Table 1 Trends in antimalarial drug resistance in Tanzania, 1950s–1990s
Period | Resistance pattern to chloroquine up to 1999 |
|---|---|
Early 1950s | A dose of 2.5 mg/kg is still efficacious (grace period) |
Mid-1970s | Owing to slow increase in resistance, the therapeutic dose was gradually increased to the maximum safe level of 25 mg/kg (alert period) |
Late 1980s | Resistance to the maximum dose began to reach levels of significant public health importance (alert period) |
Mid-1990s | WHO recommended drug policy action if resistance (total treatment failure) reaches 25% (change period) |
Late 1990s | Tanzania established sentinel sites in nine regions to monitor resistance by standard methods |