The Minnesota measles outbreak just hit an alarming benchmark. The 73 cases reported so far in the state this year have topped the entire number of measles infections reported nationally in 2016 — a milestone first reported in the Washington Post.

That this number isn’t higher, and that no child has died from measles’ potentially deadly complications, reflects the skills of Minnesota medical providers and the world-class abilities of the state’s public health response teams. Measles is a familiar yet fearsome pathogen. The virus is highly contagious and snuffs out more than 134,000 lives around the world each year.

Still, it is a moral outrage that the Minnesota epidemic exists at all. Measles is a vaccine-preventable disease. The science backing the immunization’s safety is solid and settled. And yet, there are medical providers and activists in this state who countenance or sow dangerous doubts about the vaccine, causing misguided parents to forgo the shot.

That these anti-vaccine activists are still at it so aggressively — in the midst of a large outbreak — necessitates a public health response from the Minnesota Legislature and from organizations such as the Minnesota Board of Medical Practice that police doctors’ ethics and competence.

Specifically, lawmakers must tighten exemptions for school vaccine requirements, and do this early next session. Medical providers also need to report to oversight boards the names of colleagues who spread harmful vaccine disinformation. In turn, these organizations should energetically pursue these concerns or, better yet, take a proactive approach to finding these practitioners.

The so-called “anti-vax” movement appears to be small in number in Minnesota but well-connected. Its activists promoted screenings of the controversial “Vaxxed” movie in the state over the past year. Dr. Andrew Wakefield, the discredited doctor who conducted fraudulent research suggesting a link between the measles vaccine and autism, has also visited the state.

Particularly irresponsible has been the anti-vaxxers’ vigorous efforts in the state’s large Somali-American community. There, activists have spread misinformation about the vaccine’s safety by distributing pamphlets and conducting meetings about “vaccine damage.” It is not a coincidence that children from this struggling immigrant community were the first to fall ill in the Minnesota measles outbreak.

The blame for the current outbreak rests squarely on these activists’ shoulders. And yet, their work continues unabated. It’s easy to find on social media. A west-metro medical clinic catering to anti-vaxxers has more than 3,200 followers on Facebook. On a different Facebook account, Minnesota activists have shared strategies to thwart health officials’ efforts to keep unvaccinated kids exposed to measles home from school. The concern: This is “government overreach.” The reality: This is a towering act of selfishness. These parents care more about their ill-informed belief than protecting their children and others from serious illness.

Minnesota lawmakers need to have legislation ready to go early next session to tighten school-aged vaccine exemptions. A hearing before then is in order to fully establish the legislation’s urgency and to find out if other state public health regulations need strengthening.

The current measles outbreak shouldn’t have happened. Policymakers must take seriously their responsibility to prevent another.