Legionnaires' disease imported to Denmark from Italy

Incidence of Legionella pneumophila infection in tourists: Italy

Legionella pneumophila has frequently been recognised as a cause of infection in tourists. From 1973 to 1987, 117 cases of legionellosis were reported in tourists who spent one or more weeks in Italian summer resorts. 6 (5.1%) patients died. 42 (35.9%) were sporadic cases, and 75 (64.1%) were related to clusters or outbreaks. Among the 117 cases, 63 were reported to the Istituto Superiore di Sanità by the health authorities of other countries. Some travellers became ill while in Italy, others soon after they returned home. All tourists but two had stayed in hotels. L. pneumophila was isolated from the water system of 10 hotels, and in another hotel the same Legionella species was detected by direct immunofluorescence. Persistent and/or recurrent sources of infection seem to be present in some summer resorts on the Adriatic Coast and in the Lake Garda area in northern Italy. Some groups of cases were associated with particular hotels over a period of several months and sometimes years. Investigations have implicated potable water as the likely vehicle and the source of infection for tourists. The need of a greater awareness amongst clinicians that travel is a risk factor for legionellosis, and for better international surveillance and cooperation, is stressed.

Serological investigations of Legionella infections in Denmark

During the period 1 July 1978 to 1 January 1982, sera from 728 patients suspected of suffering from Legionella infection were tested for Legionella antibodies by an indirect fluorescent antibody test. The antigens used were prepared from heat-killed strains of L.pneumophila serogroups 1-4. In 1981 we further incorporated antigens from serogroups 5 and 6 of L.pneumophila together with L.micdadei, L.bozemanii, L.dumoffii and L.gormanii. According to the criteria put forward by CDC, Atlanta, USA Legionella infection was confirmed in 78 patients with pneumonia. Sera from 35 showed at least a four-fold rise in titre to greater than or equal to 128, while 43 had single or static titres of greater than or equal to 256. There were 59 men and 19 women (3.1:1) with a median age of 51 and 49, respectively. More than half the patients showed maximum titres of antibodies to L.pneumophila serogroup 1. In an additional patient, who was not tested serologically, the diagnosis was made post mortem at CDC by demonstration of Legionella in lung tissue. There were 11 fatal cases among the 79 patients (13.9%). Thirty-two had contracted the disease on a journey abroad. All cases except the seven first cases among tourists from Garda, Italy, were sporadic. The number of cases diagnosed has increased heavily while the proportion of imported cases has decreased.