One doctor argued vampires were based on a real disease

The word 'vampire' appeared in the English-speaking world in the 1730s

However, earlier mentions of creatures with similar characteristics existed throughout Medieval Europe. For example, people often spoke of revenants—restless dead creatures who tormented the living. Historians believe these stories grew in popularity in part because of influence from the Catholic Church, which was emphasizing the idea of purgatory. These older revenant stories eventually influenced modern vampire folklore.

Bram Stoker's 'Dracula' was inspired by a seafood-induced nightmare.

Vampire bats are the only mammal to feed exclusively on blood

Scientists believe their ancestors may have eaten parasites and insects off larger animals until vampire bats started feeding directly from those animals. Colonies work together to stay fed, as a vampire bat can die without just two days of eating.

The history of blood, as told by a hematologist

Since ancient times, blood has been seen as a semi-magical substance. Alchemists theorized it was a mixture of the four elements. Others proposed it was one of four bodily fluids whose balance dictated health. This 2019 essay by a hematologist reviews blood's reputation across cultures and centuries.

The ‘Universal Monsters’ series solidified horror as a film genre

Before 1931, most scary movies were billed as “mystery” or “suspense” with grounded explanations for anything "supernatural." That changed with “Dracula,” which presented the character as a real vampire who drank victims' blood. Universal continued adapting similar titles, including HG Wells’ “The Invisible Man” and Edgar Allan Poe’s short stories.

The strange endurance of consuming blood for health

Blood's importance to humanity is best summarized this way: without it, we die. This importance naturally begets assumptions about its medicinal properties, many of which appear accessible through drinking or eating the fluid connective tissue. This article details the history of blood drinking, from ancient Roman gladiators to modern-day sanguinarians.

The virus was officially described for the first time in 1789

Michael Underwood, an English physician and surgeon, was the first to describe the disorder, noting it caused disability in the lower extremities in children. Large-scale outbreaks of the disease were not observed until the late 19th century.

When was the first blood transfusion?

In the 1600s, an English doctor transferred the blood from one dog to another via quills. The procedure ended when one of the dogs died. This article details the early days of blood transfusions, which turned toward humans shortly after the 1666 dog experiment and involved putting the blood of a sheep into a human recipient (who reportedly survived the encounter).

Before vaccines, there was 'variolation': what was it?

Before the technology behind vaccinations was discovered, some keen observers of medicine around the globe noticed how previous infections could impact future ones. Learn about the techniques early physicians used before they had vaccines.

Historians theorize Vincent Van Gogh suffered from Ménière's disease or epilepsy

A century after researchers suggested he suffered from epilepsy, some researchers in the 1990s began to support an alternate diagnosis: Ménière's disease, since he had suffered from severe, repeated attacks of disabling vertigo. Still, some researchers remain skeptical of the Ménière's diagnosis. One posits that Van Gogh had temporal epilepsy complicated by his absinthe consumption.

Light therapy was widely used as a medical treatment for various maladies in the early 1900s before it was replaced by antibiotics.

In 1892, two scientists purposefully infected themselves with cholera bacteria

When they became ill—one with mild diarrhea and the other with severe cholera—researchers pointed to that as proof that the pathogen caused the disease.

Where did zombies come from?

This 17-minute video dives into the origin of modern-day zombies. Zombies can be traced to early West African spiritual practices, specifically Vodou. Vodou evolved from the mixture of beliefs held by enslaved Africans in the French colony of...

Blood has evolved many times over hundreds of millions of years, resulting in different blood colors and compositions—and there are even some organisms that don't need blood at all.

The history of germ theory, which explains that illnesses are caused by microorganisms

For centuries, the miasma theory, which held that illnesses were caused by clouds of "bad air" produced by decaying organic matter, was the accepted explanation for the spread of disease. The development of microscopes and the subsequent technology to isolate bacteria and test disease spread in mice greatly contributed to contagionists overturning miasmatists.

