Daily Trimethoprim-sulfamethoxazole or Weekly Chloroquine Among Adults on ART in Malawi

The purpose of this study is to determine if there is a benefit to taking trimethoprim-sulfamethoxazole (TS) as prophylaxis among HIV positive adults who have viral load suppression and a good clinical response on anti-retroviral therapy (ART). If there is a benefit, then is it due to antimalarial or antibacterial properties. The investigators hypothesize that there will be a long-term benefit on survival and disease control in the context of prophylaxis and that the benefit will largely be attributed to prevention of malaria. The main study hypothesis is that 1)TS and chloroquine (CQ) will decrease the rates of morbidity and mortality among adults after 6 or more months of ART and 2) CQ prophylaxis will be associated with more prolonged viral suppression and higher CD4 cell counts than TS prophylaxis or no prophylaxis.