Nova Scotia·Q&A

Blue-green algae: A Q&A with a public health doctor

Dr. Austin Zygmunt, a regional medical officer of health in Nova Scotia, told CBC's Mainstreet about the dangers blue-green algae blooms can pose to people and animals.

Algae bloom is suspected to be the cause of contamination at a Nova Scotia lake

Algae blooms are natural occurrences. and can last from several days to a few weeks. They are generally not considered a threat to the aquatic environment but they are not without risk to people and pets. (Government of B.C.)

The Department of Environment and local veterinarians are pointing to blue-green algae as one of the most likely causes of contamination at Grand Lake, N.S., that led to the death of two dogs and one person being hospitalized this week.

An alert was issued early Thursday morning warning all residents who take water directly from Grand Lake to stop using the water immediately.

Residents near Grand Lake who don't receive water from a municipal utility are advised not to consume their water, or use it for cooking, bathing, swimming or boating, until told otherwise.

To find out more about the algae, CBC Mainstreet's Preston Mulligan spoke to Dr. Austin Zygmunt, one of Nova Scotia's regional officers of health.

The discussion has been edited for length and clarity.

Q:While we're waiting for the confirmation that this blue-green algae made a person sick and killed two dogs, let's talk about the possibility and what might be the symptoms a person might notice if they came in contact with this stuff. 

A:  Blue-green algae is something that's becoming more common in Nova Scotia, and this is caused by a bacteria called cyanobacteria and this is naturally found in waters such as lakes and rivers.

Normally the bacteria doesn't cause any problems, but under certain conditions, this bacteria can grow and multiply really fast, causing these algae blooms in the water.

Typically, those conditions include warmer weather, warmer water temperatures and also if there's a lot of nutrients in the water.

So one reason we're seeing blue-green algae blooms happening more often in Nova Scotia is really a result of climate change, where we're seeing hotter days earlier in the summer and into the fall.

The department of environment and local veterinarians suspect blue-green algae may be the cause of the contamination at Grand Lake but testing is ongoing. (Paul Palmeter/CBC)

Q:How many cases do you see a year of people getting sick in this province of the blue-green algae?

A:  So we think of how you can come in contact with blue-green algae, the most common way is when people are swimming in the water during the bloom or if they're doing other activities, such as being in the boats where the water might splash on you.

When this happens, the most common symptoms people experience include irritation of their skin or a rash, and then a less common way people can get exposed by drinking the water that is contaminated with the blue-green algae.

When that happens,the symptoms are a little bit more serious.

That can cause some stomach upset, vomiting, diarrhea, headaches and muscle aches.

It does depend on how much of the water you drink.

Most of the time, the blue-green algae is happening in lakes and rivers and most people aren't actually drinking the water. So the exposure is from really having swam in the water or some other type of activity.

Most of the symptoms are fairly minor and most people don't need to go to the hospital or seek health care and they can manage their symptoms at home. 

Halifax Fire secured part of Grand Lake late Wednesday after a possible contamination sent one person to hospital and killed two dogs. (Paul Palmeter/CBC)

Q:  Is there a specific place that the bloom is more prevalent in a body of water?

A:  The blooms can really happen anywhere in the water, but the blooms that we can see tend to be those that are really at the edge of lakes or rivers and where the water is quite shallow, it can build up there and make it visible.

What we're looking for in these scenarios is really some blue-green. It's almost like a scum, a really thick appearance on the surface of the water.

It also might have a bit of a must odour to it. Those are the telltale signs of algal bloom that you can see. But sometimes the blooms can happen really deep in a lake where you might not be able to see it.

Q:  If you come in contact with it and you start to develop some of the symptoms that you talked about earlier. What do you do to reduce the effects or what should one do?

A:  First, if you do see water that has that appearance of the blue-green scum, I would recommend you don't go in the water and those around you shouldn't go in the water. And that includes your pets.

If you do see it, you should give your local Nova Scotia Environment and Climate Change office a call to report it.

But if you do have an exposure, you were swimming in the lake at something you're worried about when you get home, make sure you take a shower or bath to wash anything off your body.

If those symptoms that we talked about develop, like a rash or a headache, you could call 811 or see your health-care provider for some further guidance. And obviously, if the symptoms are really serious, you should call 911.