“Tuberculosis is one of the biggest infect killers in the world”

Tuberculosis (TB) is progressing insidiously, with unremarkable symptoms – one of the reasons for Günter Weiss, director of the University Clinic II. internal medicine, why less TB was diagnosed during a coronary pandemic, but the number of deaths increased. The interview also explains why all patients must be tested for latent TB before starting immunosuppressive therapy.

The World Health Organization (WHO) has set a goal to eliminate tuberculosis by 2030. What is the situation with TB in the world?

Günter Weiss: Tuberculosis is still one of the biggest killers of infections in the world. Ten million people get sick every year. About half of those affected worldwide do not have access to treatment. 1.6 to 1.7 million people die from it every year. In 2020, the WHO recorded fewer new diagnoses1, but more deaths2. The COVID-19 pandemic has pushed the fight against TB a few years back. The symptoms of TB are non-specific and patients have not been thoroughly studied and therefore have not been treated. The medicine was focused only on Corona. The WHO expects the numbers to be even more drastic in the coming years.

In 1995, 1,476 cases of tuberculosis were recorded in Austria (Tyrol: 76) and 135 patients died. In 2021, there were still 399 patients (Tyrol: 27) and 20 dead in the whole country. How has this country managed to control tuberculosis?

Weiss: Tuberculosis used to be a disease of “poor people” who lived in precarious hygiene and housing conditions and were malnourished. Tuberculosis used to be called consumption – a disease that consumes the body’s energy reserves. Until the 1960s, there was no specific therapy, patients were sent for air therapy, such as Hochzirl, placed in the sun, and sometimes developed pneumothorax to lung collapse. It was hoped it would cure the infection. Thanks to improved hygiene and living conditions and the availability of therapies, TB is in decline in Austria. But this does not apply to the rest of the world.

Could TB cases increase again due to migration and flight?

Weiss: Some of these people come from countries where tuberculosis is widespread and come into contact with tuberculosis bacteria in childhood or during flight. As a result, however, a significant increase in the number of diseases cannot be expected. Healthy people as such have an extremely low risk of contracting tuberculosis after contact with sick people. There is practically no infection outside. Most infections occur in the same household. A large proportion of patients diagnosed in Austria come from endemic areas. It is transmitted when patients with open pulmonary tuberculosis cough up tuberculosis bacteria. Because tuberculosis bacteria multiply very slowly, it often takes at least six months after infection for the disease to break out. Only about one to two percent of those infected develop active / open tuberculosis. A good immune system eliminates bacteria on the spot. This is the case for 50 to 70 percent of people who come in contact with TB.

What do you need to know about open (active) and latent tuberculosis?

Weiss: In the remaining 30 to 50 percent of people who have come in contact with Mycobacterium tuberculosis, the immune system is unable to kill the bacteria immediately. The immune system is activated and a so-called primary complex is formed. This means: All kinds of immune cells accumulate around the pathogens in the lungs and accompanying lymph nodes, which keep the bacteria in check and prevent them from multiplying, but sometimes they cannot kill them. The people will not notice anything. This situation, known as latent tuberculosis, affects about a quarter of the world’s population. Latent TB can be diagnosed by an immunoassay.

With increasing age, a weakened immune system or immunosuppressive therapy, latent tuberculosis may reactivate and become active tuberculosis. This affects about five percent of people with latent TB during their lifetime. Active and reactivated TB are primarily pulmonary TB. However, in the case of a particularly poor immune status, the bacteria can spread to other organs, such as the lymph nodes or the brain. If left untreated and adequately treated, lung or organ failure occurs, TB can invade the central nervous system, leading to TB sepsis and thus death.

How does a TB outbreak manifest itself and how is the diagnosis made?

Weiss: The symptoms of active tuberculosis are initially very non-specific with night sweats, decreased performance, weight loss, chronic cough and fever, and the disease progresses insidiously. Diagnosis is made in addition to anamnesis by blood tests and radiological procedures (X-ray or computed tomography). Patients who must undergo specific immunosuppressive therapy, for example due to an autoimmune disease, are tested in advance for the possible presence of latent tuberculosis and, if positive, are treated prophylactically to prevent TB reactivation.

Who is in the risk group?

Weiss: Young children are most at risk. Weakened, malnourished people are as at risk as patients with untreated HIV infection or impaired immune function due to other diseases or therapies. TB reactivation occurs in untreated HIV patients because HI viruses turn off immune cells (called T-helper cells), which play a central role in suppressing tuberculosis bacteria in latent TB. This rarely happens here, because people with a well-cured HIV infection – and therefore an extremely low viral load – are not at increased risk.

How does the therapy work?

Weiss: Mycobacterium tuberculosis multiplies very slowly. Therefore, it is necessary to take several antibiotics simultaneously for at least six months to prevent the development of resistance. Multidrug-resistant tuberculosis, which fortunately is not yet widespread in Austria, has been treated for much longer, two to three years. The problem is that, firstly, adherence to therapy decreases, the longer the medication needs to be taken, and secondly, there can be serious side effects on the liver, blood count and nerves. We also face the challenge that there are fewer therapeutic agents for multidrug-resistant TB that are often less effective. However, with adequate therapy, there is a very good chance that the disease will be completely cured and will not return.

What’s happening in TB research?

Weiss: Science is very active in TB. Immune metabolism is currently a very hot topic of infectology. Here (also here in Innsbruck) we deal with the questions of how bacteria can survive in immune scavenger cells, macrophages or how the metabolism of macrophages or bacteria can be influenced so that the bacteria are eliminated. A better understanding of these processes between immune cells and pathogens leads to the identification of pathogen weaknesses and the development of new drugs.

1 Decrease in new diagnoses from 7.1 million in 2019 to 5.8 million in 2020 (Source: WHO Report 2021)

2 The WHO estimates that the number of deaths will increase from ~ 1.2 million in 2019 to ~ 1.3 million in 2020 for the HIV-negative world population and to ~ 214,000 from ~ 209,000 for HIV-positive people. (Source: WHO Report 2021)

To the person:

Günter Weiss, Director of the University Department of Internal Medicine II, is a recognized expert in the field of internal medicine, infectology and immunology and has already contributed numerous, internationally recognized contributions to the immunological processes of defense against infection. In February 2020, he treated the first two patients with Covid-19 in Austria.

Medizinische Universität Innsbruck 
Public Relations und Medien
Theresa Mair
Innrain 52, 6020 Innsbruck, Austria 
Telefon: +43 512 9003 71833 
public-relations@i-med.ac.at, www.i-med.ac.at

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