Dal professor takes a look at the listeriosis outbreak

By Scott Beed, Staff Contributor

Ever since the listeriosis outbreaks two years ago, Maple Leaf products likely invoke thoughts of stomach aches and violent illness. But a Dalhousie University professor is trying to dispel fears surrounding certain food borne bacteria.
Rafael Garduno, an associate professor with the department of microbiology, focuses his research on listeria and legionella. The former plagued Maple Leaf meat products two years ago. When eaten, the bacteria can develop into listeriosis, an illness with severe flu-like symptoms. According to the Canadian Food Inspection Agency, the 2008 breakout caused nine deaths with 38 confirmed cases.
Garduno says even though listeria and legionella are dangerous and can harm people, they aren’t the most dangerous food borne bacteria out there.
He has worked with several bacterial pathogens since starting at Dal in 1997 and he says his work is designed to build a basic understanding of bacteria in general.
“We focus on bacteria, not any bacteria but bacteria that are transmitted to humans through either water or food products,” he says.
Garduno says that to understand outbreak prevention methods, his research must determine how these bacteria survive and thrive in our food and water.
Legionella survives in temperatures ranging from 25 to 45 degrees Celsius and can sometimes develop into Legionnaires Disease, which is a form of pneumonia. Garduno explains that this type of pneumonia can’t spread from person to person, so it’s considered an environmental disease.
“Imagine legionella in the water,” he says. “Here in Canada, the average water temperature throughout the year is not ideal for the survival of this bacteria. But it can survive, and it makes its way into distribution centers in cities or something, where it encounters chlorine or other treatments, but still makes it into drinking water and when its consumed it causes Legionnaires’ Disease.”
Garduno explains that he’s trying to understand why legionella is able to survive in such adverse situations.
Garduno also does research on fish proteins, peptides, enzymes and marine toxins with Dalhousie’s Department of Food Science and Technology. Tom Gill, a professor in Dal’s food science program, is one of Garduno’s research partners.
His work focuses on marine toxins and the safe handling of seafood when processing and shipping these products. Garduno and Gill have collaborated to determine the effects of the listeria bacteria on salmon, shellfish and other marine wildlife.
Gill’s lab has studied paralytic shellfish poison, which can be contracted if contaminated clams, mussels, scallops or any other shellfish are consumed. Because shellfish are filter-feeding organisms, they can absorb bacteria that are found in the water where they live. This kind of bacteria can accumulate in their tissue and they can become highly toxic to eat. These toxins can cause localized paralysis in certain organs. For example, Garduno says if these toxins infect the lungs, a person can suffocate.
Garduno says he wants to develop methods that could reduce the harm bacteria have on the general population. He says he hopes his research will help in the development and implementation of new and better methods of water treatment and food processing.
This type of research isn’t new, he adds.
“The research itself was relevant before and it continues to be relevant, but because of potential outbreaks I think the perspective has changed.”