Glossary

A second-line TB drug: This is an agent reserved for the treatment of drug-resistant TB. First-line TB drugs used to treat drug-susceptible TB – ethambutol, isoniazid and pyrazinamide – may also be used in MDR-TB regimens (streptomycin is now considered a second-line TB drug and used only as a substitute for amikacin when amikacin is not available or there is confirmed resistance to it).

 

Active case finding (ACF): It is defined programmatically as systematic screening for TB disease through outreach activities outside health facility settings. 

 

At-risk Group: Is any group of people in whom the prevalence or incidence of TB is significantly higher than in the general population. 

 

Bacteriologically confirmed TB: TB diagnosed in a biological specimen by smear microscopy, culture or a World Health Organization-endorsed (WHO) rapid molecular test and adopted by NTEP such as Xpert MTB /RIF®/Truenat®. 

 

Child: For the programmatic purpose in India, a child is a person up to and including 18 years of age. (This includes adolescents aged 10–18 years). 

 

Contact: Is any individual who was exposed to a person with active TB disease.

 

Contact investigation: It is a systematic process for identifying previously undiagnosed people with TB disease and TB infection among the contacts of an index TB patient or other comparable settings where transmission occurs. Contact investigation consists of identification, clinical evaluation and testing and provision of appropriate anti-TB treatment (for people with confirmed TB) or TB preventive treatment (for those without TB disease)]. 

 

Close contact: This is a person who is not in the household but shares an enclosed space, such as at a social gathering, workplace or facility, for extended periods during the day with the index TB patient during the three months before the commencement of the current TB treatment episode. This Group will be included for all interventions as applicable for household contacts in these guidelines. 

 

Drug susceptibility testing: DST refers to in-vitro testing using either of the phenotypic methods to determine susceptibility. 

 

Drug resistance testing: DRT refers to in-vitro testing using genotypic methods (molecular techniques) to determine resistance. 

 

Extensively drug-resistant TB (XDR-TB): TB caused by Mycobacterium tuberculosis strains that fulfil the definition of MDR/RR-TB and are also resistant to any fluoroquinolone (levofloxacin or moxifloxacin) and at least one additional Group A drug (presently to either Bedaquiline or linezolid [or both]).

 

Extent or severity of the disease: In patients older than 18 years, this is usually defined by the presence of cavities or bilateral disease on chest radiography or smear positivity. In children under 18 years, severe disease is usually defined by the presence of cavities or bilateral disease on chest radiography or extrapulmonary forms of disease other than lymphadenopathy (peripheral nodes or isolated mediastinal mass without compression). In children, the occurrence of advanced malnutrition (defined by syndrome or by metrics) or advanced immunosuppression or positive tuberculosis (TB) bacteriology (smear, NAAT, culture) may also be considered when determining disease severity. 

 

High TB transmission setting: This is a setting with a high frequency of individuals with undetected or undiagnosed TB disease, or where infectious TB patients are present, and there is an increased risk of TB transmission. (TB patients are most infectious when they are untreated or inadequately treated. The transmission will be increased by aerosol-generating procedures and by the presence of susceptible individuals. These settings with healthcare workers, prisoners, miners, slum dwellers, tribal, migrant labourers etc., could be mapped out as part of the vulnerability mapping exercise done for and prioritized by states for specific TPT interventions guided by differential TB epidemiology in the respective state). 

 

Index patient of TB: This is the initially identified person of any age with new or recurrent TB in a specific household or other comparable settings in which others may have been exposed. (An index TB patient is a person on whom a contact investigation is centred but is not necessarily the source). 

 

Infant is a child under one year (12 months) of age.

 

Isoniazid-resistant TB (Hr-TB): A TB patient whose biological specimen is resistant to isoniazid and susceptibility to rifampicin has been confirmed. 

 

Mono-resistant TB (MR TB): A TB patient whose biological specimen is resistant to one first-line anti-TB drug only. 

 

Multidrug-resistant TB (MDR-TB): A TB patient whose biological specimen is resistant to both H and R with or without resistance to other first-line anti-TB drugs. MDR-TB patients may have additional resistance to any/all FQ or any other anti-TB drug. 

 

Presumptive TB: This refers to a person with any of the symptoms or signs suggestive of TB. (Diagnosis of TB is difficult in certain key groups of the presumptive TB patients like extra- pulmonary, PLHIV, children, smear negative /NA with x-ray suggestive of TB, other vulnerable groups as defined in TOG-2016 and DR-TB contacts, hence, NAAT is offered upfront for diagnosis of TB among these presumptive TB patients).

 

Presumptive DR-TB: It refers to the patient eligible for rifampicin-resistant screening at the time of diagnosis OR/and during the course of treatment for DS-TB or H mono/poly DR-TB. [This includes all notified TB patients (Public and private), follow-up positive on microscopy including treatment failures on standard first-line treatment and H mono/poly DR-TB regimen and any clinical non-responder including paediatric].

 

Pre-extensively drug-resistant TB (Pre-XDR-TB): TB caused by Mycobacterium tuberculosis strains that fulfil the definition of MDR/RR-TB and are also resistant to any fluoroquinolone.

 

Poly-drug resistant TB (PDR-TB): A TB patient whose biological specimen is resistant to more than one first-line anti-TB drug, other than both H and R. 

 

Programmatic management of TB preventive treatment: PMTPT includes all coordinated activities by public and private health caregivers and the community to scale up TB preventive treatment to people who need it. 

 

Rifampicin resistant TB (RR-TB): A TB patient whose biological specimen is resistant to R was detected using phenotypic or genotypic methods, with or without resistance to other anti-TB drugs. It includes any resistance to R in the form of mono-resistance, poly-resistance, MDR or XDR. 

 

Serious adverse events: SAEs are those adverse events (AEs) classified as Grade 3 (severe), Grade 4 (life-threatening or disabling) or Grade 5 (death related to AE), or which led to the drug being stopped permanently. SAEs are otherwise often defined as AEs that lead to death or a life-threatening experience, initial or prolonged hospitalization, persistent or significant disability, or congenital anomaly. The management of SAEs may require termination of the drug suspected of having caused the event. 

 

Systematic screening for TB disease is a systematic identification of people with presumed TB disease in a predetermined target population, using tests, examinations, or other procedures that can be applied rapidly. (Among those screened positive, the diagnosis needs to be established by one or several diagnostic tests and additional clinical assessments, which together have high accuracy).

 

Tuberculosis (TB) is a disease that occurs in someone infected with M. tuberculosis. (It is characterized by signs or symptoms of TB disease, or both, and is distinct from TB infection, which occurs without signs or symptoms of TB. In this document, it is commonly referred to as “active” TB or TB “disease” to distinguish it from TB infection).

 

Tuberculosis infection (TBI) is a state of persistent immune response to stimulation by M. tuberculosis antigens with no evidence of clinically manifest TB disease. (There is no gold standard test for direct identification of M. tuberculosis infection in humans. Most infected people have no signs or symptoms of TB but are at risk for developing TB disease. TB infection is also known as “latent TB infection” (LTBI), although this term is being discarded given that infection cannot always be considered latent).

 

Tuberculosis preventive treatment (TPT) is offered to individuals who are at risk of developing TB disease to reduce that risk. (Also referred to as the treatment of TB infection).

 

Universal DST refers to universal access to rapid DST for at least Rifampicin (and where possible INH). It also includes DST for fluoroquinolones among all TB patients with Rifampicin resistance (preferably before initiation of treatment or as soon as possible).

 

Underweight: In adults and adolescents, underweight usually refers to a body mass index <18.5 kg/m2 and in children < 10 years to a weight-for-age < –2 z-scores.