Entomological investigations on malaria and bancroftian filariasis transmission were carried out in the endemic area of Baram District, Sarawak. The Anopheles composition, survival and infection rates of malaria and filariasis were compared in the village and 0.5 km from the village ecotype, in forested areas. Anopheles leucosphyrus, An. barbirostris and An. donaldi are the vectors for malaria and bancroftian filariasis in both ecotypes. Biting and infection rates vary, but An. leucosphyrus differed with a peak around midnight in the forested area and soon after dusk in the village setting. The parous rate of An. leucosphyrus was significantly higher in the forest ecotype (P < 0.0001); however, the proportion of 3-parous and older was not overall higher in the forest ecotype (P = 0.68). The entomological inoculation of malaria parasites by An. leucosphyrus was comparatively higher in the forested areas (P > 0.5). The implications of malaria and filariasis transmission in the forested areas in Baram District are discussed.
A simple water iodizing system, which incorporates the Venturi principle in combination with the controlled release mechanism of a silicone-sodium iodide elastomer, for the iodization of rural piped-water supply in the control of endemic iodine deficiency has been developed and its effectiveness evaluated in three Iban longhouse villages in the iodine-deficient district of Lubok Antu, Sarawak. Urines were collected for iodine assays from women aged 15-40 years before and at 6 and 12 months after the connection of the iodinating device; goiter assessment was performed on the women at the start and end of the 1-year study. Water samples were collected for iodine assays at 2-weekly intervals. In all three villages, significant and sustained increases in median urinary iodine excretions, reaching levels recommended for an iodine-sufficient population, were observed; goitre prevalences were reduced in all the villages (by 22.6% to 35.8%). The iodine levels in the water ranged from 34 micrograms/l to 212 micrograms/L. In the control village, median urinary iodine excretions remained essentially unchanged but a small increase in goiter prevalence was observed. The iodized water was well received by the villagers and no adverse effects of water iodization were observed. The system functioned unattended throughout the one year period. The cost of providing supplemental iodine via the iodizing device is approximately 60 cents (U.S.) per family per year which is affordable by either the Government or the villagers. It is concluded that the iodizing system offers a new cost-effective strategy for the control of endemic iodine deficiency in Sarawak and may have applications in other areas with similar water sources.
In a survey of 974 villagers (408 males, 566 females; ages = 11-82 years) of the Ai (n = 496; 212 males, 284 females) and Lemanak (n = 478; 196 males, 282 females) rivers in the district of Lubuk Antu in Sarawak's Sri Aman Division during July 1993, goiter was found in 31.8% of the subjects. The goiter prevalence was higher in the more interior Ai river area than in the Lemanak river area (36.9% vs 26.5%). In females aged 15 years and above, the goiter prevalence was 75.4% and 49.1%, respectively, in the Ai and Lemanak river areas. The difference in goiter prevalence between the two areas was related to the degree of iodine deficiency in the two areas. The median urinary iodine excretion in the Ai river villagers was 22.1 micrograms/l compared to 72.9 micrograms/l in the Lemanak river villagers (p < 0.0001). Goitrous subjects tended to have lower urinary iodine concentration than non-goitrous subjects. In the males, smoking of tobacco was associated with a two-fold increase in goiter frequency. Despite on-going distribution of iodized salt by the medical and health services in the State, only 23% of the 135 salt samples obtained from the households in the areas contained detectable iodine.