Epidemiology
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50 free Epidemiology trivia questions with answers — science & nature quiz, new questions added Oct 2026.
Epidemiology is detective work on the scale of whole populations. Its pioneers solved outbreaks by counting the sick, mapping where they lived and asking what they had in common, often decades before anyone could see a germ under a microscope. This quiz covers the stories that built the field and the vocabulary it runs on: Victorian London's most famous outbreak investigation, the first vaccines and clinical trials, the long studies that exposed the dangers of smoking, and the terms that describe how an infection moves through a population and how deadly it is. It suits public health, nursing and medical students revising the basics, and anyone curious about how outbreaks are tracked and stopped. Every answer comes with a short explanation, so a wrong guess still teaches something.
30 of 50 questions with answers and explanations. Play the quiz
Q 01John Snow pinned London's deadly 1854 cholera outbreak on which source on Broad Street in Soho?
A water pump
A water pump on Broad Street was the source, and the parish disabled it by taking off the handle. Workers at the nearby brewery, who drank their beer allowance instead, never caught the disease.
Q 02Mary Mallon, better known as Typhoid Mary, infected dozens of New Yorkers while working in which job?
Cook
Cook to a string of wealthy families, Mallon carried typhoid without ever falling ill herself. She was forcibly quarantined in a hospital on New York's North Brother Island.
Q 03The 1918 flu pandemic was nicknamed after which neutral country, whose uncensored newspapers reported it freely?
Spain
Spain stayed out of World War I, so its press covered the outbreak while the warring nations censored the news. That made Spain look like the epicentre, though the flu did not begin there.
Q 04The word vaccine comes from the Latin for which farm animal, thanks to Edward Jenner's 1796 experiment?
Cow
Cow is 'vacca' in Latin, and Jenner's vaccine used cowpox, a mild infection caught from cattle, to guard against smallpox. His first subject was James Phipps, his gardener's eight-year-old son.
Q 05Quarantine takes its name from a Venetian word for how many days that plague-era ships had to wait in isolation?
40
40 days was the 'quarantena' that ships sat out before anyone could go ashore during the Black Death. It followed a 30-day isolation first imposed in 1377 by Ragusa, the modern Dubrovnik.
Q 06Ignaz Semmelweis slashed childbed fever deaths on a Vienna maternity ward by making medical staff do what?
Wash their hands
Wash their hands in chlorinated lime, he insisted, and the death rate fell from 18% to under 2%. Offended colleagues mocked him, and he died in an asylum in 1865.
Q 07Florence Nightingale's 'rose' diagrams showed that soldiers in which war mostly died of disease rather than wounds?
Crimean War
Crimean War hospitals lost ten times more soldiers to illnesses such as typhus and dysentery than to battle wounds. Nightingale later became the first woman elected to the Royal Statistical Society.
Q 08Which term for an outbreak's first known case arose when a CDC code, 'O' for 'Outside California', was misread?
Patient zero
Patient zero was born when readers of a 1984 AIDS study took the letter O for a nought. The man so labelled, flight attendant Gaëtan Dugas, was not in fact the first American case.
Q 09James Lind's shipboard experiment on twelve sailors, one of the first clinical trials, showed that what cured scurvy?
Citrus fruit
Citrus fruit won: the pair of sailors given two oranges and a lemon each day did best, while cider, vinegar and seawater did little. Lind ran the trial as a naval surgeon in 1747.
Q 10Which term describes the indirect protection unvaccinated people gain once most of a community is immune?
Herd immunity
Herd immunity was first named in 1894 by a US veterinary scientist describing well-fed hogs that resisted disease. It applies only to contagious infections that pass from person to person.
Q 11Which term describes a disease, like chickenpox in Britain, that is constantly present in a population?
Endemic
Endemic diseases keep a steady, predictable number of people sick, and that number can be high or low. The word says nothing about severity: such a disease can be mild or grave.
Q 12Which epidemiology measure counts only the new cases of a condition arising in a population over a set period?
Incidence
Incidence tracks new cases and so conveys the chance of contracting a disease, whereas prevalence shows how widespread the disease already is.
Q 13What name is given to an infectious disease, such as rabies or Ebola, that passes from animals to humans?
Zoonosis
Q 21Richard Doll and Austin Bradford Hill tied smoking to lung cancer by tracking 40,000 Britons in which profession?
Doctors
Doctors replied in their thousands: 40,701 of them, two-thirds of those written to in 1951, sent back their smoking habits. The study went on following them for 50 years.
