CD4 and immunodeficiency disease: Given that a clinical assessment of health status may be subjective, we next used a CD4 count <350 cells/μl as indicative of CD4+ T cell depletion and progression to immunodeficiency (by analogy to WHO recommendations for the initiation of antiretroviral therapy for HIV infection [http://www.who.int/hiv/pub/guidelines/arv2013/en/]), for data see Additional file 2: Table S2.