95 Fun Facts About Infectious Diseases

Which viral illness, common in teenagers and young adults, is nicknamed 'the kissing disease'?

Mononucleosis spreads through saliva, so you can catch it by sharing cups or cutlery, not only through kissing.

Edward Jenner's first vaccination used material from which animal disease?

Cowpox matter came from a sore on milkmaid Sarah Nelmes's hand, and Jenner later exposed his eight-year-old patient to smallpox to prove he was protected.

Which bacterium causes whooping cough?

Bordetella pertussis brings on coughing fits that end in a 'whoop' as the patient gasps for breath, yet young babies often don't whoop at all.

Which 9-year-old, badly bitten by a dog, received Pasteur's rabies vaccine in July 1885?

Joseph Meister's recovery drew patients to Pasteur from across the world, and the rush led to the Institut Pasteur, founded in 1887.

Robert Koch's 1876 discovery of the bacterium causing which disease is considered the birth of modern bacteriology?

Anthrax was the disease: in 1876 Koch cultured Bacillus anthracis and traced its spore-forming life cycle; he later identified the TB and cholera bacteria and won the 1905 Nobel Prize for his TB work.

Which biting insect spreads the parasite behind sleeping sickness?

Tsetse fly bites pass on the parasite, and without treatment sleeping sickness is usually fatal.

Before germs were understood, which rival idea blamed disease on 'bad air'?

Miasma theory lives on in the word malaria, from Italian mala aria, 'bad air', once blamed for marsh fevers.

Cholera is an infection of the small intestine by which bacterium?

Vibrio cholerae can kill within hours through severe watery diarrhoea, yet most people it infects show no symptoms and can still spread it.

Ignaz Semmelweis cut childbed fever deaths in 1847 by making doctors do what?

Wash hands in chlorinated lime was his order, and deaths fell sharply, yet Semmelweis struggled to convince his colleagues.

Which bacterium caused the Black Death?

Yersinia pestis spreads mainly through the bites of infected fleas, and as the Black Death it killed tens of millions of people in 14th-century Europe.

Which form of plague spreads directly between people through the air?

Pneumonic plague is almost always fatal if left untreated, yet early antibiotic treatment can save lives.

The 1918 pandemic was misnamed 'Spanish flu' because of what?

Spain's press was not censored because Spain stayed neutral in World War I, so its papers reported the outbreak while warring nations kept it quiet.

Roughly how many people were infected in the 1918–1920 flu pandemic?

500 million people caught it, and authorities tried to slow its spread with quarantines and limits on public gatherings.

In flu strain names like H1N1, what do the H and N stand for?

Haemagglutinin and neuraminidase are proteins on the virus's surface, and flu drugs such as oseltamivir (Tamiflu) work by blocking the neuraminidase.

In 2024, which disease was the leading cause of death from a single infectious agent worldwide?

Tuberculosis is preventable and curable, yet it killed an estimated 1.23 million people in 2024, more than any other single infectious agent.

Which illness is named after a deadly 1976 outbreak at a convention in Philadelphia?

Legionnaires' disease comes from bacteria that thrive in water systems, so people catch it by breathing mist from places such as hot tubs and cooling towers.

Malaria is caused by single-celled parasites of which genus?

Plasmodium parasites travel in the bite of an infected mosquito, which is why avoiding mosquito bites, along with preventive medicines, protects against malaria.

In 2024, which WHO region had about 95% of malaria deaths?

Africa is dominated by the deadliest malaria parasite species, the one behind most malaria deaths worldwide.

Dengue fever is chiefly spread by mosquitoes of which genus?

Aedes mosquitoes, chiefly Aedes aegypti, can bite at any time of day, which is why WHO urges people to avoid bites especially during daytime.

Which virus causes chickenpox and, on reactivation, shingles?

Varicella-zoster virus hides in nerves after chickenpox, and a shingles rash can pass on chickenpox, never shingles, to someone who hasn't had it.

Which scientist's polio vaccine was tested in 1954 on about a million children called the Polio Pioneers?

Jonas Salk had already given his vaccine to himself, his wife and their children before the national trial began.

As of 2025, which two countries remain endemic for wild poliovirus?

Pakistan and Afghanistan are the last two endemic countries, and wild polio cases have fallen from an estimated 350,000 in 1988, when the global effort began.

What was the negative-pressure ventilator used for polio patients commonly called?

