Watch an expert's take on the rare disease hantavirus—and why it's not of great concern to the general population

The US military, concerned about potential deployments worldwide, has long funded experimental hantavirus vaccines and therapies.

Collaborations between the military, biotech, and academic researchers led to an experimental antibody treatment for the Andes hantavirus strain—the one that more readily passes between humans. As of spring 2026, it had only been tested in animals. The US Army has also tested a potential hantavirus vaccine in people. It published early findings in 2023 that seemed promising, eliciting some immune system response. (Some users may encounter a paywall.)

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.

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.

Increasing contact between humans and wild animals is driving zoonotic threats

Zoonotic diseases, which spread from animals to humans, present one of the most significant emerging threats worldwide. Scientists have identified around 200 viruses capable of infecting humans, and unfortunately, the number of such diseases are on the rise—at least 60% of all emerging infectious diseases are zoonotic in origin.

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.

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.

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

Adults usually have some immunity to HFM Disease—but can still spread it

In 2025, certain eastern states including Virginia and West Virginia reported a sizable uptick in their HFMD cases, particularly in their schools and daycare centers, though the reason for the larger outbreaks remains unknown. When adults or teens get the disease, their symptoms are usually mild or even asymptomatic. Still, they may pass the disease between people, too. (Some users may encounter a paywall.)

Chimpanzees are dying from human colds

For some great apes, the threat of human-borne diseases outweighs poaching or habitat loss. This article details the danger of reverse zoonoses, which refers to diseases that spread from humans to animals.

'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.

Animal-to-human pathogens constitute 75% of emerging infectious diseases

Zoonotic diseases encompass more than 200 diseases transmitted from animals to humans, wherein humans are usually accidental hosts. Ranging from rabies to HIV to monkeypox, this overview lists some of the most common viral threats.

Rabies kills more than 50,000 worldwide each year

Rabies transmission to humans typically comes from an infected animal, and death was very common before recent protocols were developed (post-exposure prophylaxis). The virus is neurotropic, which means it has an affinity for nerve tissue, and moves quickly from broadly infecting the body to destroying the brain.

Explore this interactive visualization of illnesses known to jump from animals to people, and learn how these zoonotic diseases spread.

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

Bird Flu is spreading—what does that mean for us and other species?

The rapid global spread of H5N1 bird flu—from remote Antarctic islands to US farms—shows how animal spillover, driven by human activity and ecological disruption, is accelerating pandemic risk across species long before sustained human transmission begins.

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

Bats have evolved to carry viruses without getting sick

Bats—the likely animal reservoir for diseases including Ebola and coronavirus—tolerate viruses without getting sick. The secret lies in evolutionary adaptations allowing bats to become the world’s only flying mammal and to thrive under immense physiological stressors.

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

Zoonotic diseases: Pathogens that jump from animals to humans

Such diseases may be caused by a variety of pathogens—viruses, bacteria, fungi, or parasites—and can originate in creatures ranging from ticks and mosquitoes to pigs and bats. Because they develop in animals and are often new to human immune systems, zoonotic diseases have severe consequences for public health.

In 2012, a virus that causes HFMD may have killed dozens of kids in Asia

More than 50 young children in Cambodia died in spring 2012 for unknown reasons, but laboratory testing of samples available from a limited number of those children came back positive for Enterovirus 71. That virus, which can cause HFMD, is known to cause severe complications among some people who contract the disease. But health officials concluded that poor baseline health and then incorrect treatment using steroids helped exacerbate their condition, helping lead to the deaths.

Horses account for about 96% of known mammalian cases of West Nile virus infection beyond humans.

Mosquito-borne illnesses have killed two captive orcas at SeaWorld since they became water park attractions.

Why hibernating bears don't get blood clots

For mammals, long periods of inactivity can lead to health problems—blood flow slows and pools, veins kink and distort, and clots potentially form. Hibernation takes this risk to the extreme, yet for decades why animals like bears did not exhibit...

