A review of the avian influenza control strategies in Nigeria: a case study of the epidemiological unit of the Federal Ministry of Agriculture Enugu State, 2015-2017

¹African Field Epidemiology Network (AFENET), Abuja, Nigeria, ²Federal Ministry of Agriculture and Rural Development, Epidemiology Unit Department Of Veterinary Services Abuja, Nigeria, ³Ministry of Livestock and Aquaculture Development Yola, Adamawa State, Nigeria, ⁴Nigerian Agricultural Quarantine Services, Abuja, Nigeria

^&Corresponding author
Okoli Solomon Chieloka, African Field Epidemiology Network (AFENET), Abuja, Nigeria

Introduction    

One of the major challenges militating against the growth of the poultry subsector in Nigeria is the outbreak of avian influenza (AI). When outbreak occurs concerted efforts are geared towards containment, preventing spread to contiguous farms, thus ensuring public health safety. In 2006, the population of poultry chicken in Nigeria was estimated at over 65 million, [1]. Emergence of avian influenza in the poultry subsector in 2006-2013 [2-4], resulted in the loss of over 1.2 million Poultry chicken, with over $1.8 million paid in compensation to affected farmers, [5]. The Federal department of Veterinary services instituted the “modified AI Control policy” which consist of four distinct measures “depopulation, disinfection decontamination of farms, equipment and compensation of affected farmers”, [6], these measures were targeted at containment of outbreak and reduction in burden of loses on affected farmers. However, in 2015 through 2018, re-emergence of highly pathogenic avian influenza (HPAI), H5N1 and the emergence of a reassortant HPAI H5N8 strain in Kano State Nigeria, accounted for the loss of over 3.7 million poultry chicken with compensation paid to the tune of $7.2 million, [6,7]. The huge economic loses in the poultry subsector and the dwindling national reserve may have once again re-echoed the urgent need for a comprehensive review of the avian influenza surveillance system in Nigeria, with a view to ensuring early detection of diseases and prevent outbreaks. To this end the Federal ministry of Agriculture conducted a targeted surveillance in selected live bird markets (LBM) across 18 States in Nigeria, 2019. Three subtypes of Avian influenza virus (AIV), (two homologous (H5N8,H5N6), and one heterologous (H9N2) strain was found to be co-circulating within the LBM in referenced states, [8]. The poultry value chain in Nigeria is poorly regulated [1,6], coupled with an unstructured live birds markets, (LBM) may have played a major role in the resurgence of avian influenza in Nigeria 2015. The purpose of this study is to describe the avian influenza control policy in Nigeria, identifying its challenges with a view to providing information necessary for action.

Methods     

We reviewed policy documents on the control of avian influenza by the food and agricultural organization,(FAO) and Office of international epizootics,(OIE), [9-12], case reports on control of avian influenza in 3 local government Areas in Enugu State. We defined the case definition of avian influenza, identified specific avian influenza control measures and described challenges encountered in the control of avian influenza in Enugu State, Nigeria during the period under review.

Case definition for avian influenza: there is no pathognomonic lesions to avian influenza since, clinical signs mirrors most enzootic viral infections in poultry. However, acute mortality in poultry flocks, swollen head, pink coloured wattle, ecchymotic haemorrhages on the shank, [13], may be a presumptive diagnosis for avian influenza.

Differential diagnosis to avian influenza: Newcastle disease, fowl cholera, acute poisoning, infectious laryngotrachitis

Study area: Enugu State is located on the in the tropical savannah zone of Nigeria between latitude 6° 30N and 7° 30E south east. Its bordered Abia and Imo to the south, Ebonyi State, Benue State to the East and North east, with Kogi State bordering the North West. It has 17 local government areas. Enugu State has an estimated population of 3.8 million [6], with a poultry population of about 230,000 based on 2006 estimate, [1].

Results     

An overview of one health in avian influenza control: the control policy for avian influenza in Nigeria include: quarantine measures, Depopulation of exposed/infected birds, Disinfections of affected farms premises, equipment, contact tracing, and compensation of affected farmers.

