OpiniãoChildren aged under 5 years who are household contacts of people with bacteriologically confirmed TB have a significantly higher risk of acquiring TB infection and progressing rapidly to TB disease. Children aged under 2 years are also at particularly high risk for severe and disseminated forms of TB with very high risk of morbidity and mortality. TPT is strongly recommended in all TB household contacts aged under 5 years once TB disease is ruled out. Other household contacts are also at increased risk of acquiring TB infection compared with the general population and should be considered for the programmatic management of TPT.
WHO recommends consideration of TPT for selected household contacts of people with MDR-TB, including children, people receiving immunosuppressive therapy and people living with HIV, because the evidence shows more benefits than harm (28). The decision to treat MDR-TB contacts should be taken on an individual basis, with respect to the selection of the person to treat and the TPT regimen. WHO does not currently recommend a specific preventive treatment regimen for contacts of MDR-TB due to limited evidence. Studies that informed this recommendation, however, used levofloxacin with or without ethambutol or ethionamide daily for 6 months. TPT should be considered only after TB disease has been ruled out by a clinical evaluation or according to national guidelines and after a careful risk assessment, including intensity of exposure, certainty of the source of disease, reliable information on the drug resistance pattern of the source case, and potential adverse drug reactions.
Confirmation of TB infection by TST or IGRA is desirable before the start of TPT. This maximizes the likelihood of TPT not being given unnecessarily to prevent MDR-TB. There is less evidence on the balance of benefits and harms for the medicines used to prevent MDR-TB than for drug-susceptible TB, and therefore the decision to provide TPT needs to carefully consider any potential risks. If a fluoroquinolone is used for prevention of MDR-TB, it is important to exclude TB disease to limit the risk of emergence of resistance to this class of medicines (e.g. levofloxacin is a key medicine in second-line treatment regimens; moxifloxacin is recommended for the treatment of drug-susceptible TB as a component of the 4-month regimen in adolescents and adults aged 12 years and over) if the person requires treatment for TB or MDR-TB disease in the future. Strict clinical observation for signs of TB disease for at least 2 years after exposure should be ensured, regardless of whether TPT for MDR-TB is given or not.
Implementation considerations on reaching household contacts are described in Chapter 2.