Legionellosis

Generalities
Agent	- Legionella, Gram negative bacilli. There are 20 different species. 80% of human infections are due to L. Pneumophila serogroup 1. - Other species: L. micdadei, L. bozemanii, L. longbeachae, L. dumoffii…
Incubation period	- For Legionaires'disease: 5-6 days (2-10 days) - For Pontiac fever: 24-48 hours (5-66 hours)
Period of transmissibility	No person-to-person transmission
Reservoir	- Water: Legionnella is waterborne, found in water system, air conditionning cooling tower, whirpool spas... Legionella growth increases with warm water temperature (25-42C), sale and sediment, and low biocide levels - Potting soil may be reservoir for certain spp (L. longbeachar)
Modes of transmission	- Inhalation of contaminated aerosols - Microaspiration of contaminated water - Contaminated soil
Clinical presentation	Two forms: - Legionaires' disease: pneumonia with non productive cough. Case fatality: 15% - Pontiac fever: self-limited flu-like illness without pneumonia
Resources
Case definition	MOPH circular no. 175 (2015)
Forms	- General reporting form - Legionellosis investigation form
Data	Notifiable disease since 2014