In vitro sensitivity of Plasmodium falciparum to sulfadoxine and pyrimethamine.

An in vitro microtechnique of Rieckmann et al., (1978) modified by Yisunsri and Rieckmann (1980) using 3 media; Waymouth, Waymouth plus 10% human serum, and RPMI was assessed to determine the sensitivity of P. falciparum to sulfadoxine, pyrimethamine and its combination. The study confirmed the synergism between sulfadoxine and pyrimethamine. There was no interaction between media and drug tested. MIC1 and MIC2 of sulfadoxine in different media showed significant difference (p less than 0.001). No significant difference was observed in MIC1 and MIC2 of pyrimethamine in the three media used (p greater than 0.05). For sulfadoxine-pyrimethamine combination, MIC1 and MIC2 in Waymouth alone and plus 10% human serum showed no significance (p greater than 0.05) while in RPMI showed positive correlation (p less than 0.001). MIC1 might be more applicable for clinical evaluation than MIC2. At present Waymouth medium with 5% patient serum, is considered to be the most suitable for testing sensitivity of malarial parasites.

Studies of Coquillettidia (coquillettidia) crassipes (Vanderwulp, 1881) in relation to transmission of Cardiofilaria nilesi.

Field surveillance of Cq. crassipes was conducted in an open housing estate near Kuala Lumpur using IMR traps baited with chicken and gerbils. Chicken bait attracted more Cq. crassipes. There was significant difference between chicken and gerbil as bait. The mosquitoes preferred to feed at canopy level. The parous rate was 20.41% and the infection rate for Cardiofilaria nilesi was 2.04%. None of the 120 chicken and 5 ducks, in a village close to the open housing estate, examined for microfilariae were positive. Ar. durhami and Ar. subalbatus did not support development of C. nilesi. However, Cq. crassipes is an extremely efficient vector of C. nilesi.