Managing future epizootics of Human Pathogenic Avian Influenza (HPAI) in Nigeria

The control of epizootics of avian influenza should not rely absolutely on the enforcement and application of phytosanitary regulations (such as culling of infected or suspected birds), with improved biosecurity measures alone, as this may not ensure full proof control of the disease, especially in developing countries with poorer financial resources.

The enforcement policy of “stamping out“ for AI was drafted by OIE in 1980, but enacted in 1992, and it is no more absolutely adequate in view of upcoming challenges, scientific breakthrough, and the growth that had taken place in the industry worldwide.


THE CHALLENGES:

Such challenges include among others, the following:

These changes make poultry disease control more difficult by the application of phytosanitary measures alone. Similarly, the massive destruction of large population of birds may not be too ethical especially if we consider the negligible human health implications so far recorded in the various epizootics.

 So far, statistical information available showed that from December 1999 to April 2003 50 million birds were depopulated after HPI epizootics in European Union ref (Ilara Capua internet lecture on the challenges of avian influenza epizootics, September 2006).

The Nigeria outbreak resulted in the depopulation of about 1 million birds without any reported fatalities in man.

OIE and WHO data showed that reported human fatalities to HPAI had not recorded up to 100 fatalities when compared with million of people that die annually of malaria and of water-born diseases in Africa and other Third World Countries.

                                     
GLOBAL VIEWS:

Unfolding development by OIE points towards a policy shift from a solo strategy of stamping out to a mixed strategy that emphasize prevention by a synergy of emergency depopulation and prophylactic vaccination.

Ilara Capua, an internationally renowned expert from OIE, who had been working on global issues and management of Avian Influenza epizootics, emphasized in her web seminar of 13/sep 2006 widely viewed all over the world, for a need to change preventive strategy from mere stamping out to adopting vaccination as a synergy.

Ilara Capua believes that Biosecurity must be the first line of defenses mechanism, which must be strictly emphasized on individual farm basis.

It is in fact a fire wall against an incoming predator. However she noted that in most cases, social, economic and agricultural practices could make biosecurity measures sometimes too difficult to maintain. She concluded that a holistic control of AI has no universal solution but must embrace a multi strategy of:

She suggested that vaccination policy should adopt the DIVA 2000 strategy with its ramifying epidemiological advantages.

World AI historical analysis by this author in 2006, of initial notifications and follow up cases of Avian Influenza in 55 countries of the world, including Nigeria, Niger, Sudan, Burkina Faso and Cameroon all in the west and North Africa showed that H5 type of outbreaks were all reported between February and March 2006, pointing towards a peculiar factor in the epidemiology of this deadly and zootoxic diseases of poultry.

This analysis must also serve a historic signal in future management of possible AI outbreak.

Though the profile of the 55 countries showed earlier notification and massively reported outbreaks in countries of South East Asia and China, with pockets outbreaks in Europe, it is however worrisome to observe that of the 12 new notifications in the report, 58.3% came from Africa. This analysis must be of major concern to Africa and especially the West Africa sub region in her approach to the management of future challenges of these deadly and zoonotic diseases of poultry.

Africa countries must show a more pragmatic approach to issues of avian influenza by adapting an all embracing holistic strategy in her National, Regional, and continental policy formulation to the prevention of these zoonotic diseases of poultry.


VACCINATION AS A SYNERGYSTIC OPTION

Original concept

The original concept of vaccination was not all that popular, because of its inability to differentiate a vaccinated flock from a healthy flock as well as a vaccinated flock from an infected flock.

This reason was responsible for the placement of bans on countries enforcing vaccination policy. Using the Low egg passage (LEP) and the High egg passage (HEP) of vaccines.


New concept

However, a new concept referred to as DIVA 2000 based on the use of heterologous oil emulsion killed AI vaccines enables us to differentiate vaccinated stock from unvaccinated stock. The concept was developed in Italy and it is today the only successful method of vaccination and clinical evaluation for AI monitoring.

It was reported by OIE that between 2000 - 2003 this method successfully eradicated two epidemics in Italy.


THE DIVA 2000 STRATEGY:

The DIVA 2000 strategy is a new concept that adopt the use of inactivated oil emulsion heterologous vaccine, this strategy is evolving a break through in Trade movement of birds as flock could be demonstrated to be free of infection, vaccinated, or even as stock carrying convalescent antibodies to natural infection. Every country that is serious with its sero epidemiological investigation and monitoring of its boarder at point of entries to its territory, need to adopt this method of vaccination with its accompanied diagnostic kits.

It had proved satisfactory in Italy in eradicating two epidemics of AI with the involvement of improved biosecurity and sero monitoring. OIE explains the advantage of using inactivated homologous and heterologous vaccine and recommended thatvaccination option for AI, must ensure and adequate National stocking of vaccine Banks availability of companion diagnostics kits for field veterinarians.


