Bird flu: Deadlier than Sars
http://www.sunstar.com.ph/static/dav/2005/02/01/feat/bird.flu.deadlier.than.sars.html
Tuesday, February 01, 2005
By Henrylito D. Tacio
Health 101
MORE lethal than Sars virus." That's how the Geneva-based World Health Organization (WHO) described the bird flu--known technically as avian influenza--that is currently taking its toll in Asia, particularly China, Thailand and Vietnam. And if a pandemic breaks out, up to 100 million people could die within weeks.
"It will be incomparable to Sars," said WHO's regional director of Western Pacific Shigeru Omi, referring to the Severe Acute Respiratory Syndrome epidemic that killed 800 people around the world in 2003. There were three pandemics in the 20th century. The "Spanish flu" pandemic of 1918 and 1919 killed upwards of 20 million people. The "Asian flu" of 1957 and 1958 left 70,000 Americans dead. From 1968 to 1969, some 34,000 Americans died as a result of the "Hong Kong flu."
"(Bird flu) will come," Dr. Omi said in a press conference in Hong Kong last year. However, he added, it was impossible to predict when a pandemic would happen but said it would not take long to reach all corners of the globe. "Before it would have taken a year to spread around the world but thanks to globalization it will take just weeks."
The first bird flu outbreak was reported in 1997 in Hong Kong; 18 people were hospitalized and 6 of them died. Last year, two huge outbreaks occurred again in Asia, killing 32 people in Vietnam and Thailand. "The more we have these frequent outbreaks, the higher the risk is that the virus would change and become more contagious and be easily spread among humans," said Hans Troedsson, WHO representative in Vietnam.
Flu, also known as influenza, is a contagious disease that is caused by a virus. It attacks the respiratory tract in humans (nose, throat, and lungs). The flu usually starts suddenly and may include these symptoms: fever (usually high), headache, extreme tiredness, cough, sore throat, runny or stuffy nose, and body aches. Diarrhea and vomiting also can occur but are more common in children. "These symptoms are referred to as 'flu-like symptoms,'" the Atlanta-based CDC says. "A lot of different illnesses, including the common cold, can have similar symptoms.
The first flu virus was identified in the 1930s. Since then, scientists have classified influenza viruses into types A, B, and C. Type A is the most common and usually causes the most serious epidemics. Type B outbreaks also can cause epidemics, but the disease it produces generally is milder than that caused by type A. Type C viruses, on the other hand, never have been connected with a large epidemic.
Type A has been identified as the virus that caused the bird flu. Type A influenza A viruses are divided into subtypes on the basis of their surface proteins--hemagglutinin (HA) and neuraminidase (NA). Science says there are 15 known H subtypes. While all subtypes can be found in birds, only 3 subtypes of HA (H1, H2 and H3) and two subtypes of NA (N1 and N2) are known to have circulated widely in humans.
H5N1 is how the medical experts called the bird flu virus. "Avian flu virus usually does not make wild birds sick, but can make domesticated birds very sick and kill them," the WHO informs. H5N1 do not usually infect humans; however, several instances of human infections and outbreaks have been reported since 1997.
"Bird flu is especially pernicious to humans because we lack the necessary immune protections against the disease," the CDC claims. The reported symptoms of bird flu in humans have ranged from typical flu-like symptoms (e.g., fever, cough, sore throat and muscle aches) to eye infections, pneumonia, acute respiratory distress, viral pneumonia, and other severe and life-threatening complications.
Recent studies showed that the prescription medications approved for human flu strains would be effective in preventing bird flu infection in humans, however, sometimes flu strains can become resistant to these drugs and so they may not always be effective. Experts say flu pandemic will emerge from an animal, most probably a pig, which can harbor both flu viruses that affect humans and the bird flu variety. The two would mate and produce a virus to which people have no immunity, they say.
That has not happened yet, but Dr. Omi said the geographical spread and the impact of the H5N1 virus was unprecedented and had struck animals such as tigers and domesticated cats not previously known to be susceptible to bird flu viruses. "We have found that the virus is resilient, very, very versatile," he said.
Here's a bit of good news. Two American companies and a Japanese firm are working on a vaccine against H5N1 and clinical trials on its efficacy and safety have begun. A vaccine is currently on clinical trials in Thailand.