A prisoner at the haunted Corvin Castle in Romania helped inspire Dracula

The dungeon in Corvin Castle has hosted numerous ill-fated prisoners and many unsettling occurrences. One of its most famous former residents is the cruel ruler Vlad III, the inspiration for the character of Dracula. Listen to the eerie tales of the dungeon where psychological torture and extreme violence took place.

Using mosquitoes to vaccinate bats could curb the spread of deadly diseases.

The Hungarian countess rumored to have bathed in blood

According to legend, Hungarian countess Elizabeth Báthory killed up to 600 women to bathe in their blood and preserve her youth. Such allegations have been challenged since the 1980s when Slovakian archivist Josef Kocis published a book detailing new aspects of Báthory's life and included possible evidence of a conspiracy meant to undermine her power as part of Transylvania's ruling dynasty.

A pediatric journal ran 138 fictional case studies, and 61 were cited as real stories

The Canadian journal Paediatrics & Child Health issued corrections to 138 case studies published since 2000, acknowledging the cases were entirely fictional—a practice intended to protect patient privacy that was never disclosed to readers. At least 61 of the fabricated reports were cited as fact in other peer-reviewed journals a combined 218 times, including a 2006 Lancet article alleging an infant died from opioid-laced breast milk.

A French Army surgeon discovered that malaria is a parasitic disease in 1880—but scientists were initially skeptical.

Scientists found that if cats ate infected rodents, they could get West Nile in lab experiments.

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.

Without the option of modern blood transfusions, some doctors in the mid-1800s tried to help save cholera patients by injecting them with cow's milk, hoping it would boost their nutrition and hydration.

A list of five scientific theories that were accepted and later disproved

Humoral theory held that everyone's personality derived from different combinations of four bodily fluids: blood, phlegm, yellow bile, and black bile. The phlogiston theory stated that all combustible materials possessed a fire element—phlogiston—that was released and absorbed by the air during burning. When the air became saturated with phlogiston, the fire would go out.

Watch how viruses like Ebola can spill over from animals to humans—and vice-versa.

A scientist successfully treated her own breast cancer by injecting the tumor with lab-grown viruses.

Genetic analysis suggests Anopheles mosquitoes fed on humans some 1.8 million years ago.

Horror evolved from Gothic literature

Although creepy tales can be found in nearly every folk tradition, the roots of modern horror can be traced back to Gothic literature, which focused on the battle between humans and unnatural, evil forces.

Explore illustrative depictions of Chernobyl in comic books

Pieces related to the location since the nuclear disaster have told stories about radioactive vampires and monsters, accounts of bureaucratic corruption and creed, and visual retellings of experiences those in the region lived through before and after the event.

The human cost of creating medieval monsters

The concept and creation of monsters have been used since time immemorial to communicate social norms and the consequences of breaking them. Some so-called monsters were judged as such solely due to having features that would be considered birth defects in modern times. This in-depth article explores the human cost of creating medieval monsters, many of whom were defined by a physical appearance that deviates from the expected.

History's weirdest weight loss fads, fact-checked

Nothing catches popular attention more than a claim to have found a quick weight-loss technique. History shows us such claims are often unfounded. Dr. Michael Mosley explores extreme weight-loss tips from history, from tapeworms to vinegar diets.

A malaria case in Maryland stumped doctors in 2023—leading to the wrong treatment and underscoring the challenge of physicians being mindful of tropical diseases in our interconnected world.

Hit show 'The Last of Us' was based on the real-life Cordyceps fungus

Though it depicted a fictional world with a collapsed society due to a fungal pandemic, this television series (based on an earlier video game) helped raise awareness about fungal threats. It even prompted the US Centers for Disease Control and Prevention to publicly comment on it—clarifying the show’s plausibility. The mind-controlling fungal species in the show is based on a real-life Cordyceps species, a fungus that modifies its host’s behavior before killing it.

