| ID | 188 |
|---|---|
| Name | BIRD FLU : A CURRENT THREAT TO THE HUMANS |
| Cause | |
| Signs Symptoms | Signs & symptoms: Although the exact incubation period for bird flu in humans isn’t clear, illness seems to develop within one to five days of exposure to the virus. Sometimes the only indication of the disease is a relatively mild eye infection (conjunctivitis). But more often, signs and symptoms of bird flu resemble those of conventional influenza, including: Cough, Fever, Sore throat, Muscle aches. |
| Diagnosis | Diagnosis: If one develops flu-like symptoms, including a fever, cough and body aches, and has recently traveled to a part of the world where bird flu occurs. See your doctor immediately and be sure to let your doctor know when and where you were traveling and whether you visited any farms or open-air markets. Doctors have rapid tests to identify the flu virus, but the tests can’t distinguish between avian flu and other influenza A viruses. For that reason, specimens from anyone with a suspected case of bird flu are sent to the Centers for Disease Control and Prevention (CDC) for analysis. |
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| Management | |
| Introduction | Introduction: In the recent years, the bird flu (also known as avian influenza) has become a threat to the health officials and personels worldwide. Because, the bird flu has led to the deaths of hundreds of millions of wild and domestic birds and to a small number of human deaths. But, right now, it remains difficult for humans to contract. Avian viruses generally don’t affect humans, but in 1997, an outbreak of bird flu in Hong Kong infected 18 people, six of them died. Since then, human cases of bird flu have been reported in Asia, Africa, the Pacific, Europe and the Middle East. Most were traced to contact with infected poultry or surfaces contaminated by sick birds. Experts believe that, about 160 people have contracted the disease since it was identified as a threat 10 years ago. For now, in most places, there is not an immediate threat from the bird flu. While the bird flu can be serious, unless one has household chickens and live in a country where there’s1 an outbreak now, the bird flu probably is not an immediate health threat for him or his family. Health officials are concerned that a major bird flu outbreak could occur in humans if the virus mutates (undergo a genetic change) into a new form that can spread more easily from person to person. The grimmest scenario would be a global outbreak to rival the flu pandemic of 1918 and 1919, which claimed millions of lives worldwide. The avian flu that has affected birds and people in Asia, Europe, Africa and the Middle East, is different from the flu that many people get during the cold-weather months. Poultry - like chickens and turkeys - tend to get infected with the bird flu by migrating waterfowl (like ducks, geese, and swans), and spread it to other birds through their infected feces, saliva, or secretions. The people who have gotten sick or died from the bird flu in Asia have had direct contact with infected birds, or surfaces that have been contaminated by them. This strain of the bird flu - which is called H5N1 - can’t be spread from person to person. Health officials around the world are taking precautions to make sure that the bird flu doesn’t spread, and to keep people safe from it if it does. Many countries - including the United States - aren’t importing poultry from countries where there have been avian flu outbreaks. Meanwhile, scientists are working on developing a vaccine to keep people from getting the avian flu. The ABCs of influenza viruses: All influenza viruses are divided into three types - A, B or C - depending on the virus’ structure. Type A is responsible for lethal influenza pandemics, whereas type B causes smaller, localized outbreaks. Both types A and B are also responsible for the seasonal flu that affects many people every year. Less common and more stable than other strains, type C has milder symptoms. Influenza B and C are usually found only in humans. But type A influenza infects both people and animals, including birds, pigs, horses, whales and seals. Numerous influenza A subtypes exist, and they can combine to form even more subtypes, some of which normally are specific to a single species. At least 15 flu subtypes affect birds, the most virulent of which is H5N1. Until recently, avian subtypes have rarely been found in humans or in animals other than pigs. Type A influenza viruses are further divided into strains, which are constantly evolving. And it is exactly this - the ability of influenza viruses to change their genetic makeup and to swap genes indiscriminately- that makes them so unpredictable and potentially deadly. How humans get bird flu: Migratory