Co-trimoxazole as prophylaxis against opportunistic infections in HIV-infected Zambian children (CHAP): a double-blind randomised placebo-controlled trial. - Chintu, C; Bhat, G; Walker, A; Mulenga, V; Sinyinza, F; Lishimpi, K; Farrelly, L; Kaganson, N; Zumla, A; Gillespie, S; Nunn, A; Gibb, D (Lancet (London, England), 2004)