LEGIONELLA - World Health Organization

Country
United Kingdom
All reported
cases
LEGIONELLA AND THE PREVENTION OF LEGIONELLOSIS
Populat on
(m ll ons) Rate/m ll on
England and Wales 307 52.8 5.8
Northern Ireland 5 1.7 2.9
Scotland 32 5.1 6.3
Part = not reported from entire country
Confirmed cases = 3957 (86.3%); presumptive cases = 575 (12.5%); status unknown = 56 (1.2%)
Source: Information obtained from the European Working Group for Legionella Infections (EWGLI) 18
9.2.1 Effect of improved surveillance
Participation in an international surveillance scheme has led to improved surveillance and
higher detection rates in many European countries. For example, Figure 9.2 shows that detection
of cases in the Netherlands, France, Italy and Spain has increased with improved surveillance.
Figure 9.3 shows reported cases from 1994 to 2004, categorized by type of exposure.
At the national level, underdiagnosis and underreporting are recognized limitations in the
surveillance of Legionella infections, mainly because:
• many patients with pneumonia are not tested for Legionella
• many countries do not have epidemiological follow-up of the laboratory reports through
which data are collected and reported.
In Denmark, the annual rate of Legionella infections is 17–20 cases per million population,
compared with the European average of 4–10 cases per million population. The difference
may be due to Denmark’s long history of surveillance — the country has a high level of
testing for Legionella in patients with pneumonia, and a centralized reference laboratory for
diagnosing and reporting cases. If all countries had incidence rates similar to those of Denmark,
the total number of cases reported by the 33 countries would amount to more than 10 000 per
year, rather than the 4500 currently reported. Thus, although the burden of disease associated
with Legionnaires’ disease is not known, these estimates suggest that it is much higher than is
currently recognized.
18 http://www.ewgli.org/