ABSTRACT
The in-vivo response of Plasmodium falciparum to a single dose of 25 mg pyrimethamine was evaluated in pregnant women in a semi-rural area of Zaria, northern Nigeria. Forty-four women were enrolled in the study and followed up for 14 days. Thirty-one (70%) of the women had cleared their parasitaemia by Day 7 and they remained parasite negative throughout the 14-day period of observation. The MPCT was 2.48 +/- 0.76 days. Thirteen (30%) of the 44 women were parasite positive either on Day 7 (7.16%) or Day 14 (6.14%) and re-treatment with a curative dose of chloroquine (25 mg kg-1 over 3 days) resulted in complete parasite clearance. Of the eight P. falciparum isolates successfully cultured from these women, seven (87.5%) were highly sensitive and one was resistant in vitro to the SDX/PYR combination.
Subject(s)
Malaria, Falciparum/drug therapy , Plasmodium falciparum/drug effects , Pregnancy Complications, Parasitic/drug therapy , Pyrimethamine/therapeutic use , Sulfadoxine/pharmacology , Adolescent , Adult , Animals , Drug Combinations , Drug Resistance , Female , Follow-Up Studies , Humans , Nigeria , Parity , Pregnancy , Pyrimethamine/pharmacologyABSTRACT
Thirty-five pregnant women with Plasmodium falciparum parasitaemia were treated with chloroquine 25 mg/kg body weight over 3 days. They were followed up in vivo by use of a modified 14-day WHO extended field test. In vitro sensitivity of the parasite isolates to chloroquine was assessed by using the WHO microtest method. All pregnant women were aparasitaemic by day 7 and there was no parasite reappearance throughout the 14-day observation period. The mean parasite clearance time (MPCT) was 3.2 +/- 1.4 days. Eleven parasite isolates obtained from the women were highly susceptible to chloroquine in vitro. The effective drug concentration that gave 99% parasite growth inhibition (EC 99) was 0.36 mumol/l.
Subject(s)
Chloroquine/pharmacology , Malaria, Falciparum/drug therapy , Malaria/drug therapy , Plasmodium falciparum/drug effects , Plasmodium malariae/drug effects , Pregnancy Complications, Parasitic/drug therapy , Animals , Drug Resistance , Female , Hospitals, General , Humans , In Vitro Techniques , Malaria/parasitology , Malaria, Falciparum/parasitology , Nigeria , Plasmodium falciparum/isolation & purification , Plasmodium malariae/isolation & purification , Pregnancy , Pregnancy Complications, Parasitic/parasitologyABSTRACT
Thirty-six P. falciparum isolates collected from children with malaria were tested for their susceptibility to chloroquine, mefloquine and quinine in vitro using the WHO microtest system. 37% of the isolates grew in the presence of 1.6 mumol chloroquine 1(-1) blood, indicating resistance. The sensitivity to both mefloquine and quinine was markedly reduced. The inhibitory endpoints for quinine correlated with those for chloroquine and mefloquine, but no such correlation was found between chloroquine and mefloquine.
Subject(s)
Chloroquine/pharmacology , Malaria/parasitology , Mefloquine/pharmacology , Plasmodium falciparum/drug effects , Quinine/pharmacology , Animals , Child , Child, Preschool , Drug Resistance , Humans , Infant , NigeriaABSTRACT
The World Health Organization (WHO) extended field test was employed to assess the in vivo sensitivity of Plasmodium falciparum to sulfadoxine-pyrimethamine combination in 44 children in Zaria urban area. 36 children (82%) were fully sensitive to the drug and 8 (18%) were resistant at the RI level. 8 parasite isolates were obtained from the children and successfully cultured in vitro using the WHO microtest (mark II) system. The 8 isolates underwent schizogony at concentrations of 10,000 pmol sulfadoxine/125 pmol pyrimethamine per well, indicating in vitro resistance.
Subject(s)
Antimalarials/therapeutic use , Malaria/drug therapy , Plasmodium falciparum/drug effects , Pyrimethamine/therapeutic use , Sulfadoxine/therapeutic use , Animals , Child , Child, Preschool , Drug Combinations , Drug Resistance , Humans , In Vitro Techniques , Infant , NigeriaABSTRACT
Fifty-nine children with Plasmodium falciparum malaria were subjected to the World Health Organization (WHO) extended field test to assess the in vivo sensitivity of the parasite to chloroquine in Zaria urban area, Nigeria. The parasites in 53 children (90%) were positive but those in 6 (10%) were resistant at the RI-RII level. 36 isolates from the patients were successfully cultured in vitro for the WHO standard microtest. 13 (37%) of the isolates underwent schizogony at chloroquine concentrations of 1.6 microM/litre and above. Probit analysis showed that the chloroquine concentrations producing 50% (EC50), 90% (EC90) and 99% (EC99) schizont inhibition were 0.4, 1.6 and 4.9 microM/litre, respectively. The results indicate a rapid decline in the sensitivity of P. falciparum to chloroquine in the study area during the past 3 years.
