Influenza A: H1N1

In April 2009, an outbreak of H1N1 (swine flu) broke out in many countries across the globe. On June 11, 2009, the World Health Organization (WHO) declared that a global pandemic of novel influenza A (H1N1) was underway. By then, H1N1 had spread to more than 70 countries. The Centers for Disease Control (CDC) expects that there will be more cases, more hospitalizations, and more deaths associated with the pandemic into the fall (autumn)and winter.

Influenza is a common, contagious respiratory infection caused by a virus with outbreaks of different forms occurring almost every winter . It is characterized by fever, muscle aches, headache, and sore throat. The influenza virus appears virtually every year in a slightly different form and causes respiratory infections. Some years, cases are sporadic and local. In other years there are epidemics that can spread through cities, rural areas, and even whole countries.

The flu virus spreads through the air. It moves from person to person primarily when someone who is infected coughs or sneezes. The incubation period is one to four days, and you can be infectious, or pass the virus to someone else, starting the day before symptoms begin, and lasting through five days after you get sick. The infectious period for children can be longer. Uncomplicated flu in adults and children is characterized by the abrupt onset of the following symptoms:
- Fever and chills
- Headache
- Sore throat
- Muscle and joint pain
- Dry cough
- Runny nose

As the flu virus grows and spreads, the replication of individual cells occurs many times, and the errors compound. Eventually, though the virus remains a flu virus, the cumulative effect of many genetic errors results in a new strain. This is similar to taking a word and rearranging the letters one by one. At first it might be nonsense, but eventually you could have a new word.
If your body becomes infected with this new strain, it's as though it is meeting the virus for the very first time. The fact that you may have had the flu last year makes absolutely no difference. The antibodies your immune system produced in the past, give you little or no protection against another flu virus type or subtype. This is why it is not possible to give a vaccine that gives us long-term immunity to the flu. It is also the reason for seasonal epidemics, and for the incorporation of one or more new strains into each year's flu vaccine.

A major new strain of influenza appears approximately every 10 to 15 years, causing a worldwide flu epidemic.

Steps to protect your health:

• Cover your nose and mouth with a tissue when you cough or sneeze. Throw the tissue in the trash after you use it.
• Wash your hands often with soap and water, especially after you cough or sneeze. Alcohol-based hand cleaners* are also effective.
• Avoid touching your eyes, nose or mouth. Germs spread this way.
• Try to avoid close contact with sick people.
• If you are sick with flu-like illness, CDC recommends that you stay home for at least 24 hours after your fever is gone except to get medical care or for other necessities. (Your fever should be gone without the use of a fever-reducing medicine.) Keep away from others as much as possible to keep from making others sick.