The iron lung, a sealed tank that breathed for a paralysed patient by cycling the air pressure around the body, was usually needed for one to two weeks, though some patients lived inside one for decades.

Which doctor traced an 1854 London cholera outbreak to a single public water pump?

John Snow mapped the cases around the Broad Street pump in Soho and had its handle removed.

Who shared the 1945 Nobel Prize in Medicine with Fleming for penicillin?

Florey and Chain's Oxford team revived penicillin a decade after Fleming set it aside, purifying it and running the first clinical trials.

Which German scientist won the 1939 Nobel Prize for finding that the red dye Prontosil fights bacteria?

Gerhard Domagk, in desperation, gave Prontosil to his own daughter when a streptococcal infection threatened her life, and she fully recovered.

HIV belongs to which class of virus?

Retrovirus is HIV's class: it uses reverse transcriptase to copy its RNA genome into DNA that is then inserted into the host cell's chromosomes, which is why the infection cannot be cleared.

Which NBA star announced in 1991 that he had HIV and was retiring?

Magic Johnson came back to play in the 1992 All-Star Game anyway and was named its most valuable player.

Which mosquito-borne virus caused a 2015 epidemic in Brazil linked to babies born with microcephaly?

Zika spread so alarmingly that WHO declared it a global public health emergency in February 2016, because of the birth defects it caused.

Which animals are believed to be the natural host of Ebola viruses?

Fruit bats are thought to be the virus's natural host, which is why health agencies warn against handling or eating raw bushmeat.

Rabies was historically called hydrophobia because of what symptom?

Victims cannot swallow liquids without agonising throat spasms, so they panic at the sight of water, hence 'hydrophobia'; rabies kills an estimated 59,000 people a year, about 40 percent of them children.

Which experimental treatment helped an American teenager survive symptomatic rabies in 2004 without the vaccine?

The Milwaukee protocol put the 15-year-old, bitten by a bat, into an induced coma while her own immune response matured.

Which highly contagious disease is often said to spread from each case to 12 to 18 people with no immunity?

Measles virus can stay infectious in the air for up to two hours, so people can catch it just by breathing air an infected person has coughed into.

Tetanus, caused by Clostridium tetani, is commonly known by what name?

Lockjaw describes the jaw spasms tetanus often starts with, and the bacterium's spores wait in soil and animal faeces for a wound to enter.

'Typhoid Mary' Mallon worked in which job while unknowingly infecting people?

Cook Mary Mallon felt perfectly healthy yet carried typhoid bacteria, and she was forced into quarantine twice, the second time until her death in 1938.

Leprosy is also known as Hansen's disease, after a physician from which country?

Norway's Gerhard Armauer Hansen identified the leprosy bacterium in Bergen in 1873, and today the disease is curable with multidrug therapy.

Lyme disease takes its name from towns in which US state?

Connecticut's towns of Lyme and Old Lyme gave the disease its name after a puzzling cluster of childhood arthritis was investigated there.

What is the name of the expanding red rash that is the most common sign of Lyme disease?

Erythema migrans is a red rash that expands out from the tick bite, and spotting it early matters because untreated infection can spread through the body.

Syphilis is caused by which bacterium?

Treponema pallidum infections are curable, and early syphilis is treated with an injection of benzathine penicillin.

A prion is an infectious agent made of what?

A misfolded protein, with no DNA or RNA at all, is all a prion is, and Stanley Prusiner coined the name in 1982 from 'proteinaceous infectious particle'.

Deadly spore-laced letters passed through which country's postal service in 2001?

United States postal workers were among those killed: two employees at Washington's Brentwood mail facility died after tainted letters passed through.

Rinderpest, the first animal disease ever eradicated, mainly struck which animals?

Cattle plague is what Rinderpest means in German, and the disease killed so many herds that fighting it led to a world animal health organisation.

Dracunculiasis is better known by what name?

Guinea worm disease fell from an estimated 3.5 million cases a year in the mid-1980s to only a handful of cases a year by the mid-2020s.

How long does the CDC say to scrub your hands with soap?

About 20 seconds gives you time to scrub the backs of both hands and in between the fingers, not only the palms.

Who brought the Turkish folk practice of inoculation against the pox to Britain in 1721?

Lady Mary Wortley Montagu and the Princess of Wales backed a trial on prisoners, and once it succeeded, members of the royal family were inoculated.

Despite its name, the itchy circular skin rash called ringworm is caused by which kind of organism?

