New technology to wash away pathogens on chicken meat in Thailand, is trialled by (from left to right) scientists Naoaki Misawa of the University of Miyazaki, Lerdchai Chintapitaksakul of Thailand’s National Institute of Animal Health, and Pornsawan Pongsawat of the University of Miyazaki.
A natural filter of bacteria from Japan that has been more than 7,000 years in the making may one day help secure Thailand’s livestock production. Researchers in Japan and Thailand hope that this bacteria-trapping material, alongside innovations across livestock disease diagnosis and foodborne pathogen control, could help to establish Thailand as a global centre of secure, safe food production.
The bacterial filter is a reddish volcanic soil called ‘Akahoya’, formed in the south of Kyushu Island following an ancient volcanic eruption. Its remarkable ability to trap bacteria passing through it was revealed after researchers sampled waterways near grazing land in the region, and found them to be surprisingly free of the Escherichia coli contamination typically linked to cattle waste runoff.
Investigating further, a team led by Naoaki Misawa at the Center for Animal Disease Control at the University of Miyazaki, filtered an E. coli suspension through columns of volcanic soils. The team confirmed that – unlike other sediments – the Akahoya soil effectively filtered out the bacteria.1
Misawa now co-leads an international team exploring Akahoya-based filtration systems to prevent livestock farm E. coli runoff from reaching and contaminating drinking water sources.
The study forms part of a broader partnership between Thailand and Japan, led jointly by both Misawa and colleague, Lerdchai Chintapitaksakul, director of the National Institute of Animal Health in the Department of Livestock Development, in Bangkok. This work — implemented as part of Japan’s Scientific and Technology Research Partnership for Sustainable Development programme — is aimed at promoting safe and sustainable livestock production and meat supply in Thailand.
Several common cattle infections can be simultaneously screened in a single test developed by researchers at Tokyo University of Agriculture and Technology including Mami Oba (left) and Hitoshi Takemae (right).
Better disease diagnosis
As Thailand’s population and GDP has increased, so too has demand for meat products, and the local industry has expanded rapidly.
Meat exports to regions such as Japan and the European Union, however, are restricted by the presence in Thailand of infectious livestock diseases, such as foot-and-mouth disease (FMD) and lumpy skin disease.
A primary objective of the Japanese-Thai collaboration is to develop rapid diagnostic tests for livestock, for prompt and effective treatment. “If we can prevent such diseases we can contribute to animal welfare, food safety and also the economy,” Misawa says.
Livestock diseases can pose considerable diagnostic challenges. Bovine respiratory disease complex, for example — the most common disease in beef cattle worldwide — can be caused by infection with a range of pathogens, complicating its diagnosis.
Project collaborator, Tetsuya Mizutani, who directs the Center for Infectious Disease Epidemiology and Prevention Research at Tokyo University of Agriculture and Technology, led a team who designed a laboratory-based PCR detection system that could simultaneously screen for 10 viruses and six bacteria commonly associated with the condition in Thai livestock.2
The team has since broadened the test to cover 60 bovine pathogens. “We’ve also developed the system to screen for pathogens in chickens,” Mizutani says.3
Kingkarn Boonsuya Seeyo (right) of the National Institute of Animal Health surveyed cattle farmers in Thailand to identify risk factors associated with foot-and-mouth disease outbreaks.
Other livestock illnesses are so contagious they demand a special approach. FMD is a viral condition that infects cattle, pigs and other cloven-hoofed animals. Painful blisters and ulcers form on the soft tissue between the toes, above the hoof, on teats and in the mouth and nose.
The World Organization for Animal Health mandates lab-based PCR tests to confirm suspected cases. But this process can take one or two days, Chintapitaksakul says, and with this disease, time is of the essence. FMD can spread rapidly, causing significant economic losses to the livestock industry.
Chintapitaksakul, Misawa, and their team searched for a fast, pen-side diagnostic test for FMD. They showed that a commercial handheld device called PicoGene could detect FMD viral RNA with the same sensitivity as the standard laboratory test, in a fraction of the time.4 “PicoGene takes maybe half an hour or one hour to get a result,” Chintapitaksakul says. The veterinarian can then quickly control the disease.
Picking off pathogens
The research partnership’s exploration of pathogen reduction extends to meat processing plants, where Misawa has led a study into efficient and effective meat decontamination.
Chicken meat is often contaminated with Campylobacter jejuni, a bacterium behind up to half a billion cases of human foodborne illness each year. It colonises chickens’ intestinal tract but can contaminate raw meat during processing.
One bacterial removal method is to spray chicken carcasses with a disinfectant solution. The constant flow of liquid from a standard sprayer can produce a film of stagnant water that adheres to chicken skin, however, limiting the number of bacteria scrubbed off.
Inspired by a technique used to clean semiconductor wafers and glassware, Misawa and his collaborators at Kaijo Co. have trialled replacing the constant flow system with a high-pressure (10 MPa) jet spray that is pulsed 10 times a second. Campylobacter-contaminated chicken pulse-sprayed with disinfectant had significantly fewer bacteria left on their skin compared to untreated controls.5
“We could use this technology for the elimination of food pathogens from chicken carcasses in Thailand — not only Campylobacter, but also Salmonella, which is a big issue for the contamination of chicken meat,” Misawa says.
Even meat pulse-sprayed with tap water ended up with fewer skin microbes than untreated chicken, the team showed. They are now refining the technique to maximize bacteria removal without chemicals, something that is important for Thailand’s export market, Misawa says: “EU countries prohibit the use of chemicals in meat processing plants to eliminate foodborne pathogens. We are trying this new technology to eliminate Salmonella from chicken carcasses without disinfectant.”
Thai chicken producers could gain broader export market access if improved food processing pathogen control technologies can be developed. Credit : Bubbers BB/Shutterstock
Benchside to pen-side
These ongoing projects, once optimised, could one day be rolled out across Thailand’s livestock industry, says Chintapitaksakul.
Current limitations include the price of diagnostic hardware, such as the PicoGene handheld PCR device for FMD. “If the company can reduce the cost, it would be possible to use it in quarantine facilities,” he says.
As for bacteria-filtering volcanic soil, Thai researchers are exploring sources closer to home. The team has tested volcanic soil from at least six locations in Thailand, Misawa says. “We found some volcanic ash produced in Thailand that absorbed E. coli.”
As the world anticipates the emergence of new diseases, which could spread as livestock and meat products cross borders, the need for rapid pathogen monitoring and control is paramount. “This is a big social problem — not only economically, but also for animal welfare and food safety,” Misawa says. “That’s why we need international collaboration to prevent these infectious diseases.”
What follows will rest on the next generation of researchers, many of whom are being trained in collaboration through educational exchange programmes between the two nations, Misawa says. “We encourage young scientists and veterinarians to join this project,” Chintapitaksakul adds.
Nature Index: North-South collaboration