According to the National Institutes of Health (NIH), between five and 20 percent of the U.S. population gets influenza each year. While most people with influenza complain of fever, fatigue and lethargy, in very rare cases, influenza infection results in hyperactivity and agitation. Three distinct syndromes are described, occuring before, during and after influenza infection.
Altered Mental Status
According to a 2009 article in the journal "Lancet," there is usually an interval of a few days between exposure to flu virus and the onset of symptoms. In some people, this interval is associated with a period of altered mental status including agitation, confusion, aggressiveness and hyperactivity.
However, this finding was not unique to infection with influenza. In a 2006 article in the "Journal of the American Geriatric Society," researchers reported that symptoms of altered mental status paralleled increases in stress hormones measured from saliva and were associated with a number of illnesses other than influenza including urinary tract infections and gastrointestinal viruses.
Neuropsychiatric Events
According to a 2007 article in the "British Medical Journal," researchers in Japan first began to notice a large number of reports of abnormal behavior and even death among people treated with Tamiflu (oseltamivir) for influenza in the year 2000. Symptoms reportedly included agitation, confusion, hallucinations, delusions and hyperactivity. Approximately 50 deaths were reported, usually from accidents such as walking in front of a train or bus. Many cases were classified as suicides, despite the absence of previous history of depression or suicidal thoughts.
These neuropsychiatric events occur during acute illness with influenza and may be related to fever. Subsequent investigations have revealed similar findings in all patients with influenza, regardless of whether or not they were treated with Tamiflu. Currently, the NIH advises all flu patients to contact their physicians if they experience symptoms of mental confusion, abnormal behavior, or thoughts of self-harm. Patients with flu are also encouraged to notify family and friends of this potentially serious complication, in the event that they become unable to seek help on their own.
Reye's Syndrome
According to the NIH, Reye's Syndrome has been described in children and teenagers who have recently recovered from influenza. Initial symptoms include nausea, vomiting, agitation, irritability, confusion, combativeness and hyperactivity. The syndrome deteriorate rapidly to seizures and coma. Reye's Syndrome appears to be associated with aspirin products. Children and teenagers with influenza and other viral diseases should never be treated with aspirin or aspirin-containing products. Acetominophen appears to be safe.
References
- Lancet Infectious Disease; Incubation Periods of Acute Respiratory Viral Infections: A Systematic Review. J. Lessler, N.G. Reich, R. Brookmeyer, T.M. Perl, K.E. Nelson, D.A. Cummings; May 2009
- Journal of the American Geriatric Society; Agitated Behavior as a Prodromal Symptom of Influenza; D.L. Mentes and J.H. Woods; December 2006
- British Medical Journal; Oseltamivir's Adverse Reactions: Fifty Sudden Deaths May Be Related to Central Suppression; R. Hama; 2007
