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A tick can weigh less than two milligrams, and is comparable in size and appearance to a single poppy or apple seed. That minuscule weight is distributed across eight legs. That’s why you might not feel a tick as it climbs up your leg. Ticks instinctively seek out dark places and the parts of animals where the skin is thinnest and grooming is difficult. For humans this means the neck, head, and near the ears. A tick isn’t picky, however. It will settle for an armpit, the back of a knee, or even inside a bellybutton.

As unlikely as you are to feel a tick crawling up your body, you are even less likely to feel it bite you. That’s thanks to the tick’s saliva. Like the mosquito, as part of its feeding process a tick first injects saliva into its victim, which acts as a local anesthetic. Unlike a mosquito, who dines and dashes, a tick settles in for the long haul. When embedded, their saliva pulls triple duty, acting as an anti-clotting agent to keep blood flowing, an immune response blocker to stop the host’s body from reacting in the form of itching or inflammation, and a pain blocker.

The blacklegged tick, also known as the deer tick, may have an additional substance in its saliva: Borrelia burgdorferi, one of the five species of bacteria that cause Lyme disease, a debilitating illness. Sample testing of tick populations found that nearly half of all blacklegged ticks are carriers of Borrelia burgdorferi and are therefore capable of spreading Lyme disease.

Manitoba’s first case of Lyme disease

In 1989, four-year-old Janessa Goss didn’t feel the tick crawl up to the back of her skull, and she didn’t feel it bite. It wasn’t until it was full of blood that she noticed it and brought it to her mom’s attention. Like most parents would at that time, her mother removed the tick and discarded it. As she was doing so, she noticed a red ring rash around the site.

Today, more parents might know that getting rid of the tick was the wrong move. Any engorged tick that is suspected to be a blacklegged tick should be kept in a plastic bag or container and submitted to a doctor for testing. Identifying the tick as a carrier could be key to getting preventative treatment for Lyme disease.

Her mother took Janessa to a doctor expressing concern about the rash and the bite, but without a specimen, she was ultimately sent away. The reason: there had never been a documented case of Lyme disease in Manitoba.

Left undiagnosed, Janessa grew sicker and sicker. Her kidneys began to shut down, and she was started on an adult dose of the antibiotic amoxicillin. Nine months after the initial tick bite, Janessa had to be hospitalized. She had stage three Lyme disease.

There are three stages to Lyme disease. Stage one manifests as a large bullseye-shaped rash at the infection site. This could take up to several weeks to appear as the bacteria spreads throughout the body.

Stage two starts with headaches, stiff joints, muscle aches and fever, and progresses to affect the nervous system and heart.

After months of untreated infection, Lyme disease enters stage three. At this point, Lyme disease has spread throughout the body and can permanently damage the joints, nervous system, and brain.

Doctors still wouldn’t treat Janessa for Lyme disease. She felt hopeless about improving her condition until her mother learned of a disease study being conducted at the University of Minnesota. She faxed over her daughter’s medical files and received an invite for treatment shortly after. After three months of treatment in Minnesota, Janessa’s Lyme disease was finally manageable and she was able to return home.

Lyme disease is highly treatable with antibiotics, especially if it is caught during stage one. Stage three , however, may take up to four weeks of intravenous antibiotics to treat. Even then, the effects linger.

Janessa, now 37, has been living with the effects of Post-Treatment Lyme Disease Syndrome (PTLDS) since the initial bite.

“I basically have no immune system. I’ve had pneumonia five times, pancreatitis, and sore joints day to day. Illness will really drag on — I had laryngitis and I was hoarse for nearly six weeks.”

Janessa hasn’t let chronic Lyme stop her from enjoying the outdoors. She still hikes, dirt bikes, and loves spending time outside with her family.

“I’ve definitely developed a hyper-awareness of ticks when I’m outside. Not a phobia, but I will check myself and my son head-to-toe when we come in for the day. We’ll also use tick spray and tuck our pants into our boots.”

Lyme on the rise

And it’s not hard to see why. A single female tick can lay 3000 eggs in its lifespan. A tick has a hazard range of 20 square kilometres, meaning that there are assumed to be more ticks in the 20km radius that a blacklegged tick is found. Ticks will emerge from hibernation in early April or whenever the temperature increases above 4°C, whichever comes first. In 2022, Manitoba temperatures reached 4°C by March 19. Climate change may push spring earlier and earlier, giving ticks more time to spread.

Even colder winters work in blacklegged ticks’ favour. A 2018 study found ticks that carry Lyme disease may have a better chance of surviving cold weather. The ticks without the Lyme bacteria die out, and the ones that survive the deep freeze go on to spread Lyme in the spring.

The government solution? Self-directed prevention. Manitoba Health’s prevention of tick-borne diseases page recommends wearing long pants and long-sleeved shirts, tick repellent, and checking your body after being outdoors.

