1. Departmento of Clinical and Experimental Medicine, Section of Child and Adolescent Neuropsychiatry, University of Catania, Catania, Italy.
2. Department of Internal and Specialist Medicine, Section of Infectious Disease, University of Catania, Catania, Italy.
3. University College, London, England; University of Cape Town, Cape Town, South Africa; St George's Hospital & Medical School, London, England; University of Catania, Catania, Italy.