Quarantine measure: outbreak response to avian influenza in Enugu State was carried by one health team. They include the avian influenza desk officer of the state, the disease notification officers of the ministry of agriculture, health, and environmental health officers. The Veterinary component of the one health team collects samples (whole poultry carcass), which would be neatly packaged in a leak proof nylon bag. Sample is accompanied by diseases suspicion forms, Figure 1. Then transported to the avian influenza reference laboratory in a Giostyle , with ice pack maintained at temperature 4°-6° C. Care was also taken to ensure that samples were taken directly to the laboratory without any intermediate stops, to ensure that the qualities of sample are maintained. Statistics of moribund, dead chickens are recorded by the Veterinary epidemiologist. Farms with suspected cases a quarantine notice, Figure 2, would be placed at the entrance of the farm prohibiting movement of poultry and poultry products within and out of the farm pending the outcome of laboratory investigation. Similarly, human samples (Nasal Swab) are collected from all farm workers and individuals who may have direct or indirect contacts with the poultry chickens or her products during this period for laboratory screening. When laboratory results confirms avian influenza (in poultry), containment and eradication measures are activated, Figure 3. A 3km Protection zone (PZ) (an area established surrounding an infected zone to prevent spread of infection to surrounding area), it spans from the focus of outbreak, to the buffer zone (BZ), (an area of the farm with no contamination) between the PZ and surveillance zones (SZ). A SZ of 10km is established from the primary focus outbreak to surrounding areas, (farms, and settlements), for contact tracing.

Depopulation of poultry: is carried out in accordance with EU guideline 93/119/EC on depopulation of infected poultry flocks, procedure may include Electronarcosis by water dipping, decapitation and dislocation of the neck, Gassing with carbon dioxide, Vacuum tank, [9]. However, in Enugu State Nigeria, decapitation and dislocation of the neck is the preferred method of humane slaughter.

Disposal of birds: following the confirmation of avian influenza a pit of at least 6 feet in deep is dug, Figure 4. All non-biodegradable, disinfectable material (wood, straws, cardboard) used on the poultry farm must be buried with animal. The carcass must be covered with a layer of calcium hydroxide, and then layer of filled up to earth to ground level.

Decontamination/ disinfection of farm and equipment: decontamination of farm equipment´s and tools are integral towards ensuring biosecurity on the farm. It involves physical removal of diseases causing agents contaminated organic, inorganic material from farm equipment´s and tools used on the farm to allow permeation of disinfectants, [11]. Decontamination is dependent on the type of surface involved, (earthen floor, and broken concrete floor) and the type of poultry housing (bamboo or wire cages). As a rule the solution to this is improved surface type and cleaning equipment. Cleaning may be dry cleaning (scraping, sweeping, or scrubbing), wet cleaning, involves use of detergents, scrubbing and pressure washers. Routine cleaning focuses on those surfaces that are more likely to come in contact with poultry and production processes within the farms. Liquid detergent (Dawn) is ideal for use because it specifically cut through lipid and its nontoxic, Table 1.

Checklist for disinfection of infected farms: all units involved in production (hatchery, egg storage room, packaging room, trolley rack ), transportation of live animals, eggs, feed should be disinfected; walls, floors ceilings should be disinfected while metal cages and structures are decontaminated and disinfected by hot water treatment; drinkers, food hoppers must be washed and disinfected for at least 24hrs; reservoirs for water should be emptied and disinfected; silos should be washed with an hot water jet and fumigated.

Compensation of poultry farmers: the last strategic policy of avian influenza control in Nigeria, following depopulation of affected poultry flocks decontamination of poultry farms and equipment´s, [14]. Compensation is based on a number of parameters and information obtained from the poultry farm involved see Table 2. Poultry farmers are compensated based on the number of flocks depopulated, types of flocks (layers, broilers, chicks), poultry products and consumables, (eggs, trays), [15]. However, before compensation is paid the farm must be left fallow without re-stocking for a minimum of three months post decontamination, subject to review by the Director of Veterinary services (DVS) of the State or other designated officer.

Challenges of effective control of avian influenza in Enugu state, 2015-2017: early disease reporting is germane for effective disease control. Retrospective reviews of average disease notification time of veterinary authorities by affected poultry farmers was 2-3 weeks post suspicion of outbreaks. This may follow farmer´s unsuccessful attempt to manage suspected outbreak with cocktails of veterinary of antimicrobials which most often has a therapeutic range of between 1-2weeks. Similarly, the response time of veterinary authorities post notification of outbreak was 1-2 days. As a consequent, instituting control measures on affected farms may take a further, 3-4 days, including (preliminary investigation, collection, transportation of sample to the reference laboratory and laboratory confirmation) Figure 5 describes flow chart showing sequence of events following outbreak of avian influenza and critical point that may predispose to potential zoonoses. In general effective control of an outbreak of avian influenza by the Federal ministry of Agriculture in Enugu takes between 3-5weeks. Considering the maximum incubation period of avian influenza viruses of 3 weeks (21 days). Farmers, may record more poultry mortality this period with the attendant risk of spread of infection to contiguous farms and live bird market.

