Mosquito-borne illnesses have killed captive orcas at SeaWorld

Read the 2012 study about captive orcas and the threat of mosquito-borne illness

Written by orca trainers who went on to become scientists, it states mosquitoes bite orcas at night when the animals hang out close to the surface. What's more, antibiotics used to keep captive orcas healthy also may depress their immune response, boosting the risks of them being unable to fight off diseases like West Nile Virus and encephalitis, which have killed orcas at US water parks.

Mosquitoes top the ranking of the world's deadliest animals

Mosquitos kill about 760,000 people every year. The vast majority of those deaths are caused by malaria, which is transmitted and spread by the Anopheles mosquito. The second-place deadliest animal title goes to snakes, with an estimated human death toll of around 100,000 annually.

In recent years, orcas have begun sinking boats and other orcas are following in their footsteps

For just over five years, killer whales have been ramming (and occasionally sinking) expensive yachts, sailboats, and fishing boats in waters near European coasts. Scientists believe these incidents are the result of play rather than aggressive attacks.

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.

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.

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.

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

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.)

'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.

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.

More than 20 mosquito-borne and tick-borne diseases are found in the US

Children, older adults, and people with compromised immune systems are at particular risk of poorer health outcomes from these diseases. But dog owners and outdoor enthusiasts are among those at particular risk of contracting these illnesses, which include Lyme disease, Zika, and the condition Alpha-gal Syndrome.

Explore inside a mosquito factory where millions of mosquitoes are bred weekly

In Medellin, Colombia, scientists are infecting Aedes aegypti mosquitoes with Wolbachia, a bacterium that wouldn't otherwise infect the species, but does block its ability to transmit dengue, Zika, yellow fever, and chikungunya. In the wild, infected mosquitoes would breed with wild mosquitoes, pass down Wolbachia, and thus reduce disease transmission.

Iceland, the last mosquito-free country, detected them in 2025

Recently several of the mosquito species Culiseta annulata were documented in Iceland—the last country that had not yet seen them, underscoring that climate change is shifting the bugs' patterns. Mosquitoes can hide out in human structures to survive icy temperatures. The bugs are now known to live everywhere except the continent of Antarctica.

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.

How Disney World keeps out mosquitos

Disney World may have been built on a swamp, but it's nearly free from the annoyance of mosquitos. That hasn't been an easy task; Disney has worked with engineers and pest specialists on minimizing the invasive bugs through a variety of different methods. This Reader's Digest article breaks down how they've successfully kept the park free from these unwanted guests.

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.

Invasive species can harm infrastructure and threaten human health

The wildfires in Hawaii in 2022 were made worse by flammable invasive grasses introduced from Africa as livestock pasture, and Zebra mussels native to the Caspian and Black Seas have spread across Europe and the US, where they can clog power plant pipes. Invasive mosquitoes can carry diseases, such as dengue and malaria.

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.

Explore this hantavirus cruise ship outbreak case map from May 2026

Assembled from case information from state and health agencies, this detailed mapping includes the last known locations of each confirmed, deceased, and suspected case and their status.

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.

Watch wild elephants 'mourn' their dead

Wild elephants in Samburu National Reserve in northern Kenya visited their dead matriarch's body weeks after her death and displayed behaviors that researchers are hesitant to call "mourning" though they do believe the animals are displaying a specific reaction in response to the death. The video shows elephants using their trunks to touch and explore the carcass while standing in place for extended periods, which is uncommon for the animals.

River dolphins manhandle an unlucky anaconda

The natural world around us is endlessly inspiring, and fascinating, and often very odd too: like when researchers snapped a photo of Bolivian river dolphins swimming around with a Beni anaconda snake in their mouths, for example.

Watch how coral bleaching resembles an organism's immune system attacking itself

Microorganisms called zooxanthellae are in a symbiotic relationship with coral polyps and provide them with food created through photosynthesis. When ocean temperatures or sunlight exceed an optimal range, zooxanthellae release harmful chemicals that irritate coral cells. To protect themselves, corals sacrifice their food source and expel the colorful microorganisms, becoming white.

Swimmer's ear is America's most common waterborne illness

Federal government analysis of the roughly 7 million waterborne illness cases that occur annually in the US found that swimmer's ear comprises some 4.7 million, or 65%, of the annual waterborne illnesses and 20% of hospitalizations. Norovirus infection comes in second place.

There are at least 6 fascinating examples of mind-controlling parasites

Parasitic organisms—including flatworms and barnacles, not just fungi—can modify animal behavior. They can give rise to dancing fish, pulsating snails, suicidal rats, and more. Though some of these pathogens can sicken humans, there is no strong evidence that any can control human behavior.

Zoo animals have developed allergies, too

Although scientists do not know if allergies manifest among wild animals—and if animals can survive with them—in a zoo setting, veterinarians have observed zoo animals with common allergy symptoms, including itchiness, crusty skin, and runny eyes. Veterinarians have identified Asian elephants with pollen allergies and at least one jaguar with an allergy to fleas.

Only one strain of wild poliovirus continues to infect humans

Three strains of polio used to regularly infect humans, but two of the strains were declared eradicated in 2015 and 2019, respectively. In 2019, world health leaders estimated complete polio eradication—if achieved—would save $14B by 2050.

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

Explore the animals that populate the depths of the ocean, from fish and coral in the first few hundred feet, all the way down to the bottom of the Mariana Trench.

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.

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.

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.

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

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

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

Volcanoes 'die' when their supply of magma runs out, if they are shifted away from their underlying magma reservoir, or if they get clogged by collapsing or their magma cooling back into rock.

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.

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.

Poison ivy is in the same family as mangoes, cashews, and pistachios—and they all produce oily urushiol in their raw, unprocessed state—but they are typically prepared in ways to avoid causing human discomfort.

Lesser-known phobias include turophobia, or the fear of cheese, and nomophobia, the fear of being without your cell phone.

Firework or sparkler burns, even if they cover a relatively small area of skin, can significantly affect our range of motion.

The Great Salt Lake's distinct dual coloration results from high-salinity organisms that only live in the northern portion and produce a purple protein.

The Dracula character, now seen as the vampire archetype, was inspired by a seafood-induced nightmare its creator experienced.

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.

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.

Memecoins are a type of cryptocurrency—a form of digital currency with a wide variety of uses—created around popular 'memes,' or viral internet jokes.

In 1945, Surrealist artist Salvador Dalí and legendary animator Walt Disney began collaborating on a short film that was not completed until 2003, years after both men had died.

View the ten deadliest tornadoes in US history.

Pure water does not conduct electricity because this flow of energy requires the movement of charged particles, and water is a neutral molecule.

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.