Every doctor wants to see a smile on a patient’s face, but there is one that no doctor ever wants to see: risus sardonicus, sometimes known as the sardonic grin or the devil’s smile, the cruel mark of a tetanus infection.
After decades of success against tetanus in the U.S., there are troubling signs that the deadly bacterial infection could make a comeback, a fallout from the drop in vaccination combined with a rise in climate change-related natural disasters that can increase the risk of exposure.
In 1948, when the tetanus vaccine was first combined with diphtheria and pertussis, 601 cases of tetanus were reported in the U.S. In recent years, that has dropped to about 15 to 28 annual cases.
In 2024, however, there were 32 cases. This year, there have been at least 37 confirmed cases, the most in over a decade.
An NBC News/Stanford University investigation has found widespread declines in kindergarten vaccination against tetanus. In states that provided data back to 2019, more than 75% of counties and jurisdictions across the U.S. have seen downward trends in young children getting the diphtheria-tetanus-pertussis (DTaP) series of shots. The vaccine is first given to babies at 2 months.
Because tetanus isn’t spread from person to person, there isn’t a herd immunity threshold, but reductions in vaccination rates leave more people vulnerable to the disease.
Doctors are worried about even a small uptick in the terrible infection, often called lockjaw. Symptoms, which can take three to 21 days to appear, include muscle spasms that make it difficult to breathe. As the infection takes hold, a patient’s jaw clenches, forcing the face into what appears to be a wide smile, and the back muscles contort into a painful arch.
“It looks terrible,” said Dr. Mobeen Rathore, chief of pediatric infectious diseases and immunology at the University of Florida College of Medicine-Jacksonville.
Tetanus bacteria live in soil and manure. An infection can occur from a puncture wound, and the disease can persist through weeks of medical care.
Treatment can be arduous and costly. A 6-year-old unvaccinated boy in Oregon racked up almost $1 million in medical bills after he contracted tetanus in 2019, according to a Centers for Disease Control and Prevention case report.
Rathore compared the cost of vaccines to the cost of intensive care.
“It’s not even pennies to dollars; it’s pennies to hundreds of thousands of dollars,” Rathore said. “It’s very expensive.”
When a 9-year-old unvaccinated patient came to Rathore with muscle spasm in Florida this year, he recognized the signs. He remembered the tetanus wards from his medical school days where patients were cared for in dark and silent isolation.
“The slightest noise would cause many of these patients to go into spasm,” Rathore said.
Tetanus spasms, which can also be triggered by light (known as “photophobia”), are extremely painful and can constrict the muscles around the airway.
Amid the bright lights, loud noises and incessant beeping of the hospital’s intensive care unit, the options were limited for minimizing stimulation for Rathore's young patient. The 9-year-old was sedated, intubated and given tetanus immune globulin antibodies and the vaccine to reduce future risk of disease.
The child was hospitalized for 37 days.
Dr. Matthew Davis, enterprise physician-in-chief and chief scientific officer at Nemours Children’s Health in Florida and Delaware, said that “it wasn’t until we had widespread vaccination that we saw a decline in cases of tetanus and thereby a reduction in the risk of mortality from it.”
John Johnson, a vaccination and epidemic response adviser at Doctors Without Borders, works in countries such as the Democratic Republic of the Congo (DRC) where tetanus remains a concern. Last year, there were 540 cases in the DRC, according to the World Health Organization.
“It’s one of those things that’s so stupidly easy to prevent,” Johnson said. “If you see one case of tetanus in the U.S., it’s a shame. There’s no reason we should be seeing this disease anymore.”
'My jaw was completely locked shut'
After the initial series in childhood, a booster dose is recommended every 10 years for adults, although many are unaware of the need.
Nikki Arellano, 42, hadn't had a tetanus shot since 2010 when she was injured while she was helping her friend set up for a wedding last month. An accident with a metal arch at the altar led to a minor cut on her leg. The following week, she found it difficult to chew during lunch at work because of pain in her jaw.
Two days later, she couldn’t open her mouth.
“My jaw was completely locked shut,” said Arellano, of Reno, Nevada. “I went to the ER, and they tried to give me a bunch of sedatives and pain medicine and muscle relaxers to get my jaw to open, and nothing was making it open.”
Arellano was diagnosed with tetanus and admitted to the hospital. She was connected to an intravenous pump so she could get antibiotics.
“Every time that it would run out, it was like a really, really loud beeping noise. When that started is when my muscle contractions would pop off,” she said.
Arellano said her spasms initially started in one arm, then progressed to both arms and then to full body spasms. “It would arch your back really bad, like, it was really, really painful muscle spasms.”
Arellano began to have difficulty swallowing, prompting worries that her airway might become compromised.
“It was very scary,” she said.
She was hospitalized for nearly a week and is still recovering.
Heightened risk with climate change
Natural disasters such as hurricanes, tornadoes and floods are known risk factors for tetanus outbreaks. As people rummage through the wreckage, they are also likelier to be injured by loose nails or broken shards of glass.
“As the Earth warms, there’s already a documented increase in the frequency, intensity and duration of many extreme weather and climate events,” said Kristie Ebi, an epidemiologist and professor of global health at the University of Washington who studies the health effects of climate change. “And as there are more flooding events, then fewer vaccinations for diseases like tetanus means that people would be at greater risk.”
Some states that are at highest risk of significant natural disasters, including Florida, Texas and Kansas, are recording notable declines in tetanus vaccination, according to NBC News data.
Florida, where Rathore practices, suffered the most damage from billion-dollar weather and climate events last year in the U.S., according to the National Centers for Environmental Information.
Meanwhile, NBC News data finds that kindergarten DTaP vaccination rates have declined in the state, from a peak of 94.1% in the 2016-17 school year to 88.8% in 2024-25. Broward County, for example, is one of the counties at the highest risk of hurricanes in the U.S., and it had an overall vaccination rate of 82.2% in the 2024-25 school year.
In Texas, which has experienced major severe weather and climate disasters in recent years, NBC News data shows that 85% of counties have recorded declines in kindergarten DTaP rates since 2019.
Several counties in central Texas have had steep declines in DTaP vaccination rates over the past decade.
Kansas is hit with an estimated 81 tornadoes a year, according to the National Weather Service. In Ford County, which experiences the most tornadoes in the state, 83.98% of kindergartners were vaccinated against tetanus in the 2024-25 school year.
Ford County has had the most tornadoes in Kansas. In the 2024-25 school year, 83.98% of its kindergartners were vaccinated against tetanus.
A recent case report from Kansas details the illness of a 16-year-old unvaccinated boy after a puncture wound in his foot became infected. Initially treated at home with burdock leaves and bread mold, his spasms worsened, and he began to have difficulty swallowing. He was hospitalized a week later.
For 40 days, he underwent intensive care with sedatives and muscle relaxants. He developed ventilator-associated pneumonia and bedsores. He also required physical and speech therapy to help recover.
He got a tetanus vaccination as part of his treatment, but his family declined other vaccinations when he left the hospital, the report said.
Rathore worries about a “post-vaccination era.”
“It is unfortunate that the children are going to suffer.”
