Bringing Back DDT

In February of this year, Microsoft creator Bill Gates opened a jar of mosquitoes during the Technology, Entertainment and Design Conference. He did this to demonstrate how much of a concern malaria is for several regions of the world.

Bill Gates and many others support the idea of reintroducing DDT as an effected tool to fight against malaria. Him and other scientists believe that spending mere cents on spraying houses would be more cost effective than supplying $10 dollar mosquito nets to everyone in an area impacted by malaria. They also believe that killing the insect using DDT is better than just preventing them from biting by using a net.

The stigma around the use of DDT dates back to the 1950’s. Dichlorodiphenyltrichloroethane (DDT) was discovered during World War II by the Swiss chemist Paul Hermann Müller of Geigy Pharmaceutical. He awarded the Nobel Prize in Physiology or Medicine in 1948 for his discovery of the high efficiency of DDT as a contact poison against insects.

During WWII, DDT was used to control the spread of Typhus. In the 1945, it began to be used to fight against the spread of malaria. In 1955, the World Health Organization initiated a program to eradicate malaria worldwide, its main weapon being DDT. The attempt was semi-successful. It eradicated malaria in Taiwan, much of the Caribbean, the Balkans, parts of northern Africa, the northern region of Australia, and a large swath of the South Pacific and dramatically reducing mortality in Sri Lanka and India.

Soon after this program started, scientists began to notice certain side-effects of DDT. Birth defects and cancer-related cases began to steadily rise in the regions of the world where the drug was being heavily used. It was discovered that the pesticide was leaching into water supplies, remaining in the ecosystem for long periods of time.

In the 1970’s DDT was banned from being used in almost every region of the world. In the areas where malaria was suppressed but not successfully eradicated, the mosquito population and impact of the disease has returned with a vengeance.

DDT is without a question the most successful tool used to date in the attempt to eradicate malaria from the planet. Bill Gates and other supporters encourage the return of DDT, because they are convinced that if spraying is done in small amount in and around the home, water supplies will stand low risk of contamination and millions of lives will be saved as a result.

This data was compiled using data found at www.who.org and www.cnn.com

Space Spraying: Thermal Fog vs. Cold Fog

Space spraying can be accomplished using one of two forms of fog; thermal fog and cold fog.

Thermal Fog

The insecticide used in thermal fogs is diluted in an oil-based transporting fluid. Hot gas heats this fluid, causing the oil to become vaporized. When the hot vapor exits the machine distributing the pesticide, it hits cooler air, creating a visible, white, dense fog.

There are several advantages to using a thermal fog. The reaction with the cooler air creates a visible cloud, allowing the operator of the machine to ensure thorough placement of the spray. Because the transporting fluid is oil based and not water based, less active ingredient is needed during the treatment, allowing for a lower concentration of exposure for humans dwelling in the region being treated.

However, there are several disadvantages to this treatment. Thermal fog operations are very expensive. An oil-based transporter in very pricey and can also be a fire hazard in the areas in which it is sprayed. Oil can also cause staining and leave heavy odors. It can leave roadways slick and cause possible traffic casualties.

Cold Fog

A cold fog is just another term for a diluted insecticide. There is no transporter fluid used other than the formula used to create the insecticide. There is no heat involved, and spraying is accomplished by using a high pressure nozzle.

The main advantages to cold fogs are that they are cost effective and pose little to know fire hazard. The water-base keeps roadways from becoming slick and is virtually odorless.
There are issues with cold fogs as well. The fact that they are nearly invisible makes them nearly impossible to observe, impacting the homogeny of dispersion. Without an oil-based matrix, the chemical can often evaporate or deactivate before it treats the area thoroughly.

Which to use?

Thermal fogs would be more appropriately used in areas where the pest being treated was a severe endemic. Areas with few roadways would be ideal. It is also a choice to use when the budget for treatment is larger.

Cold fogs are more appropriate in areas where the pest is not an issue that has grown out of control. It is better for areas with high traffic and heavier populations. It is also the better choice when the budget for treatment is small.

Ideally, in areas where there are both rural and urban populations, both treatments should be used together, breaking up the region into a mosaic of treatment types.

This information was collected from data posted by http://www.who.org/.