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Tuberculosis, like Covid, spreads with aerosols, scientists report

A team of South African researchers, a centuries-old medical doctrine, have discovered that breathing can contribute more to the spread of tuberculosis than the characteristic symptom of cough.

Researchers estimate that 90% of the tubercle bacilli released from infected individuals are carried in small droplets called aerosols, which are excreted when a person exhales deeply.Survey results on Tuesday Society Held online.

This report reflects an important finding in Covid’s pandemic. Coronaviruses also spread to aerosols carried in the air, especially in indoor spaces. Widely underestimated When a pandemic begins to occur.

Tuberculosis is caused by a bacterium called Mycobacterium tuberculosis, which usually attacks the lungs. This is the world’s most deadly infectious disease after Covid-19. More than 1.5 million lives Last year — This is the first increase in 10 years, according to a report released last week by the World Health Organization.

By 2020, 5.8 million people were diagnosed with tuberculosis because Covid’s pandemic blocked access to healthcare and supply chains around the world. But WHO It is estimated that about 10 million people have been infected. Many may unknowingly spread the disease to others.

“Our model actually suggests that aerosol and tuberculosis production can occur independently of symptoms,” said a graduate student at the University of Cape Town who published the results. One Ryan Dinkele said.

The findings help explain why dense indoor spaces, such as prisons, are often breeding grounds for tuberculosis, as is the case with Covid. The study also suggests that several methods used to limit coronavirus infection (masks, open windows and doors, stay outdoors as much as possible) are important in reducing tuberculosis. doing.

“People with tuberculosis see Covid and say,’Wow, it’s a speed-up version of tuberculosis,'” said Dr. Robert Horsburgh, an epidemiologist at Boston University who wasn’t involved in the study. ..

Researchers previously believed that most tuberculosis infections occur when an infected person coughs and sprays a droplet containing bacteria on another person. Some bacteria were thought to be released when a person breathes, but much less than coughing.

New discoveries do not change that understanding: a single cough can expel more bacteria than a single breath. However, if an infected person breathes 22,000 times a day and coughs up to 500 times, coughing accounts for only 7% of all bacteria released by the infected patient, Dinkele said.

When people sit in a confined space for hours in a crowded bus, school or work, “simply breathing produces more infectious aerosols than coughing,” Dinkele said. ..

In so-called tidal breathing, inhalation opens a small air sac in the lungs, and exhalation carries bacteria from the lungs through the aerosol. Due to their small size, aerosols released by tidal breathing can float in the air longer than droplets released by a cough and can travel far.

Like Covid, some people with tuberculosis spread the disease to many, release many bacteria, and others infect a small number of people around them. However, even if 90% of the bacteria excreted by infected individuals are carried by aerosols, this route of transmission does not necessarily account for 90% of new cases, says Sylvia, who is studying the disease at Brown University. Dr. S. Chen warned.

Still, experts say, the findings suggest that doctors should not wait for tuberculosis patients to arrive at the clinic with severe coughing, weight loss, and overt symptoms.

“We need to screen the entire population, just as we would if we were looking for many Covids,” said Dr. Horsburgh.

Much of this discovery comes from technology developed by Dr. Robin Wood, an emeritus professor at the University of Cape Town in South Africa. This device can collect aerosols from infected people and identify the bacteria in them.

Diagnosis and treatment of tuberculosis has changed little in recent decades. “It’s time to start using the latest state-of-the-art technology to tackle old illnesses,” said Dr. Wood. With some tweaks, he added, the system could also be used to study other diseases, including Covid.

Tuberculosis has been around for thousands of years, and its cause has been known for nearly 150 years.

“Still, we are still discovering new things about such a basic part of that biology,” Dinkele said. “It’s humble to realize that we need to be very careful when it comes to dogmatic approaches in the field.”

Tuberculosis, like Covid, spreads with aerosols, scientists report

Source link Tuberculosis, like Covid, spreads with aerosols, scientists report

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