“No cough, no measles” was one of the many mantras and memory aids I learned in medical school. Most were designed to reduce tomes like Gray’s Anatomy and Harrison’s Principles of Internal Medicine to a few rules. Much of the time, it was easy to miss the point, especially when the subject seemed to be an obscure disease.

Five years into a six-year medical degree at a typical Western university, none of us had ever seen measles. Nor were we bothered. Apart from HIV, microbes like measles seemed prehistoric. Public health was out, plastic surgery was in. Still, I remembered this particular rule, offered by a much-revered professor. But I wondered why he was so focused on a cough instead of “Koplik spots,” the little white dots in the mouth that are specific to measles.

Then I spent ten weeks in a pediatric infectious-disease ward in Cape Town. I thought I would see “African diseases” like hemorrhagic fever and HIV, which I did. But I also saw measles, rubella (German measles), scarlet fever, syphilis, rheumatic fever, typhoid, tuberculosis and many other causes of rash and fever.

Suddenly I could see the point of my professor’s rule. The very first signs of measles are a fever and cough, followed by a runny nose and red eyes. The appearance of a rash three or four days later is usually what prompts parents to bring their child to the emergency room. The problem is that at any given time, half the pre-school children in the ER have a fever, rash or both. The differential diagnosis is hard enough in immunized children, ranging from mild roseola to devastating meningococcal sepsis; the long list includes enterovirus 68, Lyme disease and drug rashes. In an unimmunized child, the ailment might also be rubella—harmless for the child, but catastrophic for unimmunized pregnant patients—or chickenpox.

Or it might be measles, in which case you need to know. Fast. Because measles is the most contagious disease on earth. Among unimmunized people exposed to the measles virus, some 90 percent will contract the disease. Anyone with measles is contagious for several days before the rash even appears; the cough effectively spreads tiny droplets of the virus, which can remain in the air for several hours, long after an infected person has left the room. In an unvaccinated community, each person who gets measles spreads it on average to twelve others. Complications like pneumonia and meningitis can be permanent, deadly, or both, especially for immune-compromised patients such as those with cancer. And in the ER, one of these kids might be in the next bed.

Older Americans remember measles as a common childhood disease that just had to be suffered through, but in fact it is still frequently deadly in low- and middle-income countries. And because the virus weakens the body’s natural immune system, children who survive measles get more infections and have a higher risk of dying from them for several months afterwards.

So a doctor needs to be able to diagnose measles at “hello,” not wait for the results of two blood tests taken two weeks apart to see whether antibodies are rising while the child spreads measles, as happened at Disneyland. I rapidly learned to recognize measles at ten paces, and realized that the idea of using Koplik spots as a diagnostic aid was better suited to passing exams than clinical practice. Toddlers with measles tend to be extremely irritable (another clue) and not madly cooperative about opening their mouths on request for viewing. Nor would you want to get that close, if you’re uncertain whether your parents had you immunized.

So the crucial question becomes: Cough, or no cough? If there’s no cough, it’s not measles. Period. Which is good, as excluding measles early averts both parental and departmental panic. But if an unimmunized child or adult is coughing, take it very seriously. Ensure that the child is kept away from places where he or she could spread the disease to others. Educate parents on how to treat the symptoms. And get the child out of the ER as quickly as possible before he or she infects other patients and staff.

These steps are all the more vital now that measles, long forgotten, is ”back” in the United States and far too few doctors know how to recognize it. And not only is measles proliferating; so are the nasty allegations about the danger of the vaccine by anti-vaxxer ideologues and unscrupulous politicians, even though the vaccine is not only safe, but mass measles vaccination is also the single best public-health intervention we have.

As doctors, there are a few things that we know are fundamental to our well-being. Most of these are public-health measures that enable us to live much longer and better lives, even to grow taller, than 200 years ago. These measures of mass salvation include water purification, toilets and sanitation, garbage collection and disposal, and vaccination to protect children from infectious diseases like smallpox, polio and measles.

Smallpox was a seriously nasty disease, with a fatality rate of 30 percent. For those who survived, the pocks were permanent, and not pretty. Eradication of this vicious virus was the result of achieving global herd immunity, a feat of international cooperation and cost-effective investment in a global good. Herd immunity comes from mass vaccination and eliminates the virus. It protects the entire community—particularly children and adults who can’t safely be immunized and babies who are too young (a child must be 6 to 9 months old before the immune system is sufficiently developed for the vaccine to work). When the global campaign began in 1967, there were 10 to 15 million cases of smallpox each year. Places that had attained herd immunity, such as Europe and North America, had to maintain it to prevent imported cases from India and Africa from triggering an epidemic while rigorous surveillance to diagnose every last case and mass vaccination campaigns around the world created global herd immunity. Ten years later, the virus died out. Smallpox eradication is the public health success story of the twentieth century, and because of it, we are now determined to try to eradicate other infectious diseases, such as polio and measles.

