[1] WHO, Dis Control Prevent & Eradicat Parasit Dis & Vect, CH-1211 Geneva 27, Switzerland
[2] World Bank, Human Dev Network, Washington, DC 20433 USA
[3] Univ London Imperial Coll Sci Technol & Med, Sch Med, Partnership Child Dev, Dept Infect Dis Epidemiol, London, England
[4] WHO, Communicable Dis, CDS, Geneva, Switzerland