More on Swine Flu
Posted by feww on April 25, 2009
Flu virus particles, or “virions”
This colorized negative-stained transmission electron micrograph (TEM) depicts the ultrastructural details of a number of influenza virus particles, or “virions”. A member of the taxonomic family Orthomyxoviridae, the influenza virus is a single-stranded RNA organism. CDC/ Courtesy of Dr. F. A. Murphy (1973).
The flu is a contagious respiratory illness caused by influenza viruses. It can cause mild to severe illness, and at times can lead to death. The best way to prevent this illness is by getting a flu vaccination each fall.
Every year in the United States, on average:
- 5% to 20% of the population gets the flu
- more than 200,000 people are hospitalized from flu complications, and
- about 36,000 people die from flu. Some people, such as older people, young children, and people with certain health conditions, are at high risk for serious flu complications.
What you should know:
Influenza A and B are the two types of influenza viruses that cause epidemic human disease. Influenza A viruses are further categorized into subtypes on the basis of two surface antigens: hemagglutinin and neuraminidase. Influenza B viruses are not categorized into subtypes. Since 1977, influenza A (H1N1) viruses, influenza A (H3N2) viruses, and influenza B viruses have been in global circulation. In 2001, influenza A (H1N2) viruses that probably emerged after genetic reassortment between human A (H3N2) and A (H1N1) viruses began circulating widely. Both influenza A and B viruses are further separated into groups on the basis of antigenic characteristics. New influenza virus variants result from frequent antigenic change (i.e., antigenic drift) resulting from point mutations that occur during viral replication. Influenza B viruses undergo antigenic drift less rapidly than influenza A viruses.
Under a plate magnification of 37,800X, this colorized transmission electron micrograph (TEM) depicted the A/New Jersey/76 (Hsw1N1) virus, while in the virus’ first developmental passage through a chicken egg. CDC/ Dr. E. Palmer; R.E. Bates (1976).
What is Swine Influenza?
Swine Influenza (swine flu) is a respiratory disease of pigs caused by type A influenza that regularly cause outbreaks of influenza among pigs. Swine flu viruses cause high levels of illness and low death rates among pigs. Swine influenza viruses may circulate in swine throughout the year, but most outbreaks among swine herds occur during the late fall and winter months similar to humans. The classical swine flu virus (an influenza type A H1N1 virus) was first isolated from a pig in 1930.
Can humans catch swine flu? [YES THEY CAN! They already have! Moderator.]
Swine flu viruses do not normally infect humans. However, sporadic human infections with swine flu have occurred. In the past several years, on average CDC has received about one influenza virus isolate from a human that tests positive for swine flu each year. Most commonly, these cases occur in persons with direct exposure to pigs (workers in the swine industry, for example). In addition, there have been rare 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.
This negative-stained transmission electron micrograph (TEM) depicts the ultrastructural details of an influenza virus particle, or “virion”. A member of the taxonomic family Orthomyxoviridae, the influenza virus is a single-stranded RNA organism. Dated: 1981. CDC/ Dr. Erskine. L. Palmer; Dr. M. L. Martin
This negative stained transmission electron micrograph (TEM) shows recreated 1918 influenza virions that were collected from supernatants of 1918-infected Madin-Darby Canine Kidney (MDCK) cells cultures 18 hours after infection. CDC/ Dr. Terrence Tumpey (2005)
To separate these virions, the MDCK cells are spun down (centrifugation), and the 1918 virus in the fluid is immediately fixed for negative staining. The solid mass in lower center contains MDCK cell debris that did not spin down during the procedure. See PHIL 8160 for a black and white version of this micrograph.
Dr. Terrence Tumpey, one of the organization’s staff microbiologists and a member of the National Center for Infectious Diseases (NCID), recreated the 1918 influenza virus in order to identify the characteristics that made this organism such a deadly pathogen. Research efforts such as this, enables researchers to develop new vaccines and treatments for future pandemic influenza viruses.
The 1918 Spanish flu epidemic was caused by an influenza A (H1N1) virus, killing more than 500,000 people in the United States, and up to 50 million worldwide. The possible source was a newly emerged virus from a swine or an avian host of a mutated H1N1 virus. Many people died within the first few days after infection, and others died of complications later. Nearly half of those who died were young, healthy adults. Influenza A (H1N1) viruses still circulate today after being introduced again into the human population in the 1970s.
The information on his page was provided by CDC.