Four popes have died of malaria. Giambattista Castana, who was elected Pope Urban VII in 1590, would have been the fifth had he not died of the disease before his coronation. Killer mosquitoes had thrived in the Pontine marshes south of Rome for centuries until Mussolini ordered the marshes to be drained when he became Italy’s prime minister in 1922. (The word malaria comes from the Italian mal aria bad air.) The Germans flooded the marshes during their occupation in the Second World War, triggering a new outbreak of malaria which killed hundreds of Italian civilians. George Washington and George Clooney succumbed, and Michael Caine was infected with cerebral malaria in Korea. August Engelhardt, the German nudist and cocovore (one who eats nothing but coconuts) contracted the disease on his unspoiled Eden in the South Seas. Bats, snakes and apes contract malaria, and biologists are speculating that dinosaurs might have suffered too.
According to the World Health Organization, malaria infects more than 200 million people every year: in 2016, an estimated 4,45,000 sufferers died of the disease. Sub-Saharan Africa accounts for 90 per cent of cases, with children under five and pregnant women being most at risk. Discarded coconut halves that collect water have proved to be an ideal breeding ground for the mosquito responsible for transmitting malaria. Various methods preventing the mosquito from attacking its victims are used to varying degrees of success. But a vaccine for malaria has so far proved hard to find, not least because the malaria parasite plasmodium falciparum consists of more than 5,000 genes. (In comparison, the polio virus, for example, is comprised of just 11 genes.) This makes a vaccine hard to design, although a research company in Maryland now claims that clinical trials in Equatorial Guinea of its new drug could lead to the commercial production of a vaccine by 2020.
For centuries, and up until the 1940s, it was quinine that provided treatment for malaria sufferers. Seventeenth-century Jesuit priests in Peru – Jesuits were prevented from studying medicine lest it divert their attention from matters spiritual, but were nonetheless accomplished apothecaries – were the first to isolate quinine from the bark of the cinchona tree. They called their new find quina quina (bark of barks). Samples were sent to Rome, a city of swamps and marshes in the 1700s where malaria was endemic. It was so effective that the people of Rome could not help but describe it as the miracle drug, a sentiment with which seventeenth-century popes happily concurred, creating a huge and spiralling demand for the bark.
Three centuries later in the 1930s Paul Muller, a Swiss chemist, produced dichloro-diphenyl-trichloroethane or DDT which proved highly effective against all kinds of insects, including mosquitoes. It won Herr Muller a Nobel prize for medicine. But his DDT was snapped up by farmers the world over. It was cheap and the farmers used too much of it, turning what had been a life saver into a pollutant. The malaria eradication programme was halted and DDT eventually withdrawn from the market. To make matters worse for parts of the world where malaria is endemic, the malarial parasite was outsmarting every other insecticide put in its way.
But Palmira Ventosilla would outsmart the mosquitoes – with coconuts. Professor Ventosilla is a microbiologist at the Alexander von Humboldt Tropical Medicine Institute in Lima, Peru. Peru had given the world quinine; it was about to provide the world with an ingenious follow-up. Professor Ventosilla had followed the work of a group of researchers who had surveyed mosquito-breeding sites in Israel. They were looking for natural pathogens and parasites that attacked the mosquito larvae and found a new strain of the Bacillus thuringiensis bacterium, which they isolated from a stagnant pond near the Zeelim Kibbutz in the Negev Desert. They named it Bacillus thuringiensis israelensis or Bti.
What Professor Ventosilla did was to put Bti together with coconuts. There were areas in the north of Peru where malaria was a serious problem. These areas were characterized by numerous fish ponds and narrow irrigation canals. The problem was finding a way for local people to apply the Bti. There were plenty of coconuts and Ventosilla knew that coconuts contained the amino acids and carbohydrates that support Bti. And while Bti was toxic for 72 species of mosquito by killing the larvae, it was harmless to fish, birds, mammals and humans.
In her lab, Ventosilla introduced a small quantity of Bti into a mature coconut through a small hole that she then plugged with cotton and sealed with candle wax. The hard shell of the coconut protects the incubating bacillus, and the water inside contains the amino acids and carbohydrates necessary for its reproduction. After two or three days of fermentation, the coconuts were taken to ponds where the mosquitoes were known to live, the plugs removed and the coconuts thrown into the stagnant pools of water. Two or three coconuts were used to cover a typical pond.
For 12 days, eight ponds in Salitral, a small town in the north of Peru with a population of around 6,000, were almost entirely free of mosquito larva, their numbers decimated by the Bacillus thuringiensis israelensis that had escaped from the coconuts. So far so good. But Ventosilla and her small team were not about to travel the world with a bunch of coconuts in their luggage. Local communities in malaria-infected regions would have to do the work themselves. So she put together a Bti do-it-yourself kit, and designed an education programme for schools and local communities. The kits contain a cotton swab seeded with 1,000–10,000 Bti spores, another swab with 40mg of sodium glutamate, a small piece of cotton and instructions on how to inoculate the coconut. With it, anyone, even those with a basic education, could inoculate a coconut, wait for the Bti population to grow suitably potent, and then open the coconut and toss it into a pond.
These biological coconut bombs are harmless to humans and to most other organisms. The World Health Organization (WHO) issued a guideline saying that even in drinking water, Bti is not known to be harmful to people. But it is lethal to the mosquito including the Aedes aegypti variety that carries the zika virus. Word of the coconut bombs spread. Ventosilla took her simple science to Guyana, while scientists in Indonesia followed her example with their own teams and their home-grown nuts. Deaths from malaria have fallen 29 per cent since 2010 according to the WHO, although it has to be said that the coconut bombs cannot claim the credit for more than a percentage point or two of that decline.