Scientists trek through Malaya's steaming jungles deliberately exposing themselves to attack by bloodthirsty mosquitoes and leeches, to test the effectiveness of a liquid repellent, in a new bid to reduce the causes of malaria, dengue and yellow fever.
Men in jungle apply mosquito repellent and catch mosquitoes.
Men are checked for bites.
Leech on leaf, men walk through jungle, leech falls from branch of tree onto man, men leave jungle, and are checked for leeches, man without repellent covered in leeches on leg and foot.
CU. Leeches on leg, repellent is applied, and leeches fall of leg - fade out.
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Background: Scientists trek through Malaya's steaming jungles deliberately exposing themselves to attack by bloodthirsty mosquitoes and leeches, to test the effectiveness of a liquid repellent, in a new bid to reduce the causes of malaria, dengue and yellow fever.
Forty volunteers from Kuala Lumpur's institute of Medical Research spent a day and night in a mosquito-infested jungle swamp: different types of repellents in bottles, are smeared by brush on the exposed skin. Some of the human "guinea pigs" wear repellent-impregnated clothing. Other have no protection.
During the tests they were attacked by 15 species of mosquitoes. On one man without any protective repellent they caught 300 mosquitoes in one hour. One repellents proved outstandingly effective giving as much as six hours' protection with one application.
Encouraged by this, the scientists carried the fight to leeches - curse of all who journey in the jungle. While the mosquito attacks directly, the leech is an infiltrator. Teaming on low-lying leaves and branches they drop on the unwary traveller and penetrate into the thickest clothing.
The volunteers again wore impregnated or non-impregnated clothing, others smeared the repellent on their skin. After a short march through the jungle the men without the repellent found themselves the prey of blood-bloated leeches. The volunteers smeared with repellent, and those wearing treated clothing, remained unscathed.
The repellent in this jungle test was so effective that any leech touched by a drop disgorged its stolen blood, and released its grip to drop of and die.