Yesterday, in WHO: Legionnaire’s Disease Outbreak – Portugal, we saw the official announcement of one of the largest outbreaks of Legionella that we’ve seen inyears; more than 300 cases in a week’s time. While not a record (Murcia, Spain saw 800+ cases in 2001), this is a very large cluster, and the outbreak is ongoing.
Based on the size and rapid growth of the cluster, the WHO called it a `major public health emergency’. But Legionnaire’s is not a communicable disease, and so the threat is limited to those who are directly exposed to the environmental source of the bacteria.
The Legionella bacteria thrives in warm water, such as is commonly found in air-conditioning cooling towers, hot tubs, and even ornamental water fountains. When water is sprayed into the air the bacteria can become aerosolized and inhaled.
Those who are susceptible (often smokers, immunocompromised, elderly, etc.) can develop serious – even life threatening – pneumonia.
Today the ECDC has produced a Rapid Risk Assessment for the rest of the EU, which includes a good deal of background on Legionnaire’s disease. I’ve only posted some excerpts, click the link to download the entire PDF.
RAPID RISK ASSESSMENT
13 November 2014
ECDC threat assessment for the EU
The large number of cases in a short period of time suggests an environmental source that has spread contaminated aerosols in the area. The Portuguese authorities are focusing the environmental investigation on such a possibility. Since 9 November they have implemented precautionary measures in closing cooling towers of major industrial installations in the area of Vila Franca de Xira. People who have been in the affected area in the past three weeks (longest documented incubation period is 19 days) may therefore have been at risk of infection, and could be currently incubating the disease and may develop symptoms up to three weeks after exposure.
People with underlying illness or a weakened immune system are at increased risk of developing the disease if exposed and may present with more severe disease.
Since Legionnaires’ disease cannot be transmitted from person-to-person, the risk remains limited to people who have been possibly exposed in the affected area during the period when the bacteria was spread in the environment. Travellers who have visited Vila Franca de Xira in the past three weeks and who develop symptoms of Legionnaires’ disease should seek rapid medical advice and indicate their possible exposure.
The health authorities in Portugal have kept the public informed through regular press releases and local information sessions about the disease and exposure risks.
To date, no cases associated with this outbreak have been detected outside of Portugal. The suspected cases reported in Peru and Angola were further excluded for Legionella. Legionnaires’ disease cases that are detected outside of Portugal and who match the case definition (see Annex 2) should be reported through ELDSNet (email@example.com).
The outbreak of Legionnaires’ disease in Portugal with 311 cases reported as of 13 November 2014 is one of the largest in the European Union. Vila Franca de Xira is not considered a tourist destination and no case has so far been confirmed outside Portugal. Despite the magnitude of the outbreak, this event can be considered a local event. All cases were infected in Vila Franca de Xira where the outbreak is occurring.
Cooling towers of major industrial installations in the area of Vila Franca de Xira were closed and investigations to identify the source of the outbreak are ongoing.