Of the 72 reported cases with disease onset since 1 October 2016, 65 used commercial accommodation sites (hotels or apartments) and seven used private accommodation sites. Twenty-one cases used a hotel that was associated with another case falling ill since 1 October 2016 (Figure 2). Sixteen cases stayed at an accommodation in another location in the United Arab Emirates or in a country other than their home country during their incubation period. Two cases were reported as fatal. Fifteen cases stayed in Dubai during the entire duration of their incubation period.

All cases are laboratory confirmed. Five of the cases had their infection further characterised as Legionella pneumophila serogroup 1 sequence base type 616 and one as Legionella pneumophila serogroup 1 sequence base type 2382. Sequence base type 616 is uncommon in Europe and has been associated with other Legionnaires’ disease cases returning from Dubai in previous years. Sequence base type 2382 is a new sequence type closely-related to type 616 (personal communication, ELDSNet network). Two cases had their infection strains characterised as Legionella pneumophila serogroup 2-14 sequence base type 1327.

Environmental investigations

Public health authorities in the United Arab Emirates have informed ECDC that environmental investigations were undertaken at the notified hotels and Legionella count results showed acceptable levels for water systems (hot and cold water should not exceed 1000 cfu/litre) [2]. This threshold level is the same as used to determine action levels in the European technical guidelines [3].

According to United Arab Emirates authorities, risk assessment of accommodation sites notified by ELDSNet and of possible high-risk sites such as cooling plants and major fountains has been undertaken in Dubai. To date, no single source of infection has been identified. It is also reported that Dubai Municipality has undertaken supplementary water sampling, investigates new cases notified by ELDSNet and monitors the situation in accordance with Dubai laws and regulations.

ECDC threat assessment for the EU

The majority of reported cases are associated with different accommodation sites dispersed geographically across Dubai, suggesting a common source not associated with accommodation sites.

The assessment outlined in the rapid risk assessment published on 23 December 2016 has not changed, since cases have continued to be reported with illness onset in recent weeks above the level observed in previous years. Its recommendations remain valid, in particular:

to inform travellers − particularly those above 50 years of age, smokers and immunocompromised persons − to seek medical advice if they experience respiratory infection symptoms up to two weeks after travelling to Dubai to ensure early diagnosis and treatment.

Remind clinicians to consider Legionnaires’ disease in patients presenting with community-acquired atypical pneumonia with a history of travel to Dubai or the United Arab Emirates in the two weeks prior to disease onset.

References