Post-treatment Lyme disease syndrome may be caused by bacterial remnants in the liver

Chronic lyme isn't a medically recognized diagnosis in conventional medicine

It describes a constellation of symptoms attributed to a persistent Lyme infection—meaning the bacteria have remained present even after antibiotics. It often occurs among people who have never received a positive test for Lyme. Doctors do recognize "post-treatment Lyme disease syndrome," however, which can include muscle and joint pain, fatigue, and cognitive difficulties after treatment for confirmed Lyme.

Nonwhite Lyme patients tend to be diagnosed later and have more severe disease

Peer-reviewed research published in 2025 from Pfizer—a pharmaceutical company working on a candidate vaccine for Lyme disease—examined Lyme data from more than 150,000 Medicare and Medicaid beneficiaries and found that Black patients, as compared to white beneficiaries, were more likely to have disease that had spread further throughout the body at the time of care. The difference, the scientists wrote, may be partly due to difficulties recognizing the characteristic rash on darker-colored skin.

Blood tests for Lyme disease tend to come up as false negatives in the week after a bite

It can take several weeks for Lyme antibodies to develop, which is what blood tests would be detecting. That's why many clinicians will prescribe antibiotic treatment immediately after a bite if the individual develops the characteristic bullseye rash of Lyme or gets bitten in an area of the country known to have high rates of Lyme.

Lyme disease is caused by bacteria transmitted through the bite of infected ticks

It's an infectious disease caused by Borrelia burgdorferi bacteria. It's spread through the bite of two species of infected ticks, the Western blacklegged ticks on the West Coast, and Blacklegged ticks found throughout the eastern US. The ticks can transmit the disease at both the nymph and adult stage. It's not known to be transmitted from one person to another via kissing or sex.

Lyme disease-causing bacteria predate any suspected biological weapons testing

Borrelia bacteria existed long before any US biological weapons program—or human presence in North America. One study comparing genomes of the bacteria behind Lyme disease collected samples of the bacteria over three decades and calculated that the bacterium has been in North America longer than humans, at least 60,000 years. Other work found related bacteria preserved in amber from millions of years ago.

Ticks must typically be attached to a person for more than 24 hours to transmit Lyme

Infected blacklegged ticks must typically be attached to a person for more than 24 hours—and often closer to 36—to transmit Lyme. That period is enough time for the bacteria that causes Lyme to migrate from the tick's gut into the person's bloodstream while it's latched on through its bite. (There are rare documented cases of transmission under 24 hours.) Rapid removal of the tick is key to disease prevention.

Lyme disease may cost about $1B annually in the US

The economic burden of the disease in this estimate includes direct medical costs and societal costs, including productivity losses. It does not include suspected, undiagnosed, or nonacute cases, which would push that figure upward.

Two Lyme disease vaccines were in development in 2026

As of early 2026, there was no vaccine for Lyme disease available. One candidate vaccine, VLA15, was in later-stage clinical trials. Another designed to provide seasonal protection was licensed to a pharmaceutical company in 2025, and was planned for human clinical trials.

Long-term memory issues among West Nile survivors may be from immune response, not virus

Rodent research suggests that long-term neurological complications such as fatigue, weakness, difficulty walking, and memory loss, may be due to the immune system systematically destroying parts of neurons in the brain in response to the infection, rather than due to viral infection itself.

Leprosy symptoms may appear 20 years after infection, so contact tracing isn't possible

The standard approach for tracking disease transmission isn't realistic for this disease because symptoms may take decades to manifest. As a result, disease transmission is still not fully understood.

Genetic engineering mice is one idea to reduce Lyme disease transmission

Wild white-footed mice are the main carriers of Lyme. A research team is hoping to genetically engineer mice, using CRISPR, to make the animals immune to Lyme. They're proposing a field trial where they would insert a gene with an antibody to Lyme infection to break the disease transmission cycle on a private island and then try it in Nantucket if that goes well. Simply killing the mice isn't an option because it would upend food webs. Unlike traditional vaccines, this "heritable immunization" would pass from one generation of mice to the next.

Post-polio syndrome occurs decades after infection but isn't contagious

Affecting adults who contracted polio as children, this disorder can occur 15 to 40 years later, leading to slow, irreversible muscle weakening. Some research estimates that between 25% and 40% of polio survivors go on to develop this condition.

Lupus, an autoimmune disease with varied symptoms, was named for wolf bite-like lesions

The 13th-century physician behind the name (lupus is Latin for wolf) named it after a patient he saw who had facial lesions that looked to him like a wolf's bite. Other common symptoms of the disease include extreme fatigue, painful and swollen joints, fevers, and light sensitivity.

Leprosy bacteria are sometimes grown on mouse feet for research

The main leprosy-causing bacterium can't be grown in a petri dish, so the disease is challenging to study in the lab. For research purposes, it has been grown in the foot pads of mice.

Why bacterial bioremediation may help counter the negative effects of past chemical solutions

Molecules such as DDT, a synthetic insecticide, and PFAS—"forever" chemicals used to make products resistant to heat, water, and grease—have historically been used across various industries but are now known to be harmful. Microbes that can convert some of these substances into nontoxic products, such as water and carbon dioxide, have already been identified, with ongoing research to find others.

In 2011, a mysterious illness spread around LeRoy, New York

A handful of girls were stricken with bizarre twitches, tics, and spasms — all apparently involuntary. Some believed the incident to be conversion disorder, an illness where emotional troubles have physical symptoms.

Long-haul COVID: What doctors want patients to know

Long COVID continues to be a medical mystery, but some parts of the puzzle are falling into place. Learn more from intensivist Devang Sanghavi, MD.