Q 22Which term for a trait that raises the odds of disease was popularised in 1961 by the Framingham Heart Study?
Risk factor
Risk factor entered the medical vocabulary through a 1961 paper from the study, which began in 1948 with 5,209 adults from one Massachusetts town and went on to enrol their children and grandchildren.
Q 23Which inactive treatment, named from the Latin for 'I shall please', is given to a clinical trial's comparison group?
Placebo
Zoonosis covers any infection that crosses from other animals to people, salmonellosis included. Most human diseases began in other species before making the jump.
Q 14John Snow gave Queen Victoria which anaesthetic during the births of her last two children, Leopold and Beatrice?
Chloroform
Chloroform was the Queen's own request in 1853, and Snow gave it again in 1857. He had studied the drug closely and warned that it needed far more careful dosing than ether.
Q 15Which ancient Greek, who blamed illness on four unbalanced humours, first linked disease to the environment?
Hippocrates
Hippocrates, known as the father of medicine, sought a logic to sickness in people's surroundings. He also gave the word epidemic its medical meaning, using it as the title of a treatise.
Q 16Before germ theory, epidemics of cholera and plague were blamed on which noxious 'bad air' from rotting matter?
Miasma
Miasma is Greek for pollution, and the idea lives on in the name malaria, medieval Italian for 'bad air'. Medicine abandoned it after 1880 as germ theory won out.
Q 17Which Nobel-winning physician gave his name to four postulates for proving that a microbe causes a disease?
Robert Koch
Robert Koch published the refined criteria in 1890, six years after drawing them up with Friedrich Loeffler. Viruses later bent the rules, since many infect people without making them ill.
Q 18Ronald Ross won the 1902 Nobel Prize in Medicine for proving that malaria is carried by which insects?
Mosquitoes
Mosquitoes were confirmed as the culprits in 1897, when Ross found the malaria parasite in the gut of one he had dissected. His discovery laid the foundation for fighting the disease.
Q 19Legionnaires' disease was named after a 1976 outbreak among veterans at a hotel convention in which American city?
Philadelphia
Philadelphia hosted the American Legion at the Bellevue-Stratford Hotel that July. The mystery pneumonia that followed led scientists to a bacterium nobody had identified before, Legionella.
Q 20The US Centers for Disease Control and Prevention grew out of a wartime malaria programme based in which southern city?
Atlanta
Atlanta was chosen because malaria was then widespread across the American South. In 1947 the agency paid Emory University a token $10 for the land where its headquarters was built.
Placebo treatments include sugar pills, saline injections and even sham surgery. Their dark twin is the nocebo, Latin for 'I shall harm', an inert substance that hurts because people expect it to.
Q 24What is the gap between catching an infection and the first symptoms, one to three days for a common cold, called?
Incubation period
Incubation period lengths vary enormously, from as little as half a day for cholera to as long as six weeks for glandular fever.
Q 25Which public health practice identifies everyone an infected person may have exposed so they can be tested or isolated?
Contact tracing
Contact tracing aims to cut transmission by finding, testing and treating the people an infected person has met. It played a major role in Britain's handling of Ebola in 2014.
Q 26With a basic reproduction number estimated at 12 to 18, which childhood disease is among the most contagious known?
Measles
Measles spreads through the air on coughs and sneezes, and people are infectious from four days before the rash appears. One case in an unprotected community is expected to infect 12 to 18 others.
Q 27Rabies in the unvaccinated tops 99% on which measure, the share of people diagnosed with a disease who die of it?
Case fatality rate
Case fatality rate counts deaths only among people diagnosed, so statisticians note it is really a proportion rather than a true rate. It says nothing about how common the disease is.
Q 28Which type of study, like the Nurses' Health Study begun in 1976, follows a group over years to see who falls ill?
Cohort
Cohort studies start with people who do not have the disease and watch to see who develops it. The Nurses' Health Study signed up 121,700 married registered nurses aged 30 to 55.
Q 29What term describes a trial in which neither participants nor researchers know who is getting the real treatment?
Double-blind
Double-blind trials keep both sides in the dark so that expectations cannot sway the results. An early example was the Nuremberg salt test of 1835, run by the city's top public health official.
Q 30Lyme disease is named after a town in which US state, where a puzzling cluster of childhood arthritis appeared in 1975?
Connecticut
Connecticut gave the disease its name when cases first taken for juvenile arthritis turned up in three towns, Lyme among them. The oldest known sufferer is Ötzi the Iceman, a 5,300-year-old Alpine mummy.