A fungus, or rather any of about 40 species of them, causes ringworm; the ring is only the shape of the rash. Athlete's foot and jock itch are the same infection in other places.

Botulism, a word coined in German in the 1870s, comes from the Latin name of which food first blamed for it?

Sausage is botulus in Latin, and 'sausage poisoning' was the old name for the paralysing illness. Nitrites are added to cured meats partly to stop the bacterium growing.

Balto and other sled dogs raced antitoxin across Alaska to Nome in 1925 to stop an outbreak of which disease?

Diphtheria was spreading among Nome's children and the town's antitoxin had expired, so 20 mushers relayed fresh serum 674 miles in five and a half days. A statue of Balto stands in Central Park.

Anne Frank is believed to have died at Bergen-Belsen in 1945 during an epidemic of which louse-borne disease?

Typhus swept the overcrowded camp in early 1945 and killed about 17,000 prisoners. Anne and her sister Margot died there shortly before British troops liberated it that April.

Which animal of the American South can carry the leprosy bacterium and pass it to people who handle it?

Armadillo bodies run unusually cool, at about 34°C, which suits the leprosy bacterium. They are among the very few animals besides humans that catch the disease naturally.

Salmonella bacteria, a common cause of food poisoning, are named after Daniel Salmon, who was what by profession?

A veterinarian, Daniel Elmer Salmon led the research group, but it was his colleague Theobald Smith who found the bacterium. The name was proposed in Salmon's honour in 1900.

The 'patient zero' of a 1984 AIDS study was really a letter O, for a man from outside which US state?

California was the centre of the CDC's cluster study, so a man from elsewhere was marked 'O' for Out-of-California, and readers took the letter for a zero. Genetic work in 2016 showed he had not brought HIV to America.

The Ebola virus, first identified in 1976 in what was then Zaire, is named after which kind of geographic feature?

The name comes from a river, the Ebola, in the north of what is now the Democratic Republic of the Congo. The outbreak itself began at a mission hospital in the village of Yambuku.

The word quarantine comes from a Venetian term for which length of time that arriving ships had to wait?

Forty days, quarantena in the Venetian language, was how long ships lay at anchor in times of plague. It followed the trentino, a thirty-day isolation first imposed at Ragusa in 1377.

Which stomach bacterium did Australian doctor Barry Marshall swallow in 1984 to prove it causes gastritis and ulcers?

Helicobacter pylori won Marshall and Robin Warren the 2005 Nobel Prize. Their work overturned decades of doctrine that stress, spicy food and too much acid cause ulcers.

Somali health worker Ali Maow Maalin was in 1977 the last person to catch which disease naturally?

Smallpox in its milder form infected Maalin in the port of Merca, and he recovered. He later joined the campaign that rid Somalia of polio, and died of malaria in 2013 while giving vaccinations.

William Gorgas's mosquito-control campaign at the Panama Canal targeted malaria and which other deadly disease?

Yellow fever and malaria had made the isthmus notorious, and over 22,000 workers died during the earlier French attempt. Gorgas's crews went after the mosquitoes themselves, and far fewer died under the Americans.

Which piece of laboratory equipment is named after a German bacteriologist who worked as Robert Koch's assistant?

The Petri dish got its final form from Julius Richard Petri at Berlin University in 1887. He was refining a culture method that Koch had worked out in his private laboratory six years earlier.

Florence Nightingale's polar area diagrams showed disease killing far more soldiers than battle wounds in which war?

Crimean War hospitals lost ten times more soldiers to illnesses such as cholera and dysentery than to wounds. Her charts made the case so plainly that she is remembered as a pioneer of statistical graphics.

Which Greek city-state was devastated in 430 BC by a plague that the historian Thucydides lived through and described?

Athens was badly overcrowded because of the Peloponnesian War when the epidemic struck, and an estimated quarter of its people died. Thucydides left a detailed account of the symptoms.

On which Hawaiian island did the Belgian priest Father Damien care for leprosy patients at the Kalaupapa settlement?

Molokai's remote Kalaupapa peninsula received about 8,000 exiled Hawaiians between 1866 and 1969. After 11 years of caring for them Damien caught the disease himself, and he was made a saint in 2009.

Which charity, founded by Franklin D. Roosevelt in 1938, funded the research that produced the first polio vaccine?

March of Dimes was a name coined by the comedian Eddie Cantor, a pun on the newsreel series The March of Time. Roosevelt, himself diagnosed with polio in 1921, set it up as epidemics swept the country.

Which physician led the National Institute of Allergy and Infectious Diseases from 1984 to 2022, under seven presidents?

Anthony Fauci made his name in HIV and AIDS research. One citation survey ranked him the 13th most-cited scientist in the world, across every discipline, for the years 1983 to 2002.

Which 2011 Steven Soderbergh thriller about a deadly virus found a huge new audience during the COVID-19 pandemic?

Contagion climbed from 270th to second among Warner Bros. catalogue titles between December 2019 and March 2020. That month it was the seventh most popular film on iTunes, nine years after release.

Which malaria remedy from the bark of the South American cinchona tree gives tonic water its bitter taste?

Quinine was first isolated in 1820, though Jesuit missionaries had carried the bark to Europe almost two centuries earlier. The soda guns behind many bars mark tonic water with a Q for it.

Which insecticide, mainstay of the WHO's 1950s malaria campaign, came under attack in Rachel Carson's Silent Spring?

DDT won the Swiss chemist Paul Müller the 1948 Nobel Prize for discovering how well it kills insects on contact. Carson's 1962 bestseller focused the opposition and launched the modern environmental movement.

Carrying a single copy of the gene for which inherited blood disorder gives some protection against malaria?

Sickle cell disease takes two copies of the gene, while carriers with one are usually symptom-free and less likely to die of malaria. That advantage, shown in 1954, explains why the gene persists.

Which intestinal parasite, targeted by a 1909 Rockefeller campaign, usually enters the body through bare feet?

Hookworm larvae thrive in warm soil and bore through the skin of anyone walking barefoot. A million-dollar gift from John D. Rockefeller funded a commission that treated it across the American South.

Trichinosis, a roundworm infection of the muscles, was classically caught by eating which meat raw or undercooked?

Pork was the classic source, because the commonest species of the worm is best adapted to pigs. In North America the infection now comes most often from bear meat.

Babies under twelve months should not be given which food because it can carry botulism spores?

Honey is a known reservoir of the spores. In a baby's intestines the bacterium itself can develop and release its toxin, whereas in the food-borne form of the illness the toxin is eaten ready-made.

Which stomach bug, a common cause of outbreaks on cruise ships, is named after a 1968 outbreak in an Ohio town?

Norovirus was first called Norwalk virus, after the town of Norwalk. It is the most common cause of gastroenteritis, and the CDC runs a Vessel Sanitation Program that investigates shipboard outbreaks.

Which respiratory illness emerged in China's Guangdong province in 2002 and spread abroad from a Hong Kong hotel?

SARS reached Hong Kong's Metropole Hotel with a doctor from Guangzhou who checked into room 911 in February 2003. He is believed to have been a super-spreader: 23 other guests fell ill.

People who catch MERS, a coronavirus first identified in Saudi Arabia in 2012, usually get it from which animals?

Camels pass the virus on through direct contact or respiratory droplets, which is why the illness is nicknamed camel flu. In 2014 some Saudis defied official advice by kissing theirs.

Katalin Karikó and Drew Weissman won a 2023 Nobel Prize for groundwork behind vaccines built from which molecule?

Messenger RNA won Karikó little backing for years: her own university underfunded the work and discouraged her from pursuing it. The vaccines it made possible were rolled out against COVID-19.

Which surgeon pioneered antiseptic surgery in 1860s Glasgow by treating instruments and wounds with carbolic acid?

Joseph Lister also had carbolic acid used on sutures, patients' skin and the wards themselves. The mouthwash Listerine, developed in St. Louis in 1879, was named after him.

Which Dutch cloth merchant, using single-lens microscopes of his own making, was the first person to observe bacteria?

Antonie van Leeuwenhoek took up lens-making to inspect the thread in his draper's shop in Delft. In 1683 he described bacteria from the human mouth, calling such creatures 'little animals' in Dutch.

In the Gram stain, devised in 1884 to sort bacteria into two groups, thick-walled Gram-positive cells turn which colour?

Purple crystal violet dye is held by the thick cell wall of Gram-positive bacteria, while thin-walled Gram-negative ones lose it and take a pink counterstain. Hans Christian Gram devised the method in a Berlin hospital morgue.

Which kitchen gelling agent did Fanny Hesse suggest for growing bacteria in 1881, having used it to set her jams?

Agar stayed solid in the summer heat that melted the gelatin her husband was using in Robert Koch's laboratory. It had reached Europe from the East Indies as a way of setting fruit jellies.

