In December 2016, the state health department published a plan to eliminate tuberculosis in Colorado within a decade. Seven years later, the disease is making a comeback, though it’s not clear if that’s a temporary aftershock of the pandemic or a longer-term problem.

The Colorado Department of Public Health and Environment reported 84 people were diagnosed with tuberculosis so far this year, which is higher than the pre-pandemic average of about 70 cases per year. Two people have died, which is on the lower end of what Colorado typically sees.

The increase was first reported by 9News.

The state defines elimination as fewer than one case of active disease for every million residents, state epidemiologist Dr. Rachel Herlihy said. This year, the health department has recorded about 20 cases for every million residents – a significant gulf in the world of infectious diseases.

“We do still have that goal of elimination,” she said. “We certainly do have some challenges ahead of us.”

Tuberculosis is the world’s top infectious disease killer, causing about 4,300 deaths per day worldwide. Most of those deaths happen in developing countries, where the disease is more common and treatment is harder to come by.

No one is sure why cases are rising now or whether this is a temporary or longer-term problem, Herlihy said. Most tuberculosis cases are in people who’ve been infected with the bacteria for some time, so it’s unlikely this represents a rebound of delayed infections, she said. Some other respiratory diseases did increase as COVID-19 controls loosened, creating short but intense periods as they spread through populations that hadn’t seen them for months or years.

One possibility is that people didn’t come in for health care during the pandemic, or that their doctors weren’t thinking about tuberculosis and didn’t order the right testing, said Dr. Larissa Pisney, medical director for infection prevention and control for UCHealth’s metro area hospitals. The people who came to UCHealth with active tuberculosis infections this year were sicker than usual, and in some cases, the disease had infiltrated their bones or other organs, she said.

The most common symptoms of tuberculosis are a persistent cough, night sweats and a low fever. Some people lose weight or cough up blood. Many people who are exposed to the bacteria that cause tuberculosis don’t develop symptoms and can’t spread the disease, because their bodies respond and force it into a latent form.

If the bacteria later awaken, though, they could get sick and become contagious. Those who have HIV, other conditions that suppress the immune system, or diabetes are more likely to become sick if exposed, according to the Centers for Disease Control and Prevention.

Before the pandemic, active tuberculosis cases were falling steadily, said Dr. Masae Kawamura, former tuberculosis controller for the city of San Francisco. When COVID-19 hit, however, public health departments had to redeploy their staff who had the most experience with an airborne virus – typically those working with tuberculosis, she said.

The bacteria that cause tuberculosis can linger in the air after a person coughs, but most people don’t need to worry about catching the disease. Typically, it spreads to people who live or work with someone who has an active infection.

“For most people in Colorado, this is still not a concern,” Pisney said.

The risk of having a latent tuberculosis infection is higher for people who spent significant time in a region of the world where it’s more common, such as Eastern Europe, much of Asia, Africa and parts of South America. People who worked or lived in tight quarters, such as jails and homeless shelters, also are at increased risk.

Drug treatments are available, but patients who have symptoms have to take them consistently for at least six months. The course is often shorter for people with latent infections.

The United States does have some advantages in beating back tuberculosis again, Kawamura said: new blood tests make screening significantly more convenient than it was with the old skin test, and the drug regimen is shorter than it used to be. Unfortunately, in the countries with the highest rates of tuberculosis, people with symptoms often go untreated, allowing the bacteria to leap borders as visitors return home, she said.

“TB anywhere is TB everywhere,” she said.

Sign up for our weekly newsletter to get health news sent straight to your inbox.