[1] NIAID, NIH, BETHESDA, MD 20892 USA
[2] WORLD BANK, WASHINGTON, DC 20433 USA
[3] WELLCOME TRUST RES LABS, LONDON, ENGLAND
[4] WHO, TDR, GENEVA, SWITZERLAND
[5] NETHERLANDS ORG SCI RES, THE HAGUE, NETHERLANDS
[6] MRC, LONDON W1N 4AL, ENGLAND
[7] MRC, BRAZZAVILLE, REP CONGO
[8] INST PASTEUR, PARIS, FRANCE