WEBVTT

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Federal Security Agency, Public Health Service, presents

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A Communicable Disease Center Production

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With the cooperation of The State Board of Health of South Carolina

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Hand Ditching for Malaria Control

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[Speaker 1]:These wide swamps near Charleston, South Carolina were long a blight on the landscape

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and a breeding ground for the malaria-carrying mosquito, the anopheles quadrimaculatus.

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Here, water and vegetation met, and malaria drained the vitality of the people living nearby.

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Here, the malaria danger signal flashed during hot summer months and the land was worse than useless.

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Week after week, inspectors waded through these swamps, nipping for larvae.

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The larvae were collected in vials to be transported to a laboratory for examination.

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Larvaciding was necessary when the count was high, and it was usually high.

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These repetitive measures were a continued drain on public health funds,

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and public health officials became convinced that permanent elimination of the problem

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by drainage was necessary and economically feasible.

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Malaria-control engineers located the ditches and established grades.

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Labor crews following the engineers dug the main ditch from the outlet to the swamp.

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The initial cut was vertical.

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Sides of the ditch were sloped to a grade determined by the stability of the soil

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and the bottom was fine-graded to ensure a smooth flow of water.

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Excavated material was spread evenly along the banks

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so that water could not collect behind it, and to keep the spoil from washing back into the ditch.

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The main ditch was put into service by making an entrance cut, or tapping the pond.

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Good engineering and proper construction paid off as the water moved smoothly and rapidly out of the swamp.

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The completed main ditch with its smooth, well-sloped sides

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and spoils spread evenly along the banks, is a good example of hand ditching.

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Smaller areas were drained into the main ditch by laterals or side ditches.

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These were also dug from the outlet to the swamp.

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The pond was tapped and the water drained off in a steady flow,

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to enter the main ditch at angles designed to avoid any disturbance of flow in either ditch.

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Abrupt angles were avoided and the discharge enters the main ditch a few inches above its bottom.

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Complete drainage of this area has made reproduction of the malaria mosquito impossible.

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This is no longer a problem area.

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The land has been reclaimed and its development may offset the entire cost of the project.

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Here hand ditching was the practical answer to malaria control.