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What is Swine Flu?

Swine flu (SIV Swine Influenza Virus), is a type of influenza H1N1 virus that normally is restricted to pigs. During 2009 this flu virus appears to have moved from pigs to humans and now from human to human creating an epidemic (locally within a region) and possible pandemic (across a much larger area possibly world wide).

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What does H5N1 actually mean? This is the name used by scientists to identify the surface coating of the virus. H1 = Hemagglutin type 5; N1= Neuraminidase type 1. Hemagglutin helps the virus attach to the host cell and neuraminidase helps to promote release of the virus from infected cells. Reference: Wikipedia hemagglutin, neuraminidase

 

What is Mexican flu?

This is the name, given by Israeli health officials of the 2009 outbreak of swine flu that appears to infect humans. 

"The new strain is an apparent reassortment of several strains of influenza A virus subtype H1N1, which analysis at the United States Centers for Disease Control and Prevention (CDC) identified as a strain endemic in humans, a strain endemic in birds, and two strains endemic in American and Eurasian pigs (swine)." Source: Wikipedia

Why is swine flu important?

The current influenza outbreak that occurred in Mexico is thought to have originated from pigs. The main significance of this particular strain is that in mexico it may have resulted in the deaths of 100s of people who were apparently healthy.

Although currently the World Health Organisation suggests that this number may be much smaller. source: ABC news

Due to the common and frequent movement of people around the world via aircraft, outbreaks like these can result in larger numbers of people being exposed to the virus.

This requires airport officials to monitor for sick passengers. They often use thermal imaging cameras to check if people's faces are warmer than usual.

However, some people may just have the standard flu or rhino virus, the mild form of a common cold with no severe symptoms.

News about Swine flu

Reuters Global Full Coverage for Swine Flu

Try a google news search for swine flu

Try a Yahoo news search for swine flu

How does Swine flu work?

• Essentially it is the same as other influenza viruses

How does this particular form of influenza sometimes kill people?

" When a new virus emerges, it can sweep through the population, said Dr. Anne Moscona, a flu specialist at Cornell University’s medical school. The Spanish flu is believed to have infected at least 25 percent of the United States population, but killed less than 3 percent of those infected.

The leading theory on why so many young, healthy people die in pandemics is the “cytokine storm,” in which vigorous immune systems pour out antibodies to attack the new virus. That can inflame lung cells until they leak fluid, which can overwhelm the lungs, Dr. Moscona said."

Source: New York Times Online

Example of a Cytokine storm

Proposed Mechanism of the Cytokine Storm Evoked by Influenza virus.
Osterholm. New England Journal of Medicine, 352 (18): 1839, Figure 3. May 5, 2005

http://www.cytokinestorm.com/

What is History of Swine flu?

Swine flu along with flu viruses for a range of animals, typically most vertebrates have actually been around for hundreds of thousands of years.

Hemagglutinin genes have been around for thousands of years..

" In particular, the earliest divergence time was estimated to be about 2,000 years ago. Also, the A virus HA gene diverged from the B virus HA gene about 4,000 years ago and from the C virus HE gene about 8,000 years ago. These time estimates are much earlier than the previous ones." - Source: Molecular Biology and Evolution 19:501-509 (2002)

Epidemics and pandemics have occasionally occurred in pig populations.

One of the most well know pandemics was the Spanish flu of 1918.

• It is estimated that anywhere from 20 to 100 million people were killed worldwide, source: wikipedia

The Future of swine flu

This is the early stages and it is hard to tell what might happen. Due to the vigilance and improved high speed communications and reporting authorities around the world it is less likely to be problematic than previous outbreaks.

However it due to higher speeds of communications news about possible pandemics cn be exaggerated and create mass panic.

With modern anti viral medicines being developed it is likely that, at least in some places, flu outbreaks are likely to be more contained. Also with greater awareness of common sense hygiene practices transmission tends to be slightly less.

Due to the recombining nature of viruses it is often difficult to predict how an infection will spread. In Some cases it may stop suddenly or no longer be able to attach to a host.