Global warming helps spread viruses but risk in N.L. remains low, say researchers

While mosquito- and tick-borne diseases are not of major concern in Newfoundland and Labrador yet, they’re something to monitor going forward, say researchers and a public health official.

A recent Memorial Universitystudy set out to determine which mosquito species can be found in the province and what viruses they carry.

One of the study's lead scientists, Atanu Sarkar, a public health specialist from the division of population health and applied health science in the faculty of medicine, says the researchers’ interest stemmed from global warming and its effects on local populations of the insect.

"Climate change is causing havoc in the globe as far as the health impact is concerned, particularly infectious diseases," said Sarkar.

"There are so many studies showing that climate change is helping to spread mosquitoes."

The citizen science project recruited 182 residents across the province and in Saint Pierre and Miquelon, providing them with online training and a device to collect insects. They gathered around 3,500 mosquito samples for the researchers in 2018 and 2019.

After a delay due to the COVID-19 pandemic, the findings were released in the summer of 2025.

"We identified a lot of invasive species," said Sarkar. "Those mosquitoes are thriving in Newfoundland weather, which is a popular belief that any animals who are from outside may not thrive, but they're thriving. And also we identified viruses."

That included viruses which can be transmitted to humans, like Snowshoe hare and Jamestown Canyon virus, that can cause flu-like illness as well as neurological issues in severe cases.

Sarkar said the study was the first time the provincial mosquito and virus distribution was mapped — something fellow study researcher and Memorial University biology professor Tom Chapman agreed is an important step.

Chapman added the viruses the team found aren’t new to the province, as Memorial University scientists in the 1980s had already recorded the presence of both Snowshoe hare and Jamestown Canyon viruses.

Apart from changing weather patterns, he said the rapidly increasing level of international travel and trade also contributes to the introduction of non-native species.

"We've had several new mosquito species that we've identified that are known around the world but are newly, have arrived on the island," said Chapman.

"It's a concern, in that a couple of them are well-known human disease vectors."

Both Chapman and Sarkar said more research is needed to identify high-risk areas, which can be used for recommendations to both public health and people.

Risk of Lyme disease remains low

Another animal that can carry a dreaded disease and is regularly raised as a concern among residents in the summer months is the tick, which can transmit Lyme disease.

Hugh Whitney, chief veterinary officer of Newfoundland and Labrador from 1985 to 2015, spent decades researching the parasite. During that time, he said black-legged ticks gradually moved north, and the first tick discovery in the province was in Cape Broyle in 2001.

Since then, he said ticks submitted by both vet clinics and the public have been tested as part of passive surveillance.

"We would find up to 30 ticks a year generally, spread across the island," said Whitney, adding that ticks predominantly come to the province via migratory birds.

"We were getting about 20 per cent of these black-legged ticks to be carrying the bacteria [that causes Lyme disease] and that was fairly close to the national average."

Yet, Whitney said it’s unlikely for permanent populations of the tick — which has three feeding stages — to establish itself locally, as the host animals it needs for its life cycle, the white-footed mouse and the white-tailed deer, aren’t native to the province.

He said whether another species, like the caribou, could serve as host animal in the future is unclear.

"Ticks have been very close to the southern border and caribou are our northern deer species. So, they haven’t overlapped," he said.

"But as ticks move further and further north, the chances increase."

At this point, said Whitney, who was also involved in the Memorial University study, the risk for mosquito-borne illness is much higher.

It’s a view shared by the province’s chief medical officer of health.

"We do see ticks here in the province that carry Lyme disease … We don't have evidence at the moment that those ticks have set up sustained colonies or populations," said Dr. Janice Fitzgerald.

While any provincial case of Lyme disease seems to have been contracted elsewhere, Fitzgerald said public health continues to monitor the situation — something that’s also the case for mosquito-borne viruses.

"Some of them can be quite significant and they can cause significant illnesses," said Fitzgerald.

"So, we certainly want to know if we're seeing an increase in these cases in this area, without a doubt."

Any cases of diseases like West Nile or Jamestown Canyon virus, she added, are reportable to public health under legislation — and only "a few cases here and there" have been recorded so far.

As there are currently no vaccines available, Fitzgerald is urging people to take preventative measures, like applying insect repellent, wearing long clothes and eliminating any sources of standing water where mosquitoes lay their eggs.

"Our best defence at the moment is just making sure you're not allowing a hospitable environment to develop and that you're protecting yourself," she said.

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