Swine flu (deadly strain)

The World Health Organization says the new type of swine flu that has broken out in Mexico and has killed more than 100 people till now has the potential to become a pandemic.

What it is?
Swine flu is a highly contagious acute respiratory disease of pigs, caused by one of several swine influenza A viruses.

The virus
The WHO has confirmed that some of the cases in the current outbreak are a never-before-seen strain of influenza A virus, carrying the designation H1N1. The strain is a mixture of viruses from swine, birds and humans.

Symptoms
Symptoms of swine flu in humans are similar to those of seasonal influenza, so it is difficult to detect and mild cases may escape recognition. The symptoms include sudden fever, coughing, muscle aches and extreme fatigue. The new strain also causes more diarrhoea and vomiting than normal flu.

Vaccines
Vaccines are available for pigs to prevent swine influenza. But as of now, there is no vaccine to protect humans from swine flu, although the CDC is formulating one. The seasonal influenza vaccine may help provide partial protection against swine H3N2, but not swine H1N1 viruses, like the one spreading currently.

How the flu spreads to humans?
The swine influenza A virus has many strains, the newest being the H1N1 type. The respiratory virus attacks pigs and causes influenza in them. A human may contract the flu on coming in direct contact with an infected pig. It spreads like normal flu, when viral particles expelled in coughs and sneezes are breathed in.

WHO PANDEMIC ALERT PHASES
Phase 1: No viruses circulating among animals causing infections in humans

Phase 2: Animal influenza virus causes infection in humans, and is considered potential pandemic threat

Phase 3: Influenza causes sporadic cases in people, but no significant human-to-human transmission

Phase 4: Verified human-to-human transmission able to cause community-level outbreaks. Significant increase in risk of a pandemic

Phase 5: Human-to-human transmission in at least two countries. Strong signal pandemic imminent

Phase 6: Virus spreads to another country in a different region. Global pandemic under way