Discrepancies in World Health Organisation guidelines for treating children with HIV/Aids have been identified by scientists at the University of Birmingham. Counts of a cell called CD4 T are used to monitor health in HIV patients, and in sub-Saharan Africa play a key role in determining who is eligible for treatment. WHO guidelines for assessing CD4 T levels are based on data from populations in the developed world. But in research published in the Journal of Allergy and Clinical Immunology, Birmingham scientist Calman MacLennan found that CD4 T counts in the blood of Malawian children under three years old were markedly lower than those in children in developed countries. "Doctors have to compare apples to apples in the assessment of HIV infection," he said.