Influenza on the brain….

Influenza, (Flu), caused by influenza viruses, is what we all think of as a respiratory disease. It can cause acute mild upper respiratory tract illness. It can cause acute severe lower respiratory tract illness. It can even cause death or precipitate death by allowing rapid and widespread bacterial infection. But influenza viruses, like other viruses, can also have an impact on tissues outside the respiratory tract.

One of these extra-respiratory complications has been described as ‘neuroinfluenza’.[1] This includes diagnoses of encephalopathy, encephalitis, and meningitis and can occur in healthy children (the majority in the linked study) and in those with pre-existing comorbidities. These concurrent diseases can include chronic neurological or neuromuscular diseases, congenital metabolic diseases, Down Syndrome and congenital heart disease.

This particular study [1] found that the time between a patient presenting with Flu-like symptoms and them developing neurological complications was just 48-hours. Patients had laboratory-confirmed influenza A (H1N1 or H3N2) or B (unspecified) infections identified in their cerebrospinal fluid samples. Some had lasting effects from their infections and all, because of the nature of this study, had been hospitalised; most in a paediatric intensive care unit.

The authors wanted to highlight the importance of considering influenza virus infection among children, including those who are otherwise healthy, who present with fever, altered consciousness and other neurological findings, often with vomiting, during the Flu season.

Neurological complications from Flu have also been implicated among adults.[2,3]

Yet another reason to consider getting that Flu shot as soon as it becomes available. Why risk this sort of hospitalisation for yourself, for your children, or for other’s children. The Flu vaccination does not always result in immunisation, but when it does you do your family and loved ones a favour. You also do a favour for others in your community by hopefully reducing virus transmission (less sick, less virus, fewer symptoms…boom) including those who cannot be vaccinated or don’t get immunised after vaccinations.

Be a Flu hero. Take the needle. 


  1. Neuroinfluenza: evaluation of seasonal influenza associated severe neurological complications in children (a multicenter study).
  2. Acute influenza virus-associated encephalitis and encephalopathy in adults: a challenging diagnosis
  3. Fatal influenza A(H1N1)pdm09 encephalopathy in immunocompetent man.

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