waterfowl, and ducks in particular, carry the viruses that cause bird flu. Often unaffected themselves, the host birds spread the infection to susceptible species, especially domesticated chickens, turkeys and geese, resulting in severe epidemics that sicken and kill large numbers of birds -sometimes in a single day. Often, flu viruses that cross from animals to humans originate in areas where people live in proximity to chickens and pigs. That’s because pigs are susceptible to infection with both avian and human viruses and so are an ideal “mixing bowl” in which viruses can exchange genes. But at least some bird flu viruses don’t need a third party. Instead, they shuffle and rearrange their genetic material directly in humans. That seems to be the case in most instances of human-acquired bird flu. People become sick after direct contact with infected birds or bird-contaminated surfaces, not from contact with pigs or other animals. Direct bird-to-human transmission works like this: Wild birds shed the virus: Infected migratory waterfowl, the natural carriers of bird flu viruses, shed the virus in their droppings, saliva and nasal secretions. The virus spreads to domesticated birds: Domestic poultry become infected from contact with these birds or with contaminated water, feed or soil. They may also catch the disease the same way humans contract conventional flu - by inhaling the airborne virus. Bird flu spreads quickly and lethally within domestic flocks and is inadvertently transported from farm to farm on tractors and other equipment, on cages, and on workers’ shoes and clothing. Heat destroys the virus, but it can survive for extended periods in cool temperatures. Markets provide pathways to humans: Open-air markets, where eggs and birds are often sold in crowded and unsanitary conditions, are hotbeds of infection and spread the disease into the wider community. Cockfighting, common throughout much of Asia, has also been implicated in the spread of bird flu because fighting roosters are often trucked long distances and smuggled across borders. At any point along the way, humans may pick up the virus through close contact with sick birds or contaminated surfaces. H5N1: Prelude to a pandemic? In the current epidemic, two influenza subtypes have proved especially dangerous - H7N7, which sickened poultry workers in the Netherlands, and H5N1, which has been responsible for the majority of human and avion deaths in Asia. Of these, H5N1 is of particular concern for several reasons: Direct transmission: H5N1 became the first known bird flu strain to jump directly from birds to people when it surfaced in Hong Kong in 1997. It has since infected people in many countries. Other strains have caused illness in humans, but none is as severe as H5N1. Virulence: The virus is especially lethal, killing close to 100 percent of susceptible birds and more than half of infected people. Birds that do survive can shed the virus for at least 10 days, greatly increasing the flu’s spread. Rapid spread: Since 2003, hundreds of millions of birds have died, a loss that’s ecologically and economically devastating. It’s also alarming from a public health standpoint - widespread infections among birds may lead to more human disease. Genetic scrambling: H5N1 mutates quickly and is notorious for grabbing large blocks of genetic code from viruses that infect other species, a process called reassortment. For that reason, it has particular potential to combine with a human flu virus, creating a new viral strain that spreads rapidly from person to person. The emergence of such a virus would mark the beginning of a potentially devastating pandemic. The ability of H5N1 to evolve rapidly was demonstrated in October 2006 when a new strain, called H5N1 Fujian-like, appeared in China and spread quickly throughout much of Southeast Asia. The new strain is immune to the vaccines normally given to birds to prevent H5N1 infections. |
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| Etiology | |
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| Preventions | Prevention: In April 2007, doctors approved the first vaccine to prevent bird flu, (which is also approved by the PDA). If you develop flu symptoms and have recently traveled to a part of the world where the bird flu occurs, see your doctor right away. The international effort to prevent the spread of bird flu focuses on the health of both birds and humans. Measures to help control the virus among domestic poultry include: 1. Culling: Since 1997, when the first human cases of bird flu appeared, hundreds of millions of sick or exposed birds - primarily chickens - have been destroyed. In many cases, affected farms were also quarantined. The WHO considers this approach the first-line defense against avian viruses. 