Influenzanet is a system to monitor the activity of influenza-like-illness (ILI) with the aid of volunteers via the internet
The weekly symptom survey asks you to report on symptoms you've had in the past week, or since you last completed the survey.
We ask mainly about respiratory symptoms indicative of influenza infection. The 'flu status' that you receive at the end of the symptom survey is calculated using an algorithm based on the symptoms you reported.
(European Centre for Disease Prevention and Control definition)
AND at least one of the following four systemic symptoms:
AND at least one of the following three respiratory symptoms:
Other definitions (all fairly similar) are sometimes used by public health bodies, each of which gives an estimate of influenza-like-illness.
Why do we say "influenza-like-illness", not "flu"? Because without a laboratory test it's impossible to be certain whether symptoms really are caused by flu or by something similar. Public health bodies and GPs do the same thing, but one advantage of the flusurvey is that we can easily adapt our definition if better information becomes available.
At least one of the following symptoms:
AND no fever
At least two of the following symptoms: