And the Gold Medal for Vomiting Goes to…

At the Sochi Olympics four years ago, NBC sports maestro Bob Costas publicly suffered from a clearly visible case of pinkeye, or conjunctivitis. As the infection progressed, nightly television viewers learned as much about the eye disease — its staph or strep bacterial origins and its unpleasant symptoms — as they did the sporting events, until Costas found it necessary to bow out of his anchoring role entirely. This year’s Olympic Games in Pyeongchang, South Korea, now seem poised to offer spectators an epidemiological crash course in an even more pernicious human pathogen.

By Feb. 8, at least 128 people in the host city had developed the vomiting, chills, diarrhea, and fevers caused by norovirus, and another 1,200 were under quarantine restrictions, suspected of being infected. None of these people were Olympic competitors — but that may not matter. Norovirus is so ideally adapted to the body and behavior of humans that its spread in Pyeongchang — including the Olympic Village — is all but guaranteed. And that would mean that the world’s best skiers, skaters, and sledders may be too busy lunging for the toilet facilities to compete.

The world’s top cause of gastroenteritis — severe stomach pain with nausea and diarrhea — noroviruses sicken people of all ages and kill an estimated 70,000 children under 5 annually. Every year, norovirus costs about $4.2 billion in health care treatment worldwide — $2.8 billion of that in hospitalizations — and an additional $60.3 billion in lost productivity and general economic impact. There are no vaccines or curative medicines, no magic bullets for noroviruses; the sick just have to tough it out and pray their immune systems can tackle the bugs.

Worse, the virus often hitchhikes aboard common bacteria, rapidly riding down from a person’s mouth to the stomach, where it explodes in a reproductive flurry that fills the entire gastrointestinal tract. From there, it releases toxins that flush water out of the human cells that line the gut, causing uncontrollable waterfalls, rife with viruses, to flow out in diarrhea. The flow is so packed with viruses — averaging 5 billion infectious doses per fecal gram — that environments are quickly contagious.

Virologist Aron Hall of the U.S. Centers for Disease Control and Prevention called norovirus the “perfect human pathogen” because it rarely kills people but is so contagious and causes such violent illness to further spread its progeny that it is virtually impossible to eliminate the bug from a crowded human environment. Most epidemics only come to an end when the local population becomes immune to the specific culprit strain — and since noroviruses have their genetic material in the form of RNA, which is less stable than DNA and readily mutates, evolving constantly like influenza, it’s impossible for people to develop lasting immunity that protects them against future infections. For example, a new form of norovirus emerged in China in late 2014, spread throughout the entire world in a year’s time, and by 2016 faced stiff competition from another mutant form of the virus.

Little that people do to slow the germ’s march across a crowded setting makes a difference. Once noroviruses reach the environment during winter time, they are very stable and incredibly difficult to clean off of any surfaces. An infectious dose can be as few as 18 viruses — a quantity so miniscule as to be completely undetectable and impossible to remove. A thoroughly scrubbed surface, drenched in chlorine and zapped with virus-killing ultraviolet light, would still have sufficient nooks and crannies to hide 18 living, contagious viruses.

Making matters worse, these pathogens are expert hitchhikers. They catch rides to the human body by attaching to fomites — a public health term that covers just about any dust mote, shed strand of hair, bits of skin or dandruff, clothing, curtains, food particles, or other larger microbes. The sneaky norovirus goes wherever its fomite ride carries it, drifting in the air, water, along surfaces and walls, tracking on the soles of shoes, passing via doorknobs and handles, swiftly overtaking the entire ecosphere.

But the cleaning can’t stop with scrubbing and scouring, as Olympics officials in Pyeongchang are no doubt discovering. Every fomite surface — carpets, curtains, rubber gaskets, bedding — must be removed to guarantee no viruses lurk, and even steel surfaces must be sanitized. Even the most unlikely surface can attract, and spread, the virus.

Air New Zealand learned the cleaning lesson the hard way in 2009, when a passenger threw up during a Boeing 777 flight. A flight attendant quickly cleaned the mess, and the plane was professionally sanitized after the flight. Despite repeated disinfections, 43 percent of the flight attendants who flew on that jet over the subsequent week came down with norovirus.

Hospitals are often overwhelmed by norovirus and can only stop the spread by gutting rooms — destroying all the curtains, carpeting, gaskets, and other potential havens for fomites. But the virus can still find safe havens in the most unlikely places. In 2010, for example, a women’s soccer competition in Oregon suffered an outbreak that spread from a plastic grocery bag — a bag none of the sick actually touched but which became contaminated via fomite-carried viruses drifting in the air in a bathroom in which one of the soccer players vomited.

Is there anything visitors to PyeongChang can do at this point to stop the outbreak? In a word, no. Olympics staff, audiences, coaches, and athletes should wash their hands and faces many times a day to minimize personal risk, but fomites are, by definition, everywhere. If 128 cases among Olympics security personnel were confirmed in Pyeongchang on Thursday, it is likely that every surface those individuals touched or breathed upon has virally contaminated fomites.

In public health parlance, the most important predictor of outbreak-to-epidemic potential is a microbe’s R0 — the reproductive ratio, or number of people one ailing person is likely to pass the disease-causing agent onto. The Ebola virus spreads slowly, as its R0 is 2, so outbreaks slowly double in size. At the most extreme end is measles — a virus that can have an R0 of 18, so each infected person spawns 18 more cases. Noroviruses vary, based on their specific genetic forms, but can have an R0 as high as 3.7, meaning those 128 identified norovirus cases in Pyeongchang may have spread the virus to 474 more, which in turn could pass norovirus to another 1,752 people at the Olympics by the middle of next week and continue expanding throughout the games. These are, of course, worst-case-scenario numbers and certainly do not represent a forecast. If swift isolation and quarantine of identified cases limit their R0 potential, the ultimate scale of the Olympics mess may be comparatively trivial.

Olympics officials will no doubt face questions regarding anti-diarrhea medications and hydration products allowable under strict anti-doping rules. Athletes may be unable to compete safely without using such products, but the most effective medicines for slowing diarrhea act by signaling opiate receptors that line the gut. Some addicts swallow over-the-counter drugs such as Imodium, believing they enhance a heroin or fentanyl high. The active ingredient in most anti-diarrhea drugs is loperamide, which is not specifically on the Olympics anti-doping list. But loperamide can be a dangerous drug, particularly for high-speed athletics, as its side effects include dizziness, drowsiness, and difficulty concentrating, and it can have a diuretic effect — all prescription diuretics are banned by the International Olympic Committee. Because it affects opiate receptors throughout the body, loperamide can have unexpected and often disturbing interactions with medicines taken for a range of mental health problems and anti-malaria drugs.

Thankfully norovirus infections are rarely fatal for healthy adults, and the misery they cause is short-lived. But the real lesson in the Pyeongchang norovirus saga should be about hubris. Once again, in a wealthy, advanced country, a virus has outwitted human preparedness. Ever since the Ebola epidemic of 2014-2015, the World Health Organization and top global governance entities such as the G-7, World Bank, and U.N. General Assembly have been obsessed with developing systems of disease surveillance and response, aiming to guarantee, as one new book puts it, “the end of epidemics.” No matter how confident and diligent humans are, however, microbes always lurk, finding flaws in our systems and behaviors and inevitably exploding into unexpected outbreaks that none of our advanced technology and medicines can stop, cure, or detect.