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Swine Influenza : A threat from Mexico
For the last few days, the world has been worried about a flu virus which could potentially cause a pandemic. Since March 2009 at least 1,400 people have been infected by swine influenza in Mexico, 103 cases resulting in death. Furthermore, 20 more cases have been reported in the United States of America, 4 cases have been reported in Canada, and 10 cases have been reported in New Zealand.
According to the Centers for Disease Control and Prevention (CDC) website, swine influenza normally infects swine with low mortality rates, but it has been sporadically reported to infect humans. In 1976, swine influenza once infected soldiers in Fort Dix, New Jersey, USA. At least four people were seriously ill and one person had died. In September 1988 a pregnant women in Wisconsin, USA, had died after contracting swine flu from a pig fair.
In general, flu or influenza is a disease caused by viruses from the Orthomyxoviridae family. The name “influenza” is from Italian which means “influence”.
Besides human, this disease could also infect poultry, swine, dogs, cats, and horses.
There are records of flu pandemics that have killed millions of humans all over the world. The first was the Spanish Flu (1918 - 1920). This pandemic was caused by flu virus subtype H1N1 and was considered the worst ever pandemic in history. Victims were estimated to range between 20 million to 100 million lives. The next one was the Asian Flu (1957 - 1958) caused by influenza virus subtype H2N2 which killed 1 million to 1,5 million people. The third pandemic was the Hong Kong Flu (1968 - 1969) caused by influenza virus subtype H3N2 which killed 1 million people.
In 1997, Avian Influenza (H5N1) emerged in Asia and people worried that it could cause a pandemic. Luckily so far, the virus has not mutated into a form that could be transmitted from human to human.
Swine influenza is also caused by influenza virus type A. This virus was first isolated in 1930. At that time, a number of swine influenza subtypes have been identified; the subtypes were H1N1, H1N2, H3N1, and H3N2.
Swine influenza in humans cause similar symptoms to human influenza such as fever, weakness, cough, nasal discharge, sore throat, nausea, vomit, and diarrhea.
This virus is transmitted through sneezes and cough. It does not transmit through pork if cooked at a minimum temperature of 71oC.
To treat the virus, CDC recommends antiviral drugs such as oseltamivir (Tamiflu) or zanamivir (Relenza). The drugs are effective if given in the first two days of symptom.
Antigen research
H1N1 swine influenza is not the same as H1N1 human influenza. Therefore swine influenza could not be prevented by human influenza vaccines.
According to Deputy Director for CDC Science and Public Health, Dr Anne Schuchat, the swine influenza virus strain in the US is a combination of human flu, avian flu, and swine flu viruses from America, Europe, and Asia. The World Health Organization (WHO) and CDC are highly concerned about this new influenza virus strain because it transmits from human to human with a significantly high mortality rate. This could potentially cause a pandemic.
Acting CDC Director, Richard Besser, said they still don’t know why swine influenza cases in the United States are mild while in Mexico it has caused numerous deaths. He suspects there are differences in the virus strain.
From 14 samples of Mexico’s swine influenza virus sent to CDC, only seven are similar with the viruses in the US. Since April 25, 2009, a team from CDC had arrived in Mexico to conduct research along with Mexican researchers. (ATK)
Source : Kompas