See the polio cases that occur worldwide each year by region

See when the last case of wild poliovirus was found in each country

This chart shows when wild polio cases were last reported in each country worldwide. Beyond wild poliovirus, rare outbreaks can occur related to mutated strains of oral polio vaccine.

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.

Polio is currently circulating in only two countries but it remains difficult to eradicate

Wild polio virus is only endemic in two places. Afghanistan and Pakistan are the last two countries with naturally occurring polio cases. Vaccination campaigns have been plagued by misinformation, Taliban bans on vaccines, distrust of public health workers, and violence, including the killing of vaccinators.

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.

Oral polio vaccines cause approximately 250 to 500 polio cases per year globally

Live, weakened polioviruses in the oral vaccine can very rarely mutate into a disease-causing form and lead to vaccine-associated paralytic poliomyelitis. This oral vaccine is not available in the United States.

View this timeline of polio milestones and vaccine development

Polio has a long history in art and medicine, dating back centuries. It includes a representation of an apparent polio survivor with a shriveled leg in ancient Egyptian art. See milestones in the history of polio in this timeline.

See what regions report new leprosy cases

This graphic shows the burden of leprosy by region for 2023, based on data provided from the World Health Organization, which collates this information. Southeast Asia leads in the number of cases by region. (Some readers may experience a paywall.)

Wastewater testing has detected genetic evidence of polio, triggering vaccine boosters

Sampling of wastewater in London in 2022 detected fragments of polio virus, suggesting a vaccine-derived version of polio may be circulating. No one became ill, but the finding did trigger calls for a renewed booster inoculation campaign.

Improved 19th-century sanitation meant kids encountered polio later, with worse results

Almost all children likely used to contract poliovirus, but scientists suggest that when infants encountered it very early in life—due to poorer conditions and hygiene—they still had some maternal protection from pregnancy or through breastmilk, so the symptoms were more flu-like.

See the geographic spread and incidence of malaria

This graphic shows the estimated global burden of malaria in 2025 as new cases per 1000 people at risk.

A heatmap showing the drop in infectious diseases post-vaccine deployment

The number of infected people, measured over 70-some years and across all 50 states and the District of Columbia, declined significantly after vaccines were introduced.

More than 4,000 people died from cholera in 2023

This global health threat sickened more than half a million people in 2023 and killed 4,007 people. That's a 71% increase in deaths as compared to a year earlier. (Report only offered in PDF format.)

A timeline of major pandemics from 1899–2025

Modern pandemics have been defined by the race between globalization (which increases risk) and the development of new medicines. The Great Influenza epidemic claimed some 50 million lives, and the COVID-19 pandemic killed more than 7 million. In between, diseases like Ebola, cholera, AIDS, and more have devastated communities.

The HPV vaccine reduces cervical cancer rates by 90% or more

Cervical cancer is the fourth most common cancer in women globally. Almost all cases (99%) are linked to infection with high-risk human papillomaviruses. However, cervical cancer is both treatable and preventable—and we may be able to prevent most cases through vaccination.

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.

How global conditions have improved over 200 years

In an era of 24-hour news, it can feel as if the world is on a perpetual downward spiral. This set of visualizations zoom out, and show how global living conditions have improved in recent centuries. The percentage of people living in extreme...

Infographics explaining global terrorism trends

Our World in Data’s terrorism page details global trends in terrorism. Through interactive infographics, the site shows how the number of terrorist acts varies around the world and how it has changed over time. Sections investigate common definitions of terrorism, trends in global terrorism deaths, and the global distribution of terrorism. Additional segments highlight airline hijackings, public opinion, and media coverage of terrorism. Explore this website for an array of infographics on terrorism.

Under-5 child mortality has been cut in half since 2000, UNICEF reports

The United Nations Children's Fund works globally to protect children's rights and well-being. Its 2024 report on child mortality reveals that under-5 deaths have halved since 2000. The report includes interactive data visualizations that can be sorted by year or topic.

See the evolution of Ebola vaccine and treatment development.

Flu vaccines are reformulated each year based on global predictions

Twice a year, health agencies analyze circulating influenza strains and select those most likely to spread in the coming season. Because vaccines must be produced months ahead, they represent the best available forecast.

Obesity rates have more than doubled worldwide since 1990

In the US alone, the percentage of the population meeting the clinical standard of obesity rose from less than 20% to more than 40% over the past three decades. This rise has been matched by many countries across the globe, from industrialized to developing nations.

Visualizing the year in US tornadoes, 2024

Between January and November 2024, over 1,700 tornadoes were documented to have touched down in the US, a relatively high number (and similar to the numbers in 2004, 2008, and 2011). This map shows their location across the country to help capture the number.

See worldwide hearing loss by age group and country

This 2023 data from the Institute for Health Metrics and Evaluation shows the estimated number of people with complete hearing loss in different age groups per 100,000 people in the population. Individuals aged 70 or older make up the largest group with this type of hearing deficit.

Global support for free speech and press freedom has declined since 2019

A 2025 Pew Research survey found that the share of people worldwide who consider free speech and press freedom important has declined over the past several years, even though majorities in most countries still say these rights matter.

Hand, foot, and mouth is usually seasonal—peaking in summer—but not always

This painful, contagious disease most commonly has outbreaks in summer and early fall in the US because the enteroviruses that cause disease can most readily survive and be transmitted in warmer, humid conditions. It can still show up throughout the year, however.

In recent years, many private schools have seen enrollment increase

The pandemic realigned schools’ demographics, with steady enrollment increases reported since 2020. In school years 2023 to 2024 and 2024 to 20225, 40% of private schools saw enrollments increase, though the overall trend appears to be slowing.

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

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.

In 2026, Finland was named the world's happiest country for the ninth consecutive year based on its wealth, social safety network, and high life expectancy, among other factors.

Visualize the path of every solar eclipse from 1900 to 2099 and see what each looks like when observed from different locations on Earth.

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.

See the 25 of the best photos of auroras from around the world.

Electrical grids worldwide must double their power delivery capacity by 2050 to meet surging demand from AI and electric vehicles.

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.

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

Alzheimer's can lead to brain shrinkage, with an average of around 2% of volume reduction per year

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

Coral polyps reproduce via broadcast spawning, where entire reefs simultaneously release reproductive cells for about one hour, once a year.

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

44% of Americans say they pray at least once a day—discover how your state's religiosity stacks up against the rest of the country.

View the ten deadliest tornadoes in US history.

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

A century of Billboard issues documenting the evolution of popular music.

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

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

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.

Watch contemporary footage covering the US-backed Shah of Iran fleeing the country in the face of the 1979 Iranian Revolution

In 2009, the nation was gripped by the story of a missing young boy who was believed to be floating over Colorado in a homemade balloon, until it was revealed that he was at home the whole time.

The 1987 Nintendo video game 'Stadium Events' isn't known for being particularly fun, but its scarcity has made it a highly sought-after item that has sold for up to $35K at auction.

The US dollar is the most widely circulated currency in the world, and is involved in nearly 90% of global transactions