California currently is in the grip of its worst single measles outbreak in 15 years.

Public health authorities believe that the nearly 30 cases so far identified in this state, Utah, Colorado and Washington all were contracted during visits to Disneyland the week before Christmas. They also say that most of those infected are among the one in four Americans no longer protected by vaccination against this dangerous and highly communicable viral disease.

Nearly universal infant vaccination had eliminated domestic transmission of measles by 2000. About that time, vaccination rates, which were at about 95 percent, began to fall sharply and, as a consequence, the number of measles cases has risen dramatically again. Last year, there were 70 cases in California alone — all part of a willful parental retreat from one of the great public health triumphs of modern times.

Universal vaccination has quietly worked wonders in the lives of people around the world and, particularly, in the developed nations. Smallpox, once mankind’s scourge, has been globally eliminated. The battle against infectious childhood diseases — up to now — has been similarly successful, particularly in the United States. In 1950, for example, hundreds of children were afflicted by polio and diphtheria. Today, vaccination has totally eliminated them from this country. Whooping cough once afflicted more than 120,000 American children every year; last year there were only about 15,000 cases and those were the result of parents declining to vaccinate their sons and daughters.

Both the World Health Organization and the Center for Disease Control have cited the particular benefits of measles vaccination. According to the WHO, measles deaths globally fell by 75 percent between 2000 and 2013, which means that an astonishing 15.6 million lives were saved by a single inoculation. The CDC estimates that since vaccination against the battery of communicable childhood disease — including measles — became routine in 1994, 732,000 deaths have been prevented, along with 21 million hospitalizations and 322 million illnesses.

That’s a lot of bang for very few bucks and very little effort. So what’s the problem?

In 1998 an article appeared in the British medical journal Lancet in which the author, Dr. Andrew Wakefield, and his co-authors claimed to have found a link between childhood vaccinations and autism. Despite the fact that the Lancet subsequently retracted the article after its data was completely discredited and Wakefield was found to have acted unethically, the findings were seized upon by a handful of celebrities and pediatricians in this country. They have persisted in holding to these and other reservations about vaccinations despite the fact that Wakefield actually was deprived of his medical license as a consequence of his gross misconduct.

These irrational attitudes have taken hold with particular force here in California, especially in the better educated, more affluent areas, like Los Angeles’ Westside and coastal Orange County. As a result, measles and whooping cough now occur in places like Santa Monica, Malibu and Pacific Palisades, where childhood vaccination rates have fallen to the same levels as the South Sudan and Chad.

When it comes to raising children, regulating family life or the moral education of the young, the state enjoys no special competence. In fact, the opposite is arguably true. For that reason alone, any societal intervention into these areas ought to be taken with the greatest tact and circumspection. Such strictures, however, should not prevent intrusive actions to safeguard a child’s physical well-being and safety.

We’re long past the notion of children as property, subject solely to their parents’ authority and judgments. The young, too, are individuals and entitled to the state’s protection of their fundamental rights. Our courts possess a well-established body of case law that, for example, permits the authorities to order blood transfusions for sick or injured youngsters whose parents have religious scruples about such procedures. No rational person would insist that the authorities stand impotently by while parents who believe in faith healing deny their desperately ill child an emergency appendectomy. Parochial schools are not free to ignore health and safety laws. No one would argue that immigrants who adhere to traditional Muslim or animist beliefs should be free to exercise their consciences and inflict genital mutilation on their daughters.

The “personal belief” exception under which so many California parents now claim the right to withhold infectious disease vaccinations from their children is far more tenuous than any of the foregoing examples. It is, in fact, less a matter of “conscience” as we traditionally understand it than it is a self-indulgent form of fashionable foolishness. A mature conscience is the product of reason prudently applied, reflection and discernment that tests belief against the world as it actually is. The sort of “personal belief” that withholds childhood vaccinations is most often the product of a few hours rummaging through the lacy fringes of the Internet and conversations over lattes at the local Starbucks.

What we confront here is less a question of conscience than it is of something far more casual — an opinion. And just because everyone is entitled to an opinion it does not follow that all opinions are equal. Nor does it follow that the rest of us owe such respect to an opinion arrogantly held in defiance of all competent scientific and medical authorities that we should allow it to endanger not just a particular parent’s child, but the children of others, as well. Our people are entitled to hold any belief they choose, however irrational, ill thought out or eccentric. They are not free, however, to use those “beliefs” as a justification for endangering children — their own or those of others, which is precisely what the vaccine objectors are doing.

California needs to revisit and abolish the “personal belief” exemption when it comes to childhood vaccinations. Better yet, we ought to have a state law that requires parents to vaccinate all their children by the end of their first year and provides sufficient assistance for those who might find that financially burdensome. At the very least, no public or private school should be allowed to enroll any student who cannot provide proof of vaccination against the communicable childhood diseases.

The world being what it is, our children will confront challenges we cannot foresee and some perils against which we cannot protect them. The least we can do is spare them the dangers that can be put forever behind them with a quick trip to the doctor’s office.

Tim Rutten is a columnist for the Los Angeles News Group. ruttencolumn@gmail.com.