Lakshmi Chauhan, University of Colorado Anschutz

Spring’s warmer weather lures people outdoors – and into possible contact with ticks that spread Lyme disease.

Already, the 2026 tick season is booming. On April 23, the Centers for Disease Control and Prevention warned that emergency room visits due to tick bites are at their highest level since 2017. That may portend an especially severe season for Lyme disease and other tick-borne illnesses.

State health departments reported more than 89,000 cases of Lyme disease in 2023, the last year for which data is available. But public health experts believe that close to 500,000 people in the U.S. get Lyme disease every year.

As an infectious disease doctor with experience treating some of this infection’s long-term outcomes, I know that Lyme disease can be tricky because people often don’t notice tick bites and may overlook early symptoms of an infection. But left untreated, the infection can cause serious lingering – and even permanent – health issues.

Here’s what you need to know about Lyme disease to stay safe this season:

What causes Lyme disease?

Lyme disease, named after the Connecticut town where the disease was first identified in 1975, is caused by a group of bacteria called Borrelia – most often, the species Borrelia burgdorferi.

Deer ticks – also called black-legged ticks, and members of a group called Ixodes – transmit the disease after feeding on an infected animal, usually a bird, mouse or deer. When they then bite a person, they can transmit the bacteria into the person’s bloodstream.
Usually, the tick must attach for 24-48 hours to transmit the bacteria causing Lyme disease.

Where and when does Lyme disease occur?

Lyme disease can occur in most regions where deer ticks live.

These ticks are most active in late spring, summer and fall – usually April to November in most regions. They emerge when the temperature is above freezing. In years when winter is shorter, ticks can emerge earlier. And they may be active year-round in regions where freezing temperatures are rare.

Approximately 90% of U.S. cases are reported from states in the Northeast, mid-Atlantic from Virginia to eastern Canada, and Upper Midwest regions including Wisconsin, Michigan and Minnesota. A few cases occasionally pop up in California, Oregon and Washington.

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Since 1995, the incidence of Lyme disease in the U.S. has almost doubled.

Warmer weather and changes in rainfall patterns now allow ticks to survive in new regions of the country – and for longer periods. But even in regions where ticks lived before, Lyme disease has become more common due to increases in deer populations. As woodland areas are increasingly being developed, it may be bringing the habitat of deer and mice closer to people, increasing the risk of transmission.

Lyme disease symptoms to watch for

Early symptoms of Lyme disease – fever, muscle aches and fatigue – generally emerge within three to 30 days after a tick bite. Another classic symptom in the first month is a target or bull’s eye rash at the site of tick bite, which occurs in about 70% to 80% of cases.

Other rashes following a tick bite can also occur. Some may be due to irritation from the bite, and not necessarily an infection.

If you know you’ve had a tick bite and experience flu-like symptoms – or if you see a bull’s-eye rash, whether you know you were bitten or not – it’s important to check with your healthcare provider about whether you should be treated with antibiotics.

A blood test for antibodies can help confirm the infection, but it can sometimes yield a false negative result, particularly in the first couple of weeks of the disease.

In most people, the rash goes away on its own. However, treatment may shorten its duration and is important for preventing other symptoms. A two- to four-week course of antibiotics can generally treat Lyme disease. Severe cases might require intravenous antibiotics.

A promising new vaccine for Lyme disease is currently being tested. In March 2026, Pfizer, the pharmaceutical company developing it, announced that in a late-stage study, the vaccine prevented the disease in 70% of people who received it.

Later Lyme symptoms

If left untreated, the bacteria that causes Lyme can spread, potentially causing longer-term symptoms. About 60% of people who get Lyme disease and don’t treat it can develop arthritis.

In rare cases, Lyme disease can also affect the heart and the nervous system. Inflammation in the brain or the tissues surrounding it, called meninges, can cause headaches and neck pain, as well as balance issues and memory and behavior changes. It can also cause nerve damage that results in numbness, tingling and muscle weakness.

These symptoms can appear right away or much later – sometimes months to years after infection. And in cases where the disease wasn’t promptly treated, late-stage symptoms can linger even after antibiotics kill the bacteria.

Scientists don’t fully understand why, but one intriguing study found that some particles from the bacteria’s cell wall leak into the joints and can persist after treatment, spurring ongoing inflammation and arthritis symptoms.

