Emergence and re-emergence of Avian influenza

Poultry are birds such as chickens, ducks, turkeys, geese, guinea fowls and squabs, raised commercially or domestically for meat, eggs, and feathers. In Nigeria, rearing of chickens is the most preferred, followed by turkeys. Agriculture accounts for approximately 25% of Nigeria’s gross domestic product (GDP), with poultry farming contributing to about 30%. Nigeria is the fourth-largest and largest producer of poultry meat and chicken eggs, respectively in Africa. A 2020 World Bank report showed that Nigeria has a chicken population of about 180 million annually. Compared to Nigeria’s human population estimated at 206.1 million, chickens are just about 26 million below. Broilers make up 70% of the chicken population, while layers account for 30%. 

There is hardly any region of the country where you wouldn’t see these two-legged creatures roaming around the neighborhood (extensive) or being reared intensively. About 21 billion eggs are produced in Nigeria annually, however, when compared with other countries, Nigeria’s egg consumption is 60 eggs per annum per capita when compared to 250 eggs per annum per capita in advanced countries. About four in every 10 Nigerian, are into poultry production; small, medium, or large scale. The poultry subsector plays an important role in reducing malnutrition, taming poverty, promoting economic growth and is worth a whooping US$ 4.2 billion!

Poultry and pork are the two most widely eaten meat types globally, with over 70% of meat supply between them. Poultry provides nutritionally-beneficial food containing high-quality protein, minerals, vitamins (especially B12), essential fatty acids, and a low proportion of fat. It comes in handy for a number of Nigerian delicacies such as egg sauce and yam, egg and noodles, jollof rice and chicken, chicken stew, chicken suya, chicken peppersoup, grilled chicken, chicken pie, chicken shawarma, and my favourite, peppered chicken and chips! Poultry waste are used to produce value-added products such as pillow stuffing, fashion (hat and dresses), diapers, insulation, upholstery padding, paper, plastics, biodiesel, feather meal, bone meal and fertiliser.

One of the major challenges militating against the growth of the poultry industry in Nigeria is the outbreak of the highly pathogenic avian influenza (HPAI), aside other viral diseases such as Newcastle disease and Infectious bronchitis. HPAI is an extremely contagious, multi-organ disease of poultry caused by some H5 and H7 subtypes of Type A influenza viruses. These viruses are closely related to the severe acute respiratory syndrome (SARS) coronavirus and typically present suddenly, often with very high mortality while wild birds serve as carriers and spread these viruses, but may show no signs of illness. The disease can be transmitted directly from wild birds to domestic poultry via airborne transmission or indirectly through faecal contamination of equipment, feathers or feed. Clinical signs include lack of, or depressed appetite, coughing, sneezing, nasal discharge, respiratory distress, lack of energy, swelling and bluish-purple discoloration around the face, diarrhoea, lack of coordination, muscle tremors, drooping wings, twisting of the head and neck, inability to move and significant drop in egg production. The first description of avian influenza dates as far back as 1878 in northern Italy, when the notable parasitologist, Edoardo Perroncito, described a contagious disease of poultry as being associated with high mortality. Phylogenetic studies have demonstrated that the HPAI H5N1 strain was most likely directly introduced from wild birds into domestic birds as a low pathogenic virus that subsequently developed into a highly pathogenic strain due to reassortment within domestic birds.

In West Africa, Nigeria has been experiencing repeated outbreaks of different strains of HPAI since 2006. The first reported outbreak occurred, between 2006-2008, which resulted in the loss of over 1.2 million chicken with over US$1.8 million paid in compensation to affected farmers. Its re-emergence in 2015 plagued the sector with massive job losses, with over US$100 million lost in revenue. The first human case in Nigeria was detected in Lagos State in January 2007. Selected HPAI outbreaks have been reported from March 2021 to date and two Nigerian states (Kano and Plateau) reported human infections. All seven individuals were exposed to infected birds where they work or in live bird markets where live poultry are kept and slaughtered. The H5N1 strain was first detected in humans in 1997 in Hong Kong, where it infected both chickens and people, as fatal outbreaks were also reported across Europe and Asia in late last year. 

