In a statement released late on Monday, the DGS and INSA said that until 8pm that day “thirty cases of Legionnaires’ Disease have been diagnosed with a possible epidemiological link to the West Lisbon Hospital Centre (CHLO) –São Francisco Xavier Hospital” – one more case than previously announced.

Of the 30, two people have died of the disease, as announced earlier in the day, while one patient has been discharged from hospital. All others are still in hospital.

“The majority of the patients are elderly, with associated risk factors, namely serious chronic illnesses and habitual smoking,” said the statement, which was signed by the DGS’s director, Graça Freitas, and the president of INSA, Fernando de Almeida.

The statement contained assurances that work is underway to discover the circumstances surrounding the outbreak, including inspection of equipment “potentially associated to sources of transmission”, and that this work will continue “in the next few days”.

It also announced a report to be jointly drafted along with the Lisbon and Tagus Valley regional health authority to clarify “the chain of events that led to the outbreak”. This, however, will take “at least two weeks” because of the need to inspect samples from the environment and patients and trace any links.

The DGS stressed that the disease is transmitted “through the inhalation of contaminated aerosols and not through the ingestion of water”, that the infection, although serious, can be treated effectively, and that measures already adopted “are expected to be sufficient to interrupt the transmission and control te outbreak”.