Airborne Infections

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Airborne Infections

• Timothy G. Myrick M.D.
• INMED
• Kansas City, Missouri

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General Classes

• Viral
• Bacterial
• Mycobacterial
• Fungal

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Viruses

• Influenza
• Measles
• Varicella
• Rhinoviruses
• Coronavirus

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Bacteria

• Staph and strep
• Legionella
• Brucella
• Anthrax
• Plague

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Mycobacteria

• Tuberculosis
• Leprosy

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Fungal

• Histoplasmosis
• Blastomycosis
• Coccidioidomysosis
• Paracoccidioidomycosis
• Aspergillosis
• Cryptococcosis

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Influenza

• RNA virus, family Orthomyxovirus. Name from
  Italian Influenza del freddo (infuence of the
  cold)
• History pandemics of 18, 57,68
• Epidemiology- winter outbreak, epidemic,
  pandemic. Antigenic drift and shift
• Types A, B and C
• A and B cause epidemics
• C causes minor resp illness without epidemics
• A 16 hemaggutanin and 9 neuraminidase
• Currently in human circulation H1N1 and H3N2

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Influenza

• 2006-2007 Season
• Vaccine included AH1N1 Solomon Islands, AH2N3
  Wisconsin, and B Victoria
• Circulating viruses predominantly AH1N1 Solomon
  Islands, AH2N3 Brisbane, and B Yamagata
• Antibiotic Resistance
• 87 resistance to adamantanes
• 5 A and B resistance to osetamivir

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Influenza

• Avian Influenza
• H5N1
• Increasing pathogenicity
• 366 human cases so far, 60 mortality URI sx,
  pneumonia, GI sx, neuro sx
• Human to human transmission rare (9 people so
  far, all family)
• Resist to adamantanes, rare to oseltamivir
• The 1918 avian flu (H1N1)

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Measles

• Most deadly of the childhood fevers
• Kills about 1 million children yearly
• Leading cause of blindness in African kids
• Where vit A deficiency prevalent, kills up to 1/4
• Preventable by vaccine
• High rate of complications including
• Otitis 1/10
• Pneumonia 1/20
• Encephalitis 1/1000

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Varicella

• Among the most communicable
• Pre-vaccine 4mil cases, 11k hospitalized, 100
  deaths /yr in U.S.
• More severe in adults
• Cellulitis
• Cerebral edema
• Pneumonia

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Rhinovirus

• Picornovirus
• Causes 30-50 of Common cold, most prevalent
  infectious disease
• Pleconaril under development. Stabilizes
  membrane preventing release of RNA

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SARS

• SARS assoc. Coronavirus (SARS CoV)
• 8,000 cases in 2002-2003, with 800 deaths.
• Dx by history of exposure plus pneumonia
• Last outbreak in April 2004 (lab assoc.)

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Legionella

• Legionella pneumophila
• Inhaled droplets from air conditioning systems,
  water supply lines
• Causes pneumonia
• CDC estimates 8-18k cases/yr, 25 nosocomial

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Inhalation Anthrax

• Bacillus Anthracus lives in soil
• Most exposure cutaneous
• Inhalation of 10-20k spores highly lethal
• Dead bodies extremely infectious
• April 1972 Sverdlovsk, 68 of 94 pts died
• Sept 2001 Amerithrax 7 letters, 22 infected, 11
  inhalation, 5 deaths.

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Pneumonic Plague

• Yersinia pestis
• Normally transmitted by flea bites
• Multiplication of bacteria in lymphatics can lead
  to pulmonary infection and aerosol spread
• Illness in few hours to four days. SOB, chest
  pain, cough, hemoptysis
• 50-90 mortality in 1-6 days
• Gentamicin or Doxycycline 1st dy effective

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Tuberculosis

• Known since pharonic times
• Approximately 1/3 of population infected
• 5-10 become contagious
• Each spm positive case infects 10-15 per year
• About 1 new infection per second worldwide
• Inhaled bacilli eaten by macrophages, picked up
  by dendritic cells, transported to lymphatics,
  then bloodstream, then disseminated.
• Macrophages, B and T lymphocytes, and fibroblasts
  form granuloma

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Resistant Tuberculosis

• 1in 10 to 7th native resistace to given med
• Cavity fluid has 10 to 15th per ml
• Multiple meds must be used
• WHO 2008 report- MDR 5-6 of all TB
• Highest MDR rates 23 of TB
• XDR reported in 45 countries from 4-25

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HIV and Tuberculosis

• HIV makes active TB more likely
• HIV infected pt sheds more TB bacilli
• HIV increases liklihood of drug resistance
• HIV reduces effectiveness of TB meds
• Combination HIV MDR TB highly lethal
• XDR TB likely untreatable

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Leprosy

• Mycobacterium leprae
• Inhalation, pulm infx, hematogenous spread,
  neuritis, dermatitis, mucositis
• Anesthesia leads to tissue damage and loss
• Multible drug long term treatment
• 90 of 750 k cases worldwide in Brazil, Tanzania,
  Mozambique, Nepal, Madagasc

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Histoplasmosis

• Histoplasma capsulatum (dimorphic fungus)
• Acute Respiratory Illness in heavy exposure.
• Buckshot infiltrates
• Treat if hypoxemic or prolonged with Amph B and
  Itraconazole

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Blastomycosis

• Blastomyces dermatitidis (dimorphic fungus)
• Inhalation of conidia- acute lobar infiltrate,
  then chronic infiltrates with or without
  cavities.
• Dx Spm Smear or Culture
• Tx Amphotericin B

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Coccidioidomycosis

• Coccidioides immitus (dimorphic fungus)
• Inhale the spores from blowing dust
• Acute respiratory illness
• 5-10 progress to chronic lung infection,
  granuloma, dissemination
• Culture spm or matl from bronchoscopy
• Treat with fluconazole

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Paracoccidioidomycosis

• Paracoccidioides brasiliensis (yeast)
• Painful oral ulcers or nodular pulm infiltrate
• Sputum smear or cluture
• Tx with itraconazole

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Aspergillosis

• Aspergillus flavus etc. (hyaline mold)
• Allergic bronchopulmonary, Aspergilloma, Invasive
  Aspergillosis
• Dx with Spm smear and culture
• Tx with surgery for aspergilloma or voriconazole

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Cryptococcosis

• Cryptococcus neoformans
• Enters via resp tract, and neurotropic.
• Causes disease in immunosuppressed.
• Dx by culture, India Ink Prep, Antigen
• Tx in Induction, Consolidation and Maintenance
  phases with amphotericin B and Azole antifungals.

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Poverty and Airborne Infection

• Reduced immunization coverage
• Crowding
• Poor sanitation
• Malnutrition
• Open pharmacy

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Poverty and Airborne Infection

• Barriers to medical care
• Inadequate institutional infection control
• Air quality
• Domestic open cooking fires
• Workplace exposure
• Smoking

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Prevention of Transmission

• HEPA filtration (High Efficiency Particulate Air)
  
• Interception
• Impaction
• Diffusion
• UVGI (Ultraviolet Germicidal Irradiation)
• Masks
• Respiratory and contact isolation

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Useful Resources

• The Stop TB partnership- www.stoptb.org
• The Global Health Council- (poverty and disease)
  www.globalhealth.org
• World Health Organization- www.who.int
• Centers for Disease Control- www.cdc.gov
• Cooking fire pollution www.treeswaterpeople.org