| Influenza is an acute respiratory infection caused by one of three types of influenza viruses in the Orthomyoxoviridae family of viruses, which evolved from the combination of genes from human, pig, and bird flu. This strain has not been found in humans before, but its predecessor caused an international influenza outbreak (pandemic) more than 40 years ago ("2009-10 Influenza").
Influenza A virus strains are classified based on the initials of two virus surface proteins, followed by a number. In H1N1, H stands for hemagglutinin, an antigenic glycoprotein that allows the binding of the virus to the cell that is being infected, and N stands for neuraminidase, an enzyme that allows the release of the virus from the host cell. All influenza A viruses contain both, but the structure of these proteins is different from strain to strain, due to rapid mutation in the genome of the virus. An H number and an N number are assigned to each virus strain, based on the subtype of these two proteins found in the strain. In humans the only common subtypes found are H 1, 2 and 3, and N 1 and 2.
The first cases of A H1N1 influenza were identified on April 2009, and by June 2009 the World Health Organization (WHO) declared the presence of a global pandemic (stage 6) after evidence of spreading in the southern hemisphere; this status persisted until the writing of this topic (September 2009).
Initially, the severity of the 2009 outbreak was uncertain because most people are susceptible to this new strain of H1N1. Fortunately, most cases have been mild so far; the highest H1N1 flu-related morbidity and mortality rates have been reported among individuals of extreme ages, or those with other underlying medical conditions such as asthma, diabetes, obesity, heart disease, or a weakened immune system.
H1N1 flu symptoms are similar to those produced by other flu strains: fever, cough, sore throat, headache, body aches, chills, fatigue, vomiting, and diarrhea.
The H1N1 virus is susceptible to antiviral drugs, such as oseltamivir and zanamivir (neuraminidase inhibitors); sporadic cases of virus resistance have been reported. However, prevention of the transmission have been stressed has one of the best resources to fight the pandemic, with a combination of measures such has frequent hand washing; avoiding touch the own eyes, nose or mouth; minimizing social physical contact; avoiding crowded situations, and covering the nose and mouth with tissue or the upper sleeve when sneezing. The efficacy of the use of a facemask to decrease the risk of virus transmission is difficult to assess, so its use is only recommended for persons at increased risk of severe illness from influenza, and in healthcare settings that involve contact with people who have an influenza-like illness (ILI). Individuals with an ILI (fever and at least cough or sore throat, and possibly other symptoms such as runny nose, headaches, body aches, chills, fatigue, vomiting and diarrhea) should stay home, avoid contact with other people as much as possible, and avoid travel, for at least 24 hours after the disappearance of fever, except to get medical care; fever should have disappeared without the use of antipyretic drugs.
H1N1 flu vaccines will soon be available (2009 early fall) to help protect those at highest risk (pregnant women, household contacts and caregivers for children younger than 6 months of age, healthcare personnel, all individuals from 6 months through 24 years of age, and individuals aged 25 through 64 with health conditions that put them in higher risk of medical complications from influenza), and anyone else who wants to be immunized against H1N1. Effectiveness of the vaccine cannot be predicted because it depends on the match between the virus and the vaccine virus; because viruses change constantly, it is always possible that the match is less than optimal.
(For more detailed information about influenza, see Influenza.) |
Source: Medical Disability Advisor
| "2009-10 Influenza (Flu) Season." CDC. 1 Oct. 2009. Centers for Disease Control and Prevention. 27 Oct. 2009 <http://www.cdc.gov/flu/about/season/current-season.htm>. "Influenza." eMedicine Specialties. 12 Aug. 2009. WebMD Inc. 27 Oct. 2009 <http://emedicine.medscape.com/article/219557-overview>. |
Source: Medical Disability Advisor
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