Swine influenza virus (referred to as SIV) refers to influenza cases that are caused by Orthomyxoviruses that are endemic to pig populations. SIV strains isolated to date have been classified either as Influenzavirus C or one of the various subtypes of the genus Influenzavirus A.
Swine flu, unlike bird flu, is able to pass from human to human contact.
Swine influenza is known to be caused by influenza A subtypes H1N1, H1N2, H3N1, H3N2, and H2N3.
The 2009 swine flu outbreak is the spread of a new strain of H1N1 influenza virus that was first detected by public health agencies in March 2009. Local outbreaks of influenza-like illness were detected in three areas of Mexico, but the presence of this new strain was not clinically discovered for a month. Following this discovery in the states of Texas and California, its presence was swiftly confirmed in the local outbreaks in Mexico, and within days isolated cases elsewhere in the Northern Hemisphere were also identified. By April 27, the new strain was confirmed in Canada, Spain, and the United Kingdom and suspected in many other nations, including New Zealand, with over 2,300 candidate cases, prompting the WHO to raise their pandemic alert level to 4.
The new strain is an apparent reassortment of several strains of influenza A virus subtype H1N1, including a strain endemic in humans and two strains endemic in pigs, as well as an avian influenza.[ Reassortment is common in influenza viruses, due to the segmental structure of their genome. This particular reassortment is consistent with a transmission of swine influenza from pig to human (a zoonosis) combined with the mixing of two viral infections in the same person (superinfection).[citation needed]
In April both the World Health Organization (WHO) and the United States Centers for Disease Control and Prevention (CDC) expressed serious concerns about this novel strain: Because it apparently transmits from human to human, and has had a relatively high mortality rate (albeit only in Mexico), it has the potential to become a flu pandemic.[30] On April 25, 2009, the WHO determined the situation to be a formal "public health emergency of international concern", with knowledge lacking in regard to "the clinical features, epidemiology, and virology of reported cases and the appropriate responses".Government health agencies around the world also expressed concerns over the outbreak and are monitoring the situation closely.
As of April 26, 2009, Mexico City schools, universities, and all public events remained closed or suspended[32] while other schools in the U.S. closed due to confirmed cases in students. On April 27, 2009, Mexican government officials announced the first nationwide shut down of schools in history.
Prevention and Treatment:
Recommendations to prevent infection by the virus consist of the standard personal precautions against influenza. This includes frequent washing of hands with soap and water or with alcohol-based hand sanitizers, especially after being out in public. People should avoid touching their mouth, nose or eyes with their hands unless they've washed their hands. If people do cough, they should either cough into a tissue and throw it in the garbage immediately or, if they cough in their hand, they should wash their hands immediately.
Many countries confirmed that inbound international passengers will be screened. Typical airport health screening involves asking passengers which countries they have visited and checking whether they feel or look particularly unwell. Thermographic equipment was put into use at a number of airports to screen passengers. In the USA, two confirmed cases were detected through their border infectious disease surveillance. A number of countries advised against travel to known affected regions.
The previously recommended influenza vaccines for the southern and northern hemispheres, including that for the 2009/2010 flu season, are ineffective against the new strain.[87] Current development, large-scale manufacturing, distribution and delivery of a new vaccine takes several months.
U.S.-based medical product company Baxter International has requested a virus sample from the WHO in order to begin development of a new vaccine.[88] Baxter has patented a cell-based technology that may allow the company to develop a vaccine in half the time it usually takes, possibly cutting development time from six months to three.
Of the available antiviral treatments for influenza, the WHO stated that the viruses obtained from the human cases with swine influenza in the United States were sensitive to oseltamivir (Tamiflu)and zanamivir (Relenza) but resistant to amantadine and remantadine. Tamiflu and Relenza also have a preventative effect against Influenzavirus A.
On April 27, the CDC recommended the use of Tamiflu and Relenza for both treatment and prevention of the new strain.
Roche and the US government have extended the shelf-life of stock-piled Tamiflu from the original five years to seven years because studies indicated that the medication continues to maintain its effectiveness.
Some physicians in the US are recommending the use of masks when in public. The purpose of a face mask is to effectively cover a person's mouth and nose so that if a person is around someone who is infected, there is a decreased likelihood of transmission. Recommendations to protect against the avian flu indicated that using a face mask with a rating of N99, N100 or P100 in the United States or a rating of FFP3 in Europe should be effective in protecting against transmission. While face masks with these ratings provide 99% or greater efficiency in protecting against flu transmission, N95 or FFP2 face masks provide about 94% efficiency. N95 and FFP2 rated face masks may therefore also be effective.
Source: wikipedia
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