RESUMEN
The sensitivity of Zaria strains of Plasmodium falciparum to chloroquine, mefloquine, quinine and sulphadoxine/pyrimethamine was investigated 5 years after the appearance of in vivo/in vitro chloroquine resistance in urban Zaria. Infections in 36/43 children (83.7%) treated with chloroquine were sensitive while those in 7 (16.3%) were resistant. 8/13 isolates cultured (61.5%) were sensitive in vitro to chloroquine and 5 (38.5%) were resistant. Of the cultured isolates, 13/13 (100%), 12/13 (92.3%) and 5/7 (71.4%) showed mefloquine, quinine and sulphadoxine/pyrimethamine sensitivity, respectively. The results confirmed chloroquine and sulphadoxine/pyrimethamine resistance in urban Zaria and revealed emerging quinine resistance. Resistance to chloroquine and sulphadoxine/pyrimethamine is at RI level and chloroquine should continue to be the first-line drug for the treatment and prevention of P. falciparum infection in the Zaria area of northern Nigeria. We suggest that, while quinine serves as second-line drug, mefloquine should be reserved for infections resistant to chloroquine, quinine and sulphadoxine/pyrimethamine.