A 78-year-old man was brought to the emergency department in October by his family because they were concerned he was acting strangely.

His daughter-in-law explained to me that he was visiting from out of state and had been in good health recently, except for a few days of muscle aches, dry cough, and chills. Several family members at home had recently recovered from colds and his symptoms were attributed to a virus going around in the family.

He woke up that morning feeling quite a bit worse and was uncharacteristically confused. His daughter-in-law was concerned and decided it was time to have him evaluated by a doctor. After arriving at a local urgent-care center, he got out of the car and became significantly more disoriented and too weak to stand. At this point, they decided to come to the emergency department.

I walked into his room and introduced myself. He was a very pleasant gentleman who appeared, at first glance, to be quite well. As I spoke with him, however, I realized he was completely unaware of why he was at the hospital and had no recollection of the morning's events. He had trouble answering my questions, such as the year and the name of the city he was in. His neurological exam was otherwise normal. I confirmed with his daughter-in-law that the confusion was new that day, and that he was previously quite sharp and independent.

What was causing the patient to develop sudden confusion and forgetfulness?


Sudden confusion like this patient experienced is called delirium. Although not well-understood, it can often be caused by a new stressor, such as an infection, change in environment, medication, nutritional deficiencies, or trauma. Older adults are at a significantly higher risk for developing delirium, although it can occur in any age group.

But until we knew the underlying cause, we  could not treat him.

We performed a chest X-ray to check for pneumonia; it was normal. A CT scan of his brain was normal. Bloodwork was normal. But shortly afterward, I received a call from the laboratory: "Your patient's flu swab came back positive."

Now I had the answer: He was delirious because he had influenza and his body was under stress from the infection. The patient was prescribed an anti-influenza medicine and admitted to the hospital.

According to the Centers for Disease Control and Prevention, more than 10 million people get the flu annually. Most will feel miserable for a week or so, but will not require hospitalization. Young children and adults over age 65, however, are at high risk for serious complications. These two age groups often have atypical symptoms and as many as 56,000 people die from flu every year, the CDC estimates.

Everyone older than 6 months old should receive a yearly flu vaccine to help avoid getting influenza, lessen its severity if the flu is contracted, and reduce its spread to others. Flu season is October through March, and it is still not too late to get the vaccine. This year's flu season has been especially severe, and it is important to seek care early if you suspect you have the flu.

The patient left the hospital after a four-day stay, and flew back to Wisconsin, where he lives and owns a small business. While he typically gets a flu vaccine every year, he hadn't received it when he came down with the flu this season. Shortly after returning home, he went to his family doctor and got the vaccine. He plans to continue getting a flu vaccine every year.

Eric Garfinkel, D.O., is a second-year resident of emergency medicine at Johns Hopkins Hospital.