Operation Cat Drop

research blogging iconIn the news recently: Operation Rat Drop, where tylenol-laden mice were dropped from planes over Guam. It’s not a bizarre headache remedy; the idea is to try to kill brown tree snakes (a non-native invasive species) when they eat the mice.  Acetaminophen kills snakes. Who knew?

That reminded me of a similar–but much odder–project: Operation Cat Drop. It’s an oft-told story about DDT and unintended consequences.  I was excited to see it had recently been covered in a journal!

In 1955, a malaria outbreak in Borneo was fought by spraying DDT and other pesticides. Several unintended consequences were observed after the sprays, but time and distance have muddled them quite a bit.  The basic claim is that local cats died after the sprays, and this caused an explosion of rat populations, which lead to increased human disease. The RAF then (in the more exciting versions of the story) parachuted in 14,000 cats to remote Borneo.

Some things are known and documented; one unintended consequence that did occur post-spray was that caterpillars eating the roof thatch of homes increased 50%, with associated roof damage:

 “The WHO team sent to investigate determined that moth larvae (caterpillars) living in the thatch were able to distinguish the presence of DDT and so avoided eating thatch sprayed with the chemical, whereas their parasites, small chalcid wasps that injected their larvae into the caterpillars, were highly susceptible to DDT, causing their decline and the subsequent increase in caterpillar.”

This is a fairly classic pattern, where pesticides disproportiately affect natural enemies, or living organisms that act as natural brakes on pest insect populations.

It is also known that cats did often die after DDT sprays, and this was observed in several different countries on different occasions, including in Borneo. It would make sense that cats would eat rats and insects (and, in some versions, geckos) affected by the sprays, and the pesticide would biomagnify in their kitty bodies. That, however, does not appear to be the case;  cats’ habit of grooming themselves and ingesting residue of the pesticide was what allowed them to receive a lethal dose.

Which leaves us with the parachuting cats.  There was a rat problem in the area, and there is a record of 20 cats being dropped in Borneo by the  British RAF, along with some chickens, by parachute.  But that’s it. They weren’t in little harnesses; they were in special containers that would cushion the drop.

kitty and parachute

It’s a fascinating story of how something basic took on a life of it’s own. The paper I’ve cited below suggests that some of the story’s inflation in kitty numbers can be attributed to an expatriate Brit with a big ego that initially  started the rumors.  I don’t have access to his original document, which included little drawings of cats in individual parachutes, so I have done my best to recreate them here.

From there, the story was reproduced and  took on a life of it’s own–I’ve seen versions where all the cats landed in the sea and drowned, versions where there were 10,000 cats, and versions where high-velocity falling cats killed people when they fell on them.  All false, but far more interesting than reality.

Before anyone begins to trot out the usual “DDT will save us all” crap, I want you to read that paper and notice that it clearly lays out a whole sequence of unintended consequences from DDT sprays, including the problem of resistance from as early as in the 1950s.   This paper is a reminder that we should not be uniformly pro- or anti-DDT;  we should make pesticide decisions based on the best available, real evidence. Not propaganda.

Full Citation:
O’Shaughnessy, P. (2008). PARACHUTING CATS AND CRUSHED EGGS The Controversy Over the Use of DDT to Control Malaria American Journal of Public Health, 98 (11), 1940-1948 DOI: 10.2105/AJPH.2007.122523

Forbes hits the Conspiracy Trifecta

I read a lot of strange stuff on the internet. I mean, I’ve covered Extraterrestrial Cows and Mail-order public lice.  But I really don’t expect to run into silly conspiracy stuff in Forbes, of all places.

In an article entitled “The Black Death: Longing for the Good Old Days,” James Taylor ties together global warming denialism, DDT boosterism, Edgar Allen Poe, and the Black Death (i.e. Bubonic Plague) to make…a really big pile of something that steams.

He suggests that everything was hunky dory when the climate was hot, but when things got cold–OMGPLAGUE:

“What brought about the Black Death? A thousand years ago, Europe was experiencing a golden age. The fair climate of the Medieval Warm Period, with temperatures similar to or warmer than today’s climate, stimulated bountiful crop production, supported unprecedented population growth,….
Longer winters and cooler, shorter summers decimated crop production throughout Europe. The rains that fell were cold, persistent, and slow to dry up. Famine and plague, which had largely disappeared during the Medieval Warm Period, became the norm rather than the exception. And by 1350, the grim, cold climate brought about the dreaded Black Death.”