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Another reason for Lyme’s long-term effects is that it can trigger autoimmune disease, which is when the immune system attacks its own cells. What’s more, because the nervous system may be particularly sensitive to damage caused by the bacteria and related inflammation, it may take an especially long time to heal. In some situations, the damage could be permanent.

Preventing Lyme disease

Until a vaccine becomes available, there are steps you and your family can take to help protect against Lyme disease:

• Use tick and insect repellents such as DEET and picaridin, which can be applied to skin, and permethrin, which is sprayed onto clothing, to keep ticks at bay. Treating clothing with permethrin may be especially beneficial, since the substance withstands several washes.
• Wear long-sleeve shirts and pants while you are gardening, hiking or walking through grass or woods to prevent tick bites. Wearing light-colored clothes makes ticks more visible, and tucking your pants into your socks can also prevent the little buggers from traveling from your pants, shoes and socks onto your legs.
• Remove your outdoor clothes immediately. Washing and drying clothes at high temperature can help kill any ticks that managed to hitch a ride. And a quick shower immediately after spending time outdoors can wash ticks off the skin before they have a chance to attach.
• If you spend time outdoors, perform daily tick checks, paying special attention to warm areas like your armpits, neck, ears and underwear line. If you find a tick attached, pull it off with tweezers, holding them perpendicular to the skin.
• If you find a tick that may have been on the skin for more than 36 hours, ask your healthcare provider whether a dose of preventive antibiotics – generally given within 72 hours of the bite – would be appropriate.

Lakshmi Chauhan, Associate Professor of Infectious Disease Medicine, University of Colorado Anschutz

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Last Updated on April 17, 2026 by Daily News Staff

Earth Day is celebrated annually on April 22nd, and it serves as a reminder of the importance of taking care of our planet. It’s a day to reflect on our impact on the environment and to take action to create a better future for our planet.

The first Earth Day was celebrated in 1970, and it marked the beginning of the environmental movement. Since then, Earth Day has grown into an international event, with millions of people around the world participating in activities and events to raise awareness about environmental issues.

One of the main goals of Earth Day is to encourage people to take action to reduce their impact on the environment. This can include simple actions like recycling, conserving energy, and reducing waste. It can also involve more significant actions like advocating for environmental policies and supporting sustainable businesses.

Another important aspect of Earth Day is education. It’s a time to learn about environmental issues and to understand how our actions can impact the planet. Many schools and organizations use Earth Day as an opportunity to teach children about the importance of taking care of the environment.

This year’s Earth Day theme is “Restore Our Earth”, and it focuses on the idea that we can all play a role in restoring the planet’s ecosystems. This can include actions like planting trees, reducing plastic waste, and supporting sustainable agriculture.

Earth Day is an important reminder of the impact that we have on the environment and the importance of taking action to create a better future for our planet. By working together and taking small steps, we can make a big difference in protecting the planet and ensuring that it remains healthy and beautiful for generations to come.

Earth Day – April 22

https://nationaltoday.com/earth-day/

https://stmdailynews.com/category/science/

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Jacob A Tennessen, Harvard University

The fight against infectious disease is a race against evolution. Bacteria become resistant to antibiotics. Viruses adapt to spread more quickly. Diseases transmitted by insects present another evolutionary front: Insects themselves can evolve resistance to the poisons that people use to kill them.

In particular, the mosquito-borne disease malaria kills over 600,000 people annually. Since World War II, people have battled malaria with insecticides – chemical weapons intended to kill Anopheles mosquitoes infected with the Plasmodium parasites that cause the disease.

However, mosquitoes are quickly evolving counterstrategies that make these insecticides ineffective, putting millions of people at greater risk of deadly infection. My colleagues and I have newly published research showing how.

Insecticide resistance threatens public health

As an evolutionary geneticist, I study natural selection – the basis for adaptive evolution. Genetic variants that best promote survival can replace less advantageous versions, causing species to change. Anopheles mosquitoes are frustratingly adept at evolving.

In the mid-1990s, most African Anopheles were susceptible to pyrethroids, a popular type of insecticide originally derived from chrysanthemums. Anopheles control relies on two pyrethroid-based methods: insecticide-treated bed nets to protect sleepers, and indoor residual spraying of insecticide against the walls of homes. These two methods alone likely prevented over a half-billion cases of malaria between 2000 and 2015.

