WATCH ABOVE: Dr. Samir Gupta explains what you need to know about a Cyclospora outbreak in Ontario and other parts of the country in this week’s On Call.
More On Call with Dr. Samir Gupta stories on Globalnews.ca
TORONTO — Public health officials are on high alert as a Cyclospora outbreak sweeps across Ontario, with a smattering of additional infections in B.C., Alberta and Quebec over the last few months.
We thought it would be a good idea to talk about what we actually know about this organism, and how to avoid it.
Cyclospora is what we call a protozoan, which is basically a single-cell parasitic organism, originating in Latin America and East Asia.
READ MORE: What you need to know about Cyclospora
Cyclospora infection that was initially described in patients with HIV in the 1980’s, and the organism that has since been found to be responsible for several outbreaks in North America was only formally named in 1994.
Accordingly, we don’t know all that much about it.
What we do know is that humans are the only known hosts for this bug, which means that the organism relies on humans for its reproductive cycle.
Also, its spread is somewhat different than other such diarrhea-causing organisms.
Most bugs that cause diarrhea are spread through what’s called the “fecal-oral” route — i.e. the bug is excreted in feces — and if someone with the infection fails to wash their hands properly after going to the bathroom and touches someone else’s food, then that person will catch the infection by eating the contaminated food.
READ MORE: Canadian health officials warn about outbreak of intestinal illness Cyclospora
However, with Cyclospora, this direct person-to-person spread doesn’t occur (which is a good thing), because the parasite is in an inactive form when it is excreted in the feces, and needs a period of time under warm and humid conditions on the outside before it can “sporulate” to become active and infective.
Accordingly, it is thought that contaminated crop irrigation or washing water initially spreads the inactive cysts onto produce after harvest, and warm and humid conditions during storage or transport from the country of origin allow the cysts to sporulate en route to North America.
Outbreaks have been tied to various types of produce in the past.
US outbreaks in 1995 to 1997 were traced to contaminated raspberries from Guatemala.
In 2004, another US outbreak was linked to Guatemalan snow peas, and a 2009 outbreak in Sweden was associated with Guatemalan sugar snap peas.
The largest outbreak was in 2013, when over 600 Americans were infected through salad mix and cilantro.
READ MORE: FDA bans some cilantro from Mexico after officials find human feces in fields
Most recently, there was another U.S. outbreak in 2014 linked to cilantro.
The symptoms of Cyclospora infection are similar to most other causes of infectious enteritis.
We estimate that about half of people will actually not develop symptoms at all, and others will have loss of appetite, nausea, abdominal cramping, watery diarrhea, low-grade fever, and weight loss.
Symptoms start on average about a week after consuming it, and usually resolve within a few weeks.
However, there have been reports of prolonged symptoms lasting months in some cases.
Most people will clear the infection on their own, but very young and elderly patients, and those with compromised immune systems may have severe infections.
A common antibiotic called trimethoprim-sulfamethoxazole can help to clear the infection.
In terms of avoidance, the most important step is for us to figure out the source of this particular outbreak.
Until then, my advice is to avoid produce that has been linked to infections in the past, especially if it is from Latin America.
People should also be even more diligent and careful about hand washing and washing their produce, though admittedly it may be impossible to remove Cyclospora cysts completely with washing.
Keeping produce refrigerated is also good policy because the cysts won’t sporulate in that cold environment, though again, if they’ve already sporulated, the cold will probably not kill them.
Comments