With case numbers growing exponentially, self-directed prevention might not be enough. Consider another species where controlling the spread was left to self-directed prevention: the zebra mussel.

Mussel-ing in on our turf

To understand how a creature that remains planted in place for most of its life can spread so efficiently, it’s best to examine its life cycle. A female zebra mussel can release up to 1,000,000 eggs every breeding season. The microscopic larvae that hatch can swim for up to a month, getting carried along lake and river currents. When they find a solid surface, they latch on using many tiny tentacle-like fibres called byssal threads. The solid surface can be anything, including rocks, docks, boats, and even other native mussel species.

Zebra mussels have been found to gather in incredibly dense colonies, with some numbering over 700,000 individuals per square metre. Colonies will clog intake pipes at water treatment plants and hydroelectric dams, necessitating expensive removal. When zebra mussels infest beaches, their shells cover shorelines and lakebeds, and can cut up the bare feet of people swimming and enjoying the beach.

Mussel strain

When zebra mussels take root in a body of water, the effects might not be visible until it is too late. Zebra mussels are filter feeders, taking in water and eating microscopic organisms like plankton and algae. Native mussels will quickly die out without a food source, and with less competition for resources, deadly toxic microcystic algae (which zebra mussels do not eat) will flourish. Where zebra mussels thrive, algae blooms follow.

Another ripple effect of zebra mussel infestations is that in the low oxygen conditions they create, Type E Botulism bacteria thrive. Native bird species that attempt to eat zebra mussels may get infected with botulism and die. Common loons are especially susceptible, with thousands found dead every year. Humans or other animals that eat fish and birds infected with Type E Botulism could become gravely ill.  

In Manitoba, zebra mussels have been inadvertently spread across land by anglers and boaters. Fully grown zebra mussels can survive for weeks outside of water, and microscopic larvae can hide in any stagnant water left undrained from the boat. Boat owners are encouraged to clean, drain, and dry their boat after use, with fines threatened for failing to decontaminate. The Manitoba Government has set up a report line for invasive aquatic species, with the hope of catching them early. That hasn’t stopped boaters from spreading zebra mussels into Lake Manitoba.

To quote the Manitoba Government’s website, “it didn’t have to be this way.” The defeated tone is justified. Once a body of water has been infested by zebra mussels, they are nearly impossible to remove.  

Mussel contractions

Zebra mussel success stories are rare. Lake Waco, in Texas is one instance where a rapid response and a unique control method worked in tandem to prevent an infestation. In September 2014, zebra mussels were found on a boat ramp by the City of Waco employees. A total of 75 mussels were found in a localized area around the marina. To eliminate larvae, the City of Waco, the U.S. Army Corps of Engineers, and Texas Parks and Wildlife worked together to install an acre (4000 square metres) of plastic on the shoreline and lake bed near the epicentre. The plastic stopped the reproductive cycle by blocking oxygen and creating an uninhabitable environment for the zebra mussels. When the plastic was removed five months later, only a single living zebra mussel was found and eliminated. Since then, no larvae or adults have been found in Lake Waco.

Closer to Manitoba, researchers belonging to the  Minnesota Aquatic Invasive Species Research Center (MAISRC) have been experimenting with a variety of prevention and elimination methods. Some promising tactics include using Niclosamide (a chemical typically used to treat tapeworm infections), applying a non-toxic coating to underwater surfaces, and using low-dose copper treatments. Their efficacy is still being determined. In order for a treatment to be considered viable it needs to eliminate the zebra mussel population without harming native species.

Manitoba Hydro has successfully reduced the number of zebra mussels in their Nelson River generating stations using low-level chlorine treatments. Other techniques used to control zebra mussels in pipes include cooking them with thermal treatment, preventing shell formation with Extremely Low Frequency (ELF) magnetism, and killing larvae with UV light. There are different benefits and drawbacks to each treatment, but the commonality is that they only work in small, controlled systems. A safe large-scale treatment has yet to be found. Until then, Lake Manitoba belongs to the zebra mussels.

Tick tactics

Back in the woods, the search for a large-scale blacklegged tick treatment is also ongoing. Ticks can be killed with chemical insecticides. Unfortunately, so can every other invertebrate species in the treated area. Chemical pesticides have been applied directly to livestock hosts with some success. However, repeated use can cause environmental contamination and even lead to insecticide resistance in tick populations.

More recently, researchers have experimented with applying chemical pesticides to wildlife hosts. Small rodents, the most common host for juvenile ticks and the source of Lyme disease, were lured into a container of food through a tube lined with pesticide. While experiments were somewhat successful in reducing the number of Lyme disease-carrying blacklegged ticks, the extra food led to increases in rodent population numbers.

