Published Date: 2001-04-14 23:50:00
Subject: PRO/AH/EDR> Leptospirosis - Portugal (Azores)
Archive Number: 20010414.0741
LEPTOSPIROSIS PORTUGAL (AZORES)
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A ProMED-mail post
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International Society for Infectious Diseases
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Date 13 Apr 2001
From: ProMED-mail <promed@promedmail.org>
Source: WHO WER Epidemiological Bulletin [edited]
<http://www.who.int/wer>
The Azores are a group of North Atlantic islands of Portugal with an
autonomous administration. About 242 000 people live on the 9 volcanic
islands.
In recent years, leptospirosis has been considered a public health problem
of increasing importance, owing to the occurrence of fatal human cases. In
early 2001, a number of fatal cases were reported in Terceira and Sao
Miguel, rats being the main source of infection.
A national project was began in 1993-1996, as a first step in [confirming]
the role of rodents as the source of human leptospirosis in the Azores, in
which widespread occurrence of _Leptospira_ infection was demonstrated,
although there was significant variation in the prevalence rate among the 6
islands studied.
Rodents were found to be the major wild reservoirs and to carry 3 distinct
serovars: _copenhageni_and _icterohaemorrhagie_ (genospecies _L.
interrogans sensu stricto_) and _arborea_ (genospecies _L.
borgpetersenii_). It was then concluded that _Leptospira_ rodent infection
represented a major risk to the health of humans and livestock,
particularly on the islands of Terceira and Sao Miguel.
Serological studies carried out between 1993 and 2000 on the sera of 362
hospitalized patients from the islands of Sao Miguel (n = 240) and Terceira
(n = 122) demonstrated a higher incidence of positive cases in both islands
when compared to those observed in another endemic area in mainland Portugal.
Although isolation was not attempted for logistic reasons, the standard
microscopic agglutination test (MAT) was performed. MAT results (geometric
mean titre: 1/964) in serial serum samples (average 3-4 per patient) were
similar to the serogroups of the strains previously identified in rodents
(_icterohaemorrhagiae_ and _ballum_), which have been dominant overall in
recent years.
The mean age of patients was 39 years (range: 14-76 years), the majority
being males (87%). The clinical picture was mainly characterized by fever
of unknown origin, chills, myalgias, headache and jaundice. Fatal cases in
young people were not confirmed by laboratory; they were diagnosed
clinically and progressed rapidly to acute renal failure and respiratory
distress syndrome.
The following next steps are under consideration:
--isolation and/or DNA detection of human pathogenic strains;
--obtaining a better understanding of other potential sources of infection
in order to implement eradication programs according to the major risk
sources; and
--evaluating the need for vaccination of humans and/or livestock.
--
ProMED-mail
<promed@promedmail.org>
[The increase in numbers of rodents and human contact with rodents often
results in increased cases of leptospirosis. However, the fatal nature is a
concern. Mod.TG]
[The expected case fatality rate has been estimated as 5-10 percent for
clinically apparent cases. In localities for which leptospirosis is
endemic, the majority of cases will be subclinical. - Mod.ES]
......................mhj/tg/pg/es
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