Health

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

Tuberculosis (TB) progresses insidiously, with unspectacular symptoms – one of the reasons why Günter Weiss, director of the University Clinic of Internal Medicine II, explained that less TB was diagnosed during the corona pandemic, but the number of deaths is increased. In the interview, he also explains why all patients must be examined for the presence of latent tuberculosis before starting immunosuppressive therapy.

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

Günter Weiss: Tuberculosis is still one of the biggest infection killers in the world. Ten million people get sick every year. About half of those affected worldwide do not have access to therapy. 1.6 to 1.7 million people die each year. In 2020, WHO recorded fewer new diagnoses1, but at the same time more deaths2. The COVID-19 pandemic has set the fight against tuberculosis back by years. Symptoms of tuberculosis are not specific and sufferers have not been thoroughly studied and therefore have not received treatment. Medicine was focused only on Corona. WHO assumes the numbers will 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 sick people nationwide (Tyrol: 27) and 20 deaths. How has this country managed to curb tuberculosis?

Weiss: Tuberculosis was a disease of the “poor” who lived in poor hygiene and housing conditions and were undernourished. Tuberculosis was called consumption, a disease that consumes the body’s energy reserves. Until the 1960s there was no specific therapy, the sick were sent to air therapy, for example in Hochzirl, were placed in the sun and sometimes a pneumothorax was created to collapse the lungs. It was hoped that this would cure the infection. Thanks to improved hygiene and living conditions and the availability of therapies, tuberculosis is on the decline in Austria. But this is not true for the rest of the world.

Could TB cases increase again due to migration and escape?

Weiss: Some of these people come from countries where TB is widespread and come into contact with TB bacteria in childhood or while flying. However, a significant increase in the number of diseases is not to be expected as a result. Healthy people per se have an extremely low risk of contracting tuberculosis after contact with sick people. There is virtually no risk of infection outdoors. Most infections occur in the common family. Most of the 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 develop. Only about one to two percent of infected people develop active / open tuberculosis. A good immune system kills bacteria on the spot. This is the case for 50-70% of people who come into contact with tuberculosis.

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

Weiss: In the remaining 30-50% of people who have come in contact with Mycobacterium tuberculosis, the immune system is unable to eliminate the bacteria immediately. The immune system is activated and a so-called primary complex is formed. This means: All types of immune cells build up around pathogens in the lungs and associated lymph nodes, which keep bacteria in check and prevent them from multiplying, but sometimes cannot kill them. Those affected notice nothing. This situation, known as latent tuberculosis, affects about a quarter of the world’s population. Latent tuberculosis can be diagnosed with an immunoassay.

With advancing age, a weakened immune system or through immunosuppressive therapy, latent TB can be reactivated and become active TB. This is true for about five percent of people with latent TB in their lifetime. Active and reactivated tuberculosis is mainly pulmonary tuberculosis. In the case of a particularly poor immune status, however, the bacteria can also spread to other organs, such as the lymph nodes or the brain. If not treated in time and properly, pulmonary or organ failure occurs, tuberculosis can attack the central nervous system, leading to tuberculosis sepsis and then death.

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

Weiss: Active TB symptoms are initially very nonspecific with night sweats, reduced performance, weight loss, chronic cough and fever, and the disease progresses insidiously. Diagnosis is made in addition to the medical history with blood tests and radiological procedures (radiography or computed tomography). Patients who have to undergo specific immunosuppressive therapy due to an autoimmune disease, for example, are previously tested for the presence of latent tuberculosis and, if positive, are treated prophylactically to prevent reactivation of tuberculosis.

Who is in the risk group?

Weiss: Young children are at the greatest risk of a severe course. Weakened and malnourished people are at as much risk as patients with untreated HIV infection or with impaired immune function due to other diseases or treatments. Reactivation of TB occurs in untreated HIV patients because HI viruses deactivate immune cells (so-called T-helper cells), which play a central role in the suppression of TB bacteria in latent TB. This rarely happens here because people with a well-treated HIV infection – and therefore an extremely low viral load – are not at greater risk.

How is the therapy going?

Weiss: Mycobacterium tuberculosis multiplies very slowly. Therefore, it is necessary to take multiple antibiotics at the same time for at least six months to prevent the development of resistance. Multidrug-resistant tuberculosis, fortunately not yet widespread in Austria, is treated for a much longer time, ie two to three years. The problem is that, first, adherence to therapy decreases with taking the drug, and secondly, the side effects on the liver, blood count, and nerves can be severe. We also face the challenge that there are fewer therapeutic agents for multidrug-resistant tuberculosis, which are often not as effective. With adequate therapy, however, the disease is very likely to recover completely and never recur.

What is happening in tuberculosis research?

Weiss: Science is very active in the field of tuberculosis. Immune metabolism is a very hot topic in infectiousology right now. Here (also here in Innsbruck) we deal with questions such as how bacteria can survive in immune scavenger cells, macrophages, or how the metabolism of macrophages or bacteria can be affected in such a way as to eliminate bacteria. Improved understanding of these processes between immune cells and pathogens leads to the identification of weaknesses in pathogens and the development of new drugs.

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

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

Per person:

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

Medienkontakt:
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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