Discussion     

Poultry industry in Nigeria is the most capitalized of the Agricultural subsector in Nigeria. It accounts for about $22 million per annum, and 25% of the Agricultural domestic product. Fifty million Nigerians are directly or indirectly employed in the subsector, [1]. Outbreak of highly pathogenic avian influenza H5N1 in 2006 and its re-emergence in 2015, plagued the poultry subsectors with massive job losses, [7], with over $100 million dollars lost in revenue. To stem the tide of the pandemic, the World Animal Health Organization developed the “OIE terrestrial animal code” to present a common strategy in control of avian influenza worldwide, [16]. This strategy was adopted and adapted locally by member nations during outbreaks. In Mexico outbreak of avian influenza H5N2 in 1995 was controlled within one year, [17] similar fit was reported in Italy 1999-2000, Netherland 2003, and Canada in 2004, [18], control strategies employed were immediate stamping out policy of affected flocks, disinfection of affected premises, quarantine measures, strict movement controls on poultry and their products and vaccination, [17], this was in contrast to avian influenza control strategies employed in Nigeria between 2006-2008, and 2015-18. Control strategies employed in Nigeria includes, quarantine, stamping out/depopulation, disinfection, and compensation of affected farmer, [7] Nigeria practiced a “No vaccination policy´ for control of avian influenza, however, Fashina disagreed with the policy in his study were he posited that vaccination of poultry chicken against avian influenza combined with other control measures may be cost effective and reduces risk of zoonoses especially in developing economies [19]. However, Simsons and his team in a related study conducted in Indonesia to access the duration of vaccine induced immunity against H5N1, concluded that vaccination against H5N1 was largely ineffective in providing long lasting protective immunity with poultry flock requiring seven vaccination regime, [20], such may not be cost effective in developing nation. Compensation of poultry farmers affected by outbreak of avian influenza was a deliberate effort by the Federal government of Nigeria, through the Ministry of Agriculture to reduce the burden of losses incurred by poultry farmers during outbreak of avian influenza, [6].

Conclusion     

This study concluded that compensation of poultry farmers may contribute to attempts to influence poultry flock size affected during outbreak. Based on reports on attempt by farmers to sell moribund chicken from farms with confirmed cases of avian influenza despite certainty of compensation claims. We recommend that the compensation policy for avian influenza should be discontinued. Alternatively, the poultry value chain in Nigeria should be strictly regulated; movement of poultry and poultry products should be supervised by the agricultural quarantine services. Strict biosecurity routine and structures on the farms should be made a pre-requisite for registration and operation of poultry farm in Nigeria. Funds earmarked for compensation could be used to improve the capacity of the epidemiology units, with a renewed vigor geared toward, surveillance, prevention of outbreak rather than the current focus on control. A structured and dedicated live bird market should be constructed in each state to separate poultry business from other market activities, this may reduce outbreak of poultry disease and reduce the risk of emergence of reassortant influenza strains and ensure public safety.

Competing interests     

The authors declare no competing interests.

Authors' contributions     

Dr Moses read the manuscript and made useful contribution, Dr Salima Garba read the manuscript made useful contributions and designed the flow chats. All the authors contributed to the conduct of this work. All the authors have read and agreed to the final manuscript.

Acknowledgments     

Author would like to acknowledge the Chief Veterinary officer of Nigeria, Dr Olaniran Alabi, and the Head of Epidemiology Federal Ministry of Agriculture, Abuja Nigeria Dr Vakuru Columba Teru.

Tables and figures     

Table 1: selected classes of disinfectant effective against avian influenza

Table 2: how to determine compensation claims of farmers based on statistic of poultry affected during outbreaks of avian influenza

Figure 1: a copy of disease reporting form

Figure 2: a copy of quarantine notice

Figure 3: poultry chicken buried in six foot pit

Figure 4: avian influenza surveillance and contact tracing zones

Figure 5: flow chart showing sequence of events following outbreak of avian influenza, critical points that may lead to spread and potential zoonoses

References