B11. CD4 cell counts and immune responses in HIV negative and HIV positive spouses of TB patients
FBD Mwaungulu, et al
Objectives:This study aims to monitor the clinical history and the immune response in individuals with recent intensive exposure to M. tuberculosis (spouses of smear positive TB patients), and to evaluate the operational feasibility and efficacy of an intervention (isoniazid prophylaxis) targeted to HIV positive spouses of smear positive cases. Changes in CD4 cell counts, immune response and clinical status are monitored.
Methods: The study is divided into two “arms”, relating first to the recruitment and follow up of prospectively ascertained spouses (allowing follow-up from near the time of exposure) and second to the recruitment and follow-up of retrospectively ascertained spouses (allowing follow-up long after exposure and comparison of outcome without the intervention). All spouses of sputum smear positive TB patients who were living with the patient from start of cough to admission in hospital are interviewed and counselled for recruitment into the study. Blood for immunological assays, HIV tests and CD4 counts is collected from all consenting spouses at recruitment, 6 months and then yearly for three years.
Results: Only baseline HIV and CD4 cell counts are presented here. It is hoped that follow-up CD4 data set will be ready by the time of presentations. Overall, 47% of spouses of TB patients were HIV positive. Among HIV negative spouses, the mean CD4 cell count was 1059 cells/mm3 and the mean CD4% was 44%. Among HIV positive spouses the mean CD4 cell count was 538 cells/mm3 while the mean CD4 % was 25%. 34% of HIV positive spouses had a CD4 cell count below 400 cells/mm3. The prevalence of any AIDS defining illness amongst HIV positive spouses was generally low (< 10%) even at CD4 cell counts of less than 400 cells/mm3.
Conclusions/recommendations: The US Centers for Disease Control and Prevention (CDC) classification based on CD4 counts are used to monitor the progress of HIV infection and make decisions on initiating treatment. In Malawi, due to lack of resources, the WHO clinical AIDS staging is used. It is believed that CD4 cell counts in both HIV negative and HIV positive individuals are lower in African individuals than in individuals from western countries. CD4 cell count data in HIV negative Malawians is unavailable. This study shows levels of CD4 cell counts in HIV negatives that are similar to the normal ranges in Western populations. From this study, using the CD4 cell count cut-off of <=400 cells/mm3, 34% of the HIV positive spouses would qualify for initiation of ARVs, however, only 10% of these have AIDS defining illness (used for staging) and would therefore qualify for ARVs. Larger longitudinal studies to establish the CD4 levels among Malawian populations are recommended.