CAR-T is showing promise for treating lupus—previously thought to be incurable

A small number of lupus patients have remained in complete remission for years after undergoing an experimental CAR-T cell therapy that seems to eliminate enough B cells to fuel a "deep reset" of the immune system. CAR-T therapy is also being used experimentally to treat MS, myositis, and other autoimmune disorders. (Some users may experience a paywall.)

PTSD is a long-lasting mental disorder linked to past traumatic events

Posttraumatic stress disorder is a mental health condition arising from traumatic events with four key symptoms: intrusive memories, avoidance behavior, negative moods and thoughts, and changes in emotional and physical reactions.

An overview of modern clinical research on LSD

Researchers have determined that LSD, taken in a medical setting, decreases anxiety related to "life-threatening disease," reduces brain reactivity to fearful faces, increases the meaning and emotional response derived from music, and more. No complications of LSD administration have been observed in medical settings, though acute adverse effects, including exhaustion, nausea, and difficulty concentrating.

A new tinnitus therapy involves mild electric tongue shocks and sound exposures

Lenire, an FDA-approved bimodal neuromodulation treatment approach for tinnitus, aims to teach the brain to distract itself from tinnitus. It includes short-term daily sessions wearing a mouth device that delivers mild electrical pulses to the tongue while listening to different sounds. (Some users may experience a paywall.)

Lactose intolerance is not the same as a dairy allergy

Lactose intolerance can develop in adulthood and can be influenced by genetic factors, culture, and dietary practices. Times of famine may have favored those who could digest dairy, naturally selecting them more, resulting in lactase persistence.

When people stopped using GLP-1, they regained two-thirds of the weight back

Research from 2022 found that when people stopped using the injectable form of the medication, they regained up to two-thirds of lost weight within a year. The finding suggests ongoing treatment will be required for weight loss.

Some Nobel laureates have expressed beliefs in pseudoscience after winning

Examples of the phenomenon, known as Nobelitis or Nobel disease, include promoting psychic research, harmful practices like eugenics, and seeing talking raccoons. Increased external pressures after a win and a greater spotlight may contribute to developing or exposing these beliefs.

Hookworm infection, though risky, may help fight certain autoimmune conditions by tamping down the immune system's inflammatory response.

The Lazarus Effect is when a heart begins beating on its own after declared death

Formally called autoresuscitation, this rare phenomenon occurs when someone is declared dead following a cardiac arrest but their heart beats again without help—making it seem like the person came back to life. Doctors don't know the exact cause.

Experimental hantavirus vaccines and therapies, still under development, have long been funded by the US military.

Urushiol, the oily toxin in poison ivy, can remain allergenic on clothing for years.

Recent research found that the brain doesn't seem to massively rewire following amputation—upending earlier beliefs about the cause of phantom limb pain.

Listen to an in-depth conversation on the links between Parkinson's disease and herbicide exposure and the challenging pace of scientific investigation.

Read a deep dive on the 'all-purpose healing' peptide BPC-157.

Tattoos remain visible on your skin thanks to immune cells called macrophages

This real-time tracking of the hantavirus cruise ship outbreak in May 2026 offers a unique glimpse into the global reach of the outbreak and whether the virus sickened passengers and their communities around the world.

About 12.5% of US adults experience a phobia in their lifetime, a diagnosis that hinges on the intense fear interfering with daily life and persisting for at least six months.

The hormonal disorder PCOS was renamed PMOS in 2026, a move designed to improve care and research by shifting the focus to the hormonal causes of this condition that affects 1 in 8 women.

Indefinite cloning of some endangered species may not sustain their longevity because cloning success rates decrease as genetic mutations accumulate.

In 1939, baseball star Lou Gehrig delivered his inspirational 'Luckiest Man' speech after retiring due to the health condition that now bears his name.

The use of fungi to detoxify land and water—a process known as mycoremediation—has been used to clean up natural resources affected by the 2025 California wildfires.

Ebola species have historically been named after where they were discovered, stigmatizing residents who live there, including Bundibugyo, in Uganda.

Some Pokémon have been named after real and fictional organisms, while some real-world species have been named after Pokémon, such as Chilicola charizard and Binburrum zapdos.

Massive blooms of microscopic plankton called dinoflagellates produce the neon blue light seen in glowing tides.

Louisiana's 'Cancer Alley' is infamous for having some of the highest industrial pollution, toxic air emissions, and cancer risks in the US.

At the beginning of the 20th century, a group of young men ate standard American food—replete with food additives like borax and formaldehyde—as part of government research to better understand food safety.

See images of medical cases of firework injuries shared on this 'Instagram for doctors.' (Warning: Graphic content)

Planarian flatworms are small, aquatic worms with exceptional regenerative capabilities. When cut, the worms can regenerate multiple bodies in a matter of weeks.

Objects can be 3D printed with light by projecting 2D computerized tomography (CT) scans onto rotating cylinders of resin, which solidify upon exposure.

The Ramones' 'Pet Sematary,' the theme song for the Stephen King novel of the same name, was written while the band was admiring the writer's collection of horror memorabilia.

See how Budweiser's famous Clydesdales spend their days at Warm Springs Ranch, where roughly 70 to 80 of the beer brand's giant horses can be found at any given time.

When a Paris department store hesitated to sell Estée Lauder's perfume, she 'accidentally' broke a bottle, causing the smell to spread throughout the store and shoppers to start asking to buy the scent.

For centuries, it was common to sleep in two shifts: a few hours at the beginning of the night, and a longer period beginning around midnight