ILOILO CITY— A University of the Philippines (UP) professor developed a method to immediately detect the presence of toxins in shellfish that could help minimize casualties in many coastal communities prone to paralytic shellfish poisoning.
Dr. Sharon Nuñal, a faculty member of the Institute of Fish Processing Technology, College of Fisheries and Ocean Sciences at the UP Visayas, came up with a detection tool using molecular techniques that would determine the presence of pathogens and bacteria in oysters and mussels.
Nuñal presented her study to a group of community journalists participating in a science journalism workshop “Blue Economy for Sustainable Seas” organized by the UP College of Mass Communication, in line with its Communicating Science and Technology/Research and Development of the University of the Philippines program.
She said using molecular techniques offers many advantages over conventional methods of identifying the pathogens in shellfish. She added molecular technique saves time, has high throughput, reduces spoilage and contamination and increases the marketability of products.
“You can get the result within hours as compared to the usual two to seven days, depending on the bacteria, when you have to study the specimen on a petri dish. This is only for bacterial analysis, and testing for viruses is another thing,” she said.
The traditional way of studying the toxicity of shellfish samples takes many days that some victims die first before a ban on gathering and selling of shellfish in red-tide affected areas is imposed.
Even without red tide, many shellfish species have high levels of bacteria and toxic pathogens and consuming them could cause poisoning.
The World Health Organization estimates around 600 million people worldwide, or 1 in every 10 people, have become ill from eating contaminated food, resulting in the death of around 420,000 people.
Nuñal said people get sick due to the bacteria and viruses that are not killed while cooking shellfish.
“Oysters and mussels are stationary and are known filter-feeders. They maintain and accumulate what is in the water, including bacteria and viruses,” she added. “The manner that we cook is not enough to eliminate all the viruses that are present.”
Data from the Department of Health showed 1.4 million Filipinos get salmonella infection from eating shellfish every year. Also, 3 in every 4 people who eat shellfish are at risk of salmonella poisoning.
Infection caused by Escherichia coli, a type of bacteria commonly found in human waste, made up 2 percent of food-borne infection cases recorded in the country from 1995 to 2004. In the same period, 985 cases of salmonella infection were recorded out of 3,313 cases of food-borne poisoning.
Other diseases that have been associated with eating seafood include cholera, hepatitis A and norovirus infection. Norovirus is very contagious and can cause stomach, or intestine inflammation, leading to stomach pain, nausea and diarrhea.
“It is important to determine the presence of these bacteria and pathogens in oyster and mussels,” she said. “Bacteria and viruses contain DNA that can be explored so that detection can be more specific and more sensitive even if there are very few samples.”
Nuñal’s research project is funded by the UP Balik PhD, a program of the University of the Philippines to invite foreign-trained Filipinos with postdoctoral degree to pursue research and mentor undergraduate and graduate students in the Philippines.
Making seafood safe
Data from the Department of Agriculture indicated that Filipinos consume an average of 7.48 kilograms of seafood, including shellfish, a year. In 2016 18,800 metric tons (MT) of mussels and 19,500 MT of oysters were harvested, providing additional income to thousands of fishermen in the country.
Nuñal said early detection of presence of harmful pathogens in seafood will help ensure that what goes to the market is safe for human consumption.
“What we want to achieve is to develop a protocol that can be adopted by different stakeholders in the supply chain from producers to processors,” she said. She added that this will also support food-safety programs of regulatory agencies like the Bureau of Fisheries and Aquatic Resources.
“We are lobbying for the adoption of the protocol by government agencies. We don’t know how far, or near, we are now. But the science side is already complete,” she said.
Nuñal added that having a reliable detection method for food-borne pathogens will make the country’s seafood exports compliant with international standards. “We have the potential to export mussels and oysters to the United States, Europe and other Asian countries, which will mean increased income for our marginal fishermen.”
“Scientists and researchers are in continuous search for improved tools that are faster, more accurate and more sensitive than ever before,” Nuñal said. “Everybody has a role to play in keeping food safe.”