AVIAN INFLUENZA

What is Avian Influenza?

Avian (bird) influenza (flu) is a viral infection caused by strains of influenza that occur normally among birds. Wild birds worldwide carry the viruses in their intestines, but usually do not get sick from them. However, bird flu is very contagious among birds and can make some domesticated birds, including chickens, ducks, and turkeys, very sick and kill them.

Is it certain that avian influenza virus will cause a global pandemic?

No, this is not at all certain. First, not everyone who comes in contact with the virus will develop influenza.  Typically, influenza infects between 15-40% of those who come into contact with the virus.  In addition, the current avian influenza virus would probably have to change so that person-to-person transmission was efficient. Even in that case, a global pandemic is not certain.

What’s the difference between an epidemic and a pandemic?

An epidemic takes place when an infection spreads quickly at one time within a population area. A pandemic can quickly spread all over the world, infect far greater numbers of people, and could take a much longer time to run its course- perhaps months, or even years.

What is the difference between Influenza (Flu) and the common cold?

Influenza is a contagious respiratory illness caused by the influenza viruses.

The Flu and cold have similar symptoms but it is far more dangerous than the common cold. 

Flu is characterized by high fever (39° - 40°C), headaches, severe cough, extreme fatigue, dry cough, muscle aches sore throat runny/stuffy nose and in some cases stomach symptoms e.g. nausea, vomiting and diarrhoea especially in children. The symptoms of a common cold tend to be shorter and complications like pneumonia are experienced rarely.

Flu generally spreads when an infected person coughs or sneezes, sending infectious droplets of moisture into the air for others to breathe. A person also can catch the flu by touching a surface where those droplets have fallen- for example, a public telephone or doorknob- or by shaking hands with others who carry the infected droplets on their hands.

How does seasonal flu, pandemic flu and avian flu compare with one another?

Seasonal flu follows predictable patterns; it comes every year, usually in winter or the cold season. Seasonal flu symptoms can range from mild to severe, and in some cases they cause death

Although pandemic flu is rarer—it has happened only three times in the past century—it is far more serious. Experts predict that a new pandemic flu outbreak could infect millions of people around the world and kill a large percentage of those infected.

Avian flu is a dangerous virus with the potential to become a pandemic. The virus, which scientists have named H5N-1, first appeared in Hong Kong in 1997. Most cases of avian flu have resulted from close human contact with infected poultry such as chickens, turkeys, or ducks. Of the few cases involving the H5N-1 virus that have crossed from bird to humans, this virus has caused the greatest number of reported cases of severe disease and death in humans. In fact, about half of all people known to have contracted avian flu have died from it.

To date, there have been only a few reports of one infected person infecting another person. Scientists are worried, however, that the virus may change and mutate, become highly contagious, and spread easily from person to person. No one can predict when or if this will happen.

Why is pandemic flu so much more dangerous than seasonal flu?

Our health care system is generally able to handle seasonal flu, and current vaccines are effective in controlling it. Most adults build up some immunity against seasonal flu over the years, lowering their risk for serious flu-related problems. Pandemic flu, on the other hand, would come from a new strain of virus not seen before. People would have no immunity against this new virus.

Because there is no vaccine for preventing pandemic flu at this time, scientists believe pandemic flu could be far more dangerous than seasonal flu, especially as it affects the respiratory system.

Faced with a huge surge in the numbers of infected patients needing care, health care facilities could have difficulty meeting patient needs. Most facilities would experience staff shortages due to illness from pandemic flu, and most would lack space for isolating large numbers of infected patients.

Can flu be prevented?

Annual flu vaccinations can help prevent much of the illness and death related to seasonal influenza. That is because scientists usually have a good idea of the type of flu expected each year and can prepare vaccines to protect against it.

We do not yet have a vaccine that is known to be effective against a potential outbreak of pandemic flu. Experts believe that a pandemic flu will involve strains of virus not seen before. Therefore, pandemic flu will be harder to protect against.

How do treatments for each type of flu differ?

Our healthcare system manages seasonal flu with programs to vaccinate the population against flu and with a number of antiviral medications for those who get the flu. With pandemic flu, many more people may become sick and require medical care. However, there may be no useful antiviral medication available for treating people with pandemic flu, or there may be only limited supplies.

Who is most at risk for serious complications from flu?

For seasonal flu, the people most at risk are:

·         Young children who have not yet built up any immunity to flu;

·         Older people whose immune systems may have weakened over time; and

·         People with various diseases and conditions such as diabetes, cancer, HIV, or those who have had organ transplants or chemotherapy treatments—or any health condition that weakens the immune system.

For pandemic flu, everyone is at risk. Health care workers and first responders would be at special risk due to exposure to large numbers of infected patients.

Why is there so much attention being paid to avian influenza?

