Robins are a major host for West Nile in North America

Nearly 5,500 crows died during four months in 1999 from West Nile in NYC

Subsequent testing made clear the disease at that point was 100% fatal to crows. From 1999 to 2004, millions of birds died as West Nile spread across North America, but the virus fortunately became less virulent as it moved westward.

West Nile Virus is maintained in nature, even without human infections

Mosquitoes pick up the virus when they feed on birds, and then pass it to other birds with their bite, delivering it via virus-laden saliva. Hundreds of different North American bird species can harbor the virus—even if they don't all get sick from it.

How a scientist discovered West Nile is spread by birds

Listen to Tracey McNamara, former chief pathologist at the Bronx Zoo, detailing her surprising late 1990s discovery that established West Nile virus is spread by birds. Financing animal disease surveillance studies, she says, saves human lives and surveillance gaps may fuel missed opportunities to identify dangerous diseases before they jump between species.

West Nile has been detected in at least 2 species of reptiles

Birds remain the main reservoir for the disease, but scientists have detected the virus across a wide range of species, including at least 48 mosquito species, over 320 bird species, more than 25 mammals, and two species of reptiles.

West Nile virus found in the UK for the first time

The West Nile virus, which mainly spreads between birds and mosquitoes, was detected in the UK for the first time. While no evidence exists for any human infections, climate change may be expanding mosquitoes—and the diseases they carry—farther north.

US West Nile case numbers were up 40% in 2025, nationally

This surprising surge may be due to warmer temperatures and elevated rainfall—leading to the ideal conditions for mosquitoes to thrive and breed in standing water. Symptoms can be hard to recognize when the disease is mild—similar to a flu. But neurological complications can lead to hospitalization and be deadly.

Hear from a NYC public health official who led the first US investigation into West Nile

This podcast walks through the investigation into the first US outbreak of West Nile, and how the virus had never been seen in the Western Hemisphere. The official discusses how she thinks the origin of West Nile in the US may have been birds or other animals that were brought here illegally.

There's a West Nile virus prevention rap—and it's amazing

This catchy rap from biologist MC Bugg-Z and the Fairfax County government in Virginia walks people through prevention steps and the dangers of the virus, telling listeners to "rock" insect repellant and talking about the history of the disease in the US.

Scientists found that if cats in the lab ate infected rodents they could get West Nile

But beyond the lab setting there have been no known cases of cats or dogs contracting the virus this way. Instead, those animals have been sickened when an infected mosquito bit them—just as with human infection.

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.

Lyme disease is the most common vector-borne illness in the US

In the US, ticks account for 90% of all disease transmission from bites, including mosquitoes. And Lyme disease is the most common vector-borne disease in the US overall, with estimates suggesting there are about 475,000 Lyme cases annually across the nation.

Some mosquitoes are key pollinators—and eat disease-carrying mosquitoes

​​There are more than 3,500 species of mosquitoes, and only a small fraction of them bite humans. They also play vital roles in the ecosystem: One young elephant mosquito, for example, can eat dozens of smaller mosquitoes that bite humans in just one day. Sometimes mosquito-gobbling species are released by humans to control other mosquitoes.

Scientists have struggled to pin down Ebola's natural reservoir species for decades, but the available evidence suggests that it's very likely fruit and insect-eating bats found in Africa.

The secret life of urban crows

Crows are believed to have intelligence on par with a seven-year-old child and demonstrate complex behaviors, from problem-solving with tools to recognizing human faces.

Rabies is nearly 100% fatal once symptoms appear

Rabies, a viral disease attacking the central nervous system, is nearly always fatal once symptoms appear. It spreads through the infected animal saliva (typically through bites) and causes encephalitis, leading to severe neurological symptoms and death. See how the lyssavirus—the bugs behind rabies—work once inside the body.

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.

BirdCast provides real-time data and forecasts of US nocturnal bird migration

The dashboard provides a live feed from March 1 to June 15 and August 1 to November 15 that includes radar-based data on the number of birds, directions, speeds, and altitudes, offering insights into migration patterns, species, and environmental impacts.

