By Jing Ren
BOSTON– Fish is regarded as a heart-healthy dinner option, but seafood lovers should be aware of the potential health risks from improperly handled fish.
Food-borne illnesses sicken 48 million Americans each year, according to the U.S. Centers for Disease Control. Seafood-borne pathogens caused 188 outbreaks and 4,020 illnesses from 1973 to 2006, according to an analysis published at Clinical Microbiology Reviews.
At the 2017 AAAS meeting in Boston, Paul K.S. Lam, professor of the City University of Hong Kong, discussed the consequences of ciguatera fish poisoning, which is caused by eating seafood contaminated with a naturally occuring toxin. Lam said that 50,000-5000,000 cases of ciguatera fish poisoning are reported globally every year. Clinical symptoms include abdominal pain, vomiting, nausea, decreased blood pressure, dizziness and numbness.
The global distribution of ciguatera fish poisoning and ciguatoxic fishes suggests the influence of global warming. After studying sea surface temperatures from 1960-2007, Lam and his colleagues found that the higher the average sea surface temperature is, the higher the rate of poisoning. Their study showed that the Pacific Island countries and territories, which had the warmest sea surface temperatures, had the highest level of outbreaks.
Lam also explained how ciguatoxins move through the food chain. The toxins can attach to micro algae, turf algae, sand, seagrasses and coral rubble. The smaller plant-eating fishes living in coral reef waters ingest the toxins, and these fishes in turn are preyed upon by larger carnivorous fishes. Humans beings, on top of this food chain, consume the fishes and toxins within them.
In the study, Lam and his colleagues collected invertebrates and fishes from the coral reef system in Marakei, an atoll of the Republican of Kiribati. They discovered that the Pacific ciguatoxins are the most toxic ones among these poisonous organic compounds.
The tricky issue here is that the toxin is itself odorless and tasteless, and cooking does not destroy it. “These syndromes can last for several weeks up to several years,” Lam said.
People may ask how to address this problem. Lam said people could stop eating fish, but fish should make up part of a healthful diet. Therefore, he proposed that the right way to avoid the illness is not to completely forbid the trade of these fish, but to discover a method to better detect the toxins and extract them.
However, since there is a lack of cheap and reliable detection methods for ciguatoxins, a “breakthrough” technology is needed to prevent poisonous fish from entering the market, he said.