In recent months, the European Centre for Disease Prevention and Control (ECDC) has observed an increase in the number of cases of Legionnaires’ disease among European travellers returning from Dubai compared to previous years (1, 2). As the source has not yet been identified, there could still be a risk for exposure to Legionella for persons visiting or living in Dubai.
What is Legionnaires’ disease?
Legionnaires’ disease is a type of pneumonia caused by the bacteria Legionella pneumophila and other Legionella species. The illness usually starts with flu-like symptoms including fever, tiredness, headache, and muscle pains. This is followed by a dry cough and breathing difficulties which may progress to a severe pneumonia. Death occurs in 10-15% of otherwise healthy people and may be higher in some groups of patients. All ages can be affected. However, most cases occur in people who are over 40 years of age. Men are more at risk than women, as are smokers, those with excessive alcohol intake, and people with chronic illnesses or people whose immune system is weakened.
The disease is spread through the air from a water source. People become infected when they breathe in aerosols (tiny droplets of water) which have been contaminated with Legionella bacteria. Legionella bacteria are found in many types of water systems. They multiply in warm, and stagnant water, such as can be found in air conditioning cooling towers, certain plumbing systems especially showers, spa pools, decorative fountains, sprinklers and nebulisers. Sporadic cases and outbreaks are frequently associated with commercial accommodation such as hotels due to the nature of the plumbing systems in such buildings, and also the presence of aerosolising water features such as spa pools and fountains. There is no evidence that spread from person-to-person can occur.
Further information on LD is available here.
Because the incubation period is 2-10 days, cases associated with commercial accommodation overseas may not be diagnosed until their return to their home country. For this reason ECDC operates an EU wide surveillance system for travel associated Legionnaires’ disease in order to identify any clusters of LD associated with commercial accommodation sites (3). This system is called ELDSNet.
Up to the 6 April 2017, 50 cases with a history of travel to Dubai within 2–10 days prior to illness and with onset since 1 October 2016, have been reported to ECDC (1). The majority of cases stayed in commercial accommodation sites. However, a number did stay in private accommodation. Because the ELDSNet does not require cases which stayed in private accommodation to be notified, the number of European cases who stayed in private accommodation may be underestimated (2). Twenty percent of the cases spent time in another location in the United Arab Emirates (UAE) or in a country other than their home country during their incubation period, and therefore they may not have been infected in Dubai.
Reported cases are associated with different accommodation sites dispersed geographically across Dubai, which suggests that cases may have been exposed to a common source other than their accommodation site. The UAE authorities have informed ECDC that there has been no increase observed in pneumonia cases in the local community during the period October to December 2016. They have also informed ECDC that environmental investigations at hotels where European cases stayed showed that Legionella count results were within acceptable limits. These two factors could possibly indicate an environmental exposure in areas frequently visited by tourists, e.g. airports, shopping malls or tourist attractions. No information from the UAE authorities has been provided to ECDC as to whether environmental investigations have been carried out in such sites in Dubai.
ECDC published a rapid risk assessment on the situation in December 2016. The assessment outlined in this still stands. In the absence of identified and controlled sources of Legionella bacteria exposure, there could still be a risk for exposure to Legionella for persons visiting or living in Dubai.
Advice for travellers to Dubai or those recently returned
The WHO has not issued any advice against travel to Dubai. The risk of LD to travellers to Dubai is considered to be low. However, the risk may be increased for those who are at an underlying increased risk for LD. This includes:
If you are travelling to Dubai, be aware of the symptoms of LD. If symptoms develop while in Dubai you should seek medical care. If symptoms develop within two weeks of returning home you should seek medical care and inform your healthcare provider of your travel history.
Travellers to the UAE should also be aware of the symptoms and the advice on Middle East respiratory syndrome coronavirus (MERS-CoV), a different respiratory infection which is ongoing in the Arabian peninsula. Travel advice on MERS-CoV is available here.
Advice for healthcare providers
Healthcare providers should consider LD in patients presenting with pneumonia with a travel history to Dubai or the UAE in the two weeks prior to symptom onset.
Guidance information on LD for healthcare providers is available here.
On diagnosis of a travel associated case of LD healthcare providers should inform the Department of Public Health in their area (contact details are available here).
Sporadic cases and outbreaks of MERS-CoV continue to occur in the Arabian peninsula, including the UAE. As symptoms of MERS-CoV and LD may be similar, MERS-CoV should also be considered in a person presenting with respiratory symptoms and a travel history to Dubai or the UAE in the two weeks prior to symptom onset. Guidance on the assessment and appropriate management of a possible case of MERS-CoV is available here.
Eve Robinson, Tara Mitchell, HPSC
1. European Centre for Disease Prevention and Control. Increase of cases of Legionnaires’ disease in EU travellers returning from Dubai, October−December 2016 – 22 December 2016. Stockholm: ECDC; 2016. Available here
2. European Centre for Disease Prevention and Control (ECDC). Epidemiological update: Legionella in Dubai [online]. Stockholm: ECDC; 2017 [updated April 7 2017; cited 2017 April 21]. Available here
3. European Centre for Disease Prevention and Control (ECDC). European Legionnaires’ Disease Surveillance Network (ELDSNet) − Operating procedures. Stockholm: ECDC; 2012.