Evaluation of shading of fish farming ponds as a larval control measure against Anopheles sundaicus Rodenwaldt (Diptera:Culicidae).

Larval density of Anopheles sundaicus in shaded and unshaded fish farming ponds was monitored at a coastal village in North Sumatra, Indonesia. The average density in the experimentally shaded ponds with Nipa leaves was reduced to < 1/10. Disappearance of algae and decline of water temperature also were observed, but the salinity did not change. The larval density was lower in ponds with Tilapia sp than without fish, but that in ponds with Ophiocephalus sp was not significantly lower. Dominant insects collected by dipping were Agrionidae and Libellulidae (Odonata), Corixidae, Notonectidae and Nepidae (Hemiptera), and Dytiscidae (Coleoptera). Density of nymphs of both Odonata and Notonectidae was higher in unshaded ponds. Taking into account longevity of the materials, and easiness in construction and applicability, shading by Nipa leaves was an easy and effective larval control measure against A. sundaicus in non-operating small fish farming ponds if leaves were renewed once in every two months.

Gametocytocidal effect of primaquine in a chemotherapeutic malaria control trial in North Sumatra, Indonesia.

The effect of primaquine as a gametocytocidal drug was investigated in 218 P. falciparum (Pf) malaria cases detected during passive case detection (PCD) from August to December 1985 in two coastal villages of North Sumatra, where chloroquine-resistant and Fansidar-sensitive Pf was prevalent. Sulfonamide + pyrimethamine (SP) in combination with primaquine (Pr) was administered in Kuala Tanjung village and SP alone in Nana Siam village. Parasitologically confirmed Pf cases were followed up to observe the fluctuation of gametocytemia after the treatment. In 87 cases treated with SP alone, no significant change was observed in gametocyte positivity rate (GPR) and density on day 2 and day 7. In 131 cases treated with SP and Pr, no significant change was found on day 2 but significant reduction was observed in GPR and density on day 7. The gametocyte positive cases on day 7 were followed up weekly until gametocytes disappeared. SP alone did not reduce GPR from day 0 to week 2, then afterward GPR began to decline but was still 11.5% at week 5. On the other hand, SP with Pr reduced GPR from 77% on day 0 to 30% on day 7, after which GPR declined further to 7% at week 3. Reduction of parasite rate was observed in Kuala Tanjung after the PCD activities, reflecting a reduction in Pf prevalence rate from 18.6% in August 1985 to 2.9% in January 1986. These data indicate that a single dose of Pr 45 mg with SP was partially effective in reducing gametocytes and reducing malaria prevalence rate when administered through PCD activities.

Chemotherapeutic malaria control operation by single dose of Fansidar plus primaquine in North Sumatra, Indonesia.

Selective age group treatment and village scale chemotherapeutic malaria control operation were carried out in east-coast villages in North Sumatra, Indonesia in 1987/1988. A single dose of Fansidar plus primaquine was adopted as the drug regimen to cut the transmission of malaria at the gametocyte stage. After the treatment on day seven, the gametocyte positive rate was reduced to only 2.7% in 72 Plasmodium falciparum gametocyte carriers. A significant reduction of P. falciparum prevalence in the community was observed after successive selective age group treatment in primary school, however P. vivax prevalence persisted. Village scale active case detection was carried out by one health center staff and two village health volunteers. After eight months P. falciparum prevalence was reduced from 14% to 1%. As the result of the chemotherapeutic control activities covering high-prevalence villages in the coastal area, malaria prevalence in 1988 became very low, as compared with the status in 1985/1986.

Malaria and glucose-6-phosphate dehydrogenase deficiency in North Sumatra, Indonesia.

A screening test for glucose-6-phosphate dehydrogenase (G6PD) deficiency was carried out in North Sumatra, Indonesia by using a simple agar plate method. The prevalence of G6PD deficiency in male was 6.0% (9/151) in Nias prefecture, 3.9% (12/307) in Asahan prefecture and 0.9% (1/110) in Medan city (average 3.9%). The prevalence of malaria was investigated at the same time in Nias and Asahan. It was 8.6% (13/151) and 10.4% (32/307) in males. The parasite rate of Plasmodium falciparum in normal and G6PD deficient groups was 4.1% and 9.5%, respectively. There was no statistical significance between them. The usefulness of the system of detecting malaria and G6PD deficiency at the same time was discussed in relation to malaria control.