2. Surveillance programs: Some nations have instituted strict vaccination and surveillance programs for poultry farms and markets, taken steps to prevent bird smuggling, and put in place programs that quarantine new birds until they’re proved healthy and that require poultry farmers to disinfect boots and tires. 3. Banned birds: Many countries have banned or restricted the importation of birds and hatching eggs from regions with bird flu epidemics. In February 2004, the CDC banned the importation of poultry into the United States from most Asian nations. Recommendations for travelers: If you’re traveling to Southeast Asia or to any region with bird flu outbreaks, consider these public health recommendations: 1. Avoid domesticated birds: If possible, avoid rural areas, small farms and especially any close contact with domesticated fowl. 2. Avoid open-air markets: These can be colorful or dreadful, depending on your tolerance level, but no matter how you see them, they’re often breeding grounds for disease. 3. Wash your hands: This is one of the simplest and best ways to prevent infections of all kinds. When you’re traveling, alcohol-based hand sanitizers, which don’t require water, are an excellent choice. They are easy to use, safe for children, and they can be more effective than soap and water in killing bacteria and viruses that cause disease. Not all hand sanitizers are created equal, however. Some “waterless” hand sanitizers don’t contain alcohol or have enough alcohol to kill germs. Use only hand sanitizers containing at least 60 percent alcohol. 4. Watch your kids: Keep a careful eye on young children, who are likely to put their hands in their mouths & who may not wash thoroughly. 5. Steer clear of raw eggs: Because eggshells are often contaminated with bird droppings, avoid mayonnaise, hollandaise sauce, ice cream, and any other foods containing raw or undercooked eggs. 6. Ask about a flu shot: Before traveling, ask your doctor about a flu shot. It won’t protect you specifically from bird flu, but it may help reduce the risk of simultaneous infection with bird and human flu viruses. 7. Preparing poultry: Because heat destroys avian viruses, WHO officials don’t consider cooked poultry a health threat. Even so, it’s best to take precautions when handling and preparing poultry, which is often contaminated with salmonella or other harmful bacteria. 8. Wash well: Carefully wash cutting boards, utensils and all surfaces that have come into contact with raw poultry in hot, soapy water. Wash your hands thoroughly before and after handling poultry and dry them with a disposable towel. 9. Cook thoroughly: Cook chicken until the juices run clear, and it reaches a minimum internal temperature of 165 F. Courtesy: Mayo Foundation for Medical Education & Research (MFMER) Source: Content provided by MayoClinic.com (A little edited) |
| Treatment | Treatment: Several bird flu vaccines are in the works, and at least one may be available in early 2007. Although that vaccine seems to protect against the H5N1 strain currently circulating, it’s not known whether it will be effective against a mutated form. For now, the primary treatment option remains the flu drug oseltamivir (Tamiflu), that works by preventing the virus from escaping its host cell. It’s not clear how effective Tamiflu will ultimately prove against H5N1. In Southeast Asia, resistance to it seems to be developing quickly. Another antiviral flu drug, zanamivir (Relenza), may be an alternative. These drugs must be taken within two days after the appearance of symptoms, something that may prove logistically difficult on a worldwide scale, even if there were enough to go around. Because they’re in short supply, it’s not entirely clear how flu drugs would be allocated if there were a widespread epidemic. |
| Complications | Complications: People with the most virulent type of bird flu virus - H5N1 - may develop life-threatening complications, particularly viral pneumonia and acute respiratory distress syndrome, the most common cause of bird flu-related deaths. But the greatest complication of bird flu is still hypothetical - the emergence of a new viral strain that spreads easily from person to person. If a person were simultaneously infected with human and bird flu viruses, the reassortment of genetic material could produce an entirely new subtype with a preponderance of human genes. This could make the virus highly contagious and, with little natural immunity among the world population, specially lethal. So far this hasn’t happened. A few cases of person-to-person transmission have occurred, but they were limited in scale. Still, some health officials fear that it’s just a matter of time before avian viruses figure out a way to spread easily among people. |
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