Neglected tropical diseases affect more people than the population of Europe

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.

Hookworm infection, though risky, may help fight certain health conditions

Early clinical trial research suggests that the parasites trigger the production of specific proteins that quiet our immune systems. This keeps the parasites from being killed, but it also quiets the inflammatory response that underpins allergies, type 2 diabetes, celiac disease, and other autoimmune conditions. Researchers still caution that infection with too many hookworms can cause serious medical complications and that this is not a standardized or approved medical treatment.

1 in 4 people around the world don't have access to clean water

Poor water sanitation puts people at risk of acquiring this diarrheal infection. Cholera infections are on the rise due to extreme weather events and conflict. In recent years there have been cholera outbreaks in locations that hadn't seen the disease in many years, including Haiti.

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

More than 1 in 7 people worldwide have had Lyme disease

Research published in 2022 suggests that 14.5% of the world's population has contracted Lyme disease. Researchers arrived at that estimate by analyzing the presence of Lyme disease antibodies (indicating prior infection) across 89 studies conducted between January 1984 and December 2021. The works collectively included blood samples from more than 150,000 people. (Some user may encounter a paywall.)

How a worm helped give the southern US its reputation

"The germ of laziness" that blanketed the southern US for centuries with unshakable fatigue, brain fog, and distended bellies paired with emaciated frames was actually a worm. This parasitic worm lives in the gut, where it can stay up to five years, laying up to 10,000 eggs daily. Hundreds of millions of people worldwide continue to suffer from hookworm infections, often obtained by walking barefoot across infected soil.

See the global blindness burden by cause and continent

These charts show the estimated number of people worldwide with blindness due to cataract, glaucoma, refractive disorders, age-related macular degeneration, malaria, river blindness, trachoma, and other causes.

'Sloth fever' is an emerging health threat, especially to pregnant women

This disease, caused by the Oropouche virus, is found in animals including sloths, primates, and birds. It primarily spreads through the bite of midges—insects commonly called "no-see-ums." It's endemic to the Amazon region, but US travelers are increasingly contracting it internationally.

Children under 5 account for 76% of all malaria deaths in Africa

The main hypothesis for why the disease hits this age group the hardest is that children this young have still-developing immune systems. Pregnant women and people with HIV/AIDS are also at higher risk of severe infection.

More than 200,000 people are diagnosed with leprosy annually

The disease still occurs in more than 120 countries. Brazil, India, and Indonesia continue to report more than 10,000 new cases annually.

One in 10 adults worldwide has diabetes

As of 2021, diabetes claimed at least 6.7 million lives and continues to kill one person every five seconds. Nearly one in two adults with diabetes don't know they have the condition, which is expected to increase in prevalence from 537 million in 2021, to 783 million in 2045.

Ringworm is caused by a fungus, not a worm

Ringworm, formally known as tinea and known for its red circular rash, is responsible for about 325 million infections at any given time—comprising roughly half the world’s fungal skin infection burden. It’s caused by a type of fungus called a dermatophyte, which also causes athlete’s foot and jock itch. Doctors typically prescribe antifungal tablets or powders to stamp out these fungal invaders.

Europeans' arrival to America brought disease to Indigenous populations

Indigenous people lived in the Americas for centuries before the arrival of the first Europeans in the 15th century. Their arrival was disastrous for Native tribes; in addition to being enslaved and losing their land, they had no natural immunity to the diseases brought by colonists. Eventually, up to 95% of the Native American population was killed by illnesses including typhus, chickenpox, and cholera, an event now known as the Great Dying.

19 fungal pathogens are of key concern to world health officials

In 2022, this global health body issued its first-ever list of top fungal threats to human health. It said fungal threats are spreading and occurring more frequently. The WHO’s list included 19 fungal pathogens to watch, and said that the most dangerous ones to public health are Cryptococcus neoformans, Aspergillus fumigatus, Candida albicans, and Candida auris. There are only a handful of classes of medication currently available to combat fungal pathogens, with few others in the pipeline even though antimicrobial resistance is growing.

Antibiotic resistance is a growing global health problem

Over decades, bacteria have grown increasingly resistant to antibiotics. This resistance now causes an estimated 1.27 million deaths each year and is associated with nearly 5 million deaths worldwide, according to the World Health Organization.

Western babies often are missing a key gut microbe common elsewhere

Studies show infants in Europe and North America often lack Bifidobacterium infantis, a microbe widespread in babies in Africa and South Asia that helps digest breast milk and train the immune system. Researchers link the gap to antibiotics, formula use, and sanitized spaces.

1 in 6 Americans get food poisoning each year

The US federal government estimates there are about 48 million cases of foodborne illness in the country annually, resulting in as many as 3,000 deaths and 128,000 hospitalizations. Food poisoning puts those with weakened immune systems, the elderly, pregnant people, and young children at particularly high risk. This chart of common disease-causing pathogens highlights common threats and details about them, including likely food sources.

South Asia and sub-Saharan Africa are most at risk from falling pollinator numbers

Researchers at the Harvard T.H. Chan School of Public Health found that declines in pollinator populations would lead to higher rates of nutritional deficiencies, particularly in developing nations. Nations with large populations, such as China and India, would also be significantly impacted.

