A two-armed trial was conducted in July 2000 in 4 villages near Muheza, Tanga Region, in Tanzania, asymptomatic children with P.falciparum parasitaemia > 200/ul (Mutabingwa et al. 2001 Trans Roy Soc Trop Med Hyg 95: 433-438). In one of the arms 188 children were treated with sulfadoxine-pyrimethamine and only 14.3% showed parasite clearance at day 7 (16.1% at day 14). The SP batch used was checked for good quality and the low clearance rate is indicative of one of the worst levels of SP resistance yet recorded in Africa. SP resistance in this area has increased from about 20% in 1995 (Trigg et all 1997 Acta Trop 63: 1865-189) to 45% in 1998/9 (Mutabingwa et al 2001 Lancet 358: 1218-1233) and is now 86
