Assessment and evaluation of contact as a risk factor for tuberculosis in rural Africa.

SETTING: A rural district in Malawi. OBJECTIVE: To determine the effect of inaccurate recall on estimates of the proportion of tuberculosis (TB) cases attributable to contact with identifiable prior cases. DESIGN: Case-control study of laboratory-confirmed TB cases and community controls, comparing family, household and area contacts identified from a database of TB cases with those named at interview. Estimation of prior contact as a risk factor for TB and identified factors associated with being a named contact. RESULTS: Ninety-five per cent of named contacts were known TB cases. The proportion of total identified contacts who were named at interview was 75%, and was similar for cases and controls. Cases were twice as likely as controls to identify prior contacts. Adding database information did not affect odds ratios, but increased the proportion of TB cases attributable to prior contact. Smear-positive, male and human immunodeficiency virus (HIV) negative TB patients were more likely to be named by subsequent cases. Identifiable recent contact with known smear-positive cases accounted for 12.5% of the TB burden. CONCLUSIONS: Reporting of putative source contacts showed little evidence of recall bias and gave estimates of the relative risk of TB associated with identifiable contact. The lower likelihood of HIV-positive cases being named as contacts may reflect reduced infectiousness

Using tuberculosis suspects to identify patients eligible for antiretroviral treatment.

SETTING: A district in rural sub-Saharan Africa with a recently introduced antiretroviral (ARV) programme. The population has high human immunodeficiency virus (HIV) prevalence and high tuberculosis (TB) incidence. OBJECTIVE: To determine the prevalence of HIV and acquired immune-deficiency syndrome (AIDS) related symptoms in people presenting with chronic cough who are not diagnosed with TB. DESIGN: A cross-sectional survey of TB suspects. METHODS: Patients with chronic cough were recruited from out-patient facilities. After standard diagnostic procedures and providing informed consent, they received counselling and testing for HIV, and were interviewed and examined with respect to staging criteria for HIV/AIDS. Suspects were followed up for 3 months after the end of the recruitment period to allow for delayed diagnosis of TB. RESULTS: Of 145 suspects, 79% had not been diagnosed with TB by the end of the follow-up period. Of these, 108 (95%) agreed to HIV testing and 61 (56%) were HIV-positive. More than half of these were eligible for ARV treatment (Stage III or IV disease) under national programme criteria. CONCLUSION: Established chronic cough clinics are a useful setting for recruitment of patients to ARV clinics. Attendees should be offered HIV testing and simple clinical screening to identify those who should be referred for ARV treatment