Silent Spring, indeed. The prophecies have been fulfilled. We were warned. There was plenty of time to avert this catastrophe but no one wanted to listen.
From the BBC we learn that mosquitoes are ‘disappearing’ in some parts of Africa. All goofing aside, this is very good news.
Malaria-carrying mosquitoes are disappearing in some parts of Africa, but scientists are unsure as to why.
Figures indicate controls such as anti-mosquito bed nets are having a significant impact on the incidence of malaria in some sub-Saharan countries.
But in Malaria Journal, researchers say mosquitoes are also disappearing from areas with few controls.
They are uncertain if mosquitoes are being eradicated or whether they will return with renewed vigour.
Data from countries such as Tanzania, Eritrea, Rwanda, Kenya and Zambia all indicate that the incidence of malaria is dropping fast.
Researchers believe this is due to effective implementation of control programmes, especially the deployment of bed nets treated with insecticide.
But a team of Danish and Tanzanian scientists say this is not the whole story. For more than 10 years they have been collecting and counting the number of mosquitoes caught in thousands of traps in Tanzania.
In 2004 they caught over 5,000 insects. In 2009 that had dropped to just 14.
More importantly, these collections took place in villages that weren’t using bed nets.
Malaria causes over 1 million deaths annually in infants and children under age 5 in sub-Saharan Africa – which works out to one every 30 seconds. A 400 fold decrease in the mosquito population would obviously have a huge impact on the spread of malaria.
The crazy part is that scientists are baffled as to why they’re seeing such a dramatic decrease in the bloodsucking parasites.
“It could be partly due to this chaotic rainfall, but personally I don’t think it can explain such a dramatic decline in mosquitoes, to the extent we can say that the malaria mosquitoes are almost eradicated in these communities.
“What we should consider is that there may be a disease among the mosquitoes, a fungi or a virus, or they’re may have been some environmental changes in the communities that have resulted in a drop in the number of mosquitoes”
The research team also found anecdotal evidence that their discovery was not an isolated case.
Prof Meyrowitsch added: “Other scientists are saying they can’t test their drugs because there are no children left with malaria.
“They observed this in communities with no large interventions against malaria or mosquitoes. It may be the same scenario that the specific mosquitoes that carry malaria are declining very fast now”
Fascinating. On a whim I did a web search for “ddt tanzania” and what do I see?
Tuesday, 15 July 2008
Tanzania has started using Dichloro-diphenyl-trichloroethane (DDT) for Indoor Residual Spraying (IRS) from July this year.
It will be the first East African country to start using the insecticide which is credited with eliminating malaria in the Western world decades ago before it was outlawed in many countries in 1972. Critics said it was harmful for the environment and humans.
Yeah yeah, post hoc ergo proctor hoc. Or does the fact DDT is credited with eliminating malaria in the Western world disprove the notion of a logical fallacy? The BBC and quoted scientists curiously omit any mention of renewed DDT spraying as a potential cause of the mosquito decline. It’s almost conspicuously absent. Must be a non-factor.
Malaria surged back in the wake of the introduction in 1992 of a total ban on the use of DDT in Tanzania, according to local available statistics.
Though DDT was effective against mosquitoes that spread malaria and against lice that carry typhus, the insecticide was blacklisted as one of 12 persistent organic pollutants under the 2001 Stockholm Convention.
No worries. What are the lives of 100,000 Tanzanian women and children each year when well-heeled environmentalists living in lands free from vector-borne disease can feel better about themselves for saving the planet?