Mapping the spread of a dangerous fungus growing in US healthcare facilities

Explore the data showing how the fungus C. auris has spread in the US, with more than 10,000 reported cases since 2016. Recommended steps to prevent infections and limit their spread have been successful in some areas, but infection control remains complicated because the fungus is often now multidrug-resistant.

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.

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.

Supertoxic rat poisons are wreaking havoc on unintended targets, including predator birds, mammals, amphibians, crustaceans, and insects.

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.

Although rare, HFMD can spreads in pools due to poor bathroom hygiene

In pools with inadequate levels of chlorine, this disease can spread via the poop-to-mouth route, though this isn't one of the most common ways the disease is transmitted. People can become infected by swallowing contaminated pool water after little kids (or their parents) don't do an adequate job removing virus-laden feces from the child before the child enters the water.

The 1957 and 1968 influenza pandemics caused millions of deaths worldwide

The 1957 H2N2 pandemic spread from East Asia, killing more than 1M globally, while the 1968 H3N2 pandemic began in Hong Kong and caused a similar toll, with both strains rapidly moving across continents.

Long-haul COVID: What doctors want patients to know

Long COVID continues to be a medical mystery, but some parts of the puzzle are falling into place. Learn more from intensivist Devang Sanghavi, MD.

Ebola virus, with an average fatality rate of around 50%, has been responsible for more than 2,000 confirmed deaths during the 2026 outbreak in the Democratic Republic of the Congo and Uganda.

There have been close to 40 Ebola outbreaks since 1976

Ebola is a rare but deadly virus that causes severe illness, organ damage, and sometimes internal bleeding. It spreads through contact with infected bodily fluids and is most common in parts of sub-Saharan Africa. This explainer covers its symptoms, transmission, and treatment options.

What are zoonotic diseases?

Interspecies interactions are a breeding ground for disease transmission. This basic background information on zoonotic disease from the Centers for Disease Control and Prevention (CDC) chronicles the different ways humans can get sick, identifies what groups are particularly vulnerable, and offers links to other resources.

Horses can—rarely—get West Nile, too

The animals can contract the virus via infected mosquito bites, but for horses there are four vaccines available. Though West Nile's often asymptomatic or mild in horses, the disease can sometimes be deadly, killing via severe neurological inflammation. There are no reported instances of people becoming sickened by infected horses or vice-versa.

Humans are the only known reservoir of poliovirus

The virus has not been found in any other species, which makes humans the only known reservoir for polio. In laboratory settings, nonhuman primates have also been infected with the virus, but there's no evidence that they contract the virus in nature.

Measles is one of the most contagious preventable diseases—it was eliminated in the US in 2000, but it is now making a resurgence due to declining vaccination rates.

About 95% of people are naturally immune to leprosy.

NASA worries about the reactivation of dormant viruses during missions—particularly the virus that causes shingles—because spaceflight suppresses the human immune system and elevates stress hormones, making it more challenging to stay healthy.

Most people breathe fungal spores daily without getting sick

Most people breathe in hundreds of Aspergillus fumigatus spores daily without getting sick—it’s a common microscopic fungus in our environment. But people who are severely ill, including those who have undergone an organ transplant, are at risk of developing infections from these spores.

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.

A novel H1N1 influenza strain sparked a 2009 global pandemic

First detected in Mexico, the 2009 “swine flu” pandemic infected up to 1.4B people worldwide. While mortality rates were lower than earlier pandemics, the outbreak still caused more than 150,000 deaths.

Climate change is influencing the spread of disease

Rising temperatures and water levels are forcing animals and pathogens beyond their typical boundaries. This article and its data visualizations explore the proliferation of climate-driven diseases.

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.

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.

West Nile Virus has been detected in American alligators, and outbreaks have led to substantial economic losses on alligator farms.

Dr. Henry Heimlich, famous for his antichoking technique from the 1970s, was a proponent of controversial and discredited approaches, including infecting cancer and HIV patients with malaria to try to trigger a heightened immune response.

Explore what it's like Inside a patient isolation unit.

There were 23 reported cruise ship outbreaks of gastrointestinal illness in 2025—something that happens often enough that there's a whole program at the US CDC devoted to tracking them.