First ever record of Legionella being transmitted person to person
An outbreak of Legionnaires disease occurred in Vila Franca de Xira, Portugal between October and November 2014. The source of the outbreak was established as being an industrial cooling tower in the town infected by Legionella pneumophila serogroup 1 (LpSG1). One of the first people to fall ill in the outbreak was a maintenance worker at the industrial complex. He travelled to his mother’s home in Porto, 300 km away. He became seriously ill with severe respiratory symptoms and intense cough. His mother tended him until he was admitted to hospital where he later died. The mother, a previously healthy woman of 74 years, fell ill shortly thereafter with similar symptoms. She was admitted to hospital where she died. Subsequent studies of urine samples using an antigen immunoassay test showed that the causative agent was LpSG1. Further DNA tests established that both patients were infected by the same strain of LpSG1. As far as can be ascertained no water was taken from Vila Franca de Xira to Porto and the only connection with the outbreak was the son. Tests showed that the water in the mother’s house contained no Legionella and the mother had never been to Porto in her life.
As Legionella is transmitted by aerosols it is probable that the mother was exposed to infection through her son’s coughing. As reported in the New England Journal of Medicine this is, however, the first ever suggestion of a transmission of Legionella from person to person.