Flu rarely causes serious complications but in about 1% of cases, it can cause a number of illnesses requiring hospitalization.
Defining Flu
Influenza, commonly called “the flu”, is caused by a specific type of virus. It infects the respiratory tract (nose, throat, and lungs). The viruses are divided into three types: A, B. and C.
- Types A and B are responsible for the outbreaks of respiratory illnesses that occur almost every year and are associated with increases in the rates of hospitalizations and death.
- Type C usually only causes either a mild respiratory illness or no symptoms at all.
Flu viruses continually mutate over time so the one causing illness in one season may vary from year to year.
Flu Symptoms
Symptoms of the flu include fever, headache, extreme tiredness, dry cough, sore throat, stuffy nose, and muscle aches. Children can also experience symptoms such as nausea, vomiting, and diarrhea which are usually uncommon in adults. Flu-like symptoms can also be caused by certain other viruses, bacteria, and parasites.
Flu Season in the United States
The flu season in the United States can start as early as late November and go through March. Its impact can vary from year to year. The U.S. Center for Disease Control and Prevention monitors the progress of the flu season. Its surveillance, which consists of seven components, allows the CDC to determine when and where influenza activity is occurring. These include tracking
- Number and percentage of influenza-positive tests.
- Percentage of doctor visits for flu-like symptoms.
- Percentage of deaths caused by pneumonia and influenza in 122 cities.
- Number of states affected by flu and the degree to which they are affected.
- Number of deaths in children of confirmed influenza infections.
- Number of children hospitalized by flu-related complications.
These help the CDC determine where influenza activity is occurring and what types of viruses are circulating. However, there can be a week to two week lag from the time the data is compiled to when it is released to the public.
Flu Viruses Spread from Person to Person
The main way flu viruses are transferred are from person to person when “droplets” are spread by coughing or sneezing that can reach as far as 3 feet through the air and then be deposited on the mouth or nose of anyone nearby. It can also be spread when the droplets touch another person or lands on an object that is then touched. The signs of being exposed to a flu virus begin in one to four days after exposure.
Flu Complications
Among the complications caused by flu are bacterial pneumonia, dehydration, and worsening of chronic medical conditions, such as congestive heart failure, asthma or diabetes. Older adults are at the highest risk for serious complications from flu and children may get sinus problems or ear infections.
Flu Prevention
Avoiding the flu consists of a few preventive steps:
- Washing hands frequently with soap and water.
- Covering the nose and mouth and nose with of facial tissue when sneezing, never with the hands.
- Not sharing anything that goes into the mouth such as drinking cups and straws.
- Avoid touching the eyes, nose or mouth while in public to avoid transferring bacteria that can cause the flu.
Because the complications from flu can be so serious, an awareness of what it is, the symptoms, and preventive measures to be taken, can avoid being the 5% to 20% of U.S. residents who experience the illness.
Source: U.S. Center for Disease Control and Prevention
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