AVIAN INFLUENZA A/H5 or A/H5N1 in humans

Clinical Criteria
Any person with one of the following two:
– Fever AND signs and symptoms of acute respiratory infection
– Death from an unexplained acute respiratory illness

Laboratory Criteria
At least one of the following three:
– Isolation of influenza A/H5N1 from a clinical specimen
– Detection of influenza A/H5 nucleic acid in a clinical specimen
– Influenza A/H5 specific antibody response (fourfold or greater rise or single high titre)

Epidemiological Criteria
At least one of the following four:
– Human to human transmission by having been in close contact (within one metre) to a
person reported as probable or confirmed case
– Laboratory exposure: where there is a potential exposure to influenza A/H5N1
– Close contact (within one metre) with an animal with confirmed A/H5N1 infection other
than poultry or wild birds (e.g. cat or pig)
– Reside in or have visited an area where influenza A/H5N1 is currently suspected or
confirmed⁷ AND at least one of the following two:
– Having been in close contact (within one metre) with sick or dead domestic
poultry or wild birds⁸ in the affected area
– Having been in a home or a farm where sick or dead domestic poultry have been
reported in the previous month in the affected area

Case Classification
A. Possible case
Any person meeting the clinical and the epidemiological criteria
B. Probable case
Any person with a positive test for influenza A/H5 or A/H5N1 performed by a laboratory
which is not a National Reference Laboratory participating in the EU Community Network of
Reference Laboratories for human influenza (CNRL)
C. Nationally confirmed case
Any person with a positive test for influenza A/H5 or A/H5N1 performed by a National
Reference Laboratory participating in the EU Community Network of Reference Laboratories
for human influenza (CNRL)
D. WHO confirmed case
Any person with a laboratory confirmation by a WHO Collaborating Centre for H5

⁷ See World Organization for Animal Health –OIE- and European Commission (SANCO) Animal
Disease Notification System (ADNS), available at: http://www.oie.int/eng/en_index.htm and
http://ec.europa.eu/food/animal/diseases/adns/index_en.htm#)
⁸ This does not include seemingly well birds that have been killed, for example by hunting