How a scientist discovered West Nile is spread by birds

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.

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 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.

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.

West Nile is named after the district in Uganda where it was first isolated from a patient

In 1937, scientists isolated the virus from a woman in the West Nile District of Uganda. It's since been detected in much of Africa, Eastern Europe, West Asia, the Middle East, and was first detected in US patients during an outbreak in 1999.

Dead birds are often the warning sign health officials look for as a sign of West Nile danger

Public health officials look for various clues to stay ahead of outbreaks of potentially fatal diseases, like West Nile. Issues like standing, untreated pool water—detectable if the pool is turning green—or dead birds—are important to report to local public health officials.

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.

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.

Robins are a major host for West Nile in North America

Explore this interactive with key details and interesting facts about the disease, including that Culex genus mosquitoes are the main US vector for its spread, and that certain species—American crows and blue jays—are quite infectious with the disease, while American robins—despite being a significant host for the virus in North America—are less infectious.

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.

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.

Horses account for about 96% of the known mammalian cases of West Nile beyond humans

That's partly because horse owners likely notice and take veterinary action when their animals get sick. There is no way to know how frequently wild animals are getting infected with the virus.

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

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.

Protecting yourself from West Nile involves avoiding getting bites and clearing standing water

The best prevention against West Nile is avoiding getting bit. That means covering your arms and legs with long, loose-fitting clothes, wearing insect repellant—on top of, not under sunscreen, and making your environment as inhospitable to mosquitoes as possible, including clearing any standing water.

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

More than 70% of all new infectious diseases originate in animals. Referred to as zoonotic diseases, these are diseases that originate in animals and occasionally spill over or jump from animals to humans. Bats, mosquitoes, and primates have all been linked to spillover events. As human populations push further into previously uninhabited wilderness, animal-human contact increases, and disease spillover is inevitable.

California condors have been vaccinated against West Nile to protect their limited population

The condors became endangered in the 20th century primarily due to lead poisoning from consuming animals shot with lead bullet fragments inside them, so condors in captivity and in the wild are vaccinated against diseases including highly pathogenic avian flu and West Nile.

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

Researchers in China tested a transmissible rabies vaccine in the lab by feeding mosquitoes blood containing the vaccine and observing what happened to bats when they were either bitten by the mosquitoes or fed on them. The bats developed antibodies against rabies and survived subsequent rabies infection. (Some users may encounter a paywall.)

Scientists can suck animal DNA from the air

A look at how researchers filtered the air around two zoos and identified genetic material from dozens of species, a technique that could help track and conserve wildlife.

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.

Zika virus shocked scientists because the mosquito-borne disease causes birth defects

This revelation, confirmed in 2016, marked the first time that a mosquito-borne disease was known to cause birth defects. Fetuses exposed to the Zika virus during pregnancy sometimes suffer from neurological complications and microcephaly, a small-headed condition associated with neurological development issues and impairment.

How we helped make Aedes aegypti mosquitoes such a problem

Mosquito genome sequencing data suggests that Aedes aegypti mosquitoes first started specializing on human blood around 5,000 years ago—when climates shifted and humans started domesticating plants in Africa and stored large amounts of water that may have attracted the bugs.

A network of live bird song trackers

Do you know where the birds are singing? In a kind of magical way, now you can see where the latest literal tweets are happening with this innovative network of birdsong trackers dispersed around the world. The network automatically identifies which bird produced the sound and shares the data with the network. See who's singing here.

The flu vaccine has evolved alongside discoveries of new virus strains

After influenza B was identified in 1940, researchers created a two-strain vaccine by 1942. The WHO later built a global surveillance system to track mutations, enabling vaccines to be updated annually to target the strains most likely to circulate.

Discovering how the dinosaurs went extinct may have helped avert nuclear war

This NPR Throughline episode explains how the 1980 discovery that an asteroid-driven dust cloud killed the dinosaurs inspired Cold War scientists’ fears of “nuclear winter”—a sunlight-blocking aftermath of nuclear war that may have discouraged leaders from launching one.

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

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

Charles Louis Alphonse Laveran won the Nobel Prize for his work "on the role played by protozoa" in causing diseases. His work included discovering and reporting the malaria-causing parasite in the blood of a patient suffering from malaria.

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.

Watch Cordyceps, a parasitic fungus, turn an ant into a ‘zombie’

This National Geographic TV clip shows how a parasitic Cordyceps species—sometimes colloquially called the “zombie ant fungus”—controls an ant’s behavior and kills its host. The fungus can rapidly wipe out entire insect colonies.

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

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.

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.

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.

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

After 25 people used virtual reality headsets to practice flying with virtual wings—flapping their arms—their visual cortex responded to the wings almost as if they were real arms, treating them as body parts.

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.

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.

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.

Poison ivy was sent to Europe in the 1600s as an exotic, ornamental oddity, where it was purposefully grown in the English royal gardens at Kew, the Faculty of Medicine in Paris, and a few other locations.

Fish populations in the Great Barrier Reef have increased after installing waterproof speakers on the ocean floor that played recordings of sounds from healthy coral reefs.

The tragic Pulitzer Prize-winning image 'The Vulture and the Little Girl' (1993) generated controversy, raised concerns about ethics in photography, and eventually led to the photographer's death.

For centuries, Niagara Falls has been a magnet for daredevils seeking to conquer one of nature's most powerful wonders, with its 200-foot drop and water rushing at 32 feet per second with 280 tons of force.

Exploring the Larry Bird punch that almost changed March Madness

Scientists can determine Earth's past climate conditions by analyzing air trapped in microscopic bubbles within ice cores—columns of compressed snow layers that build up over hundreds of thousands of years.

The name 'Silicon Valley' arose from the founding of Shockley Semiconductor Laboratory in Fairchild Semiconductor in 1956-57, founded near Stanford University in Palo Alto

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.

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

'Grand Canyon of the Yellowstone,' a work by American painter Thomas Moran, inspired Congress to establish Yellowstone National Park.

View the ten deadliest tornadoes in US history.