 The impact of lymphatic filariasis LF on HIV is assessed by measuring HIV viral load before and after DEC treatment of filariasis in double-infected individuals. The impact of HIV on lymphatic filariasis is assessed by measuring the success of DEC treatment on W. bancrofti antigenaemia and microfilaraemia in double-infected individuals. The effect of DEC treatment in individuals with lymphatic filariasis andor HIV is assessed by measuring the pre- and post-treatment level of HIV viral load, immunological responses and micronutritional parameters, including antioxidants and markers of oxidative stress, in single- or double-infected individuals. The study is carried out as an anonymous, unlinked and double-blind placebo controlled study with cross-over design. The study groups comprise: 1 18 double-infected individuals HIVLF, 2 16 HIV infected individuals HIVLF- and 3 25 individuals with lymphatic filariasis HIV-LF. Based on stratified, blocked randomisation the study participants receive DEC treatment or placebo. Pre- and post-treatment 1 week, 12 weeks and 24 weeks post-treatment blood samples are collected and analysed for HIV viral load, CD4 T cell count, distinctive Th1 and Th2 cytokines, circulating filarial antigens CFA, micronutrient status, antioxidant enzymes and markers of oxidative stress. After 12 weeks the study participants get the opposite treatment and post-treatment blood samples aree collected four times with the same intervals as above. 