Polio, perhaps the most frightening disease of the twentieth century on account of its invisible spread and devastating effect, crippled tens of thousands of children each year before the discovery of a vaccine sixty years ago. Americans can be rightly proud of the March of Dimes, an enormous effort driven by American mothers, which raised tens of millions of dollars to find a vaccine. The global campaign to eradicate polio required massive international cooperation, overcoming Cold War divisions, to bring the number of global polio cases today down to a few hundred a year—tantalizingly close to eradication.

Measles, like polio and smallpox, is a horrible disease. Second only to smallpox in the total number of deaths it has caused over the past two millennia, it’s still a major killer of children under 5 years of age in the developing world. The development of a vaccine was widely welcomed. It is usually delivered jointly with vaccines for mumps and rubella, known in combination as MMR. One shot provides at least 95 percent protection and offers enduring immunity.

But because of vaccination lapses, measles is now on the rise. There were twenty separate outbreaks in the United States in 2014, involving 644 individual cases—a record number since measles was eliminated from the US in 2000. So far in 2015, there have been 141 cases in seventeen states, 80 percent of which are linked to Disneyland. Blaming it on Mexico and porous borders, as some opportunistic politicians have done, has no basis in reality; there were only two cases in Mexico in January, both imported from the United States. Globally, the number of cases rose from 122,000 in 2012 to 146,000 in 2013, reversing a twelve-year downward trend. In November 2014, the World Health Organization (WHO) gave up on meeting its target for measles control.

It gets worse. Measles is so contagious that it is used as the indicator disease to show deficits in immunization coverage of all vaccine-preventable diseases—which means the problem goes well beyond measles. We should hardly be surprised, then, that last year saw WHO announce a Public Health Emergency of International Concern for polio.

Why is this happening?

In Syria, the government’s efforts to withhold routine childhood vaccinations in areas considered politically unsympathetic to the dictatorship was one of the reasons for the popular uprising. Small wonder that polio returned to Syria and that there have been more than 10,000 cases of measles in 2014. Parents are desperate for vaccines, and last year medical workers braved Assad’s barrel bombs to vaccinate 1.4 million unimmunized children in northern Syria for polio, achieving 92 percent coverage, equivalent to the rate in the United States. Similarly in West Africa, people are begging for Ebola vaccines. Yet in the United States the anti-vaccination movement has seen increasing numbers of parents refuse measles and other vaccines “on behalf” of their unprotected children.

That misguided movement began with the unconscionable malpractice of Andrew Wakefield. A doctor who has since lost his license, he and his coauthors of a 1998 article in The Lancet made up a syndrome consisting of diarrhea and developmental disorder (“regressive autism”) that he tried to link to the MMR vaccine for the sole purpose of financial gain. He was not at the time a practicing doctor, and had no expertise with autism, but he manipulated parental fears and an editor’s penchant for controversial papers to secure publication in The Lancet, a respected medical journal. Extraordinarily, despite his financial conflict of interest, despite having fabricated the syndrome and falsified the data to “fit” his criteria, his paper passed peer review.

That paper was then used to support litigation against three companies that produced the MMR vaccine, and to lobby for use of Wakefield’s own measles-only vaccine. Wakefield went on to make more than more $600,000 in the process of the lawsuit alone.

In his 1998 paper, Wakefield alleged that eight children developed autism six days after receiving the MMR vaccine. I remember the paper well, because I was a pediatric fellow in London at the time. I and every other pediatrician were immediately besieged by parents demanding measles-only vaccines. We were staggered by Wakefield’s ridiculously small, uncontrolled and clearly biased study about a syndrome that none of us had heard of, even though the MMR vaccine had been widely used since 1968. But it was also hard to imagine that The Lancet would publish something with such obvious global ramifications unless there was irrefutable scientific evidence uncontaminated by financial interest.

It took six years for The Lancet to admit Wakefield’s financial conflict of interest but it did not retract the paper until 2010. Meanwhile, the rise of measles in the United Kingdom and United States reflects the damage done, and the consequences extend well beyond the West. In Nigeria in 2014, Ebola was successfully stopped and polio seems to have been eliminated, yet this country houses the greatest number of kids not vaccinated for measles after India. Parents keen on protecting their children from polio are known to refuse the measles vaccine, not because of myths about “a Western conspiracy of sterilization” or fears that vaccinators are “spies for the CIA” (after the CIA’s clumsy attempt to use a fake hepatitis B campaign to access Osama Bin Laden’s compound); rather, they are familiar with the anti-vaccine movement incited by Wakefield, asking, “If parents in California aren’t getting their kids vaccinated, why should we?”