A different experiment targeted deer, the most likely host for adult ticks. Deer were lured to feeders where paint rollers covered in pesticide were strategically placed to rub against them. The feeding sites had significantly lower blacklegged tick density, but the cost of building and maintaining the sites make them impractical at scale. It was also impossible to keep non-target animals, such as raccoons and squirrels, from visiting the sites.

The natural alternative to pesticides is biological control agents, species that target pests. Biological control agents have been used with great success, and even greater failure, on invasive species. When the biological control agent is a non-native species, it may prey on other native species and lead to unpredictable ripple effects in the ecosystem. Take the cane toad, for example. In 1935, 102 cane toads were brought to Australia to eat cane beetles. Today, they number in the billions and have done irreparable harm to native plant and animal species.

For ticks, potential biological control agents include bird species, parasitoid wasps, nematodes, bacteria, and fungi.

There are three species of birds that eat enough ticks to be considered biological control agents: wild turkeys, guineafowl, and oxpeckers. Wild turkeys eat blacklegged ticks when grooming, but are also hosts to lone star ticks, a different species of harmful tick. Guineafowl only targeted adult ticks, and their feed ended up attracting rodents, leading to the opposite intended effect on Lyme disease carrier reduction. Oxpeckers, despite eating hundreds of thousands of ticks daily, were ineffective outside of their natural habitats.

Parasitoid wasps were proven more successful as a biological control agent, but only when blacklegged ticks are hyperabundant. They thrive in an area with excessive ticks but will eventually balance both the tick population and their own. Tick parasitoids are also impractical to breed in captivity. Since they exclusively prey on ticks, a tick colony must be kept as a food source. 

Nematodes are microscopic organisms that kill ticks by entering through an orifice and releasing bacteria. The downside to nematodes is that they mainly target engorged female ticks, can’t sustain populations (their lifecycle ends after they enter a tick), and can’t survive winter temperatures. Bacteria is understudied as a biological control agent, mostly due to impracticality. Bacteria would need to be ingested by a tick in order for it to be effective, and ticks only feed on host blood.

Pathogenic fungi have so far been the most successful biological control agent against ticks preying on livestock, both in lethal and sublethal ways. Ticks that survived fungi exposure were found to have reduced body mass and smaller egg clutches. An added benefit is that unlike chemical pesticides, fungi don’t have a toxic effect on livestock or the environment. Unfortunately, fungi have been much less effective when applied to wild hosts. There’s also the added danger of introducing a non-native fungus into an environment without knowing the long-term effects it could have on the ecosystem.

Researchers are still searching for new ways to combat blacklegged ticks, and most recently have discovered that the oil extracted from balsam fir needles acts as a natural pesticide in the winter. Needles were found to kill hibernating ticks over the course of several weeks, and exposing the ticks to the extracted essential oil reduced that to days.

Lyme cocktails

If the vector can’t be outright eliminated, what about Lyme disease itself? Can Lyme transmission be prevented in human hosts?

Surprisingly, this problem was solved 25 years ago. A human vaccine for Lyme disease, LYMErix, was approved by the United States Food and Drug Administration (FDA) in 1998 but was ultimately pulled from the market four years later. At the time, Lyme disease wasn’t common enough to be thought of as dangerous, and some recipients of LYMErix claimed it induced a form of arthritis. LYMErix’s failure set back human Lyme vaccine research for decades. At present, a vaccine is only available for dogs.

Janessa didn’t know there was a Lyme disease vaccine until she got her puppy vaccinated.

“I remember being really annoyed when I learned that there’s a Lyme disease vaccine for dogs, but not for people,” said Janessa. “I’d hate for my son to ever go through the same experience I did.”

The rising number of Lyme disease cases and the spread of blacklegged ticks have reignited interest in a preventative vaccine. There are currently three promising projects nearing completion.

VLA15, developed by Pfizer and Valneva, works by preventing the bacteria from leaving a tick and infecting a human host. The vaccine is expected to be licensed for human use by 2025.

Lyme Pre Exposure Prophylaxis (Lyme PrEP), developed by Mass Biologics, delivers a monoclonal antibody that gives immunity to Lyme within hours. Lyme PrEP is expected to start phase two of clinical trials this year, in 2023.

Yale School of Medicine is trying a different preventative approach and has designed a vaccine that prevents Lyme by causing an immediate body reaction to a tick bite. A tick that can’t feed unnoticed is a tick that can’t spread Lyme disease. The vaccine is currently being tested on guinea pigs with successful results, and is expected to progress to human testing in 2023.

Self-directed prevention is a good start by the Manitoba government, but also the bare minimum when it comes to invasive species. Rather than accept defeat as inevitable, we can be proactive in our research efforts, public awareness campaigns, and population control measures. Zebra mussels may have won Manitoba’s waterways, but that doesn’t mean we have to let blacklegged ticks win Manitoba’s woods.