causes (all bacteria)Mycoplasma pneumoniaeCoxiella burnetiiChlamydiaNot viruses
18Mycoplasma, coxiella and Chlamydophila psittaci Therapyall respond to tetracycline and macrolides (eg clarithromycin)Mortalityvaries with pathogen, but generally lower than classical bacterial pneumoniaOften known as “atypical pneumonia”relates to presentation and response to therapy in the pre-antibiotic era
19Lab confirmation of mycoplasma, coxiella and Chlamydophila psittaci By serologysend acute and convalescent bloods to labgold top vacutainerAntibody tests
20Mycoplasma pneumoniae Common cause of community acquired pneumoniaOlder children, young adultsPerson to person spreadOnly one of the 3 causes of atypical pneumonia described today that is common in UK
21Coxiella burnetii (Q-fever) Diseasespneumoniapyrexia of unknown origin (Q fever)Uncommon, sporadic zoonosisSheep and goatsComplicationculture negative endocarditisOccasional outbreaks
22Chlamydia and respiratory disease Chlamydophila psittaci causes Psittacosispreviously called Chlamydia psittaciuncommon, sporadic zoonosiscaught from pet birdsparrots, budgies, cockatielspsittacosis usually presents as pneumonia
23Bronchiolitis Clinical presentation Severe cases 1st or 2nd year of lifeFeverCoryzaCoughWheezeSevere casesgruntingPaO2Intercostal / sternal indrawing
24Bronchiolitis - complications Respiratory and cardiac failureprematuritypre-existing respiratory or cardiac diseaseScottish Intercollegiate Guidelines NetworkSIGN guideline 91
25Bronchiolitis Aetiology Lab confirmation Therapy >90% cases due to Respiratory Syncytial VirusLab confirmationBy PCR on throat or pernasal swabs(direct IF on NPA in some labs)Therapysupportivenebulised ribavirin no longer used
26Bronchiolitis - epidemiology and control Epidemics every winterVery commonNo vaccineNosocomial spread in hospital wardscohort nursinghandwashing, gowns, glovesPassive immunisationpoor efficacy and cost-effectivenessPassive immunisation with a monoclonal antibody preparation has not been shown to reduce mortality and so is not widely used.
27MetapneumovirusFirst isolated 2001 children with Acute Respiratory Tract InfectionNat Med 2001;7:Contribution of ARTI to inc in winter deaths is well recognised
28Epidemiology Most children antibody positive by age 5 found in a wide range of agesVirus is newly discovered, not newWorld-wide distributionHighest incidence in winter8% of samples in Canadian children’s hospitalJ Clin Micro 2005;43:
29Association with disease May be sole pathogen isolatedPossibly second only to RSV in bronchiolitisSimilar symptoms to RSV in both children and adultsRange of severity from mild to requiring ventilationIncidence of asymptomatic infection low (in children at least)Williams JV et al. NEJM 2004;350: (and editorial)2% of cases of influenza-like illnessEmerging Infect Dis 2002;8:
32Current Respiratory tests Samples for PCR: Throat swabs in viral transport medium, bronchoalveolar lavage (BAL), endotracheal aspirate etcFlu A, Flu B, parainfluenza 1-3, metapneumo, adeno, RSV
33Chlamydia trachomatis and Chlamydophila pneumoniae and respiratory disease STI which can cause infantile pneumoniadiagnosed by PCR on urine of mother or pernasal / throat swabs of childChlamydophila pneumoniaeperson to person (formerly Chlamydia pneumoniae)mostly mild respiratory infectionsmay be picked up by test for Psittacosis
34Microbiology Problem Solving Session Remember to bring the relevant pages from the study guide with you to the class.Code for the classroom’s cloakroom is 1245Worthwhile looking at tuberculosis diagnosis and management before coming along.Remember to wash your hands before leaving the classroom as other students use live bacteria in their practicals in that room.
35Lecture objectivesAn understanding of the epidemiology, presentation, management and prevention of many of the most important viral and “atypical” causes of respiratory infection.