No abstract

In Ghana, resistance of Plasmodium falciparum to chloroquine was observed for the first time in 1986. By the end of 1991 it had reached a high frequency and a substantial degree. A combined study in vivo and in vitro of the response of P. falciparum to chloroquine and sulfadoxine/pyrimethamine was carried out in Madina, Accra, in the coastal area of Ghana, late in 1991. 96 valid tests in vivo were performed with children and adolescents. There were 52 successful tests in vitro with chloroquine, and 52 with sulfadoxine/pyrimethamine. 45% of the chloroquine tests in vivo and 37% of the sulfadoxine/pyrimethamine tests in vivo indicated RII/RIII resistance. Results in vivo and in vitro were significantly correlated. The presence of RIII responses, 9% with chloroquine and 14% with sulfadoxine/pyrimethamine, indicates a need for third-line antimalarial drugs, the unregulated use of which may entail the risk of early and rapid occurrence of multi-resistance.

No abstract

The response in vitro of Plasmodium falciparum to chloroquine, mefloquine and quinine was studied in a hyperendemic peri-urban area of Accra, Ghana, during the fourth quarter of 1991, yielding a total of 159 valid tests. Schizont maturation in drug-free controls and effective chloroquine concentrations were strongly correlated. This was not seen with mefloquine or quinine. Higher mean parasitaemia in untreated oligo-symptomatic carriers of overtly chloroquine-resistant P. falciparum than in carriers of more sensitive parasites was another indication of higher viability and biological advantage of chloroquine-resistant P. falciparum that may conceivably have clinical implications.

No abstract