Avian influenza: a threat to rural livelihoods, agricultural production and human health
FAO forms task force to monitor crisis, sends technical support missions to affected countries, convenes urgent meeting
Avian influenza was first identified over 100 years ago during an outbreak in Italy. Since then, the disease has cropped up at irregular intervals in all world regions. In addition to the current outbreak in Asia, recent epidemics have occurred in Hong Kong in 1997-1998 and 2003, in the Netherlands in 2003, and in the Republic of Korea in 2003.
Once domestic birds are infected, avian influenza outbreaks can be difficult to control and often cause major economic damage to poultry farmers in affected countries, since mortality rates are high and infected fowl generally must be destroyed -- the technical term is "culled" -- in order to prevent the spread of the disease.
As a result of the ongoing outbreak in Asia, FAO estimates that around 45 million birds had been culled in the region as of 2 February 2004.
This figure accounts for just over 1 percent of the region's total inventories, FAO data show. However, the impact can be devastating to local economies and to both commercial poultry operations and smallholders -- particularly in Thailand, where the industry is heavily reliant on trade.
In 2003, poultry exports from Thailand accounted for nearly 7 percent of global poultry meat trade, with an export value of approximately US$1 billion.
What is FAO doing to respond to the current crisis?
In its response to the outbreak, FAO is emphasizing safety and prevention, assistance to affected countries and cooperation with other relevant international organizations.
FAO has established an Avian Flu Technical Task Force, led by its Animal Health Service and including technical staff at its Regional Office in Bangkok, in order to closely monitor the current situation in Asia, provide FAO's country representation offices and member countries with technical support for handling the crisis and facilitate communication between relevant international organizations, such as the World Organisation for Animal Health (OIE) and the World Health Organization (WHO).
FAO is also mobilizing emergency funds that will be used to send technical support missions to affected countries. On 2 February the first four missions -- to Cambodia, the Lao People's Democratic Republic, Pakistan and Viet Nam -- received the green light.
The Organization anticipates that additional missions will follow soon after, as official requests come in from governments.
These FAO technical missions will:
- assist governments in improving the capacity of laboratories to diagnose the disease;
- strengthen countries' abilities to conduct field investigation when new reports of possible infection are received;
- begin mapping outbreaks in order to predict possible spread patterns;
- deepen public awareness of proper food handling and disposal of birds;
- offer advice regarding handling of sick birds and, in collaboration with WHO and other partners, help provide countries with the necessary protective gear.
Beyond these national missions, a regional initiative aimed at improving epidemiological surveillance and monitoring of avian influenza in the region is being prepared by FAO.
The Organization also stresses that once the current crisis subsides, countries will need assistance in safely repopulating domestic bird flocks.
Technical support missions will be coordinated by the Organization's Asia office, located in Bangkok, Thailand. FAO's Asia office is also maintaining close communication with national governments in the region as well as other relevant international organizations in order to disseminate technical advice and help coordinate international responses.
FAO representatives based in every country of the region are playing a key role in regional communication and coordination regarding the situation.
Additionally, on 3-4 February 2004, FAO convened an urgent meeting with veterinary officials from affected countries, international experts, and representatives from the OIE, WHO, the United States' Centers for Disease Control and Prevention and other organizations in order to generate more detailed guidelines and recommendations for handling the crisis at the national and international levels.
(For more on what FAO is doing to help, visit the Animal Production and Health Division's special Web site on Avian Influenza and the Asian outbreaks.)
What causes avian influenza?
Avian influenza can be caused by 1 of around 23 different strains of virus, all of which are type A members of the Orthomyxoviridae virus family. However, serious outbreaks such as that currently affecting Asia usually involve only the H5 and H7 strains. These are highly pathogenic -- that is, easily spread -- and cause system-wide problems for infected birds; other strains mainly affect birds' respiratory systems and are neither as contagious nor as fatal as H5 and H7.
