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09.03.2006 Health

What we need to know about Bird Flu

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A GNA Feature by Sumaila Seidu Saaka wit inputs by Dr Emmanuel Ahiable

Mampong (Ash), March 9, GNA - The continued spread of the deadly H5N1 strain bird flu across the world has become a source of concern to many individuals, local and national authorities in government and public health, the media as well as other civil society groups. It is even more worrying for the developing countries with weak health infrastructure and low ability to respond.

Until the presence of the H5N1 virus in Nigeria and Egypt, previous cases were confined to Asia and Europe. India, France and Iran have become the latest countries to confirm new cases.

The interesting thing is that wild birds that are responsible for the spread of the virus are universal travellers that do not need passports or visas to cross borders. Thus, in effect, every country is vulnerable. It is for this simple reason that there is the need to know a few facts about this deadly virus.

Avian influenza is an infection caused by avian (bird) influenza (flu) viruses. These influenza viruses, according to scientists, occur naturally among birds. Wild birds worldwide carry the viruses in their intestines, but usually do not get sick from them. However, avian influenza is very contagious among birds and can make some domestic birds, including chickens, ducks and turkeys, very sick and kill them. Infected birds shed influenza virus in their saliva, nasal secretions, and faeces. Susceptible birds become infected when they have contact with contaminated secretions or excretions or with surfaces that are contaminated with secretions or excretions from infected birds. Domestic birds may become infected with avian influenza virus through direct contact with infected waterfowl or other infected poultry, or through contact with surfaces (such as dirt or cages) or materials (such as water or feed) that have been contaminated with the virus.

Infection with avian influenza viruses in domestic poultry causes two main forms of disease that are distinguished by low and high extremes of virulence. The "low pathogenic" form may be undetected and usually causes only mild symptoms, such as ruffled feathers and a drop in egg production. The "highly pathogenic" form, on the other hand, spreads more rapidly through flocks of poultry. This form may cause disease that affects multiple internal organs and has a mortality (death) rate that can reach 90 per cent to 100 per cent often within 48 hours.

Human Infection with Avian Influenza Viruses

Usually, "avian influenza virus" refers to influenza "A" viruses found chiefly in birds, but infections with these viruses have occurred in humans. The risk from avian influenza is generally low to most people, because the viruses do not usually infect humans. However, confirmed cases of human infection from several sub-types of avian influenza have been reported since 1997. Most cases of avian influenza infection in humans have resulted from contact with infected poultry (for instance, domestic chicken, ducks and turkeys) or surfaces contaminated with secretion/excretions from infected birds. The spread of avian influenza viruses from one ill person to another has been reported very rarely, and transmission has not been observed to continue beyond one person.

According to the United States Centre for Disease Control and Prevention (CDC), during an outbreak of avian influenza among poultry, there is a possible risk to people who have contact with infected birds or surfaces that have been contaminated with secretions or excretions from infected birds.

Symptoms of avian influenza in humans have ranged from typical human influenza-like symptoms; such as fever, cough, sore throat, muscle aches, eye infections, pneumonia, severe respiratory diseases and other severe and life-threatening complications. It is, however, important to note that the symptoms of avian influenza may depend on which sub-type of the virus caused the infection.

Avian Influenza A (H5N1)

Influenza "A" (H5N1) virus - also called "H5N1 virus" - is influenza "A" virus sub-type that occurs mainly in birds. It is highly contagious among birds, and can be deadly. The H5N1 strain of bird flu does not usually infect people, but infections with these viruses have occurred in humans since 2003. Most of the recent reported cases have occurred among people having direct or close contact with H5N1 - infected poultry or H5N1-contaminated surfaces.

Human Health Risks during H5N1 outbreak

Of the few avian influenza viruses that have crossed the species barrier to infect humans, H5N1 has caused the largest number of detected cases of severe disease and death in humans. In the current outbreaks in Asia, Europe and Africa, more than half of the people infected with the virus have died. As has been reported, the H5N1 strain that emerged in 2003 has claimed the lives of at least 90 people worldwide. Majority of cases have occurred in previously healthy children and young adults. However, scientists contend that it is possible that the only cases currently being reported are those in the most severely ill people, and that the full range of illness caused by the H5N1 virus may not as yet been established.

Again, the spread of H5N1 virus from person to person has been limited and has not continued beyond one person. Nonetheless, because all influenza viruses have the ability to change, scientists are concerned that H5N1 virus if allowed to mutate could infect humans and spread easily from one person to another. It is even more worrying in that because these viruses do not commonly infect humans, there seems to be little or no immune protection against them in the human population. Besides, if the H5N1 virus were to gain the capacity to spread easily from person to person, an influenza pandemic (worldwide outbreak of disease) cannot be ruled out. It is difficult to predict when a pandemic might occur. However, experts from around the world are watching the H5N1 situation as it is now, very closely and are preparing for the possibility that the virus may begin to spread more easily and widely from person to person. Individual countries, including Ghana, are also developing preparedness strategies to contain any eventuality.

About The Authors

Dr Emmanuel Ahiable is the Medical Superintendent of the Asante Mampong Government Hospital and Mr Sumaila Seidu Saaka is a Journalist, specialising in Population and Health Communication. The material for the article was largely drawn from the CDC pandemic influenza website.

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