Illness in humans have ranged from no symptoms or mild illness to severe disease that resulted in death. Pregnant women, people with weakened immune systems, and the aged are more at risk. As at now, there is no evidence of human-to-human transmission, no risk of infection from consuming well-cooked poultry, and the risk of an outbreak among humans remains very low. The disease is often treated with antiviral drugs and immune boosters, but the best therapy, however, is still prevention. After all, prevention, they say, is better and cheaper than cure. The United States Centre for Disease Control (CDC) recommends four distinct measures: quarantine; depopulation of exposed/infected birds; disinfection of affected farms and equipment, contact tracing; and compensation of affected farmers. These measures are targeted at containment of outbreak and reduction in burden of losses on affected farmers. 

Quarantine measures are usually done by the one health team, comprising veterinarians, physicians, law enforcement officers, depopulation is by humane slaughter and carried out in accordance with European Union guidelines, while birds and all non-biodegradable, non-disinfectable material such as wood, straws, cardboard, must be properly disposed off. Decontamination of farm equipment is an integral action towards ensuring biosecurity on the farm. All units involved in production including hatchery, egg storage room, packaging room, trolley rack, transportation of live animals, eggs, feed, walls and floors ceilings, should be disinfected. Thankfully, most viruses can be killed using simple detergents or diluted bleach. If chemicals are not desired, the virus also dies in the presence of steam, a well-known fact for over 100 years. The last and most controversial strategy is the compensation of affected farmers. 

Poultry farmers are compensated based on the number of flocks depopulated, types of flocks, namely layers, broilers, chicks, poultry products and consumables like eggs and trays. Before compensation is paid, the farm must be left fallow for a minimum of three months post-decontamination. CDC also recommends that travelers to countries and states with HPAI outbreaks should limit visits to poultry farms, bird markets and other places where live poultry are raised, kept, or sold. Raw or undercooked poultry products should not be eaten and washing of hands after handling uncooked poultry. Early disease reporting is germane for effective disease control, but many cases of HPAI in Nigeria seem to be swept under the carpet due to fear of stigmatisation and delay in compensation for an average notification time of veterinary authorities by affected poultry farmers may be up to 2-3 weeks post suspicion of outbreak. This usually is after the farmer’s unsuccessful attempt to manage the situation with cocktails of veterinary antimicrobials. 

Similarly, the response time of veterinary authorities post-notification takes an average of 1-3 days. Consequently, instituting control measures such as preliminary investigation, collection, transportation of sample to the reference laboratory and laboratory confirmation, may take a further 3-4 days. During this time, more mortality is recorded and the attendant risk of spread of infection to contiguous farms and live bird markets.  In Mexico, Italy, The Netherlands and Canada, HPAI outbreaks in 1995, 1999, 2003, and 2004, respectively were put under control within a year. This is in sharp contrast to HPAI control in Nigeria, between 2006-2008, 2015-2018 and 2021-2022. It must be recognised that Nigeria is a hot spot and falls within the migratory route of wild birds from Europe and Asia. As such, the introduction of emerging and more deadly strains cannot be ruled out.

The huge economic loses in the poultry subsector with over 3.7 million poultry and compensation paid to the tune of US$7.2 million, and the dwindling national reserve re-echoes the urgent need for a comprehensive review of the HPAI surveillance system, especially in live bird markets in Nigeria. There has to be a deliberate and sustainable national drive to promote early detection of diseases and prevent outbreaks. It should be noted that the poultry value chain in Nigeria is poorly regulated, coupled with unstructured live bird markets, and this may play a major role in the continued resurgence of the disease. Strict biosecurity measures, quarantine, surveillance and tracing of potentially-infected or exposed poultry, and any at-risk vehicles, should be done strictly, to limit the spread and eradicate the disease. Adequate information should also be passed across to people involved in the production chain, using formal and informal settings.

Despite the expansion of the poultry industry in recent years, amounting to 300 metric tons of meat and 650 metric tons of eggs per year, this only caters for 30% of the needs of Nigerians. About 1.2 million poultry meat is reported to be smuggled into the country from the Benin Republic annually, even with the ban and closure of borders. In addition, the Poultry Association of Nigeria in 2017, reported that the annual demand for poultry products exceeded US$1.39 billion, which equates to 165 million birds, 290,000 metric tons of meat and 650,000 tons of eggs. In 2019, the Governor of the Central Bank of Nigeria (CBN), Godwin Emefiele, said the poultry industry in Nigeria was worth about N1.6 trillion, making it the most commercialised subsector of the agricultural sector. The good news is that there is huge opportunity and viable market in poultry for intending entrepreneurs. We should also not forget that an egg a day actually keeps the doctor away!

Dr. Adenubi, an Associate Professor and Veterinarian, is a columnist with FarmingFarmersFarms;+2348025409691; bukiadenubi@gmail.com