Mosquito-borne illness with high fatality rate detected in the U.S.: 11 expert tips for preventing bug bites, ticks and insect-borne illnesses

This article is for informational purposes only and is not a substitute for professional medical advice, diagnosis or treatment. Contact a qualified medical professional before engaging in any physical activity, or making any changes to your diet, medication or lifestyle.

Mosquitoes can be a pain — especially if you're someone who tends to get bitten more often than others. But while itchy mosquito bites can be a nuisance, they can also have serious consequences for your health.

Recently, a mosquito-borne illness with a high fatality rate was detected in the United States, prompting the town of Plymouth, Mass. to close all public parks and fields daily from dusk to dawn. Eastern equine encephalitis (EEE), a rare but serious illness, was detected in horse in the town approximately 60 km outside of Boston. According to a press release from the town, the illness has a human fatality rate that varies “from 33 per cent to 70 per cent, with most deaths occurring two to 10 days after the onset of symptoms.”

According to the U.S. Centers for Disease Control and Prevention (CDC), most people bitten by an mosquito infected with EEE won't develop symptoms. However, those that do will develop symptoms can develop either a febrile illness (fever, chills, body aches, joint pain) or neurologic disease, which can include meningitis and present with vomiting, drowsiness, diarrhea, unconsciousness and seizures.

People who recover from EEE can have long-term physical and mental complications, like paralysis, seizures and severe intellectual disability. There is no specific treatment for EEE; anyone who exhibits symptoms should seek immediate medical attention. A third affected with the disease will die.

Earlier this month, Yahoo Canada spoke to Winnipeg-based entomologist and mosquito expert Taz Stuart, who shared his tips for protecting you and your family from mosquitoes and ticks from now and into November.

Mosquito-borne viruses in Canada: West Nile, EEE and more

Since the West Nile virus arrived in Canada in 2002, it has affected anywhere from five to 2,401 people per year. Culex mosquitoes, the genus that carries West Nile, is active from mid-April to November, as they like “lots of water bodies, high organic matter and hot temperatures,” said Stuart. The more Culex mosquitoes in an area, the higher the risk of contracting West Nile virus.

So far this year, West Nile virus has been detected in mosquito pools in Manitoba and Ontario, as well as in dead birds in Quebec and Saskatchewan. Though 70 to 80 percent of people who are infected with West Nile virus will have no symptoms, rare severe cases of the virus can be fatal.

Like the United States, mosquitos in Canada can also carry western equine encephalitis and eastern equine encephalitis.

“It's just the reality of where we live and climate change,” Stuart said. “We have some really good conditions to see human disease from mosquitoes.”

Why do mosquitoes like me?

Your best course of action to protect yourself from mosquito-borne illnesses is to avoid getting bitten altogether. Unfortunately, some people will naturally attract mosquitoes more than others due to body odour that’s undetectable to humans, but there are still steps you can take to lower your risk of being bitten.

Stay indoors at high-risk times

Stuart noted that mosquitos are most active between dusk and dawn. Staying indoors in the evenings can help lower your chance of being bitten. If you do spend time outside at night, wear protective sprays and keep your arms and legs covered to avoid being bitten.

Avoid exercising outdoors at night

Even though it might be cooler to go for an evening jog, it's prime time for mosquitos who are attracted to CO2. “If you’re running around in a field, they’ll be more attracted to you because you’re throwing off more CO2 than normal," Stuart said.

Wear light-coloured pants and long sleeves

It turns out, mosquitos can be picky when it comes to clothes. Stuart said female mosquitoes, which are the ones that feed, "don’t seem to be attracted to somebody that’s in a white shirt versus a dark colour.”

Opting for light coloured clothes in combination with protective sprays can help keep you safe from pesky bites.

Choose the right insect repellent

The most common ingredient in effective insect repellents is DEET. Typically, 25 to 30 per cent DEET will provide protection for several hours, though you’ll want to reapply if you go swimming. Also make sure you read the instructions.