However, Dr. Omi cautioned people against thinking that vaccines were a cure-all. "Vaccine will protect you from the disease and reduce the impact individually. But vaccination alone will not prevent this outbreak," he said.
http://www.sunstar.com.ph/static/dav/2005/02/01/feat/bird.flu.deadlier.than.sars.html
Tuesday, February 01, 2005
By Henrylito D. Tacio
Health 101
MORE lethal than Sars virus." That's how the Geneva-based World Health Organization (WHO) described the bird flu--known technically as avian influenza--that is currently taking its toll in Asia, particularly China, Thailand and Vietnam. And if a pandemic breaks out, up to 100 million people could die within weeks.
"It will be incomparable to Sars," said WHO's regional director of Western Pacific Shigeru Omi, referring to the Severe Acute Respiratory Syndrome epidemic that killed 800 people around the world in 2003. There were three pandemics in the 20th century. The "Spanish flu" pandemic of 1918 and 1919 killed upwards of 20 million people. The "Asian flu" of 1957 and 1958 left 70,000 Americans dead. From 1968 to 1969, some 34,000 Americans died as a result of the "Hong Kong flu."
"(Bird flu) will come," Dr. Omi said in a press conference in Hong Kong last year. However, he added, it was impossible to predict when a pandemic would happen but said it would not take long to reach all corners of the globe. "Before it would have taken a year to spread around the world but thanks to globalization it will take just weeks."
The first bird flu outbreak was reported in 1997 in Hong Kong; 18 people were hospitalized and 6 of them died. Last year, two huge outbreaks occurred again in Asia, killing 32 people in Vietnam and Thailand. "The more we have these frequent outbreaks, the higher the risk is that the virus would change and become more contagious and be easily spread among humans," said Hans Troedsson, WHO representative in Vietnam.
Flu, also known as influenza, is a contagious disease that is caused by a virus. It attacks the respiratory tract in humans (nose, throat, and lungs). The flu usually starts suddenly and may include these symptoms: fever (usually high), headache, extreme tiredness, cough, sore throat, runny or stuffy nose, and body aches. Diarrhea and vomiting also can occur but are more common in children. "These symptoms are referred to as 'flu-like symptoms,'" the Atlanta-based CDC says. "A lot of different illnesses, including the common cold, can have similar symptoms.
The first flu virus was identified in the 1930s. Since then, scientists have classified influenza viruses into types A, B, and C. Type A is the most common and usually causes the most serious epidemics. Type B outbreaks also can cause epidemics, but the disease it produces generally is milder than that caused by type A. Type C viruses, on the other hand, never have been connected with a large epidemic.
Type A has been identified as the virus that caused the bird flu. Type A influenza A viruses are divided into subtypes on the basis of their surface proteins--hemagglutinin (HA) and neuraminidase (NA). Science says there are 15 known H subtypes. While all subtypes can be found in birds, only 3 subtypes of HA (H1, H2 and H3) and two subtypes of NA (N1 and N2) are known to have circulated widely in humans.
H5N1 is how the medical experts called the bird flu virus. "Avian flu virus usually does not make wild birds sick, but can make domesticated birds very sick and kill them," the WHO informs. H5N1 do not usually infect humans; however, several instances of human infections and outbreaks have been reported since 1997.
"Bird flu is especially pernicious to humans because we lack the necessary immune protections against the disease," the CDC claims. The reported symptoms of bird flu in humans have ranged from typical flu-like symptoms (e.g., fever, cough, sore throat and muscle aches) to eye infections, pneumonia, acute respiratory distress, viral pneumonia, and other severe and life-threatening complications.
Recent studies showed that the prescription medications approved for human flu strains would be effective in preventing bird flu infection in humans, however, sometimes flu strains can become resistant to these drugs and so they may not always be effective. Experts say flu pandemic will emerge from an animal, most probably a pig, which can harbor both flu viruses that affect humans and the bird flu variety. The two would mate and produce a virus to which people have no immunity, they say.
That has not happened yet, but Dr. Omi said the geographical spread and the impact of the H5N1 virus was unprecedented and had struck animals such as tigers and domesticated cats not previously known to be susceptible to bird flu viruses. "We have found that the virus is resilient, very, very versatile," he said.
Here's a bit of good news. Two American companies and a Japanese firm are working on a vaccine against H5N1 and clinical trials on its efficacy and safety have begun. A vaccine is currently on clinical trials in Thailand.
However, Dr. Omi cautioned people against thinking that vaccines were a cure-all. "Vaccine will protect you from the disease and reduce the impact individually. But vaccination alone will not prevent this outbreak," he said.