Since the first human cases of influenza A/H5N1 were widely reported from Turkey in early January, many European patients with suspected influenza, who might have been exposed to influenza A/H5N1 in countries reporting human or avian cases, have been tested for the infection. The 28 countries participating in the European Influenza Surveillance Scheme (EISS, http://www.eiss.org) have been invited to report any laboratory tests for H5N1, and by 25 January, six countries had reported a total of 19 tests [personal communication, A Meijer, 25 January 2006]. This small number of tests – all of which were negative – probably represents only a small proportion of the suspect cases of influenza A/H5N1 that have been treated in Europe in recent weeks. We present here Belgium’s experience in managing its first suspected human case of influenza A/H5N1.

On 13 January 2006, a Russian journalist presented at the emergency department of a Brussels hospital with high fever, muscle pain, general discomfort, cough, nasal discharge and sore throat. He had visited poultry farms in the eastern province of Van, Turkey, from 9 to 12 January, while making a documentary film about avian influenza.

According to the standard operational procedures (SOP) for the management of a potential case of human A/H5N1 in Belgium, the hospital reported the case to the Health Inspectorate of Brussels and the Scientific Institute of Public Health (IPH) in Brussels. After epidemiological evaluation, the patient was classified as a probable case* because he had visited poultry farms in an area affected by avian influenza [1]. In accordance with the SOP, nasopharyngeal swabs were taken, using the sampling material and the protection equipment that had been sent to all the clinical laboratories in Belgium as a preparedness measure [1]. The specimens were immediately sent to the National Influenza Centre at the IPH for testing. In line with recommendations for the management of probable cases, the patient was transferred to the Saint-Pierre referral hospital in Brussels for immediate isolation. He received a presumptive treatment of oseltamivir 150 mg bid and specific protective measures were applied.

As soon as the case was notified, a list was made of all people who could potentially have been exposed to avian influenza. These included those who were exposed to the same risk as the patient, or had had recent contact with the patient. The cameraman who had also been working on the documentary film in Turkey was considered to have been exposed. Household contacts and healthcare workers who had been in contact with the patient without wearing protective equipment at the first hospital, before he was considered to be a potential case of A/H5N1, were informed. The cameraman and the household contacts did not report any flu-like symptoms.

Passengers who had travelled on the three connecting flights taken by the patient between Turkey and Belgium were also considered to be contacts. Investigators attempted to obtain passenger lists so that the passengers could be contacted if the case was confirmed, but the airline companies refused to disclose the names of the passengers, citing the need to protect passenger privacy.

The nasopharyngeal swabs were processed in a biosafety level 3 laboratory with a rapid enzyme immunoassay test (EIA) and with subsequent RNA extraction. RNA was subjected to two real time PCR (typing A and subtyping H5) and four nested RT-PCR tests (typing A and B, subtyping H5, subtyping H3 and H1, subtyping N1 and N2). The specimen was positive for influenza A using real time PCR, nested RT-PCR and the less sensitive EIA test. H5 subtyping was negative using both real-time and nested RT-PCR. Further subtyping using nested RT-PCR identified a human influenza A/H3N2 infection. Preliminary laboratory results were available one hour (EIA) and four hours (real time PCR) after receiving the specimens. Confirmation results from the nested RT-PCR tests were reported to the public health authorities after 16 hours (the time taken for A and B typing, and H5, H3 and H1 subtyping) and 36 hours (the time taken for N1 and N2 subtyping).

These laboratory results allowed investigators to discard the possibility of an A/H5N1 infection, and showed that the patient was the first case of influenza A/H3N2 infection in Belgium to be identified by the National Influenza Centre during the 2005-2006 season. During the first week of 2006, clinical influenza activity in Belgium was very low, as in most European countries [2].

Precautionary measures were discontinued when the final confirmation of A/H3N2 was made on 15 January. The patient left the hospital on the same day, without fever and in good general health.

Information on seasonal influenza from Turkey is scarce, but influenza activity is reported to be low [3]. Taking into account the influenza incubation period, it is not possible to determine whether the patient was infected in Turkey or in Belgium, before beginning his journey.

Lessons learned
This incident raises the question of whether travellers to areas affected by avian A/H5N1 influenza should be advised to receive the seasonal influenza vaccination during the influenza season.

This case has demonstrated that the Belgian case definition for suspect avian influenza A/H5N1 is capable of detecting influenza. The SOP for the management of suspect cases of human A/H5N1 case in Belgium, validated by health authorities and communicated to health professionals in late 2005, were appropriately and rapidly applied.

International guidelines are needed on the management of international flight passengers who have been in contact with a confirmed A/H5N1 case. Coordination is also needed at international level to facilitate the process of tracing passengers.

*Belgian case definitions for categories of avian influenza A/H5N1 cases, phase 3 (WHO), updated November 2005 [1]:

	Possible case: any individual with fever (>38°C) and cough and general discomfort, who has been in closed contact during the seven days before the onset of symptoms with wild or domestic birds, live or dead, or with their droppings, in a country affected by avian influenza A/H5N1.
	Probable case: possible case with preliminary positive laboratory results for avian flu, or with respiratory distress/death for which an alternative diagnosis has not been established, or with a highly suggestive epidemiological context evaluated by experts.
	Confirmed case: Positive PCR for A/H5N1, or virus isolation by culture, or a fourfold increase of specific H5 antibodies.

Acknowledgements
We would like to thank Dr Y Vandeput and the staff of the emergency department at the Clinique Sainte Elisabeth in Brussels who alerted health authorities and took the first measures, as well as the staff of the Hôpital Saint-Pierre, for their work.