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Wednesday, May 6, 2009 Understanding influenza virusesAcross the nation 911 emergency dispatch centers are inundated with calls for swine flu information. Hospitals and clinics are overrun with patients who think they have contracted the swine flu; yet on examination, many don't even have a fever. Is it media hype, mass hysteria or erring on the side of caution? Maybe it's a little bit of each. What is Swine Flu? Early on the current flu virus was called Swine Flu because initial laboratory tests showed many genes in the novel (or new) virus were similar to viruses that normally occur in pigs throughout North America. Now, the new virus is referred to by its subtype: Influenza A (H1N1), or just H1N1. Hereafter, it will be referred to as "Swine A" for purposes of differentiation in this article. Current lab studies have shown that the novel virus is very different from what normally circulates in North American swine herds. Scientists refer the new virus as a "quadruple reassortant" virus because of its combination of four gene segments. Swine A has one segment that is typical of the endemic swine flu found in North America; one segment that is typical of pig flu viruses in Europe and Asia; one avian segment that is typical in North American birds; and one segment that is common in human seasonal influenza. There are many viruses that commonly cause outbreaks of influenza and similar illnesses in pigs. Most of the time these viruses do not affect people, but influenza viruses can spread back and forth between pigs and people. Does this mean no pork chops or green chili stew for dinner? Absolutely not! There is no danger in eating well-cooked pork or pork products. A person is more in danger of trichinosis, which is a parasitic disease caused by eating undercooked or raw pork. What Is a Pandemic? The World Health Organization has classed the Swine A epidemic as a Phase 5 pandemic. This means the virus has the ability to spread rapidly from human to human, and there is evidence of widespread human infection. According to information from WHO, a pandemic occurs when a new influenza virus appears and humans have little or no immunity to the new virus. This results in worldwide epidemics with enormous numbers of illness and deaths. As with any serious illness, death can be a very real factor, especially for young children and the elderly. At this time there are no certain risk factors for Swine A, everyone is a potential victim but most will recover, as is true with any other flu illness. For some perspective, here are some figures for a random sampling of life-threatening conditions: 3 million deaths worldwide are reported each year due to the affects of diabetes; in 2007, there were 55,000 cases worldwide of meningococcal meningitis, with 4,000 deaths, this is a severe bacterial infection of the membrane that surrounds the brain and spinal cord. For seasonal flu epidemics that occur every year in the U.S. there are more than 200,000 people hospitalized from flu-related complications, and about 36, 000 deaths. The most severe flu pandemic of the 20th century was the 1918 Spanish Flu. This virus killed 40 million to 50 million people worldwide. It is one of the reasons that casualty numbers are so hard to determine for World War I. A large number of deaths were caused by influenza instead of battle injuries. Medical journals of the time are filled with stories and examples of how rapidly the Spanish Flu claimed its victims. As of Tuesday, May 5, 9 a.m. MDT, there have been 1,490 confirmed cases of Swine A reported worldwide in 21 countries. Of those, Mexico has 822 confirmed cases and 29 confirmed deaths. The U.S. has 403 confirmed cases in 38 states, and had initially listed only one death in Texas, that of a toddler from Mexico visiting the U.S. However, the first death of a U.S. resident has been confirmed. A Cameron County, Texas, woman in her 30s has died, according to information from the Texas Department of State Health. The report also stated the woman suffered from chronic underlying health conditions. Here in New Mexico the Department of Health is investigating 24 additional reports of Swine A. According to statistics on the Centers for Disease Control and Prevention's Web site in Atlanta, Ga., there is only one confirmed case to date, that of a home-schooled teenager in Valenica County who is now recovered. However, on Monday, May 4, the New Mexico Department of Health received CDC confirmation on the two cases from Socorro County (a 14-year-old female and a 15-year-old male), which brings New Mexico's number of confirmed cases to three. Both Socorro County cases have recovered as well. What are the symptoms? This is a difficult question. The symptoms for Swine A are pretty much the same as with any flu-like condition: high fever, cough, sore throat, body aches, headache, chills, fatigue, and some reports of diarrhea and vomiting. If a person has these symptoms, especially a high fever, medical attention is needed. High fevers can create a very serious condition, especially in young children and the elderly, known as dehydration. That's why it's always important to drink lots of fluids when illness strikes. Preventing Swine A Preventing the spread of illness is actually very easy. It's a matter of simple, common sense things that people should be practicing as basic, everyday habits.
A Time for Every Season Here in the U.S., the flu season can start as early as October and usually peaks in January or later. According to information from the CDC, there are three main influenza viruses that cause seasonal flu: A, B and C. Out of these three, types A and B are responsible for the seasonal flu epidemics; type C is not thought to cause epidemics. Type A influenza virus also has subtypes based on two proteins that surround the virus: hemagglutinin (H) and neuraminidase (N). There are 16 different H subtypes and nine differentsubtypes. These can be further broken down into strains. The current subtypes of Influenza A virus that is found in people are A(H1N1) and A(H3N2). In 1989, a subtype known as H1N2 was reported in six cities in China, but the virus did not spread outside of these six cities. This subtype has had only a few instances reported worldwide since 2002 and is not considered a common flu virus. Type B influenza virus is not divided into subtypes, but it can also be broken down into different strains. Type C influenza virus is also not broken down into subtypes. This is the virus form that causes a mild respiratory illness. Flu viruses are constantly changing through a process scientists call "antigenic drift," or more simply, mutation. This accounts for the many strains in virus subtypes, which are classed according to their common protein types. For instance, a variant strain of Type B virus will not turn into a Type A virus. Vaccines Yearly flu shots and nasal spray vaccines are also used to help the body create an immune barrier against flu viruses. These work in much the same manner as people who take allergy medicines. The person is given a small amount of what they are allergic to so the body can develop an allergic immune barrier. The same is true for flu vaccines. A small amount of flu virus is administered to help humans build antibodies. Each year, in February, a panel of people from the Food and Drug Administration study worldwide reports on flu samples from the previous flu season. The panel then approves a concoction of viruses for vaccines based on these studies. Vaccines change every year based on international studies and what scientists estimate to be the flu viruses that will be prevalent for the upcoming flu season. Flu vaccines are comprised of three viruses: one A(H1N1), one A(H3N2), and one B influenza virus. There are no vaccines for Type C influenza virus. Flu shots are suitable in those who are age 6 months and older, and for those who are healthy or suffer from chronic conditions such as asthma, diabetes or heart disease. Nasal sprays are approved for those who are healthy and between the ages of 2 years and 49 years, the spray is not approved for pregnant women. The effectiveness of a vaccine is dependent on how well-matched the circulating viruses are to the vaccine. For instance, during the 2007-2008 flu season, the vaccines were effective for 66 percent of H1N1 virus, 78 percent for H3N2 virus (because of fewer lab reports), and only 29 percent for Type B virus, which became prevalent later in the season. In a well-matched year, flu vaccines can have a 90 percent effectiveness rate. Information In-depth information, recommendations and restrictions are readily available, either through Web sites or health care providers. These are:
England is a member of El Defensor Chieftain staff.
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