Wild birds unlikely culprits in Nigeria bird flu outbreak
On 8 February, an outbreak of the deadly form of Avian Influenza (H5N1) was confirmed in poultry farms in Nigeria: the first country in Africa to be affected.
Various officials and media suggest that the flu was transported to Nigeria by migratory waterbirds. This does not seem likely though, given that the timing of this outbreak is three months after their arrival, and the region of Northern Nigeria concerned is some distance from the nearest wetland complex used by large numbers of these species. It seems more likely that the outbreak is a result of the illegal trade in infected poultry.
Trade in poultry is known to be large in scale and global in scope, but because (for very good reasons) this trade is now illegal, it is difficult to obtain exact details of its scale and extent.
Both the location of the outbreak and the timing make it unlikely that the flu was spread by wild birds. Around thirty waterbird species migrate from the infected areas in Asia and the Black Sea region to Nigeria for the winter. Three of these have been identified by Wetlands International as showing a “higher risk” to spread Avian Influenza. They are: Garganey Anas querquedula, Northern Pintail Anas acuta and Northern Shoveler Anas clypeata. A majority of these birds will have arrived in West Africa between September and November. If these birds carried the disease, it would seem reasonable to expect outbreaks earlier in the winter, soon after their arrival.
The area where the outbreak occurred is not attractive to congregations of waterbirds. The nearest sizeable wetland complex with large congregations of these species in some years, is Hadejia-Nguru, about 250-300 km north-east of the original outbreak area and 100 km east of Kano.
Many questions about the ability of wild birds to carry this disease have not yet been answered, although urgent work is ongoing. Infected birds usually seem to become very ill and weak and often die within days. Such birds cannot migrate. Some species may be able to carry the disease asymptotically.
If this is proven, then transmission would be possible at any time in a wintering population, and outbreaks such as that in Nigeria would not be unexpected. However, we do not yet know whether this is the case.
In line with earlier statements by the UN led Scientific Task Force on Avian Influenza, the Ramsar Convention, the Convention on Migratory Species, the FAO, the WHO and others, Wetlands International urges that more research is urgently needed. Also, much greater awareness of the real science based facts is needed. National preparedness plans need to be developed and a world wide system for monitoring HPAI in wild birds needs to be put in place.
The bird population of Garganey wintering in West Africa is estimated at 2 million and birds are concentrated in the Sahel zone from Senegal to Chad. The population of Northern Piintail wintering in West Africa has a similar distribution and was recently estimated at fewer than 500,000 individuals. Northern Shovelers are less numerous with perhaps 15,000 spending the winter in West Africa. Most of these birds are found at three very large wetland complexes: the lower Senegal River Basin in Senegal/Mauritania, The inner Niger Delta in Mali and the Lake Chad Basin in Chad, NE Nigeria, N Cameroon and E Niger, which is about 700 km from the recent outbreak. There are also concentrations of these waterbirds in Hadeja-Nguru in Nigeria and these birds can be found in Kano and Kaduna provinces and on the Jos Plateau, the areas initially affected by the Avian Influenza outbreak.
They are not present in the region of the outbreak large numbers, however, because these areas mark the southern edge of the limits of their distribution
It seems unlikely that poultry from the infected commercial farms has come into contract with these higher-risk migratory waterbird species, which are generally restricted to the open waters of extensive, usually remote wetlands and do not stray into villages or towns.
For several reasons culling of waterbirds, or destroying their habitats, is not an option in controlling HPAI. Such actions are immoral and in many cases illegal. Moreover, they should be regarded counter-productive as they would interfere with the normal movements of migratory birds and could lead to unpredictable dispersion of individuals. Similarly, actions to drain habitats used by wild waterbirds should not be attempted as this would lead to the diversion of migratory waterbirds into other habitats not normally used by the birds. Moreover, the wetlands these birds feed on serve many other important functions for local economies and for other animal and plant species.
Whether the Avian Influenza is spread by poultry or waterbirds, there is a risk that the two possible sources of infection infect each other. The possibility exists that domestic poultry in affected areas in Nigeria could come into contact with wild birds and transmit the virus to them before they migrate north to Europe. Precautions should therefore be taken in areas affected by this episode in Nigeria to prevent contact between domestic poultry and wild waterbirds.
The migration north of the high-risk species named above starts before the end of February. Wetlands International is particularly worried about the implications on the livelihoods of the people in Africa. For many of them, poultry is essential for their survival. A critical evaluation is needed of biosecurity standards and practices in the poultry industry in the region and immediate actions should be taken to eliminate the risk of transmission of this virus between poultry farms and from poultry to wild birds (both resident and migratory species).
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