ReacciónContact screening should always be done when a person with TB has any of the following characteristics: bacteriologically confirmed pulmonary TB, proven or presumed multidrug-resistant TB or extensively drug-resistant TB, is a person living with HIV or is a child younger than 5 years. Among contacts of patients with bacteriologically confirmed TB, the weighted pooled prevalence of TB was 3.4% (95% CI: 2.9–3.8). Among contacts of patients with multidrug-resistant or extensively drug-resistant TB the weighted pooled prevalence of TB was 3.7% (95% CI: 2.4–5.3). The weighted pooled prevalence of TB among HIV-positive contacts was 11.6% (95% CI: 8.2–15.4), with a median NNS of 9 (95% CI: 5–13). The weighted pooled prevalence among contacts younger than 5 years was 3.9% (95% CI: 2.5–5.4), with a median NNS of 30 (95% CI: 12–62), while the prevalence among contacts aged 5–14 years was 2.4% (95% CI: 1.6–3.4), with a median NNS of 36 (95% CI: 17–61). Contact investigation may also be performed for TB patients with all other forms of disease.
The definition of a household or close contact can vary greatly across settings, and in some contexts there is no clear distinction between households; therefore, decisions about screening household and close contacts should be based on local definitions and policies, prioritizing contacts for screening based on an assessment of their level of exposure.