The outbreak of Legionnaires disease in Melbourne has attracted a great deal of media attention over the last few weeks. Is it a concern for travellers? The short answer is yes, but it must be qualified. While some people are more at risk of Legionnaires disease, everyone should be aware of where it is found and how it may present.

In February 2022, a 55-year-old male holiday maker to the United States territory of the Virgin Islands was diagnosed with Legionnaire’s disease. He had developed a cough, shortness of breath and fatigue shortly after returning home. Testing for the disease was based on history of travel and symptoms. He was managed according to standard treatment protocols, and he recovered over 2 days.

According to the case report, he had stayed in a rental property which provided several water sources including a swimming pool, hot water tubs and drinking water. Environmental water sampling was undertaken by a team from CDC (Centres for Disease Control) with the owner’s permission. Legionella Pneumophila was identified in 11 samples. Remediation was undertaken by the property owner. The Department of Health in the Virgin Islands worked with CDC to alert other property owners of the need for proper maintenance of water sources and the need for Legionella surveillance. All the above happened within 7 days of the individual’s return from the Virgin Islands.

Legionnaires disease has historical interest for many older travel health physicians. In 1979, a paper was published on “Legionnaire’s disease and the Traveller”.

Its focus was on a group of travellers who had undertaken a “package tour” to Benidorm in Spain in 1973. Three of the travellers had died of a mysterious pneumonic disease and another 86 had various presentations of respiratory tract illness. The publicity surrounding the 1973 outbreak resulted in the investigation of over 230 returned travellers from Spain being investigated in 1978 for past Legionnaires disease. Blood tests were performed on 220 individuals and 33 returned positive results. Many of the positive tests were in travellers who had returned from Benidorm and a number had stayed in the hotel associated with the outbreak.

This retrospective analysis followed the discovery of Legionella Pneumophila as the cause of a major outbreak of respiratory illness at the American Legion Conference in Philadelphia in 1976.

The European Surveillance for Travel Associated Legionnaire’s disease was established in 1987 and collaborated with a Working Group on Legionella Infections (EWGLI). It was responsible for detecting and following up outbreaks of possible disease. By 1999, thirty-one countries were participating in surveillance of Legionnaires disease. The number of reported cases grew from 3 in 1987 to 289 cases in 1999. Many tour operators became active participants in the scheme.

In 2019 there were 1,657 cases of travel-associated Legionnaire’s disease (TALD) with 176 new clusters (defined by at least 2 cases from the same accommodation). See the Legionnaires’ disease Annual Epidemiological Report for 2019

In 2020, there were 551 cases of travel-associated Legionnaire’s disease (TALD) with 66 new TALD clusters. This would have been affected to a large extent by travel restrictions imposed during the COVID-19 pandemic.

An outbreak of Legionnaires disease has been reported recently in Italy in 2024. As of 8 August 2024, a total of 49 cases have been reported by public health authorities in Milan. None are considered to be travel-related. Most had underlying comorbidities.

Legionnaire’s disease is an important cause of potentially preventable mortality and morbidity amongst travellers. It is important for both primary care services providers and travellers to be aware of the possibility if returning home with a chest infection.

According to European surveillance data for 2015:

• 2/3 cases were reported between June and October (summer months)
• 69% male
• Median age 62 years
• Increasing reports over time