Twin studies helped scientists understand why mosquitoes like some of us more than others

A combination of carbon dioxide output, skin chemistry, genetic factors, hormones, and clothing choice can make us particularly vulnerable to mosquito bites. Watch how mosquitoes responded to one man in the video versus his wife, a research approach typically conducted with identical and fraternal twins to test mosquito attractiveness.

'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.

Receptors on the cell surface are key to whether a virus is successful

Viral receptors are key regulators of host range, tissue tropism, and viral pathogenesis—basically, the door locks on cells allowing viruses to invade, if they have the right key. How this process works at the microscopic level determines whether a virus is able to trigger a widespread illness in the host.

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

This podcast delves into the history of Periplaneta americana and explores why the bugs elicit such fear, disgust, and, at times, shame. The bug likely climbed aboard the slave ships because they had both unprotected food sources and places to hide during their journey.

These invasive spiders are weaving their way across the US

The Joro spider was first spotted in the US in 2013 and has since spread throughout the Southeast. Get the 101 on this massive (and massively) invasive Asian spider in this article and infographics.

Leprosy has been detected in British red squirrels

The animals have been infected with both strains of the bacterium that cause leprosy. Researchers have found that squirrels living in different parts of the UK were infected with different species of the disease-causing bacteria. (Some users may experience a paywall.)

Marburg virus, related to Ebola, is also extremely deadly, and has no available vaccine.

Dragonfly migration season is believed to run from August to November

Researchers know much less about dragonfly migrations than they do about bird or whale migrations. However, North America may have up to 18 migratory dragonfly species. A recent study revealed that the species undertakes complex long-distance migrations every year that span generations and seem to be influenced by temperature, making them particularly vulnerable to climate change.

Cryptococcus neoformans, a growing threat, causes infections in the brain and lungs

This inhalable, microscopic pathogen is found worldwide. It rarely causes illness, but it can take root in those with compromised immune systems, including people with advanced HIV/AIDS. Symptoms of cryptococcal infection—such as a stiff neck, vomiting, and confusion—can begin weeks or months after breathing in spores, though sometimes symptoms won’t appear for years. There are no known cases of transmission between people or between people and animals.

The R0 value is how epidemiologists quantify disease contagiousness

The basic reproduction number indicates the average number of people a person with a disease will infect. Measles is the most contagious disease, with an R0 of 12-18, though vaccines have significantly reduced the number of susceptible individuals.

Native, wild bees are at much greater risk of extinction than honey bees

It is estimated that there are more honey bees, which often compete with native bees for resources, on the planet than at any point in human history. Meanwhile, 40% of invertebrate pollinator species, including wild bees and butterflies, face extinction in the coming decades.

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.

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

Visualize how CRISPR-Cas9—a type of immune system used by single-celled organisms to attack invasive viruses—targets and makes precise changes to a gene's DNA.

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.

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

Poison ivy can cause rashes year-round since all parts of the plant contain urushiol, the oil that triggers our allergic response.

See these 16 pieces of art evoking phobias of snakes, flying, spiders, and more. 

View the ten deadliest tornadoes in US history.

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

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.

Hurricanes, which rely on air consistently spinning in the same direction, cannot cross the equator because air curves in opposite directions north and south of it.

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

Elk Cloner, the first computer virus to spread in public, was written as a practical joke by Richard Skrenta, a Pittsburgh high school student.

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

The US first hosted the World Cup in 1994, a tournament that lives in soccer infamy for its poor planning and the murder of Colombian player Andres Escobar, who'd accidentally scored on his own net.

Coral reefs get their colors from zooxanthellae—microorganisms that line corals' digestive tracts and provide them with sugars in exchange for a home within this protective tissue.

Power lines are dotted with large, brightly colored balls to improve the visibility of these thin wires to helicopters and small planes and help prevent potential crashes.

Hotels in Cannes, the glamorous city on the French Riviera, hire hawks to ward off seagulls during the city's famous film festival.

Prince's sexually explicit 1984 track 'Darling Nikki' attracted the ire of the Parents Music Resource Center, an advocacy group that inspired the Parental Advisory sticker, even though the song ends with a Christian message.

Before humans, the Soviet Union and the United States sent animals—including apes, dogs, and cats—to space during the Space Race.

The Nasdaq's 'Magnificent 7' companies are responsible for roughly 40% of the Nasdaq 100 index's gains, while the remaining 93 companies account for the other 60%.