Could bacteriophages play a part in poultry farming?
BY DR NICHOLAS SVITEK AND DR ANGELA MAKUMI, INTERNATIONAL LIVESTOCK RESEARCH INSTITUTE, NAIROBI, KENYA
A
frica’s population continues to boom, from 476 million in 1980 to 1.4 billion today to a projected 2.5 billion by 2050. More than four out of five of those new Africans will be city-dwellers. This has
resulted in a deepening dependency on livestock as a source of income, livelihood and as a source of protein and micro- nutrients. In African countries such as Kenya, poultry is a bedrock for livestock farming because of their small body size, permitting more birds in a smaller holding, their relatively short life cycle and their robust adaptability to environmental conditions. The FAO has predicted that demand for poultry in Kenya will rapidly increase from 89,000 tons per year in 2010 to 238,000 tons by 2030, and to almost 537,000 tons by 2050.
Challenges facing poultry farming in Kenya As in many other low- and middle-income countries, Kenyan poultry farming and production face challenges such as low hygienic standards, low-quality feed, uncontrolled bird trade, lack of bird containment and limited access to veterinary and diagnostic laboratory services. Backyard poultry farming remains the primary source of protein among households while high-density commercialisation is practiced by only a few farmers. Adding to these challenges, some farmers practicing backyard poultry farming rear different species of birds in one holding area, creating a concern about cross- species transmission of diseases that could influence pathogen dynamics of poultry agriculture. Common bacterial pathogens isolated during spill over events between backyard chickens and wild birds include Mycoplasma spp., Escherichia coli and Salmonella spp. Most farmers opt to use antibiotics to prevent, manage and treat infections as well as to stay competitive in the poultry industry. The improper use of antibiotics such as for prophylaxis, growth promotion, egg production improvement, and a lack of awareness among poultry farmers about the problem of antimicrobial resistance all contribute to a high prevalence of antimicrobial resistance in poultry. Data generated from studies in Kenya found a high prevalence of resistance to ampicillin (76%), tetracycline(71%), sulphamethoxazole(70%), and co- trimoxazole (66%).
Many Kenyan poultry farmers still opt to use antibiotics to treat infections. Studies show however, there is a high prevalence of resistance to clinically relevant antibiotics for example. Bacteriophages could aid in alleviating antibiotic resistance in poultry farming in Africa.
Bacteriophages to the rescue The indiscriminate use of antibiotics may in fact aid in promoting the health and general welfare of birds within a flock, but this comes at the cost of a growing proportion of antimicrobial resistant bacteria. Of particular importance is the interdependence between human, animal, and environmental dimensions of antimicrobial resistance. Most of the classes of antimicrobials used to treat poultry or livestock infection end up in the environment and could end up in humans, creating a One Health problem—that is, a problem that taxes the resources of human, environmental and veterinary health experts. That possibility has generated growing interest in bacteriophage therapy, both against foodborne pathogens and as an alternative to antibiotic usage in poultry. Phages are effective antibacterial agents that are active against both antibiotic-resistant and antibiotic-sensitive strains while leaving the normal microbiota unaffected. Phages can be isolated from any environment their bacterial hosts inhabit, such as faecal material obtained from farms, food processing plants, slurry lagoons and sewages. The phages that are recommended for various applications typically follow the
▶ ANTIBIOTIC REDUCTION | DECEMBER 2021
An example of backyard farming in Africa.
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PHOTO: DR NICOLAS SVITEK-ILRI
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