Let’s say, for the sake of argument, you plummet from a ski gondola. Or, equally bad, you contract a fatal illness from eating human brains.

Your risk of experiencing such disasters is low. But these calamities, and many more, are nonetheless covered by the world list of illnesses and injury known as the International Classification of Diseases, or ICD, published by the World Health Organization (WHO). The document tells doctors what to look for, insurers what they might pay for, and health officials—by virtue of numbers—what needs attention.

Last June, seven years into a project involving 30 committees and 11,000 proposals, the WHO released the eleventh version of this tally of human malady. Its 55,000 entries were undergoing final, mostly technical, review when, in December of 2018, something unusual happened: one diagnosis—congenital Lyme disease—slipped from the list. The condition occurs when a pregnant woman infected with the tick-borne disease passes the bacterium, known as a spirochete, to her developing fetus. 

Cases of Lyme spirochetes crossing the placenta have been documented since the 1980s, with sometimes terrible consequences for fetuses and newborns. Consider a report in the journal PLOS One, published in November, which examined, among other evidence, the outcomes of 59 women with Lyme disease in pregnancy. 

“Newborn died at 39 hours,” reads one entry for a baby with a heart deformity. “Spirochetes … found in spleen, renal tubes and bone marrow.”

“Newborn died at 23 hours due to prenatal brain damage,” reads another. “Spirochetes identified in the brain and liver.”

In all, 10 miscarriages and 10 deaths occurred, along with 16 complications and defects, six of them long-lasting. The overall tally: bad outcomes in 61 percent of cases.

Nine other studies have found indirect evidence of harm: among Lyme-infected mothers who were not treated in pregnancy, 50 percent had adverse outcomes such as congenital abnormalities and miscarriage; just 11 percent of treated women did. This suggests that Lyme disease should be on every obstetrician’s radar.

These and other studies had convinced ICD overseers to include the diagnosis in the first place. But the expansive PLOS One review, published after the new list was unveiled, actually might have convinced WHO otherwise. Fetal outcomes were simply too varied, knowledge gaps large, and study results inconsistent, said the article. For example, six studies showed no significant association between infection and fetal harm. “The global evidence does not fully characterize the potential impact of gestational LD,” the PLOS One article concluded.

In response to questions about the removal of the diagnosis, WHO said in a statement: “(T)here is not sufficient evidence to justify a separate statistical category for congenital Lyme disease.” Instead, when newborns are found to harbor Lyme spirochetes, the statement said, other diagnostic codes can be used. But patient advocates fear this does not give the condition the recognition it deserves.

To its credit, WHO accepted 14 Lyme-related conditions in the new ICD, compared to just four in the previous edition. The new list includes Lyme-related dementia; central nervous system demyelination (similar to multiple sclerosis); ophthalmic complications; neuroborreliosis (which afflicts the nervous system); and carditis, a potentially fatal heart-rhythm dysfunction.

Like congenital Lyme disease, these conditions have long been reported in the scientific literature, but may not be tied by doctors to the common and harmful bite of a tick. “For babies riddled with spirochetes, there needs to be a way to describe them to simply have the discussion,” Jane Marke, a New York City psychiatrist who treats Lyme patients, told me. This is why ICD recognition is important.

A 17-year-old upstate New York boy collapsed and died in 2013, when, to that point, only four such Lyme carditis deaths had ever been reported. An inquisitive pathologist then studied donated organs and found three more cases in the Northeast, two in a single month. Lyme disease had not been considered in those deaths.

Similarly, singer Kris Kristofferson suffered for a decade with what was thought to be Alzheimer’s disease. He was treated in 2016 for Lyme disease and got better. Significantly, the Lyme disease bacterium is closely related to another infamous spirochete—syphilis—known for centuries to cause dementia. Congenital syphilis, notably, has a place on the WHO list. The similarity “likely explains the congenital malformations that are implicated” in Lyme infection, wrote two physicians from Pennsylvania College of Medicine in 2017.

The on-again, off-again status of congenital Lyme borreliosis, as it is officially called, is most certainly an outgrowth of the larger issues that plague Lyme disease, which infected more than 400,000 Americans in 2017. The infection is difficult to diagnose, and the pathogen difficult to culture, certainly inhibiting identification in babies and mothers. Treatments also fail many patients for unknown reasons. And research funding has been scant, leaving questions unanswered, about congenital and other forms.

American medicine, which sets the standard for Lyme disease care worldwide, has done little to remedy these long-standing impediments, instead minimizing their importance. The prevailing treatment guidelines of the Infectious Diseases Society of America famously refer to lingering symptoms as the “aches and pains of daily living,” even as other science has documented their severity.

In the 1980s, AIDS was initially marginalized—shamefully—because it most affected gay men and intravenous drug users. But Lyme disease remains a controversial, politicized and underestimated disease because of how it has been framed, wrongly, by American medicine: easy to diagnose and treat. The reality is far different.

Ask physicians in prime Lyme disease areas about the standard diagnostic test. They’ll tell you it fails often, and scientific studies back them up. Yet, the standard test has been the only one endorsed by the U.S. Centers for Disease Control and Prevention for more than two decades—while countless infections have advanced to intractable chronic illnesses.

Check the medical literature on Lyme disease outcomes. You will find that 10 to 20 percent of patients treated early—the lucky ones who respond best—nevertheless remain ill 12 months afterward. That means tens of thousands a year suffer from what is officially (and vaguely) called “post-treatment Lyme disease syndrome.”

In the 21st century, in vast expanses of the United States, Canada, Europe and Asia, uncounted billions of infected ticks riddle the landscape. A changing climate and an unbalanced environment have ushered in a new era of tick-borne illness. 

To be sure, questions remain on the consequences of Lyme disease infection in utero. But the notorious pathogen has been found in the damaged bodies of fetuses and babies who could not have been bitten by a tick. Pediatricians and obstetricians should know this. Research should be funded on the long-term consequences.

The chances that a pregnant woman will contract Lyme disease are far greater than those of falling from a gondola or eaten poisoned brains—and equally consequential.