14.2.2 Definition of types of TB cases
You are already aware that a ‘case of TB’ is an individual in whom tuberculosis has been confirmed by microscopic examination, or diagnosed by a clinician or medical doctor.
However, there are several different types of TB cases (in other words different case definitions) and these are based on the smear result, history of previous treatment and severity of disease. These different case definitions are listed in Table 14.1, from which you’ll also see that if a patient does not fall into any of the main types, they are registered as ‘other’.
Knowing these different case definitions will help in your recording and reporting of cases, as well as giving you important information about the infectiousness of the patient, the risk of drug resistance, and where there is a need for follow-up of patients.
Table 14.1 Case definitions of TB patients
|Type of patient||Case definition|
|New||A patient who has never had treatment for TB, or has been on anti-TB treatment for less than four weeks.|
|Relapse||A patient who has been declared cured or treatment completed for any form of TB in the past, but who reports back to the health service and is found to be sputum smear-positive or culture positive.|
|Treatment after previous treatment failure||A patient who, while on treatment remained sputum smear-positive or became sputum smear-positive at the end of the five months or more, after commencing treatment.|
|Treatment after default (did not complete previous treatment)||A patient who had previously been recorded as defaulted from treatment and returns to the health service with smear-positive sputum.|
|Transfer in||A patient who is transferred from another district to continue treatment.|
|Other||A patient who does not fit into any of the above categories.|
|Chronic case||A patient who is still sputum smear-positive at the completion of a re-treatment regimen.|