Swine Flu H1N1

Swine flu infects people every year and is found typically in people who have been in contact with pigs, although there have been cases of person-to-person transmission. Symptoms include fever, disorientation, stiffness of the joints, vomiting, and loss of consciousness ending in death. Swine influenza is known to be caused by influenza A subtypes H1N1, H1N2, H3N1, H3N2, and H2N3.

In swine, three influenza A virus subtypes (H1N1, H3N2, and H1N2) are circulating throughout the world. In the United States, the H1N1 subtype was exclusively prevalent among swine populations before 1998; however, since late August 1998, H3N2 subtypes have been isolated from pigs. As of 2004, H3N2 virus isolates in US swine and turkey stocks were triple reassortants, containing genes from human (HA, NA, and PB1), swine (NS, NP, and M), and avian (PB2 and PA) lineages.

Swine flu in Humans

The Centers for Disease Control and Prevention (CDC) reports that the symptoms and transmission of the swine flu from human to human is much like seasonal flu, commonly fever, lethargy, lack of appetite and coughing. Some people with swine flu also have reported runny nose, sore throat, nausea, vomiting and diarrhea. It is believed to be spread between humans through coughing or sneezing of infected people and touching something with the virus on it and then touching their own nose or mouth. The swine flu in humans is most contagious during the first five days of the illness although some people, most commonly children, can remain contagious for up to ten days. Diagnosis can be made by sending a specimen, collected during the first five days, to the CDC for analysis.

The swine flu is susceptible to four drugs licensed in the United States, amantadine, rimantadine, oseltamivir and zanamivir, however, for the 2009 outbreak it is recommended it be treated with oseltamivir and zanamivir. The vaccine for the human seasonal H1N1 flu does not protect against the swine H1N1 flu, even if the virus strains are the same specific variety, as they are antigenically very different.

Veterinary swine flu vaccine

Swine influenza has become a greater problem in recent decades as the evolution of the virus has resulted in inconsistent responses to traditional vaccines. Standard commercial swine flu vaccines are effective in controlling the infection when the virus strains match enough to have significant cross-protection, and custom (autogenous) vaccines made from the specific viruses isolated are created and used in the more difficult cases.

Present vaccination strategies for SIV control and prevention in swine farms, typically include the use of one of several bivalent SIV vaccines commercially available in the United States. Of the 97 recent H3N2 isolates examined, only 41 isolates had strong serologic cross-reactions with antiserum to three commercial SIV vaccines. Since the protective ability of influenza vaccines depends primarily on the closeness of the match between the vaccine virus and the epidemic virus, the presence of nonreactive H3N2 SIV variants suggests that current commercial vaccines might not effectively protect pigs from infection with a majority of H3N2 viruses.

The current vaccine against the seasonal influenza strain H1N1 is thought unlikely to provide protection. The director of CDC's National Center for Immunization and Respiratory Diseases said that the United States' cases were found to be made up of genetic elements from four different flu viruses—North American swine influenza, North American avian influenza, human influenza A virus subtype H1N1, and swine influenza virus typically found in Asia and Europe. On two cases, a complete genome sequence had been obtained. She said that the virus is resistant to amantadine and rimantadine, but susceptible to oseltamivir (Tamiflu) and zanamivir (Relenza)

Read more about Swine Flu H1N1 cases and symptoms on http://amnom.com/swine-flu-h1n1-cases-symptoms/