Swine influenza (swine flu) is a respiratory disease of swine caused by type A influenza viruses that cause regular outbreaks of influenza in pigs. Swine influenza virus cause high levels of illness and low mortality in pigs. Influenza viruses circulate among swine may throughout the year, but most outbreaks happen in the late fall and winter outbreaks in humans. Viruses of classical swine fever flu (influenza A virus H1N1) was first isolated from a pig in 1930.
Like all influenza viruses, swine flu viruses are constantly developing. Pigs can become infected with avian and human influenza viruses and virus of swine influenza. When influenza virus from different species infect pigs, the virus can re-assort (ie the exchange of genes) and the new virus that is a mixture of pork, the man and / or avian influenza viruses can occur. Over time, different types of influenza viruses have emerged. At this time, the four major influenza A virus subtypes have been isolated in pigs: H1N1, H1N2, H3N2 and H3N1. However, most influenza viruses recently isolated from pigs were H1N1 viruses.
Swine flu viruses do not normally infect humans. However, sporadic human infections with swine flu have occurred. Most commonly, these cases occur in persons with direct exposure to pigs (e.g. children near pigs at a fair or workers in the swine industry). In addition, there have been documented cases of one person spreading swine flu to others. For example, an outbreak of apparent swine flu infection in pigs in Wisconsin in 1988 resulted in multiple human infections, and, although no community outbreak resulted, there was antibody evidence of virus transmission from the patient to health care workers who had close contact with the patient.
In the past, CDC has received reports of one person infected with the swine flu every one to two years in the U.S., but from December 2005 to February 2009, 12 cases of human infections with swine influenza have been reported.
The symptoms of swine influenza in the population should resemble the symptoms of seasonal flu ordinary people and include fever, lethargy, loss of appetite and cough. Some people with swine flu has also reported a runny nose, sore throat, nausea, vomiting and diarrhea.
No virus of swine influenza is not transmitted by food. You can not get influenza from eating pork or pork products.
Influenza viruses can be transmitted directly from pigs to people and people of pigs. Human infection with influenza viruses of pigs is most likely to occur when people are in the vicinity of infected pigs, as in the stables and animal exhibitions housing pigs at fairs. Human to human transmission of swine influenza can also occur. It is believed to occur in the same way as seasonal flu in people, mainly from person to person through the transmission of cough or sneezing of people infected with influenza virus. People may have been infected by touching something with influenza virus and then touching the mouth or nose.
In September 1988, a healthy 32-year-old and the pregnant woman was hospitalized with pneumonia and died 8 days later. A virus of swine influenza H1N1 was found. Four days before becoming ill, the patient has visited a county fair swine exhibition where it was common flu in pigs.
In follow-up studies, 76% of pigs tested antibody evidence of infection with swine influenza, but no serious diseases have been detected in this group. Other studies suggest that one in three of the health personnel who had contact with the patient a mild flu-like illness with antibody evidence of infection with swine influenza.
To diagnose an infection with swine influenza, an airborne model generally must be collected within the first 4 to 5 days of illness (when an infected person is most likely to be shedding virus). But some people, especially children, can shed virus for 10 days or more. Identification of swine flu influenza A virus requires sending the sample to the CDC for laboratory study.
There are four different antiviral drugs that are licensed for use in the US for the treatment of influenza: amantadine, rimantadine, oseltamivir and zanamivir. While most swine influenza viruses have been susceptible to all four drugs, the most recent seven swine influenza viruses isolated from humans are resistant to amantadine and rimantadine. At this time, CDC recommends the use of oseltamivir or zanamivir for the treatment and/or prevention of infection with swine influenza viruses.
Probably the best known is an outbreak of swine fever flu among soldiers at Fort Dix, New Jersey in 1976. The virus caused the disease with x-ray evidence of pneumonia for at least 4 soldiers and 1 death, all these patients had been healthy. The virus was transmitted to close contacts in an environment of basic training, with limited transmission outside the basic education group. The virus is suspected of having circulated for a month and disappeared. The source of virus, the exact time of its introduction at Fort Dix, and factors limiting the spread and duration are unknown. The outbreak at Fort Dix in May was caused by the introduction of an animal virus in a population, “said close contact in crowded facilities during the winter. Virus of swine influenza A collected from a soldier at Fort Dix has been named A/New Jersey/76 (Hsw1N1).
No, the H1N1 swine influenza viruses antigenically very different from H1N1 viruses of man and therefore vaccines for seasonal influenza does not provide protection against the H1N1 virus of swine influenza.