“You don’t want to be spraying a 30 percent–level DEET on a six-month-old,” Stuart explained. Many brands carry family-friendly bug sprays with lower concentrations of DEET or insect-repelling ingredients like icaridin (also called picaridin) and oil of lemon eucalyptus.

Shop insect repellents

Drain or treat water around your house

Mosquitos will lay their eggs either on or near standing water. “The gutters on the top of your house? Those can be mosquito sites,” Stuart said. “The low spot in the back corner of your cottage where there’s water? You need to cover it or drain it.”

If you’re not able to dump, drain, fill or cover the space where water collects, then it’s time to treat it. Stuart said people can buy Bacillus thuringiensis israelensis (BTI), a type of bacteria that mosquitos ingest that kills larvae. According to Stuart, BTI is considered very low risk to humans, other animals and honeybees.

Shop the best BTI water treatment

Track the mosquito forecast in your area

To some degree, you can predict if your region might have a mosquito explosion in the near future. “If it rains and it's 30 degrees out, you can have mosquitoes go from egg larvae to pupa to adult in as little as seven days,” said Stuart.

He suggests visiting the OFF!Cast Mosquito Forecast, which is based on municipal data and an algorithm that will produce an idea of how heavy the mosquitoes will be in your area —or the area you're travelling to — this summer.

Ticks and tick-borne illnesses

Tick bites can transmit Lyme disease and Powassan virus disease to humans, both of which can have serious impacts on our health.

Lyme disease is an infection caused by spirochetes (corkscrew shaped bacteria) called Borrelia burgdorferi. The illness is transmitted by infected blacklegged ticks and when detected early, can be treated with antibiotics. However, five to 10 per cent of cases will develop post-treatment Lyme disease syndrome (PTLDS) with symptoms like fatigue, body aches and difficulty thinking.

Powassan virus disease is a low risk virus that can cause flu-like symptoms that range in severity and can cause long-term neurologic issues such as headaches, memory issues and muscle wasting. Although rare, 10 per cent of Powassan virus cases are fatal, due to inflammation of the brain (encephalitis).

How do you protect yourself from ticks?

Stuart said it's important to stay alert when it comes to ticks — especially now that summer's almost over. “Now that we're into August, there aren’t many adults out there anymore,” Stuart said. “They're very small — about the size of a poppy seed.”

Although ticks may be small, there are still ways you can protect yourself and your four-legged friends.

Stay on cleared paths or trails

Avoid walking in tall grass or the tree lines and long-grassed edges of fields and trails where ticks like to "quest." According to Stuart, ticks like to "sit with their two arms waving in the air" waiting to attach themselves to a host.

Do a thorough tick check after spending time outside

Stuart recommended taking a look “along your hairline, behind your knees, on your back and underneath your armpits” if you’ve spent time in grassy or treed areas. Consider changing into a fresh set of clothes when you come back indoors and put the clothes you wore outside in the wash immediately. Hot water and a high temperature dry cycle can help kill any ticks that may have attached themselves to you.

Always check your pets for ticks

Animals can carry ticks indoors and spread them to humans. Consider using flea and tick prevention from April to November and check your pet’s fur—especially after walks in long grasses or forested regions.

Wear repellents when venturing outdoors

Like mosquitos, DEET, icaridin and permethrin (found on treated clothing) have all been approved to repel ticks in Canada.

When is it time to visit the doctor after a bug bite?

If you’re bitten by a mosquito and develop symptoms like a severe headache, high fever, stiff neck, vomiting or trouble swallowing, visit your healthcare provider. They can do a blood test to confirm if you’ve been infected with West Nile virus and provide you with fluids, medications and other support.

The most commonly reported symptom of Lyme disease is a skin rash that develops around the site of a tick bite. It will often grow to more than five centimetres over several days and may be circular or oval or even look like a bull’s eye. If you don’t develop a rash but have symptoms like fever, chills, fatigue, headache, swollen lymph nodes or muscle and joint aches, see your healthcare provider ASAP. Without treatment, the virus could spread to your joints, heart and nervous system and cause more serious issues.

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