Tackling avian influenza in Nigeria: Surveillance and national preparedness (I)
Being a paper presented by DR. SHEHU IBRAHIM BAWA, Ministry of Agriculture, Kano, at a workshop on Avian and Human Pandemic Influenza organised by VOA and BBG.

Introduction

THE disease avian influenza (AI) is divided into:
a. Low pathogenic avian influenza (LPAI)
b. Highly pathogenic avian influenza (HPAI)
LPAI: Is a contagious viral disease of birds which usually cause mild clinic disease in infected birds and does not pose immediate significant dangers to human health.
HPAI: Is an acute and highly contagious vital disease affecting the respiratory, digestive and or nervous systems of almost all domestic and wild birds, it is characterized by high morbidity and high mortality in birds and can affect humans, with fatality.
Spread transmission and risk factors
The risk factors in AI spread are either commercial, management or human.
AI is primarily spread by direct contact between healthy and infected birds through respiratory secretions and faeces. It can also be spread through indirect means if healthy birds are exposed to contaminated equipment and materials.
Migratory water flows are the most resistant to the infection. They excrete high concentration of viruses in their respiratory secretions and faeces.
The domestic poultry which is particularly susceptible to the disease, becomes infected through indirect contact with the infective agent.
Spread transmission and risk factors
AI outbreaks have been reported in the US due to the presence of natural and artificial lakes and ponds near poultry farms, the water attracts migratory water fowls.
Outbreaks in the world show seasonal pattern which coincides with the migratory birds activity in the risk areas.
Live birds markets and man-driven movement for commercial purposes also plays important role in the spread of the disease within the state and the contrary.
Other risk factors
Movement of equipment and personnel between farms.
*Poor bio-security in the farms
*Use of untreated poultry manure
*Improper carcasses disposal
*Rearing poultry of different species in this same farm.
*Lack of protective clothing of farm personnel
*Lack of restriction of movement in the poultry farm.
*Delay in release of funds for emergency field activities.
Other risk factors continues.
And once AI, is introduced into a flock or an area it does not need wild birds to spread it from flock to flock or farm to farm. It is achieved through movement of infected bird, contaminated persons, equipment and materials.
Clinical signs
The following may be seen:
*LPAI
*Ocular and nasal discharge
*Swollen head
*Reduced egg production
*Morbidity and mortality usually low.
HPAI
*Per acute cases:
*Birds died without any clinical signs.
Clinical signs
*Acute cases
*Cyanosis and edema of comb and wattle.
*Discoloration of the shanks and feet.
*Blood tinged nasal and ocular discharges.
*High morbidity and high mortality.
*Greenish diarrhea in severe cases
*The very high morbidity and high mortality helps in making the differential diagnosis in AI cases. The clinical signs and the lesions obtained are usually less helpful. The confirmation of the diagnosis is made in the laboratory.
Treatment
*LPAI
Treatment of infected flocks with broad spectrum antibiotics to control secondary bacterial infections and minimizing stress factors may reduce morbidity and mortality. Treatment with antiviral drug is not allowed.
*HPAI
*Infection by HPAI is not treated.
Prevention and control
These involves: Taking care of this risk factors mentioned earlier. Early reporting of outbreaks to the authority. Early detection. Depopulation of the affected flocks including in contact. Decontamination of the entire affected farm premises. Close coordination with health ministry. Proper disposal of carcasses and other infected materials.
Prevention and control continues
Improvement of bio-security practices in farms
Vaccination of uninfected flocks may be adopted as a matter of national policy.
Discourage movement of people between farms
Adequate and prompt compensation payment,
Mass mobilization to enlighten the public.
Creation of animal health ministries in the states and at the federal level.
Influenza pandemic
Influenza pandemic here refers to the global outbreak of influenza in humans which occurs when a new virus emerges, spread and cause disease and death worldwide.
AI virus does not usually infect humans, however, several instances of human infections usually of poultry handlers have been reported since 1997.
Introduction continues
When such infection occurs, the public health authorities monitor the situation closely because of the concerns about the potentials for more wide spread infectious in the human population if the virus mutates or mixes with human flu viruses, to suddenly start spreading and devastatingly among people like it does to the poultry population.
The pig is susceptible to both human and animal influenza and if it happens that both infections take place concurrently in the pig the virus could ‘mix’ within it and produce a new virus than can be passed from human to human, and this situation which is called the ‘antigenic shift’ can mark the beginning of a pandemic situation.
Also the same antigenic shift can occur in the human population when both human and AI infectious take place at the same time, in which case it is the human that serves as ‘mixing vessel’ where information of a new virus with the capability to be passed from human to human is achieved. Resulting in a pandemic situation.
Past influenza pandemics have led to high level of illness, death, social disruptions and economic losses.
Stages in pandemic influenza development
1. Bird to bird.
2. Bird to human
3. Human to human
Introduction and spread of AI in Nigeria
There are indications that AI did not start in Sambawa farm in Kaduna state, nor was it imported into the country by a farmer in Kano as was ignorantly and mischievously claimed in certain quarters. But it was only first diagnosed in that farm.
Investigations revealed that even before that initially confirmed outbreak, many farms in Kano had lost all their birds through an unconfirmed disease that did not respond to various treatments and had similar clinical signs as AI.
Again this investigation revealed that some villagers in Jigawa state had lost all their local chickens, ducks, turkeys and G. fowls. A scenario different from the usual new castle disease outbreaks in which some of the bird usually survived.
It is possible that the initial outbreak started between late November and early December 2005 in Jigawa or Yobe states around the wetland through the activities of migratory birds and went on undetected until February 2005.
And we should not forget that Nigeria lies along two important wild birds migratory routes. The Atlantic fly way and the East Africa, West Asia fly way.
The following practices contributed to the spread of the disease in the country.
1. On farm sales of eggs. On farm feed millers that sold feeds to other farms.
Carnivorous birds that feed on infected carcasses commercial feed millers that deliver feeds to different farms at the same time. Live birds trade within and outside the state sales of eggs by poultry feed and drug sellers at the same place. Lack of adequate and prompt compensation to farmers whose birds were depopulated. Lack of preparedness of the government to handle the outbreak when the disease was introduced.
Surveillance and national preparedness
Following the outbreak and spread of AI in South East Asia, the federal government put in place some preventive measures in 1994, such as: Total ban on importation of poultry and poultry products from affected countries and high risk areas. Improvement of quarantine services, strengthening of surveillance nationwide, public enlightenment campaign.
And when the disease situation in that continent worsened, a technical committee of experts was set up in November 2005 to come up with emergency preparedness plan against the possible outbreak of AI in Nigeria.