Travel associated probable case of SARS, Finland, with commentary
from Health Canada
A 24 year old, previously healthy Finnish man travelled to
Toronto from 24-28 April 2003 to attend a large conference. After returning
to Finland, he became ill with a high fever (40 °C) and mild cough on 30
April. The patient was admitted to Turku University Central Hospital and placed
in isolation as a suspect case of severe acute respiratory syndrome (SARS).
On admission, his chest radiograph was normal. On 2 May, a perihilar infiltrate
was observed in his chest radiograph. A diagnosis of community acquired pneumonia
was made and the case was reclassified as probable SARS. Fever lasted for five
days and the patient did not require supplemental oxygen or mechanical ventilation.
From 2-13 May, the patient received oral levofloxacin, which appeared not to
influence the clinical course or laboratory parameters. There was no lymphopenia
and the lactate dehydrogenase was normal. Nasopharyngeal samples for respiratory
antigen detection (influenza A and B, adenovirus, parainfluenza 1,2,3 and respiratory
syncytial virus) were negative.
Chlamydia pneumoniae and
Mycoplasma
pneumoniae antibody testing did not indicate acute infection. Blood cultures
were negative. No aetiology for the pneumonia was identified.
The Finnish man did not report contact with persons with SARS-like illness
or visiting healthcare facilities while in Toronto. Details of the case and
his travel history were provided to the Canadian health authorities and the
World Health Organization (WHO). According to the Canadian health authorities,
no epidemiologic link to any known exposure setting was identified in Toronto.
There have been no other reports of SARS-like illness among participants of
the conference the Finnish man attended. After onset of symptoms in Finland
he had had close contact with two persons, who were placed in quarantine.
A nasopharyngeal aspirate sample taken from the patient on 8 May tested positive
for SARS associated coronavirus (SARS-CoV) by real time reverse transcriptase-polymerase
chain reaction (RT-PCR) test done at the Department of Virology, Helsinki
University Central Hospital. The test used was the commercially available
assay developed in a German laboratory in collaboration with WHO. The specimen
was also tested for SARS-CoV with another RT-PCR method which was negative.
On 14 May, the original sample was retested for SARS-CoV using the same method
that initially gave the positive result. The second test was negative. RT-PCR
on new nasopharyngeal aspirate and stool samples were also negative. Cultures
from the patient's respiratory secretions and stools were negative for SARS-CoV.
Serum samples have been collected for antibody testing. The patient has recovered
well from his illness. On 13 May the patient had been afebrile for >7 days,
the chest radiograph was normal and he was discharged. To date, none of the
patient's close contacts have had symptoms compatible with SARS infection.
On 14 May, WHO removed Toronto from the list of areas with recent local transmission
because >20 days had passed since the last locally acquired case was isolated
or died. At that time, the last locally acquired case in Canada had been isolated
on 20 April (1). Toronto was also removed from the list of areas for which
WHO had issued recommendations pertaining to international travel. On 26 May,
however, Toronto was put back on the list of areas with recent local transmission
as a result of a new hospital based cluster of SARS cases currently being
investigated (2).
This is the first patient managed as a probable case of SARS in Finland.
At the time of onset of illness, the case met the WHO case definition of a
probable case of SARS because of the link to an area classified as having
recent local transmission of SARS (3,4). No validated laboratory test for
infection with SARS-CoV is currently available. A single positive PCR result
does not fulfil the WHO criteria for a laboratory confirmed SARS case and
does not affect the classification of the case as probable (5). Laboratory
confirmation requires a second positive PCR result or a positive result by
another laboratory test for SARS-CoV. In the absence of an epidemiologic link
to a known SARS case or exposure setting, the clinical case definition of
SARS is non-specific. In a population where the prevalence of a condition
is low, the positive predictive value of any test is likely to be low.
The single positive test result in the Finnish case does not affect the current
SARS prevention and control guidelines in Finland but it highlights the need
for continuous vigilance for cases of potentially travel associated SARS.
Health Canada commentary
Arlene King (Arlene_King@hc-sc.gc.ca),
Director, and Susan Squires, Senior Epidemiologist, Immunization and Respiratory
Infections Division, Health Canada, on behalf of the Health Canada SARS Response
Team.
Follow up of persons presenting with SARS-like illnesses occurring outside
of Canada, but with a history of travel or residence in the Greater Toronto
Area in the 10 days prior to the onset of symptoms, has been a priority
for Canadian public health authorities since the beginning of the outbreak
in the Greater Toronto Area on 13 March 2003. To date, we have investigated
29 international reports of SARS cases potentially exposed in Canada. Only
two, one from the Philippines and one from the United States, had an epidemiologic
link to known SARS cases in Toronto (6). In the remaining cases, including
the Finnish case reported above, no epidemiologic link could be established.
Although international collaboration on the follow up of exported suspect
or probable 'cases' of SARS continues to be extraordinary, it is extremely
labour intensive - locally, regionally, nationally, and internationally,
for WHO staff and for personnel in the involved countries. Furthermore,
whether follow up activities can inform effective public health action to
prevent international movement of infectious diseases (eg, appropriate travel
screening protocols) should also be debated. Such follow up may divert resources
from the public health investigation or management of SARS cases, or from
other public health program activities. Exported 'cases' often result in
significant media attention and create considerable public anxiety and negative
perceptions about the country of origin. The impact of the identification
of such cases, often in the absence of an epidemiologic link or presence
of SARS-CoV in appropriately collected and processed specimens, may also
extend to WHO considerations of whether travel advisories should be implemented
(7). Although the economic, social and political impact of such advisories
requires further evaluation, they will likely prove to be significant.
The dissemination of precise, real time information on the epidemiology
of the SARS is invaluable in determining whether travel advisories may be
indicated. Alternatively, it may enable those considering international
travel to assess their own personal risk. Additionally, where possible,
refinement of case definitions is essential, particularly in the absence
of a rapid, reliable diagnostic test, to enhance both their sensitivity
and specificity.
References:
- WHO Communicable Disease Surveillance & Response Situation Updates.
SARS update 55 - Change in status of Toronto, situation in China and Singapore.
14 May 2003. (http://www.who.int/csr/sars/archive/2003_05_14/en/)
[accessed 29 May 2003]
- WHO Communicable Disease Surveillance & Response Situation Updates.
SARS update 66 - Situation in Toronto, interpretation of "areas with
recent local transmission". 26 May 2003. (http://www.who.int/csr/don/2003_05_26/en/)
[accessed 29 May 2003]
- World Health Organization. Case Definitions for Surveillance of Severe
Acute Respiratory Syndrome (SARS) (http://www.who.int/csr/sars/casedefinition/en/)
[accessed 13 May 2003]
- World Health Organization. Areas with recent local transmission of Severe
Acute Respiratory Syndrome (SARS) (http://www.who.int/csr/sars/areas/en/)
[accessed 13 May 2003]
- World Health Organization. Use of laboratory methods for SARS diagnosis
(http://www.who.int/csr/sars/labmethods/en/)
[accessed 13 May 2003]
- Health Canada. SARS Epidemiologic Summaries: April 26, 2003. Summary of
SARS cases potentially exposed in Canada and diagnosed internationally.
(http://www.hc-sc.gc.ca/pphb-dgspsp/sars-sras/pef-dep/sars-es-int20030426_e.html)
[accessed 29 May 2003]
- World Health Organization. SARS Travel Recommendations Summary Table.
(http://www.who.int/csr/sars/travel/2003_05_27/en/)
[accessed 29 May 2003]
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