This virus first infected people in 1997 in Hong Kong. In  late 2003 and early 2004, outbreaks of influenza H5N1 were reported among poultry in eight countries in Asia (Cambodia, China, Indonesia, Japan, Laos, South Korea, Thailand, and Vietnam) resulting in more than 100 million bird deaths in the affected countries either from the disease or from culling to try to control the outbreak.

More than 110 human infections associated with these outbreaks have been reported in Cambodia, Indonesia, Thailand, and Vietnam.

Most recently, H5 infections among birds have been reported from Russia, Kazakhstan, Mongolia and China although the infections have not been firmly verified in all locations.

Among the children that have contracted avian influenza, a large proportion has died.  UN Country Teams must be strongly engaged in control and prevention efforts.

http://www.wpro.who.int/health_topics/avian_influenza/

http://www.who.int/csr/disease/avian_influenza/en/

Why are people worried about avian influenza? 

The H5N1 virus does not usually infect humans. In 1997, however, the first case of spread from a bird to a human was seen during an outbreak of bird flu in poultry in Hong Kong. The virus caused severe respiratory illness in 18 people, 6 of whom died.

Since that time, there have been other cases of H5N1 infection among humans. Most recently, human cases of H5N1 infection have occurred in Thailand, Vietnam and Cambodia during large H5N1 outbreaks in poultry. The death rate for these reported cases has been about 50 percent. Most of these cases occurred from contact with infected poultry or contaminated surfaces; however, it is thought that a few cases of human-to-human spread of H5N1 have occurred.

So far, spread of H5N1 virus from person to person has been rare and spread has not continued beyond one person. However, because all influenza viruses have the ability to change, scientists are concerned that the H5N1 virus could one day be able to infect humans and spread easily from one person to another. Because these viruses do not commonly infect humans, there is little or no immune protection against them in the human population.

If the H5N1 virus were able to infect people and spread easily from person to person, an “influenza pandemic” (worldwide outbreak of disease) could begin. No one can predict when a pandemic might occur. However, experts from around the world are watching the H5N1 situation in Asia very closely. There were pandemics of new flu strains before, most recently in 1968.

How is avian influenza spread?

Among birds, infected birds are thought to contaminate the environment by shedding virus in their feces. However, some avian viruses appear to also be spread among birds by respiratory transmission.

The exact way that people get infected by avian influenza viruses is not clear, but most cases appear to involve direct contact between the person and the infected bird.

For more information on animal transmission see:  http://www.oie.int/eng/AVIAN_INFLUENZA/Disease%20card.pdf

Can bird (Avian) viruses infect humans?

Bird flu viruses do not usually infect humans, but several cases of human infection caused by different kinds of bird flu viruses have occurred since 1997. Occasionally the virus jumps from infected birds or their infected material (bird’s droppings) to human beings. However, even though there are large epidemics of the disease amongst birds, there are very few human beings who have suffered from the infection.

What is the treatment for bird flu in humans?

The current H5N1 viruses appear to be sensitive to two other antiviral medications, oseltamavir and zanamavir, that have direct effect on influenza viruses. Many (but not all) of the current viruses appear to be resistant to two different antiviral drugs. Although oseltamivir and zanamivir should be effective when used early, there is still very little direct experience with these drugs when used to treat people ill with the H5N1 virus.

Is there a vaccine to protect humans from H5N1 virus?

No.  There is currently no commercially available vaccine to protect humans against the H5N1 virus. Vaccine development efforts are under way. However, research studies are being carried out in several countries in this regard.

What is being done to stop bird flu?

The UN and national governments are working together to address the problem of avian influenza. There are several main activities under way.

• Efforts to control the infection among poultry.
• Efforts to reduce the possibility that humans will be exposed to and infected by avian influenza, and
• Efforts to prepare for wide-spread infection in humans if the avian virus control efforts fail and the virus should gain the ability to spread easily among people.

The WHO has appointed Dr. Margaret Chan as Chief of Pandemic Influenza to coordinate WHO's efforts. Previously as director of the Hong Kong, China, health department, she directed its response to two major disease outbreaks that threatened the world's health and economy, avian influenza and SARS.

Animal Control: Since the virus predominately infects birds, the most important first step in stopping bird flu is to identify and arrest the spread of the virus in birds.  Affected national agricultural and veterinarian departments are working closely with FAO, the Organization for Animal Health (OIE), WHO, the World Bank and others to quickly set-up and strengthen monitoring systems that rapidly identify sick birds and destroy them.  Combinations of surveillance, quarantine, destruction of sick birds and vaccination of poultry are some of the steps being taken to stop the virus from spreading.

Human health controls: WHO is coordinating the UN portion of international response in this area. Because avian influenza and pandemic influenza both pose threats to people, WHO is working with governments and other partners to improve monitoring of influenza viruses and infections in people, on increasing the availability of antiviral drugs and reducing the time needed to make bird flu vaccines, and development of contingency plans.