Domestic fowl and wild birds alike are susceptible to avian influenza. The virus is in all likelihood extremely widespread in wild populations, in much the same way that the Herpes Simplex A virus, which causes cold sores, is widespread among humans: Infection is common, but symptoms are mild and nonlethal. Fatal outbreaks occur most frequently in domestic fowl -- which are not as resistant to the virus -- when a pathogenic strain emerges in a wild flock and there is contact between the two populations.
Once avian influenza is established in a domestic flock, it is highly contagious and wild birds are no longer an essential ingredient for spread, notes FAO. Infected birds excrete the virus in high concentrations in their faeces and discharges from the nose and eyes. Once introduced into one flock, the virus can spread to others through the movement of infected birds and contaminated equipment, egg flats, feed trucks or service crews.
The signs of avian influenza infection vary from case to case and are influenced by factors such as the virulence of the infecting strain, the bird species involved and the age and sex of infected fowl. The incubation period is usually three to seven days.
In virulent avian influenza, the disease usually appears suddenly, with many birds dying either without warning or after giving only small signs of distress: lack of appetite, ruffled feathers, fever.
But this pattern can vary.
Sometimes, birds show weakness and a staggering gait. Hens may lay soft-shelled eggs and then stop laying. Sick birds may sit or stand in a semi-comatose state with their heads touching the ground. Combs and wattles might be blue and puffy with some slight haemorrhaging at their tips. Profuse diarrhoea is frequently present, and birds are excessively thirsty. Respiration may be laboured.
The mortality rate for infected domestic fowl ranges from 50 to 100%. In addition to bird die-offs, control of outbreaks requires that infected animals be killed, and that other control measures are enacted -- these losses and extra costs mean a serious economic squeeze for affected farmers.
Responses to outbreaks need to be tailored to local conditions; there is no silver bullet for all situations and places.
In the face of sudden, multiple outbreaks like those in China, the first step is raising biosecurity levels to order to contain breakouts and prevent their spread.
Practically, this means imposing immediate, temporary bans on shipments of birds in affected regions and countries, destruction of infected animals, and disinfection of facilities where infection occurred.
People working on farms or participating in eradication programmes such as the culling of sick birds should avoid close contact with the animals and should wear protective clothing.
Vaccines do exist that have been demonstrated to be effective in reducing mortality or preventing disease, or both, in chickens and turkeys.
Experts at the meeting in Rome on 3-4 February agreed that a targeted vaccination campaign for poultry at risk of being infected may be required in heavily affected countries to control the further spread of the epidemic. They emphasized that culling infected flocks remains the recommended response when the disease is detected, but added that vaccination, when used together with other control measures and appropriate surveillance, offers a suitable means to reduce the incidence of new cases and viral load in the environment and thereby reduce the potential of the disease spreading to humans.
On a long-term basis, says FAO, prevention is key, and relies on good farming practices, veterinary and human health surveillance programmes that can sound the alarm at the first sign of infection, and mechanisms that allow for a rapid response to contain localized outbreaks.
Avian flu and humans
Avian influenza poses serious human health risks as well. It is a zoonotic illness -- native in animal populations but capable of being passed to humans via direct contact with infected birds.
But even during serious outbreaks the virus rarely affects large numbers of people. Still, as the number of infected people increases, so too does the possibility that a new virus strain might evolve from an exchange between human influenza and avian flu genomes.
As of 28 January 2004, WHO was not recommending any restrictions on travel to countries experiencing outbreaks of H5N1 avian infection in poultry flocks, including countries that have also reported cases in humans. WHO does recommend that travellers to areas experiencing outbreaks of this disease in poultry should avoid contact with live animal markets and poultry farms.
FAO's Animal Health Service has prepared an extensive list of answers to Frequently Asked Questions about bird flu that cover these and other issues in greater deal. Use the links that appear to the right to locate this and other information about the disease and FAO efforts to assist countries experiencing outbreaks of the virus.
6 February 2004
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