A team of scientists in Kenya are making progress in the development of medicine to address a diarrhoeal disease in pigs known as porcine infectious diarrhoea (PID) for the swine industry in Kenya and beyond.
The scientists – who work at University of Nairobi – are collaborating with their counterparts from Ohio State University to develop probiotics to improve pig health and help farmers reduce use of antibiotics.
PID is caused by rotaviruses which pigs get from interaction with other infected animals or contaminated environments, says Dr Joshua Onono, a veterinarian and project co-ordinator for the Kenyan team.
“Rotaviruses affect pigs; especially piglets. The infection by this virus causes diarrhoea which result in stunted growth and death of piglets in a farm.”
“They will lose weight and the farmer will spend more on feed for the pigs to reach mature market weight. This, together with costs incurred in treatment will eat into the farmer’s profits,” Dr Onono says.
Probiotics on the other hand are good bacteria that are beneficial to an animal’s bodily and health functions.
“In this project we are determining which probiotics would work in pigs (to combat rotavirus infection) and in what doses," Dr Onono says.
“The probiotics we are using have shown great promise: they bind the virus and block it from infecting healthy cells. Or, they bind epithelial cells lining the gut; blocking the virus from accessing healthy cells,” he explains.
The probiotics being tested, the team says, have already worked in combating the virus under restricted conditions in the laboratory based on experiments conducted in Ohio State University.
“What we are doing now is testing how well the probiotics would work under field conditions; to see if it is replicable in farms,” says Alfred Mainga, one of the Kenyan scientists involved in the project.
Diarrhoeal diseases are common in pig farms, says Lydia Karume, a pig farmer from Murang’a county.
“They usually diarrhoea when they feed on wet feed or feed that is contaminated (with germs),” she says.
Farmers in Murang’a have dubbed the disease ‘Kuhurwo,’ for diarrhoea in Kikuyu.
In most cases, Onono says, diarrhoea in pigs is caused by rotaviruses.
Ms Karume notes that the most affected pigs on her farm are four-month-old and smaller.
“It is the major cause of death among piglets. In my farm, out of every 10 piglets with diarrhoea 3 die,” she says.
“The diarrhoea is usually virulent: in some piglets they start to diarrhoea in the morning and by sunset they are dead.”
“As a pig farmer you have to have medicine – or the money to acquire them – ready at all times so that you can respond quickly,” she says.
Karume usually treats her pigs with Kaolin powder and antibiotic, PenStrep.
Dr Onono explains that infection with rotavirus can lead to secondary bacterial infection and veterinarians might prescribe antibiotics as part of treatment.
Antibiotics, he says, are also easily accessible on a walk-in-walk-out basis at agro vets countrywide.
“This unchecked use of antibiotics by farmers in response to diarrhoea in pigs – caused by rotaviruses and other pathogens – is leading to antimicrobial resistance (AMR),” Onono says.
He explains that antibiotics are meant to treat infection caused by pathogenic bacteria but when used in response to viral diseases this would cause AMR since the bacteria will be exposed to low doses of the antibiotics.
“AMR lead to many pathogenic bacteria developing ability to withstand available antibiotic treatments and therefore cause greater havoc in the human population,” notes Dr Onono.
Rotaviruses are zoonotic and as such are transmissible between animals and human beings, with adverse effects on children under the age of five and the elderly.
“The virus can easily jump to human population. Remember, in most farms, we use manure to grow food. Farmers also interact in close contact with the animals. So, such a scenario is not really farfetched,” Dr Onono says.
“We hope to develop this new technology to offer pig farmers a healthier anti-viral solution while also combating development of AMR,” he says.
Broad use of antibiotics, Dr Onono warns, increases chances of animal products with antibiotic residues making it to the market.
Products such as meat that still have antibiotic residues transfer the active ingredients to the human population, setting off another route to development of AMR in human beings because of exposure of bacteria to low doses of antibiotics.
He says that many farmers do not observe the withdrawal period – when an antibiotic is still present in the body of an animal following treatment.
“Some antibiotics can be cleared from the animal’s body in a few days and others in months. We have to be careful to reduce the risk of transfer of antibiotic residues from animal products to humans,” he says.
Dr Onono and his team have collected samples from pigs in local farms and tested for rotavirus, about 10 per cent were positive.
He warns that rotaviruses spread quickly within a herd and contaminate the environment.
“The only way for a farmer to rid the farm of the virus is to cull the herd and stay without animals for some time, while continuously disinfecting the farm, before re-introducing a new and healthy herd,” Dr Onono says.
The probiotics under trial are currently being served in a solution form to the farm animals.
The project – which is supported through the Innovative Veterinary Solutions for Antimicrobial Resistance (InnoVet-AMR) initiative: a partnership between Canada’s International Development Research Centre (IDRC) and the United Kingdom’s Global AMR Innovation Fund – is expected to be complete by February 2023.