COVID-19 has taken over the top position of the most common infectious diseases leading to death in recent years, but tuberculosis (TB) still ranks second worldwide. In Switzerland, cases of TB have become rare. But when and with whom do we still have to look for it today? At the SGAIM Autumn Congress, an expert provided insight.
The typical TB patient today is mostly young (16-40 years), predominantly male, and mostly immigrated to Switzerland from a high-endemic area (e.g. Syria, Afghanistan, South Africa). One should not underestimate how much the cultural background influences the view of a TB disease, explained PD Dr. Stefan Zimmerli, University Clinic for Infectious Diseases, Inselspital Bern. For very many of these people, tuberculosis is a stigma that is not talked about. The background is often the fear of assuming that another, chronic disease could be hiding behind the TB. Especially in Africa, it can be a sign that the patient also has an HIV infection – which is also not talked about. Knowledge of TB infection can affect whether the patient can find a spouse, enter certain professions, or even purchase life insurance for themselves or family members. All of this should be kept in mind when discussing treatment options and adherence with a migrated patient from a high-risk area or when trying to identify contacts.
About 70% of tuberculosis cases today affect the lungs, nevertheless it is a systemic disease that can manifest in other organs as well. In 2014, a Dutch study investigated the risk of contracting TB when there was contact with a patient with recognized overt pulmonary tuberculosis [1]. This showed that young children under 5 years of age develop TB very rapidly. This is less common in children between the ages of 5 and 15, but they are also more affected than older people. Both age groups usually develop tuberculosis 4-5 months after exposure. “However, if they haven’t had the disease after six months, they won’t get it again,” Dr. Zimmerli said. Older persons develop tuberculosis later, usually after 6 months to a year. However, the observation also applies here: those who have not yet contracted TB after 2 years will not contract the disease thereafter (Fig. 1).
Contact Tracking
Symptomatic contacts of a person with TB require immediate medical examination, including x-ray. With asymptomatic children younger than 12 years and immunocompromised individuals, an γ-interferon assay (interferon-γ release assay, IGRA) should be done immediately; asymptomatic individuals >12 years should be tested after no earlier than
2 months to be tested.
If a test for latent infection is positive, TB preventive therapy must follow – but this must be discussed and agreed with the patient prior to the test . Contacts with positive test results or with symptoms require further evaluation (symptomatology, clinical workup, chest x-ray) to rule out active disease before starting TB preventive treatment.
Tracking the contacts of an ill person can reveal a sometimes “shocking level of social isolation,” as the expert put it: many young, immigrant TB patients live very isolated lives, and the few contacts they have are from the same country of origin. Often, these individuals have a history of M. tuberculosis infection themselves. An IGRA test in such individuals may therefore identify prior infection and be positive. If a contact has a negative IGRA test, they should be retested after 2 months. If the result is then positive, it is a fresh infection that may warrant prophylaxis.
Treatment options for latent tuberculosis include:
- daily isoniazid for 9 months or
- daily rifampicin for 4 months or
- Isoniazid and rifampicin daily for 3 months.
Especially in symptom-free patients who feel healthy, nine months of isoniazid therapy leads to discontinuation in almost 60% of cases. In direct comparison to rifampicin over 4 months, isoniazid over 9 months was almost six times more likely to result in grade 3/4 hepatotoxicity [2].
Rifampetin as a possible “gamechanger
A 2019 study in a high-risk population showed that combination therapy of rifapentine (rather than rifampicin) plus isoniazid for 1 month can prevent TB equally well as prevention therapy with isoniazid mono for 9 months [3]. “This could become a gamechanger, because the significantly shorter duration of therapy alone would already speak in favor of the combo.”
WHO already recommends taking rifapentine/isoniazid either daily for one month (28 doses) or once a week for 3 months (12 doses) for prevention. The catch is that rifapentine is still not approved or available in Switzerland and Europe.
MDR Tuberculosis
A major and growing problem is multi-drug resistant tuberculosis (MDR-Tbc). Rifampicin resistance can be detected in the GenXpert (PCR) test. Dr. Zimmerli’s advice: “If you find rifampicin resistance, take it as a marker for possible multi-drug resistance.” From 2008 to 2014, 81.3% of all rifampicin-resistant cases in Switzerland turned out to be MDR-Tbc. In such a case, TB treatment should not be started, but further resistance testing should be awaited (exceptions are tuberculous meningitis, for which therapy must be started quickly, and possibly miliary TB).
Take-Home Messages
- TB has become very rare in Switzerland.
- Most patients presenting with TB are young and contracted the disease abroad.
- The disease manifestations may be unusual.
- A high degree of suspicion is needed in these young patients to arrive at a diagnosis.
- The indication for preventive therapy should be well considered. Prospects for success and burdens should be weighed with the patient.
- Standard therapy for TB is well tolerated and may be even shorter in the future.
Source: “Nevertheless Tuberculosis”, Prof. Dr. med. Andreas Zeller, SGAIM Autumn Congress, 23.09.2022
Literature
- Sloot R, Schim van der Loeff MF, Kouw PM, Borgdorff MW: Risk of Tuberculosis after Recent Exposure. A 10-Year Follow-up Study of Contacts in Amsterdam. Am J Respir Crit Care Med 2014; 190: 1044-1052; doi: 10.1164/rccm.201406-1159OC.
- Menzies D, Adjobimey M, Ruslami R, et al: Four Months of Rifampin or Nine Months of Isoniazid for Latent Tuberculosis in Adults. N Engl J Med 2018; 379: 440-453; doi: 10.1056/NEJMoa1714283.
- Swindells S, Ramchandani R, Gupta A, et al: One Month of Rifapentine plus Isoniazid to Prevent HIV-Related Tuberculosis. N Engl J Med 2019; 380: 1001-1011; doi: 10.1056/NEJMoa1806808.
HAUSARZT PRAXIS 2022; 17(10): 32-33