Some North American bats can glow in the dark

After examining 60 museum specimens from six different species, scientists found that all of them emitted light after being exposed to ultraviolet radiation. Researchers are perplexed by this natural phenomenon and are currently unable to deduce the reason behind it.

Early English fantasy writers built on horror and Gothic texts

After the success of 19th-century books like Mary Shelley’s “Frankenstein” and Robert Louis Stevenson’s “The Strange Case of Dr. Jekyll and Mr. Hyde,” readers were eager for more stories that deviated from realism. Early 20th-century texts like George MacDonald’s “Phantastes” and Lord Dunsany’s “The King of Elfland’s Daughter” met the moment, laying the groundwork for the fantasy genre.

How the most famous Ebola book, The Hot Zone, which sold 3.5 million copies and was translated into 30 languages, got aspects of the disease so wrong.

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.

See this diverse list of vector-borne diseases

Human illnesses caused by parasites, viruses, and bacteria, and transmitted by a living organism—often small, bloodsucking ones like mosquitoes, ticks, and sandflies—are known as vector-borne diseases. That carrier is called a vector. These diseases disproportionately affect the poorest populations in tropical and subtropical areas.

Powassan virus, a rare tick-borne disease named after the Canadian town where it was discovered in 1958, is on the rise in the northeastern United States, and it kills roughly 10% to 15% of patients with symptomatic disease.

An overview on germ theory, the crucial framework developed by Louis Pasteur

Germ theory of disease is based on the concept that many diseases are caused by infections with microorganisms, typically only visualized under high magnification. Read this general overview to understand the basic framework which allowed for development of vaccines.

Imagining how genetics works in 'Harry Potter' and how muggle-born Hermione is a witch

Dr. Robert Pyatt, director of Sanford Health’s medical genetics lab, talks through real-world genetics scenarios in the Harry Potter series, from the Weasley's red hair and freckles to why Hermione, a witch, could be born to "muggle"—or nonmagical—parents.

Bats are uniquely suited to act as reservoirs of viruses.

Some of the deadliest diseases to jump from animals to humans originate in bat species. This rich visualization explores the diversity of bats and the factors that make them efficient vectors for harboring and transmitting disease, from their long lifespans to their migration patterns.

In 1933, the influenza virus was first identified through 'ferret flu' experiments, which proved that the disease was viral—not bacterial.

After the first gene-edited pig heart transplant patient died, a latent pig virus was discovered inside his xenotransplant.

Every virus is classified into 7 groups based on genetic differences

Viruses infecting humans have been named based on symptoms ("chickenpox") or the location or animal in which they were first discovered ("Bolivian Haemorrhagic Fever" and "Monkeypox"). For clarity among scientists and to reduce stigma, virologists classify the 15,000 known viruses (270 of which infect humans) by their basic genetic material.

Vector-borne diseases kill more than 700,000 people globally each year—and are growing

The diseases with the greatest potential to spread widely aren't the ones that quickly kill human hosts. Instead, the best hosts or reservoirs for vector-borne diseases would be chronically ill over the long term, increasing the likelihood that the pathogen could be transmitted to others.

Volcanoes in the 1340s likely helped trigger the Black Death

The "bubonic plague" that wiped out roughly half of Europe and Asia originated from many factors. Recent research suggests volcanic eruptions contributed as well. The "aerosol" effects of matter released from eruptions likely prompted famine and accelerated the spread of infected fleas riding on grains avoiding spoilage.

Scientists now know that Henrietta Lacks, a Black woman whose 'immortal' cancer cells were nonconsensually sampled and used for research, had been infected with human papillomavirus, a group of pathogens responsible for most cervical cancers.

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.

Cholera was called the 'Blue Death'

In the mid-1800s—when John Snow identified cholera in London—the disease was known simply as the "Blue Death." That's because blood would thicken in patients' veins when they were struggling with extreme dehydration. As a result, their skin would turn a blueish hue as their blood was starved of oxygen.