However, mosquitoes today from Ghana to Malawi are often able to survive insecticide concentrations 10 times the previously lethal dose. Along with Anopheles control efforts, agriculture also inadvertently exposes mosquitoes to pyrethroids and contributes to insecticide resistance.

In some African locales, Anopheles is already showing resistance to all four main classes of insecticide used for malaria control.

Adaptation in Latin American mosquitoes

Anopheles mosquitoes and the malaria-causing Plasmodium also occur outside Africa, where insecticide resistance is less well-researched.

In much of South America, the main malaria vector is Anopheles darlingi. This mosquito species has diverged evolutionarily from the African vectors so extensively that it might be a different genus, Nyssorhynchus. Along with colleagues from eight countries, I analyzed over 1,000 Anopheles darlingi genomes to understand its genetic diversity, including any recent changes due to human activity. My collaborators collected these mosquitoes at 16 locations ranging from the Atlantic coast of Brazil to the Pacific side of the Andes in Colombia.

We found that, like its African counterparts, Anopheles darlingi shows extremely high genetic diversity – more than 20 times that of humans – indicating that very large populations of this insect exist. A species with such a vast gene pool is well poised to adapt to new challenges. The right mutation giving it the advantage it needs is more likely to pop up when there are so many individuals. And once that mutation starts to spread, it’s protected by numbers since it won’t be wiped out if a few mosquitoes die by chance.

In contrast, bald eagles in the contiguous U.S. were never able to evolve resistance against the insecticide DDT and approached extinction. Evolution is more efficient among millions of insects than mere thousands of birds. And indeed, we saw signals of adaptive evolution in the resistance-related genes of Anopheles darlingi occurring over the past few decades.

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Mosquitoes evolve to detoxify poisons

Insecticides like pyrethroids and DDT share the same molecular target: channels in nerve cells that can open and close. When open, the nerve cell stimulates other cells. These insecticides force the channels to remain open and continuously fire, causing paralysis and death. However, insects can evolve resistance by changing the shape of the channel itself.

Earlier genetic scans performed by other researchers had not detected this type of resistance in Anopheles darlingi, and neither did ours. Instead, we found that resistance is evolving in another way: a group of genes encoding enzymes that break down toxic compounds. High activity of these enzymes, called P450, frequently underlies resistance to insecticides in other mosquitoes. The same cluster of P450 genes has changed independently at least seven times across South America since insecticide use began in the mid-20th century.

In French Guiana, a different set of P450 genes exhibits a similar evolutionary pattern, cementing the clear connection between these enzymes and adaptation. Moreover, when we exposed mosquitoes to pyrethroids in sealed bottles, differences among the P450 genes of individual mosquitoes were linked to the length of time they stayed alive.

Insecticide-heavy campaigns against malaria have been only sporadic in South America and may not be the main driver behind this evolution. Instead, it’s possible that mosquitoes are being exposed indirectly to agricultural insecticides. Intriguingly, we saw the strongest signs of evolution in places where farming is prevalent.

Toward more sophisticated vector control

Despite new vaccines and other recent advances against malaria, mosquito control remains essential for reducing disease.

Some countries are launching trials of gene drives to control malaria, which involve forcing a genetic modification into a mosquito population to reduce their numbers or their tolerance for Plasmodium. Such prospects are exciting, though the relentless adaptability of mosquitoes could be an obstacle.

I and others are revising methods to efficiently test for emerging insecticide resistance. Genome-scale sequencing remains important to detect new or unexpected evolutionary responses. The risk of adaptation is highest under a continuous, strong selection pressure, so minimizing, switching and staggering pesticides can help thwart resistance.

Success in the fight against evolving resistance will require a coordinated effort of monitoring, and reacting accordingly. Unlike evolution, humans can think ahead.

Jacob A Tennessen, Research Scientist in Immunology and Infectious Diseases, Harvard University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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The science section of our news blog STM Daily News provides readers with captivating and up-to-date information on the latest scientific discoveries, breakthroughs, and innovations across various fields. We offer engaging and accessible content, ensuring that readers with different levels of scientific knowledge can stay informed. Whether it’s exploring advancements in medicine, astronomy, technology, or environmental sciences, our science section strives to shed light on the intriguing world of scientific exploration and its profound impact on our daily lives. From thought-provoking articles to informative interviews with experts in the field, STM Daily News Science offers a harmonious blend of factual reporting, analysis, and exploration, making it a go-to source for science enthusiasts and curious minds alike. https://stmdailynews.com/category/science/

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