Among mosquitoes, only the females of which genus transmit human malaria?

Anopheles are also known as marsh mosquitoes, and no other genus carries the human disease. Only the females feed on blood, which is how they pick the parasite up from one person and pass it to the next.

Onchocerciasis, a worm infection spread by black flies and treated with ivermectin, is better known by what name?

River blindness is the second leading infectious cause of blindness: the worm's larvae migrate to the cornea. Control teams sprayed larvicide into the fast-flowing waters where the flies live.

Schistosomiasis infects people who wade or bathe in fresh water contaminated by parasites released from which animals?

Snails are the halfway house where the worm multiplies before its larvae swim free and pierce human skin. Among parasitic diseases of the tropics it ranks second only to malaria for economic impact.

Which illness, named after the Brazilian physician who described it in 1909, is spread by blood-sucking 'kissing bugs'?

Chagas disease reaches people when the bug's infected droppings get into its bite wound. Carlos Chagas first recognised it in a two-year-old girl with fever and swollen lymph nodes.

Which fatal brain disease spread among the Fore people of Papua New Guinea through funerary cannibalism?

Kuru means 'trembling' in the Fore language, and the illness was also known as laughing sickness. Women and children, who usually ate the brain, were the ones most often affected.

Naegleria fowleri, the 'brain-eating amoeba' of warm lakes, infects swimmers by entering the body through what?

The nose gives the amoeba a path along the olfactory nerve and through the skull's cribriform plate into the brain. Swallowing contaminated water does not cause infection.

Which Ebola-like virus is named after a town where laboratory workers handling monkeys fell ill in 1967?

Marburg virus arrived in monkeys imported from Uganda for work on polio vaccines. They went to Behringwerke, a company founded by Emil von Behring, the first winner of the Nobel Prize in Medicine.

Harald zur Hausen won a 2008 Nobel Prize for discovering that cervical cancer is caused by which virus?

Human papillomavirus was his hypothesis as early as 1976, and it drew a great deal of scientific criticism when first published. It was later confirmed and became the basis for work on other high-risk types.

Which virus, first seen in 1964 in tumour cells sent from Uganda to London, was the first linked to a human cancer?

Epstein–Barr virus was spotted in cells cultured at Middlesex Hospital, and the finding appeared in The Lancet. It is one of the most common viruses in humans: about nine in ten American adults show signs of past infection.

Which liver infection, first identified in 1989, can be cured in over 95 percent of cases with antiviral tablets?

Hepatitis C was once nicknamed the Emperor's New Virus, because the company that found it at first published nothing others could check. Its discoverers went on to win a Nobel Prize.

Faecal microbiota transplants are used mainly to treat recurring gut infections caused by which bacterium?

C. difficile infections that return after antibiotics are where a transplant of donor stool earns its place: it works in roughly 85 to 90 percent of such patients.

Which German scientist, a 1908 Nobel laureate for work on immunity, coined the term 'magic bullet' for a targeted drug?

Paul Ehrlich's word was Zauberkugel: a compound that would seek out one disease-causing organism and kill only that. He shared his Nobel Prize with Élie Metchnikoff.

Maurice Hilleman based a 1960s vaccine on material taken from his own sick daughter Jeryl Lynn against which disease?

Mumps struck Jeryl Lynn in 1963, and the vaccine strain cultivated from her carries her name. Her father developed more than 40 vaccines, an unparalleled record.

Which mosquito-borne virus, first isolated in Uganda in 1937, reached North America in 1999 and often infects birds?

West Nile virus is named after a district of Uganda, not directly after the Nile. After 1999 it spread across the continent, and in 2007 it even killed a killer whale in Texas.

The Q in Q fever, a livestock-borne infection first described in Australia in 1935, stands for which word?

Query was chosen because nobody yet knew the cause. It beat 'Queensland rickettsial fever' and 'abattoir fever', names that might have embarrassed the state or its meat industry.

Which mysterious illness struck England in five epidemics from 1485, then vanished after its last outbreak in 1551?

Sweating sickness first appeared in August 1485, at the end of the Wars of the Roses, prompting speculation that French mercenaries had brought it. The physician John Caius left the main account of it in 1552.

Leishmaniasis, whose deadliest form is known as kala-azar or black fever, is spread by the bite of which insects?

Sandflies of the genera Phlebotomus and Lutzomyia carry the parasite. Kala-azar is a Hindustani phrase, and that form of the illness attacks the internal organs and is generally fatal if untreated.