The Swine Flu

The influenza viruses are classified into types A, B and C on the basis of their core proteins. Only A and B types will cause human diseases of any concern.

The subtypes of influenza A viruses are determined by envelope glycoproteins possessing either haemagglutinin (HA) or neuraminidase (NA) activity.
High mutation rates and frequent genetic reassortments of these viruses contribute to great variability of the HA and NA antigens. All of the currently identified 16 HA and 9 NA subtypes of influenza A viruses are maintained in wild, aquatic bird populations. Humans are generally infected by viruses of the subtypes H1, H2 or H3, and N1 or N2. Minor point mutations causing small changes (“antigenic drift”) occur relatively often.

Antigenic drift enables the virus to evade immune recognition, resulting in repeated influenza outbreaks during interpandemic years. Major changes in the HA antigen (“antigenic shift”) are caused by reassortment of genetic material from different A subtypes. Antigenic shifts resulting in new pandemic strains are rare events, occurring through reassortment between animal and human subtypes, for example in co-infected pigs. Influenza A (H1N1) virus emerged in 2009.

It is a new reassortment that has never before circulated among humans. This virus is not closely related to previous or current human seasonal influenza viruses.

H1N1
H1N1 flu is also known as swine flu. It’s called swine flu because in the past, the people who caught it had direct contact with pigs. That changed several years ago, when a new virus emerged that spread among people who hadn’t been near pigs.
In 2009, H1N1 was spreading fast around the world, so the World Health Organization called it a pandemic. Since then, people have continued to get sick from swine flu, but not as many.
While swine flu isn’t as scary as it seemed a few years ago, it’s still important to protect yourself from getting it. Like seasonal flu, it can cause more serious health problems for some people. The best bet is to get a flu vaccine, or flu shot, every year. Swine flu is one of the viruses included in the vaccine.

Transmission
Respiratory transmission occurs mainly by droplets disseminated by unprotected coughs and sneezes. Short-distance airborne transmission of influenza viruses may occur, particularly in crowded enclosed spaces. Hand contamination and direct inoculation of virus is another possible source of transmission.

Nature of the disease
An acute respiratory infection of varying severity, ranging from asymptomatic infection to fatal disease. Typical influenza symptoms include fever with abrupt onset, chills, sore throat, non-productive cough and, often accompanied by headache, coryza, myalgia and prostration. Complications of influenza viral infection include: primary influenza viral pneumonitis, bacterial pneumonia, otitis media and exacerbation of underlying chronic conditions. Illness tends to be most severe in the elderly, in infants and young children, and in immunocompromised hosts. Death resulting from seasonal influenza occurs mainly in the elderly and in individuals with pre-existing chronic diseases.

Influenza A (H1N1) is similar to seasonal influenza but has been characterized by higher activity during the northern summer season, higher fatality rates among healthy young adults and higher incidence of viral pneumonia.

Diaease burden
Influenza occurs all over the world, with an annual global attack rate estimated at 5–10% in adults and 20–30% in children. In temperate regions, influenza is a seasonal disease occurring typically in winter months: it affects the northern hemisphere from November to April and the southern hemisphere from April to September. In tropical areas there is no clear seasonal pattern, and influenza circulation is year-round, typically with several peaks during rainy seasons.

Precautions
Whenever possible, avoid crowded enclosed spaces and close contact with people suffering from acute respiratory infections. Frequent hand-washing, especially after direct contact with ill persons or their environment, may reduce the risk of acquiring illness. Ill persons should be encouraged to practice cough etiquette (maintain distance, cover coughs and sneezes with disposable tissues or clothing, wash hands).

How is it treated?
Some of the same antiviral drugs that are used to treat seasonal flu also work against H1N1 swine flu. Oseltamivir (Tamiflu), peramivir (Rapivab), and zanamivir (Relenza) seem to work best, although some kinds of swine flu don’t respond to oseltamivir.
These drugs can help you get well faster. They can also make you feel better. They work best when you take them within 48 hours of the first flu symptoms, but they can help even if you get them later on.

Should we take antibiotics?
Antibiotics won’t do anything for you. That’s because flu is caused by a virus, not bacteria in fact taking antibiotics may cause secondary disease related to killing normal flora so (antibiotics must not be taken under any circumstances)

OTC Medications
Over-the-counter pain remedies and cold and flu medications can help relieve aches, pains, and fever. Don’t give aspirin to children under age 18 because of the risk of Reye’s syndrome. Make sure that over-the-counter cold medications do not have aspirin before giving them to children.

Is there a vaccine for Swine Flu?
The same flu vaccine that protects against seasonal flu also protects against the H1N1 swine flu strain. You can get it as a shot or as a nasal spray. Either way, it “teaches” your immune system to attack the real virus.
Besides a flu shot, there are other things you can do to stay healthy:

• Wash your hands throughout the day with soap and water. Sing the “Happy Birthday” song twice to make sure you’ve washed long enough.
• Use an alcohol-based hand sanitizer.
  Don’t touch your eyes, nose, or mouth.

• Avoid people who are sick.