Vaccination rates of 94 percent are needed to prevent measles transmission in high-risk areas such as child-care centers and schools. Yet in Orange County and West Hollywood, many schools have documented childhood immunization rates of less than 92 percent, with some schools having rates as low as 38 percent—levels seen in developing countries. The Lancet could help by publishing not just a retraction but also an unequivocal editorial discarding the myth once and for all.

Using vaccination as a political tool is contrary to the public good. Yet some politicians seem unable to assert collective responsibility over individualism: Chris Christie dithers about balancing parental choice and public health, while Rand Paul offers uniformed opinions and contradictory behavior. The White House spokesman said that “people should evaluate this for themselves,” though he urged a bias toward “good science.” Seriously? Should we also start debating the value of safe drinking water and sanitation? Throwing mud means lost ground, which measles relentlessly gains.

In medical school, I couldn’t see myself in a career in public health. (I instead became a critical-care pediatrician.) Public health seemed a “done deal” that everyone could see the value of. I returned to it ten years later, a convert to public and global health. Kids are the most vulnerable, with their poorly developed immune systems. They are also vulnerable to the politicization of the public good, the only ones without a direct say in the debates about their welfare.

And vaccines alone don’t save lives: vaccinations do. There’s little point in having vaccines if parents are allowed to refuse vaccination not only “on behalf” of their own children, but also, effectively, on behalf of other parents’ babies who are too young for vaccination, to say nothing of kids born with immune disorders, for whom the vaccine is ineffective. Parents are understandably confused, but the increasing polarization isn’t helping. Amid the controversy, it’s easy to miss the point: a very serious disease is getting on with its job of invading, infecting and re-colonizing the country, and we are losing control of it. The public good of herd immunity can afford an occasional free-rider, but when large numbers of people place their own ideologies and idiosyncrasies above public health, it’s children who suffer the consequences.

It is particularly because of those children that we need to take infectious disease more seriously. Pandemics didn’t happen until the earth’s population reached a critical mass. We think of rats on ships spreading bubonic plague in the Middle Ages, but it was the far deadlier human-to-human pneumonic version that travelled far and wide. (Both have now reappeared in Madagascar’s prisons.)

Nor it is enough to focus on national health. In an increasingly crowded and connected world, we need to think of public health not simply locally but globally. Air travel now means it is impossible to stop viruses from spreading around the globe. Germs are frequent flyers. Building the homeland walls higher won’t help—the only reliable antidote is building global public health. We have to pay attention to the neglect of infrastructure in West Africa, where Ebola erupted, and the Syrian military’s deliberate destruction of public-health systems in opposition-held areas, where polio emerged. SARS became a global threat when China suppressed word of its emergence. MERS now threatens from the Persian Gulf. All of these diseases can easily spread to the West with profound implications. Just look at the effect of a few cases of Ebola in the United States.

Returning to measles, if the threat of that deadly disease isn’t enough for you to reject anti-vax folklore, here’s a little known fact about the benefit of vaccination. The measles vaccine doesn’t only protect against measles. Because it contains a small amount of a live virus, the immune system must rev up to fight it, which in turn reduces mortality from other infectious disease—including pneumonia, sepsis and others—by 50 percent. This protective effect lasts until a vaccine is administered with a killed rather than a live virus, such as the one for diphtheria and tetanus. So do you want to protect your kids? Give them the measles vaccine.

And all of us should get educated. Education is a social vaccine against sustained ignorance that blocks effective and responsible responses to public-health threats. But education alone is insufficient to overcome self-interest. We all need to act for the public good. Because when public health is at stake, it’s the children who take the fall. Individuals and institutions that are allowed to prioritize personal preference or financial and political gain ahead of children’s health are irresponsible and unethical, and they should not call the shots. In the short term, children’s health and lives are at risk; in the long term, we jeopardize the local and global control of these previously conquered diseases. Prevention is not only better than cure—which isn’t an option for most of these diseases—it’s also more cost-effective. Current and past pandemics reveal that when public health is neglected, history repeats itself in an entirely predictable way.

Our common desire to protect the health and well-being of children was always the best reason to eliminate these diseases, and it remains our best hope of bringing us all back to common ground. Public health is about common sense and common goods. Let’s not allow spin doctors and myths to prevail over our shared aim of protecting the world’s children from the world’s oldest and deadliest diseases.