Natal, Brazil, March 1930
She sniffed land. And decided to leave the ship. Found her way to the nearest pool of water. And dumped the egg load she’d been developing whilst travelling across the Atlantic Ocean. This mosquito sparked what would later become known as one of history’s most remarkable triumphs against tropical diseases.
She came from Dakar, Senegal, West Africa. Picked up the scent of a soldier sleeping in a cabin on a French marine ship, gorged on his blood, and remained as a stow-away there during the five-day trip to Brazil. Her name: Anopheles arabiensis, a notorious transmitter of malaria in most of sub-Saharan Africa.
Remarkably, her presence in the New World did not go unnoticed for long. Whilst enjoying a Sunday morning walk a few weeks later, American entomologist Raymond Shannon saw some strange looking larvae in a roadside pool. Shannon was shocked to discover that these were African malaria mosquitoes. But Brazil was in the grip of yellow fever, transmitted by Aedes aegypti mosquitoes, and the authorities were not alarmed by Shannon’s discovery and ignored it.
By the end of 1930, the African invader had seized an area of six square kilometres. She felt so happy in her new homeland that conquering new land was the easiest thing on earth. People for blood, water for breeding, and the tropical sun of Brazil that provided her with a climate similar to that in Senegal. By 1938 she’d expanded over an area of 54,000 square kilometres.
And then she struck. Hard. And caused a massive epidemic of malaria. Nearly 200,000 Brazilians fell victim, tens of thousands perished. All over, people were lying by the roadside, begging for drugs. “The situation was appalling”, reported a malaria inspector years later.
Winning the war
On 5 August 1939, when the world was preparing itself for WWII, president Vargas declared war on the African mosquito. The field marshal in charge of the battle became Fred Soper. The war had one goal: to exterminate the invasion, not to control it, but free Brazil to the very last mosquito of African origin.
But the enemy did well. Huge chunks of inhospitable and inaccessible land had been invaded. The Brazilian malaria parasite developed even better inside the African mosquito then in native malaria mosquitoes. Freeing 54,000 square kilometres of this mosquito seemed an impossible task. But not for Soper.
Soper launched the war by setting up an army. He enrolled a total of 4000 men, and each of these was assigned a 25 square kilometre area. The gun was replaced by Paris Green, a toxic compound used to kill mosquito larvae in standing water. The men had to locate each and every possible breeding site in their area, and treat it.
Soper staged the war much in the same way as Eisenhower and Churchill did with D-day. By asking the utmost of their troops (see image), driving and inspiring them to do what seemed to be impossible, yet fraught with uncertainties. Nobody before had declared victory over a mosquito invasion of this magnitude, nobody before had freed Europe from the Nazis through a landing in Normandy.
But these men did. And won. Soper freed Brazil of the African mosquito after a battle that lasted just eighteen months.
Mbita Point, Kenya, June 2000.
The seminar room was filled with 24 of us, mostly Africans. All working in malaria research. Shortly before, Malcolm Gladwell had published a story on Soper in the New Yorker and we decided to have a debate on it. Former colleague Dr. Gerry Killeen would defend our current approach to malaria mosquito control (mostly with bednets at that time), and I would argue in favour of Soper’s strategy. After an hour, all voted anonymously for one of the strategies. Eighteen favoured the Soper approach.
Malarious Africa, 2010
Today, there is no place in Africa where Soper’s strategy is revived. Science has come up with a perfect biological alternative for Paris Green, the biopesticide Bti. We now have 4x4 vehicles where Soper’s men used horses or went on foot. We have satellite imagery that enables you to see a sheet of A4 paper from space. We have geographical information systems. Computers. Mobile telephones. The lot.
Fourteen countries in Africa, where children die of malaria each day, are smaller than the 54,000 square kilometres that Soper’s army freed of African malaria mosquitoes. To the very last one of them.
Zanzibar (I discussed the difficulties of malaria elimination here) is 1,554 square kilometres. Just 2.9 % of Soper’s area. With Soper’s strategy you would need 115 men to do the job. Let’s double it – 230. Train them well, nurture them, pay them well. Give them two years. End malaria, for good. In Soper’s words: “There is no such thing as partial success. It is either glorious victory, or dismal failure". The man died in 1977, long before he could witness the tools we now have at hand but not use.
If tomorrow an announcement would be published in the Tanzanian newspapers to recruit ‘soldiers’ for such a campaign, thousands of youngsters would respond. With massive unemployment in most of Africa, the army is out there, waiting to be enrolled. And with the sorts of money that are being poured into malaria these days, paying for it all wouldn’t be an issue.
So what are we waiting for?
[For a small video on Soper click here]
GF Killeen, U Fillinger, I Kiche, L Gouagna, BGJ Knols (2002). Eradication of Anopheles gambiae from Brazil: lessons for malaria control in Africa? Lancet Infectious Diseases, Volume 2, Issue 10, Pages 618-627
Image Fred Soper: National Library of Medicine, Washington DC.