Of Myths and Mosquitoes

Female Anopheles albimanus mosquito, a vector of malaria.  This image is in the public domain, and is #7861 in the U.S. Center for Disease Control's Public Health Image Library (PHIL).

Here’s a question that I was asked this weekend, one which I’ve been asked more than once: how anyone can justify the ban on DDT when millions of people are dying of malaria?

It’s a good question.

Unfortunately, it’s the wrong question. It’s wrong because it’s based on three premises:

  1. DDT has been banned;
  2. In areas where mosquitoes are endemic millions are needlessly suffering and dying from malaria deaths that are preventable if spraying DDT is allowed; and
  3. DDT is a panacea that strikes down mosquitoes without fail.

All three premises are wrong.

First, DDT has not been banned in most areas where malarial illness is endemic. In fact, even in the United States, DDT may be used under a “special use” clause in cases where there is an outbreak of mosquito-borne disease such as malaria.

Second, in areas such as Africa, guess what? Spraying DDT is allowed. So those millions that are dying from malaria (which is indeed happening and is indeed horrible) aren’t dying because DDT is banned. So what’s the deal there? The answer is that in poorer countries, like those in Africa, in order to use DDT (or any other chemical) for insect control correctly, you need the infrastructure in place to actually carry out your plans. That infrastructure simply doesn’t exist in the war-torn and poverty-stricken African (and other) areas where malaria is endemic. Additionally, spraying for insect control is only one piece of a very complex problem when it comes to the control and elimination of malaria. All of those pieces need to be addressed for success.

Third, the world’s mosquito population has became resistant to DDT. That means that the mosquito of today isn’t the mosquito of 1950. Just like germs that are now resistant to certain antibiotics, mosquitoes are resistant to DDT. So countries that have used DDT have found it’s no longer particularly effective at killing mosquitoes.

So what does work?

  1. Where possible, kill mosquitoes when they are still larvae. That is more effective than spraying to kill adult mosquitoes. Use the least toxic method to do so, such as vegetable-based oils added to standing water. The oil suffocates the larvae with minimal negative effect on fish, wildlife or humans, and is cheap, biodegradable and widely available even in poor countries. And because it works based on a mechanical function (it suffocates the larvae), mosquitoes don’t develop resistance to it.
  2. Support organizations that are working to get bed netting to every individual at risk, and trying to especially help countries where poverty-ridden families can’t afford to buy bed netting for themselves. Bed netting is one of the most effective and economical solutions possible for preventing malaria. It works.
  3. Treat individuals who have malaria with drugs that kill the parasite, not the older drugs that control the symptoms. If you eliminate the parasite from humans, then a mosquito can’t bite an infected person and then transmit the parasite it sucks in with the blood to another human. That requires drugs and the actual treatment using those drugs to get to the right places, a daunting task but one that countries like Brazil have successfully undertaken.
  4. Until research provides us with insecticides that aren’t toxic to anything but what they’re aimed at killing, use products that have the least collateral damage to non-target species. Translated: it doesn’t help to kill mosquitoes if you kill the birds that eat the mosquitoes, and seriously harm (or kill) the other wildlife and humans that you’re trying to protect.

Underlying all of this, btw, is a fourth false premise: DDT is pretty safe. Everyone knows that Rachel Carson was a wingnut, and the loony-left-granola-crunching-tree-huggers can’t trot out a single bit of evidence that proves DDT is a problem.

Wrong again.

I could list quite a few studies and authorities, but I think I’ll let the United States Fish and Wildlife Service sum it up:

The Service continued to conduct studies on, and to voice its concern over, the effects of DDT on fish and wildlife for more than 25 years. It was not until 1972, and then because of the potential harm to human health, that the Environmental Protection Agency (EPA) banned the use of DDT in the United States barring a public health or economic emergency.

And that decision was made before scientists even began to scratch the surface on how DDT is a strong endocrine disruptor, with the potential to cause reproductive, behavioral, immune system and neurological problems.

So, about that ban on DDT which is causing the loss of millions of innocent human lives?

It’s a myth.