Lexie Shadix, Campus Carrier deputy news editor
According to the Centers for Disease Control and Prevention (CDC), tuberculosis (TB) was once the leading cause of death in the United States. However, thanks to investments in domestic TB control activities, the US now has one of the lowest TB rates in the world. TB is a chronic bacterial infection that can spread throughout the body but primarily affects the lungs.
“Tuberculosis can get into the tissues and move into different parts of the body,” Professor of Biology Bruce Conn said. “It can move into the brain area and cause meningitis, into the spinal cord, it can move into the kidneys and other organs. When it does that, it becomes very serious and much more deadly because then it starts affecting those organs.”
TB is caused by a bacterium called mycobacterium tuberculosis.
“It was actually one of the very first diseases ever linked to a particular bacterium, or a particular pathogen, so it carries the name of the disease,” Conn said.
Symptoms include coughing, fever, weight loss, night sweats and fatigue, among others. It is a slow-progressing disease, meaning it develops over a period of weeks or months. High-risk people include elders or those immunocompromised in some way.
“The risk depends a lot on what population it’s in and so forth,” Conn said. “One of the biggest things that can compromise your immune system is to be poorly nourished, so people in third world countries, for example, that don’t really have a good diet and live in [poor] conditions, are a lot more likely to have real severe outcomes, including death.”
It is a communicable disease, meaning that it can be spread from person to person by coughing or breathing.
“Large cities tend to be a high-risk area, because it is a communicable disease,” Conn said. “Cities are more densely packed with people, so they’re more hazardous for [TB].”
Over the last twenty years, TB has been in the spotlight for global health initiatives.
“It’s one of what we call the ‘Big Three,’” Conn said. “The ‘Big Three’ have been, for the last couple of decades, AIDS (acquired immunodeficiency syndrome), malaria and tuberculosis. These are considered to be the three highest priority problems, even for the last twenty years.”
Worldwide, it is the leading cause of death by infectious disease, David Dowdy, professor in the department of epidemiology at Johns Hopkins Blomberg school of public health said.
“It’s not necessarily as common as some other diseases like HIV (Human Immunodeficiency Virus) or malaria, but [if] you get it and it doesn’t get treated, it is a deadly disease,” Dowdy said. “We see more people dying of it.”
While it has been a priority on the global stage, in the US, tuberculosis is not incredibly common. However, outbreaks are becoming more common.
“The incidents of tuberculosis has been declining in the US for the past thirty years now,” Dowdy said. “We’ve only, in the last two years, seen an increase in TB incident by about ten to fifteen percent per year. This is the first time we’ve seen a year-on-year increase over the past three decades, so it is unusual for us to see that.”
In the past, the US has done well reducing the contraction of tuberculosis.
“There were two big things that came about in the early part of the 1900s that really changed medical science,” Conn said. “One was vaccines, the other was antibiotics. The bacterium that causes tuberculosis was very easily controlled by antibiotics. Now, what we have is antibiotic resistant strains that are causing a lot of the problems. They have adapted and developed a resistance to the antibiotics.”
Living organisms can change based on the stresses they encounter. Once the bacteria that are vulnerable to antibiotics die, the ones left are the ones that are resistant to them. Then, those reproduce and repopulate.
“We’re not dealing with bullets or bombs, we’re dealing with living organisms and all living organisms are designed to adapt to their environment and change based on the stresses they encounter,” Conn said.
Drug-resistant TB is, “caused by TB bacteria that are resistant to at least one of the most effective TB medicines used in treatment regimens,” according to the CDC. Multidrug resistant (MDR) TB is caused by a TB bacteria that is resistant to two or more of the main medications used to treat TB: isoniazid and rifampin. In 2023, the CDC reported that resistance to at least isoniazid at initial diagnosis comprised 589 (8.5%) of TB cases in the US. The majority of these cases were found among non-US born persons.
“An immigrant population could be bringing in a disease at a higher level than what we currently have,” Conn said. “There’s one of our emerging diseases in the US right now called Chagas disease. It was all in South America, a little Central America. It slowly crept up through Central America into Mexico, now the CDC estimates that we have at least 300,000 active cases in the United States.”
Diseases are bound to spread when people move throughout the world, and this is not a reason to disallow immigration. However, it is a reason to provide health services to immigrants, to not only keep them safe but to keep whatever country they may be immigrating to safe.
“I think, in general, if you are coming from an area with higher rates of TB, you are often indicated for testing to see if you have been infected with TB and, if so, to receive treatment to prevent the development of TB in the future,” Dowdy said.
When COVID-19 was prevalent, many scientists and citizens were concerned about asymptomatic spreaders of the virus. People who are asymptomatic have a virus but show no symptoms of infection. However, asymptomatic spreaders are not a large concern with TB.
“It is likely that most people who are spreading tuberculosis have symptoms,” Dowdy said. “But it is possible to have an asymptomatic form that is often called Latent Tuberculosis Infection. You’re not contagious and you don’t have any symptoms, but, in the future, if your immune system is reduced in any way, for example if you start taking drugs that would affect your immune system, then you’re at an increased risk of developing the more contagious and symptomatic forms of TB.”
In 2023, the CDC reported that number of reported TB cases and incidence rate increased for the third year since 2023, surpassing pre-COVID-19 pandemic levels. In 2023, there were 9,633 cases of TB disease in the US.
“TB is one of these diseases that is strongly reliant on our public health system, so when our public health system starts to deteriorate, one of the first things we will see are increased outbreaks of TB,” Dowdy said. “It’s one of these conditions that may not affect a large number of people, but when we see outbreaks it suggests that we need to be investing in our public health system to prevent those sorts of outbreaks from becoming larger and cropping up more largely in the future.”
Currently, public health systems such as the CDC, are working to address the situation by finding and treating active TB and latent TB.
Students who want to be involved can reach out to the Partners in Health (PIH) Engage chapter at Berry on Instagram at @berrypihengage. PIH collaborates with national governments to strengthen public health systems in areas including tuberculosis.