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Biomedical subjects

R Velayudhan

Publications and source records attributed to R Velayudhan.

4 recordsLinked to original sources

Environmental influences on helminthiasis and nutritional status among Pacific schoolchildren.

This paper describes a study undertaken to: (1) determine the prevalence of Ascaris lumbricoides, Trichuris trichiura and hookworm infections and nutritional status among Pacific Island school children; (2) identify factors influencing helminthiasis; (3) identify interventions to improve school health. A total of 3,683 children aged 5-12 years attending 27 primary schools in 13 Pacific Island countries were surveyed along with school environmental data. Stool samples were collected from 1996 children (54.2%) and analysed for ova and helminths. Total prevalence of helminthiasis was 32.8%. Anaemia prevalence was 12.4%. Children with helminthiasis and anaemia were found to be 8.7 times more likely to be stunted and 4.3 times more likely to be underweight than non-anaemic and non-infected children. Four significant environmental influences on helminthiasis were identified: (1) an inadequate water supply; (2); availability of a school canteen; (3) regular water/sanitation maintenance regimes; and (4) overcrowded classrooms. Helminthiasis was found to be strongly associated with anaemia, stunting and underweight and environmental influences identified. Although mass anti-helminthic drug administrations (MDA) have been taking place, reinfection is common as drug therapy alone is not enough. Programme effectiveness depends upon upgrading school environments to include an adequate water supply, controlled food preparation/provision, well-maintained water/sanitation facilities and class sizes of 30 students or less.

Ancylostoma↗

Tralomethrin (OMS-3048), a new synthetic pyrethroid against vector mosquitoes.

Tralomethrin (OMS-3048) a synthetic pyrethroid, was tested for its insecticidal properties in the laboratory against normal strains of Culex quinquefasciatus, Cx. tritaeniorhynchus, Cx. sitiens, Anopheles stephensi, An. culicifacies, Aedes aegypti and Armigeres subalbatus and against strains of Cx. quinquefasciatus resistant to fenthion and malathion. Tralomethrin showed good larvicidal activity against all the species tested. LC50 ranged between 7.00 x 10(-6) and 9.10 x 10(-3) mg (ai)/l. Resistant strains of Cx. quinquefasciatus showed higher tolerance than the normal strain. Tralomethrin was more effective against adults of An. culicifacies (LD50 0.18 micrograms/cm2) than the other species. Residual activity of this compound lasted for 15 weeks on thatch surface at a dosage of 50 mg (ai)/m2 against all the mosquito species tested. In the field, this compound was effective for a period of 1-2 days in polluted water viz., cesspits and drains and 10-24 days in less polluted water as in cement tanks, when applied at the rate of 0.002-2.0 mg (ai)/l against immatures of Cx. quinquefasciatus.

Aedes↗

Insecticidal activity of carbosulfan (OMS 3022) and pyraclofos (OMS 3040) against mosquitoes.

Carbosulfan (OMS 3022), a carbamate and pyraclofos (OMS 3040), an organophosphate were evaluated for their biological activity against vector mosquitoes, both in laboratory and field conditions. Carbosulfan (25% EC), was found to be active against adults and immatures of Culex quinquefasciatus, Anopheles stephensi and Aedes aegypti. The LD values for adults were 6.65, 5.19 and 8.35 micrograms/cm2 and LC 50values for immatures were 5.4 X 10(-5), 1.6 X 10(-4 and 5.4) X 10(-4) 50mg/1 respectively. Pyraclofos (50%) showed neither larvicidal nor adulticidal activities. The residual effect of carbosulfan (25% WP) on cement, thatch and mud surfaces at 400 mg (ai)/m2 lasted for 3, 16 and 21 weeks respectively. In the field, carbosulfan at 2.00 kg (ai)/ha resulted in complete control of C. quinquefasciatus larvae for a period of one week in cement tanks and less than a week in other polluted water bodies, such as cesspits, cesspools and drains. Pyraclofos was not effective at a dose of 2.00 kg (ai)/ha in any of the habitats.

Animals↗