Influenza or "Flu"?

Overview

People commonly refer to upper respiratory infections as the “flu”. This is used as a catch-all term, however true “flu” is caused by specific influenza viruses that affect the respiratory tract, usually with more severe symptoms, and can rarely cause death (0.1% mortality rate during each average severity seasonal epidemic). Worldwide pandemics occur occasionally, the most devastating occurring in 1918 when 40 to 100 million people died. Mortality rates during these pandemics can be much higher than the usual 0.1%.

Influenza viruses that can cause severe epidemic illness are the A & B types. While humans can develop immunity to these viruses either through infection or immunization, these viruses genetically alter their RNA from year to year, so that immunity is temporary. This is why influenza re-vaccination is recommended by the CDC on a yearly basis.

Influenza season typically occurs from November to April in North America. Peak season is from January to March. In our medical house call practice here in San Francisco, we see many travelers from the southern hemisphere including throughout South America. It is not unusual for us to diagnose influenza in the summer months in these patients, since they have come from their winter season back home.

Influenza Illness

• high fever (fever not always present)
• cough
• sore throat
• runny nose or nasal congestion
• headache
• muscle aches
• profound fatigue or weakness

Nausea, vomiting, diarrhea can occur with influenza, but are not typical symptoms of influenza. “Stomach flu” is a catch-all term used to describe illnesses that include these symptoms, but does not specifically refer to influenza.

Influenza illness usually lasts a few days to 1 or 2 weeks. Occasionally complications such as pneumonia may develop, which can lead to more serious illness or even death. Those at more risk for complications include the elderly, very young, and people with other chronic illnesses. During the recent H1N1(type A) influenza outbreak, a significant number of deaths occurred in otherwise healthy young persons.

Prevention

1. Frequent hand washing, and avoidance of touching hand to mouth, eyes and nose. Use antiseptic hand wash such as alcohol based wipes.
2. Influenza easily spreads via respiratory droplets from patients who are coughing, so avoidance of close proximity to people who are coughing is prudent. Cover mouth and nose when sneezing or coughing when sick.
3. Consider yearly influenza vaccination. For specific recommendations see CDC guidelines.

Treatment

• Bedrest
• Minimize contact with others
• Rehydrate
• Use over-the counter medications as directed for symptom relief
• See your doctor within 48 hours of the onset of symptoms if possible, since antiviral medication may be of benefit if started within the first two days.
• Antibacterial treatment may be recommended for certain cases, since bacterial pneumonia is a common complication of influenza.

House calls & Influenza

For patients with influenza symptoms, a physician house call is always a welcome service. Patient’s with influenza should ideally remain at rest, and should not expose other patients to this highly contagious illness. Patients with shortness of breath or severe symptoms should call 9-1-1 or go to their nearest hospital emergency department immediately.

Related articles

• The Flu: A Guide For Parents (education.com)