Vector mosquitoes of Wuchereria bancrofti at Bicol region in the Philippines. 1. Transmission capability.

Mosquitoes were surveyed for the capability of filaria transmission at Sitio Bacolod and Barrio Salvacion, in Bicol region, Luzon, Philippines. The results of indoor collections and experimental infections showed that the infective rates and the median density of infective larvae per infected mosquito were significantly higher in Aedes poicilius than in Culex quinquefasciatus. Aedes poicilius was found to be the principal vector of bancroftian filariasis in this region.

An epidemiological study of filariasis in Sorsogon province, Republic of the Philippines, with notes on experimental mosquito infection.

An epidemiological survey was conducted on Bancroftian filariasis in Sorsogon province, the Philippines, with special regard to low density microfilaremia (LDF). Filtration technique using nuclepore membrane examining 1 ml blood revealed 31% positive rate for microfilaria out of 262 volunteers. Out of 82 positives 21 (25.6%) had LDF (less than 10 in 1 ml blood). No conspicuous grouping of LDF was noted in younger age groups or sexes. In three out of 12 clinical filariasis, microfilaria was detected but none of them were LDF. Among 22 cases treated with diethylcarbamazine, nine subsequently had LDF suggesting necessity of improvement of drug administration regimen to avoid incomplete treatment. A series of feeding experiments using two mosquito species, Aedes poicilius and Culex quinquefasciatus, on volunteers showed that both species could act as vectors in the region. No larva was detected in either species fed on LDF carriers. It was concluded that there is little possibility that LDF plays an important role in the transmission of Bancroftian filariasis in the region.

Clinical trials of broad spectrum anthelmintics against soil-transmitted helminthiasis.

Clinical trials on the three broad spectrum anthelmintics against trichuriasis, ascariasis and hookworm infection were carried out in a rural community in Irosin, Sorsogon. Flubendazole (Fluvermal) appears to be a promising drug against trichuriasis particularly when periodic mass treatment of a community is carried out. Mebendazole (Antiox) also appears to be promising given as single dose during mass treatment of soil-transmitted helminthiasis. As shown in previous studies, oxantel-pyrantel (Quantrel) should be given at 15 mg/kg body weight at 12-hour intervals or 20 mg/kg body weight single dose rather than 10 mg/kg body weight in a single dose when treating trichuriasis.