He goes on from this to imply that environmentalists want to curb global warming in order to kill us all by bringing back the Black Death. Oh, and malaria, but we’ll get to that part later.

I actually have spent a lot of time over the years researching Bubonic plague, and the 14th century European “Black Death” in particular. I have never read of climate being implicated as a cause for the European plagues.  Never.

I would also like to point out that the Little Ice Age actually occurred several hundred years AFTER the period of the bubonic plague outbreaks in Europe.  A recent review paper listed the start date around 1570.  So, the dots he’s trying to connect, in addition to being unrelated factually, are also unrelated chronologically.

The more interesting theories about why the Black Death was so devastating to Medieval Europe center on increasing urbanization and commerce.  In order to have a massive epidemic, you need populations of potential victims to be concentrated. If you get the plague in the middle of nowhere, you will die horribly…and that’s it.  There is no one to transmit the plague TO.

On the other hand, if you have concentrations of people in cities and towns; and you have movement of both people and animals between cities and towns, then you have a situation that is ripe for an outbreak.  If you add in poor sanitation, it’s a dream for a disease bacterium.

There is a well-documented timeline of outbreaks moving from Asia over to Italy, and then up through Europe.  Rats in grain and rats in ships moving from place to place for commerce were probably the primary movers of the disease.  (In case you’ve forgotten, fleas are the vector of plague between humans and other animals. In other words, fleas transmit the plague bacteria from infected people/rats to new victims.)

Mr. Taylor is a lawyer working for the Heartland Institute, which advocates for unregulated trade (and also says that cigarettes are harmless). Somehow he seems to have missed the obvious connection between free markets and plague.  Hmm.

So, what else? Oh, the Malaria–right.  From the article:

“Malaria was becoming a distant memory 50 years ago, but the World Health Organization now reports that over 200 million people contract the disease each year and nearly one million people die from the disease each year. A single, small application of DDT to the inside walls of a hut – in which malarial mosquitoes most frequently infect their victims – will keep malarial mosquitoes at bay for months, but environmental activists have forbidden this chemical infringement on The Natural Condition.”

Let’s start with that first sentence.  50 years ago, Malaria was becoming a memory for the US and Europe; they launched very successful campaigns to control mosquitoes. Malaria eradication was not, however, successful in Africa, Asia, or Latin America. In fact, some areas never were part of any Malarial control campaign.  It’s certainly correct to say that too many people die of malaria each year; but it is not correct to say  that more die now than in the past. If you look at WHO data for most regions, there is a clear downward trend.  Global control of malaria has been slowed by resistance to treatment drugs, as well as mosquito resistance to DDT.

Which brings us to his next claim.  In his second sentence, he claims that DDT can be applied to the walls of a “hut” and provide protection from malarial mosquitoes.  News flash–not everyone lives in huts–your imperialism is showing.  But, hey, let’s run with it.

This is an incorrect statement for a variety of reasons.  Indoor Residential Spraying (IRS) is actually not a preferred methodology for the World Health Organization Malaria group; they specifically recommend against using the same chemical year after year.  Increased resistance to pesticides is strongly tied to indoor sprays in the report I linked.  A quote: “it is unlikely that universal vector control coverage can be achieved in Africa by IRS alone.”   

Taylor’s pollyanna approach ignores the the reality of DDT and malaria in the world today.  A hundred countries currently have a malaria problem. It is patently absurd to think that one single chemical (and methodology) can solve a problem that is global in scope.

There isn’t only ONE species of malaria mosquito–there are dozens (And they don’t all bite you when you are inside). There is not just ONE kind of ecosystem in which people and malaria interact. Designing a malaria control methodology has to take into account  the political, environmental, and socio-economic situation of a particular community.  What, if any, data do we have on the resistance of the mosquitoes to insecticides? It is not a one-size-fits-all problem with one solution.

His last sentence is also untrue.  DDT is part of current WHO treatment guidelines. It is not “forbidden”.  But DDT is only one piece of a huge, huge complicated problem, and over-reliance on it can actually make things worse by leading to greater insecticide  resistance.

What I want to know now is–Why did Forbes let this douche write an article full of BS that was VERIFIABLY FALSE?  And what are they going to do about it?