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Home Eurosurveillance Weekly Release  2003: Volume 7/ Issue 22 Article 1 Printer friendly version
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Eurosurveillance, Volume 7, Issue 22, 29 May 2003
Articles

Citation style for this article: Nuorti P, Kotilainen P, Lappalainen M. Travel associated probable case of SARS, Finland, with commentary from Health Canada. Euro Surveill. 2003;7(22):pii=2234. Available online: http://www.eurosurveillance.org/ViewArticle.aspx?ArticleId=2234

Travel associated probable case of SARS, Finland, with commentary from Health Canada

Case recognition and management in Finland

Pekka Nuorti (Pekka.Nuorti@ktl.fi), Department of Infectious Disease Epidemiology, National Public Health Institute (KTL), Helsinki; Pirkko Kotilainen, Turku University Central Hospital; Maija Lappalainen, Department of Virology, Helsinki University Hospital Diagnostics, Finland, for the Finnish SARS surveillance and outbreak control group.

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:

  1. 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]
  2. 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]
  3. 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]
  4. 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]
  5. World Health Organization. Use of laboratory methods for SARS diagnosis (http://www.who.int/csr/sars/labmethods/en/) [accessed 13 May 2003]
  6. 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]
  7. 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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