SITUATION IN ASIA WITH LEP AND HEP VACCINES:

Efforts at controlling AI infection in Asia with H5 and H6 y homologous and recombinant still required persistent and strict monitoring. Though did protect against clinical signs and mortality, the viruses were still found to replicate in clinical healthy vaccinated birds. This was the risk encountered with the use of a low passage AI (LPA1) and high passage AI (HPAI) vaccines. Report showed that the first outbreak in Hong Kong was sequel to LEP/HEP AI vaccines in 2002. However this event has since been overtaken by the DIVA 2000 concept of the use of inactivated oil emulsion vaccine.

Vaccination alone may not be adequate for a national control of epizootic except with strict biosecurity procedures, like farm depopulation, which must be efficiently coordinated by the establishment of National or state “AI crisis control unit” zoonotic diseases of poultry.


PROPOSED NATIONAL CONTROL POLICY FOR NIGERIA

Despite the last ravaging effect of the out break of H5N1 in Kaduna state, and specifically at Igabi local Government where the disease ravaged about 46000 birds of mixed species, more outbreaks had since occurred in other states of Nigeria.

Economic assessment of the recent outbreak in Nigeria put the estimated market losses of the last outbreak to about 14 billion naira within the first 4 weeks of the epizootics (PAN economic assessment).

National strategy for the control of these epizootics had relied absolutely on stamping out, an uncoordinated porous biosecurity and unscientific sanitary measures by most poultry farmers in Nigeria.

Except in some few cases, most biosecurity measures by poultry farmers are very porous and highly deficient in their efficacy assessment.

Most rural farmers in Nigeria are still ignorant of the essence of strict biosecurity, as most farmers have not grasped the import of biosecurity as the first line of defenses in the epidemiological control of avian influenza.

The choice of appropriate disinfectant, and the control of mobile and nutritional factors in the management of the disease prevention, is still alien to many farms.

There is no doubt that a lot still needed to be done in educating our farmers on these vital issues, rather than the too much emphasis been shifted to compensation and loan disbursement.

International NGO wishing to assist Nigeria must focus more on these aspects to which we are prepared to collaborate.

So far, the Federal Republic of Nigeria had not approved vaccination as a synergistic option to phytosanitary measures of stamping out and depopulation.

I strongly believe that government initial posture of indecision on vaccination and the urge on investors to protect their investment had led to unscrupulous inflow of live homologous AI vaccines rather than the approved oil emulsion vaccines that would have been controlled by government.

In my position paper to the Veterinary Council of Nigeria of which a copy was forwarded to the ministry of Agriculture Oyo state, I strongly proposed the need for government through its various director of veterinary services to create vaccine banks of oil emulsion heterologous vaccines, with the diagnostic DIVA 2000 KITS as reserve strategic stock and ready tools to protect and diagnose unchallenged and challenged farms in the vicinity or areas where outbreak had been reported, while the nucleolus farm alone, should be stamped out.

This strategy would have helped to limit spread of the infection while adjacent farms would have been solidly protected.

The fear with the current strategy of stamping out is the perpetual subjection of our poultry farmers to an on going psychological phobia of a likelihood of an outbreak and a subsequent economic devastation imminent of such outbreak for which developing countries have limited financial resources to manage and compensate.

Beside, lack of appropriate definitions of approved phytosanitary actions at our defined and designated buffer zone could have been partially responsible for the fast downward spread of AI Epizootic to the main producing regions of Nigeria.

Though vaccination alone may not be adequate for a national control of epizootic except with strict biosecurity procedures, like farm depopulation, it must be efficiently coordinated by the establishment of National or state “AI crisis control unit”.


THE WAY FORWARD:

Nigeria Government should fund and support Advocacy group on massive education of poultry farmers and live birds sellers on bio security and health tips aimed at minimizing the risks of epidemics.

Federal Government must overhaul and re evaluate its current control measures that rely on stamping out and defective policing of porous control posts all over the country. As a matter of urgency and as a proactive strategy against a future risk of outbreak in the upcoming year, preventive policy must embrace strategic and monitored vaccination, with availability of vaccine banks of oil emulsion heterologous vaccines to be managed by the directorate of veterinary services of the state governments and Abuja Territory under the National supervision of the federal ministry of agriculture, veterinary division.

Adequate stocking of the DIVA 200 KIT to be widely distributed to poultry veterinarians will serve as a vital tool to readily identify presence of the virus in flocks with the responsibility of immediate notification to appropriate government officers.

Banks and other financial institutions should show more interest in the management of risks that are inherent, or may accompany the policy of compulsory funding of Agriculture by banks, since many of such projects may come out to be poultry projects.

State and local Governments must ensure that all poultry farms in their jurisdictions are properly registered, while state directors must reemphasize prompt reporting of all notifiable diseases apart from Avian Influenza.

Seroepidemiological investigation of the AI viruses that lack the multicleavages tendencies but are found sub clinically in primary hosts such as water fowls, sentinels and the wild life must be accessed nationally, with the possibility of developing regional risk map of potential epizootics.

In conclusion, I wish to share the view of international experts that critics of vaccination as a synergistic option, must realize that vaccination is not the initial cause of AI but remain a valuable tool if used wisely under a properly formulated policy for a national control with cost and public health implications that will be more advantageous to the entire society.