Phage Therapy: Animal Infectious Diseases

Phage Therapy: Animal Infectious Diseases

The agriculture-food industry is seen to play a crucial role in the emergence of multi-drug resistant bacteria, with livestock farming accounting for up to 80% of total antibiotic use. Research has shown that antibiotics in livestock have not only been used to treat an infection but also as growth-promoting factors. Unfortunately, most antimicrobials in animal production are very closely related, if not identical, to those in humans. Therefore, extensive use of antibiotics in the food industry and their subsequent casual use can increase the spread of multidrug-resistant bacteria in humans too.

Animal health is key to supporting the transition towards healthy, resourceful, and sustainable food systems with high animal welfare. Not only this, but livestock health is key to maintaining global health, economic development, and poverty reduction. To reach the UN’s Sustainable Development Goals, attention needs to be given to control of diseases such as sheep pox, goat pox, avian/swine influenza, foot and mouth disease, bovine tuberculosis, and many more.

Infectious animal diseases can be split into three categories: epizootic (the equivalent of an epidemic in humans in animals), zoonotic (an infectious disease that can be spread between species) and enzootic (constantly present in an animal population, but usually only affect a small number of animals at one time). Unfortunately, many of these diseases in animals do not have any appropriate control tools, but the control measures that are currently available, such as marker vaccines and associated diagnostics, have managed to successfully control diseases like infectious bovine rhinotracheitis. However, the need for enhanced control is still needed, especially as these infections not only impact the animals themselves but can cause serious infectious diseases in humans. The recent COVID-19 pandemic has certainly highlighted how essential it is that these diseases are controlled to manage future pandemic threats too.

This is where phage therapy is changing the fight against infectious diseases.

Bacteriophage (phage) therapy has been proposed as a promising alternative for the treatment of infections in animals in the veterinary field and in general livestock maintenance. Recent studies have examined the use of phages in cattle, bovine, swine, rabbit, and horses to treat infections like septicaemia, mastitis, cholera-like diarrhoea, keratitis and salmonellosis. Phages are useful in that they can multiply at the site of infection, specifically targeting the pathogen causing the infection. This is unlike antibiotics, which have a more general mechanism of action. Phages are also able to evolve with bacteria while antibiotics cannot, making them more efficient in the fight against infectious diseases.

While undoubtedly, phage therapy could help with the control of many aspects of infectious animal diseases, it is perhaps most helpful for the control of enzootic diseases – which can be exacerbated by animal management and is usually largely the responsibility of an individual farmer.

Staphylococcus aureus is one example of a bacteria that can infect both humans and animals and can easily become resistant to antibiotics. S. aureus is a bacterium that causes mastitis in cattle, normally requiring significant costs to treat and control. Treatment of mice with S. aureus infection meant to mimic mastitis in cattle, with a combination of phages resulted in reduced infection and, in many cases, complete recovery. A similar trial has been performed looking at Escherichia coli-associated metritis, a disease that affects cows after calving and can cause problems with future reproduction. Again, a cocktail of phages was used to treat the infection. Results showed that the growth of the infection was reduced significantly

Phage therapy could also be used to treat swine infections like Salmonella. In a preliminary study, pigs were given anti-Salmonella phage cocktails and inoculated with Salmonella enterica. The infection was reduced by more than 99%.

Antibiotics for Animal Health and Welfare

Diseases are inevitable in animals, whether farmyard or pets. Veterinary vaccines and antibiotics are essential for dealing with current and emerging diseases. The use of antibiotics in animals varies between species and can be given by injections (intravenously, intramuscularly, or subcutaneously), orally in food or water, topically on the skin, and by intramammary and intrauterine infusions.

Treatment can vary based on the patient. Bacterial diseases in companion animals, it is naturally directed at the pet themselves.  However, the treatment of animals raised for food is generally directed more at groups or herds of animals, making treatment less targeted. In food animals, antibiotics are not only used to treat and prevent clinical diseases but can also increase feed conversion, growth rate and yield. Clearly, antibiotics have their advantages.

However, the overuse of antibiotics over the last few decades has caused many of the targeted bacteria to build up resistance, making the development of bacterial and parasitic resistance to currently available drugs for these diseases the largest threat to animal health and welfare.

Antibacterial Solution in Animal Health

Phages are an alternative to antibiotics in the treatment of many bacterial and parasitic infections in livestock, veterinary, and companion animals.

Nexabiome is addressing bacterial challenges across the animal health sector, to support healthier livestock and companion animals. Our phage solutions can be delivered via feed, topical cream, or as a powder added to a water supply – whatever suits the consumers’ needs. 

There are currently three options for phage treatment with Nexabiome. To address bacterial challenges while replacing antibiotics, the use of farmPHIX™ in feed or as a powder to be added to water supplies is a perfect example of how to support healthier livestock. The farmPHIX™ solution is currently engaged in academic and field studies looking into E. coli infection in pigs and salmonella in chickens. 

Alternatively, the aquaPHIX™ solution can be used to coat feed, having been shown to improve clinical outcomes of diseases like Early Mortality Syndrome in shrimp. 

There is even an option for companion animals – PetPhix™ is a perfect solution for your companion animals through topically applied formulations such as gels and creams. 

Conclusions and future prospects

Phages are quickly becoming a very promising field in livestock maintenance and veterinary medicine. More and more studies are being conducted looking at different diseases from cattle to companion animals like dogs and cats, with some very exciting results.

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