More than half of the 7,000 'kissing bugs' locals sent to Texas A&M University had parasites

Texas A&M University scientists began a community science program in 2012 asking people to send in kissing bugs (any of the 11 species of bugs potentially infected with Trypanosoma cruzi parasites). About 1,500 people sent in over 7,000 bugs for scientific research, and about 55% of the bugs were infected with the parasite that causes Chagas disease.

Three Ebola species are responsible for most large outbreaks of the disease, yet the only approved Ebola vaccine is known to work against just one of them.

The 2026 Ebola outbreak is hampered by a lack of vaccine against the species of the virus, heightening the need for rapid tests to aid in disease control

Clinics in the Democratic Republic of Congo saw patients with Ebola symptoms months before the disease was identified. The identification lag was due to inadequate diagnostics that could not accurately or quickly identify the virus's myriad species. Contact tracing and better diagnostics will be required to tamp down the outbreak.

More than 5% of the world's population has disabling hearing loss

Disabling hearing loss is defined as hearing loss greater than 35 decibels in the better hearing ear. (For context, that means the sound of leaves rustling, at roughly 30 decibels, would be inaudible even to your better-hearing ear.) The World Health Organization's data suggests that more than 5% of the world's population has this level of loss requiring rehabilitation, which amounts to 430 million people—including 34 million children.

The COVID-19 pandemic led to a decrease in immunizations in the US and worldwide

Public health funds and resources that were diverted to COVID-19 response reduced efforts to combat polio and vaccinations for polio and other diseases declined during the pandemic, putting more people at risk for polio.

What conditions can be treated with stem cells?

Stem cell research is a global enterprise, and much of the work is being done in Europe. This page gives readers a good sense of the medical conditions stem cell researchers in Europe focus on, and the specific research challenges they address. This page also offers links to in-depth information about many of the research projects.

Breaking down the health effects of the El Niño-Southern Oscillation

Second only to the seasons, ENSO is the most significant source of variability in global climate, shifting rainfall and temperature patterns, particularly in Africa, Latin America, and South and Southeast Asia. The incidence of vector-borne diseases like malaria, respiratory diseases related to wildfire smoke, food insecurity, and drought-related health and nutritional impacts has been observed to be affected by ENSO.

More than 2 billion people across the globe include bugs in their diets

Entomophagy is the practice of eating insects. It has been around for millennia. Bugs are nutritious and, in some places, considered a delicacy.

Common genetic disorders

As research continues, it's clear that disease and genetics go hand in hand. Here's a selection of 50 National Human Genome Research Institute (NHGRI) articles providing basic information on genetic, orphan, and rare diseases caused by mutations in DNA sequences, whether inherited from parents or brought about by outside factors.

Human-to-human transmission of hantavirus remains extremely rare, so the 2026 hantavirus cruise ship outbreak doesn't mean we're facing a COVID-style pandemic risk.

Volcanic activity may have triggered the Black Death by spewing gases that led to crop failures in Europe, thus forcing the import of grain ships with plague-infested fleas.

Larger animals like giraffes, elephants, and blue whales have developed a unique defense against cancer, a phenomenon known as Peto's Paradox

The American cockroach is actually from Africa, an apparent hitchhiker aboard ships carrying enslaved people, with evidence suggesting the bug may have arrived in the New World as early as the 1600s.

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.

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

The Russia-Ukraine conflict is the largest ground war in Europe since World War II in terms of casualties, forces mobilized, and displacement of civilians.

See how each of the more than two million known species relates to each other—and to common ancestors—in this zoomable tree of life.

Between 10 million and 50 million people in the US develop rashes from poison ivy, poison sumac, and poison oak each year.

While El Niño moves warm Pacific Ocean waters east along the equator, La Niña moves them west, shifting where rainfall will become more common for months.

Explore an interactive map built from more than 100,000 survey responses on where people find joy in their lives

Some researchers have labeled nomophobia, the fear of being without your phone, as 'the phobia of the 21st century.'

About 2,000 US babies are born annually without some portion of their limbs, potentially leading to a lifetime of pricey prosthetics.

View the ten deadliest tornadoes in US history.

In 2018, 26-year-old missionary John Allen Chau was killed by tribesmen after attempting to reach and evangelize on India's isolated North Sentinel Island

An investigation suggests a Scottish island became awash in forever chemicals via seafoam and seaspray—raising questions about what that means for the safety of other coastal areas.

The syncytiotrophoblast is the outer layer of the placenta and the largest human cell, spanning an area about twice that of a king-sized bedsheet.

The US Constitution is widely regarded as the longest-standing written national constitution still in force—see how it has influenced rights worldwide.

Fireworks-related ER visits are on the rise—in 2024, they increased by 52% as compared to the prior year.

Up to a million Girl Scouts sell about 200 million cookie boxes every spring, generating $800 million, largely because refusing a child is frowned upon

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

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

To reduce wrinkles in clothing, research recommends gentle wash cycles with more water and tumble drying with smaller loads and longer times.