View source for 24. Epidemiology and prevention of airborne bacterial infections

Airborne infections:

* Inhalation of organisms suspended in the air on water droplets or dust particles
* Prevention:
** Handwashing
** Keep distance from sick people
** Sick people should keep distance from healthy people
** Vaccines

Bacterial airborne infections:

* Tuberculosis
* Diphtheria
* Pertussis
* Neisseria meningitidis (meningococcus)
* Haemophilus influenzae
* Streptococcus pneumoniae (pneumococcus)
* Legionnaire disease

Tuberculosis

* Mycobacterium tuberculosis hominis/bovis
* Epidemiology
** 9th leading cause of death worldwide
** 27 000 new cases every day
** Leading cause of death in HIV-positive
** Incidence and mortality dropping in the last 20 years
** Globally the incidence decreases by 2% each year
** 95% of TB-related deaths occur in low- and middle-income countries
** Incidence of multidrug and extensively drug resistant TB increases
* Risk factors for severe TB
** HIV (or other immune suppression)
** Severe disease (DM, renal failure)
** <abbr>TNF</abbr> alpha inhibitors
* TB is most prevalent among
** Migrants
** Homeless
** Poor people
** Drug abusers
* Treatment
** Childhood TB is generally treatable
** Adult TB is less treatable
* Prevention
** Isolation of TB patients
** Disinfection by UV light or tuberculocidial disinfectants
** Special air filters
** Routine TB testing for high-risks
* BCG vaccine
** Live attenuated Mycobacterium bovis
** Unchanged since 1921
** Only 50% effective against TB
** Good protection against childhood TB meningitis and miliary TB
** Poor protection against adult pulmonary TB
** Intradermal injection in the deltoid
*** If given subcutaneously -> can form abscess

Diphtheria

* Corynebacterium diphtheriae
* Epidemiology
** Global reported cases down since vaccine was introduced in the 80s
** Very rare in countries with high coverage with vaccine
* Clinical features
** Short incubation period
** Produces pseudomembrane in the pharynx
*** Makes breathing and swallowing difficult
** Produces diphtheria toxin
*** Myocarditis
*** Peripheral neuropathy
*** Nephritis
* Vaccine
** Toxoid vaccine – toxin is inactivated with formalin
** DTaP vaccine at 3, 5 and 12 months, 7, 15 years (in Norway) + booster (Tdap) every 10 years
** Vaccine lasts 10 years
** Intramuscular vaccine
** Because vaccine doesn’t protect against the infection itself, only the (toxin-mediated) disease, there is no herd immunity!

Pertussis

* Bordetella pertussis
* Epidemiology
** Important cause of infant death worldwide
** It’s a public health concern even in countries with high vaccination coverage
* Produces pertussis toxin
* Clinical features
** Whooping cough – paroxysmal coughing
** Pneumonia
** Apnoea
* Vaccine
** Acellular pertussis (DTaP)
** Given at 3, 5 and 12 months, 7, 15 years (in Norway) + booster (Tdap) every 10 years

Streptococcus pneumoniae (pneumococcus)

* Epidemiology
** Often in fall, winter
* Clinical features
** Common cause of community-acquired pneumonia, bacterial meningitis
** Bacteraemia
** Otitis media
* Colonizes nasopharynx
* Vaccine
** Conjugate vaccine
** Given at 3, 5 and 12 months

Haemophilus influenzae

* Colonizes nasopharynx
* Causes otitis media, meningitis, epiglottitis, sinusitis
* Vaccine
** Conjugate vaccine
** Only for H. flu type b – the only type with a capsule and therefore only pathogenic type
** 3, 5 and 12 months

Legionellosis

* Legionella pneumophila
* Epidemiology
** Mostly affects older males
* Risk factors
** Smoking
** Lung disease
** Recent intubation
* Inhalation of contaminated aerosol
* Two forms
** Non-pneumonic form – causes Pontiac disease (influenza-like illness)
** Pneumonic form – causes Legionnaire disease – severe pneumonia
*** -> respiratory failure -> death in 5%
* No vaccine available

Neisseria meningitidis

* Epidemiology
** Mostly occurs in sub-Saharan Africa
** Epidemics during winter, spring
** Serotype B and C account for most cases in western world
** Serotype A accounts for most cases in Africa
* No animal reservoir – only human
* Clinical features
** Lethality 10% when treated, 50% when untreated
** Mainly affects children and infants
** Causes bacterial meningitis
** Asymptomatically colonizes nasopharynx in 10 – 30% of healthy
* Vaccine
** Polysaccharide vaccine used during outbreaks
** Conjugate vaccine used for prevention
* Chemoprophylaxis
** Antibiotic prophylaxis for people in close contact to infected

[[Category:Public health 4 - Preventive medicine]]