Introduction
After France and Spain, Italy receives the largest number of foreign tourists
per year. In 2002, in Italy, 639 cases of Legionnaires' Disease (LD) of
which 119 were travel associated, were notified to the Instituto Superiore
di Sanità. Furthermore, a further 90 cases diagnosed in foreign
tourists who travelled to Italy were notified to the Institute by EWGLINET
(The European Working Group for Legionella Infections, http://www.ewgli.org),
bringing the total number of cases of travel associated LD to 209. This
is an increase of approximately 60% on the previous year when 130 cases
were notified. Most of the foreign tourists came from other European countries,
such as the United Kingdom (23%), Netherlands (19%) and France (13%).
In July 2002, European guidelines for control and prevention of travel
associated Legionnaires' disease were voluntarily adopted by most EWGLINET
participant countries, even though at that time they were not yet officially
approved by the European Commission.
This article reports on the Italian experience following the adoption
of the European Guidelines.
Methods
According to the guidelines, a "cluster" is defined as two
or more cases who stayed at or visited the same accommodation site in
the ten days before onset of illness and whose onset is within the same
two year period. Identification of a cluster is sufficient to warrant
immediate action by the coordinating centre in London and by the EWGLINET
collaborator in the country where the cluster is located. The collaborator
in the affected country immediately arranges for the accommodation site
to be inspected by a local public health authority who carries out a
risk assessment as well as an environmental investigation. A preliminary
report (Form A) stating whether control measures are in progress and
if the accommodation site may remain open or not is sent to the coordinating
centre within two weeks of the cluster alert. A full report (Form B)
is sent within six weeks of the cluster alert. If the coordinating centre
does not receive the reports on time or if the control measures adopted
are unsatisfactory, the name of the accommodation site is published
on the EWGLI website (2).
In Italy, the procedure for reporting and responding to cluster is as
follows: when EWGLINET alerts the Istituto Superiore di Sanità
of a cluster, the EWGLINET collaborator immediately informs local and
regional health authorities and the Ministry of Health by fax. The day
after the notification the EWGLINET collaborator makes a phone call
to the doctor in charge of the investigation, in order to ensure that
cluster alert was received. One or two days before the deadline for
Form A and B, a reminder is sent to the local health authority.
Data related to clusters were entered into a database and analysed by
EPI Info 2000.
Results
From July 2002 to October 2003, 35 clusters of travel associated Legionnaires'
disease occurred in Italy.
Of the 35 resorts involved, five were campsites and 30 were hotels/residences.
The number of clinical cases per cluster was the following: 2 cases
in 20 clusters, 3 cases in 7 clusters, 4 cases in 5 clusters, 5 cases
in 2 clusters and 6 cases in 1 cluster. Overall, 87 patients were involved
(8 patients visited 2 hotels, 1 visited 3 hotels) in a total of 97 visits.
The second case occurred less than 6 months after the notification of
the first case in 69% of the clusters.
The age of the cases ranged from 27 to 78 years, with a mean of 58 years.
The male to female ratio was 2.1/1. Italian citizens represented 40.2%
of all cases and were involved in 19 clusters. In 9 clusters, only Italian
citizens were involved. Dutch citizens were affected in 14.9% of cases,
French citizens 9.2%, and German and English citizens both in 6.9% of
cases. The remaining 21.9% of the cases were patients from other European
countries.
The accommodation sites were located in 14 different Italian regions,
as shown (Figure). The median length of stay in an accommodation was
7.8 days, with a range of one to 152 days.
The diagnosis was confirmed in 92% of the cases and investigations were
mainly performed using urinary antigen detection (84.7%). A clinical
isolate was available only in one case. The outcome of the disease was
known in 74.4% of the cases. Of these, 59% recovered, 36% were still
ill and 5% were dead by the time the cluster was alerted.
Environmental investigations were performed by the local health authorities
and samples were collected from the water system at the locations of
all 35 clusters. In Italy, a full environmental investigation is undertaken
even after notification of a single case, and in 15 resorts out of 35,
when the first case was an Italian citizen, at the time of EWGLI cluster
notification, investigations were already in progress.
Legionella pneumophila was found on 23 occasions (65.7%). In 6 cases
(26%), Legionella pneumophila was present in the water supply at a concentration
ranging from 102 and 103 CFU/L, while in 12 (52%) cases the concentration
was higher than 104 CFU/L. For the remaining cases (22%), the Legionella
concentration was not known. In clusters with 2 or 3 cases the percentage
of positive investigation results was 58% while in clusters with 4 or
more cases this percentage was equal to 87%.
Control measures were implemented in all accommodation sites at risk
and only one hotel was closed.
Form A and B were sent on time for all clusters, and so no names of
accommodation sites were published on the public part of the EWGLI website.
Discussion
The rapid exchange of information among European countries through the
EWGLINET network allows the detection of clusters even when cases are
from a different country of origin. For the cases associated with travel
in Italy, 8 clusters (28.6%) would not have been identified without
this network since each included one national from different countries.
The clusters detected were small, ranging in size from 2 to a maximum
of 6 cases.
Investigation immediately following a cluster alert found that 65.7%
of the sites were positive for Legionella. This highlights the fact
that risk assessment for control measures against Legionella bacteria
proliferation should be carried out not only in response to a cluster
but on a regular basis in order to prevent cases of disease.
This information is also important for assessing the impact of control
measures at a site, as well as for providing evidence for any legal
action arising from an infection. However, interpretation of the significance
of environmental data results is limited when there are no matching
clinical isolates from associated cases. The environmental investigations
conducted show that investigation and reporting procedures take varying
amounts of time, depending on the structure and organization of public
health services in each region. Nevertheless, for all 35 clusters, reports
were completed and sent in on time, demonstrating that it is possible
to comply with the procedures requested by the European guidelines.
Investigations and control measures were successful in preventing further
cases in 31 out of 35 accommodation sites investigated. In the 4 accommodation
sites where a new case was notified in a time period ranging from 2
to 8 months after implementation of control measures, a longer and stricter
follow-up is foreseen.
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