Malaria

The World Health Organization estimates that several hundred million people are infected with malaria each year, of which more than a million die. Science has been waging war against this disease for more than one hundred years. A few decades ago it had seemed that victory lied ahead, but malaria adapted and struck again.

The deadly “mosquito conspiracy”
Malaria can kill a man in a matter of days. The disease is caused by a small, single-celled parasite, Plasmodium, which inhabits the red corpuscles of the infected person and starts to divide, doing so until the cells bursts. Destroyed blood cells can clog blood vessels causing damage to organs which may lead to the death of the affected person. It is most likely that, throughout the history of mankind, this tiny parasite has killed more people than any other disease.

For a long time people believed that malaria was caused by infected air. Hence its name: male aria, in Italian, means “bad air”. The key discovery in understanding the functioning of the disease was made in 1897 when a British military doctor, Ronald Ross, who was stationed in India, was testing the hypothesis that the true carriers of malaria were actually mosquitoes. Malaria experts of the time thought that the mosquito theory was quite absurd, but Ross decided to try it out anyway. He carried out an experiment that soon proved to be one of the most important ones in the history of medicine. He bred some mosquitoes and fed them blood taken from infected individuals. He wanted to find out if a malarial parasite can even survive inside a mosquito host. He tested his theory on several species of mosquitoes, but the parasite always perished. That was until he discovered a mosquito of the Anopheles genus and was surprised to find out that the parasite seems to thrive inside the intestines of this particular species of mosquitoes. Not only does the parasite survive inside the mosquito, it reproduces and waits to be transmitted to its next human victim.

Ross’s findings, for which he was also awarded the Nobel Prize in 1902, gave the human race a real chance to fight malaria for the first time ever. The idea was simple: as malaria was transmitted by mosquitoes, it was necessary to change the natural environment in a way that would make it as inhospitable for mosquitoes as possible. Extensive projects were started, draining swamps, stagnant waters and slow rivers where the populations of mosquitoes were most abundant. For the first time in history, the number of malaria infections started to dwindle. However, the method of draining was not as effective in certain tropical areas of the world, so the search for a more powerful weapon began.

Chemical weapons enter the battle
When fighting in the tropics, armies were horrified to find out that in these areas more soldiers were killed by malaria than by bullets, so they became very keen on finding an effective method of confronting the disease. During the Second World War, the Americans developed an insecticide that effectively destroyed the mosquitoes’ nervous system even when applied in small doses. After being dispersed over an area, it remained effective for several years. In addition to that, it was cheap. The insecticide was called dichloro-diphenyl-trichloroethane or DDT. After the war, the World Health Organization decided to use DDT to completely eradicate Malaria in the decades to come.

At first, the plan worked like a charm. In India alone, the number of malaria infections decreased from eight million cases before the eradication began to a “mere” fifty thousand. It seemed that the battle with malaria was already won when mosquitoes struck again. Their weapon against DDT was evolution. Every day, millions of mosquitoes come to life all over the world, and occasionally, some appear that have different traits than the majority. It only took one mosquito that had mutated in such a way that it became resistant to DDT. The insecticide had no effect on this particular mosquito, so it was able to reproduce without any difficulty and soon a population of DDT-resistant “supermosquitoes” started taking over the world.

Chemists put their heads together and started developing new insecticides, but mosquitoes eventually became resistant to those as well. The war on mosquitoes was a war on evolution itself. New insecticides had to be developed faster than mosquitoes could develop new defense systems with the aid of random mutations which kept the species from becoming extinct. As a rule, however, every new insecticide is more expensive than the previous one. In 1969, the World Health Organization gave up its struggle against mosquitoes and called off its plan to eradicate the chief carrier of malaria. Once more, the mosquitoes multiplied and the number of deaths caused by malaria increased again. The number of infections in India leaped from a couple of thousands to a couple of millions.

Because of mutations, the malarial parasite also became resistant to once relatively effective medicines, such as quinine, brought from Peru by the Jesuits in 1640. Some twenty years ago it seemed that humanity had lost its battle with one of the deadliest diseases plaguing the planet.

An ancient Chinese remedy turns out to be highly effective
In the 1970s, nobody in the West knew that the Chinese had developed a very effective remedy against malaria which was, in the spirit of the Cold War, kept top secret. The cure was discovered while – allegedly following Mao’s advice – carefully studying the functioning of more than 200 different mixtures intended for curing malaria, known in traditional Chinese medicine. And one of them truly worked.

Delving into traditional recipes, scientists stumbled upon 2000-year-old instructions for preparing the Quing Hau Su tea which was tested and proven to effectively cure malaria. They set about analyzing the tea’s ingredients and extracted the active substance that possessed the healing effects. Today, this substance is called artemisinin and is believed to be the most effective antimalarial drug known to man. Because of the Cold War and the concealment of the discovery from the world, it took thirty years before the medicine began to be used on a large scale.

The news about the miraculous antimalarial drug reached scientists from beyond the borders of China due to an article published in a Chinese medical review, a source that did not inspire much confidence at the time. In addition, the Chinese authorities did not allow for the ingredient to be analyzed by any laboratory outside of China. I took several years for westerners to find the plant that produced artemisinin and test the medicine themselves.

How to produce enough medicine for all the infected?
Because the drug turned out to be very effective, the demand for it today largely exceeds the capacity for its production. It takes eighteen months from planting Artemisia annua to isolating the drug which means that, using the conventional method, it is impossible to produce sufficient amounts of the substance to answer the needs of all those infected with malaria. That is why scientists today are striving to develop a method that would enable a faster and more efficient production of the drug.

By transferring some of the genes responsible for the production of artemisinin from the Artemisia annua plant into yeast plants, researchers have succeeded in making microorganisms produce artemisinic acid which, later on, undergoes a chemical procedure that produces the actual drug, artemisinin. With the help of yeast plants and this procedure it will most probably soon be possible to manufacture large quantities of the drug and save countless human lives. In Africa alone, two children lose their lives because of the devastating consequences of malaria every minute.

As with every new drug, however, precaution is necessary. In January 2006, the World Health Organization appealed to the pharmaceutical industry to stop advertising and selling drugs based solely on artemisinin. Last year, researchers realized that the mutation of a single amino acid could be enough for resistance to reappear. One of the best strategies in preventing malaria to become resistant to the latest, most effective solution is combining it with other antimalarials when treating patients. This reduces the possibilities for the potential survival of a mutated form of the disease and its spread over the world, preventing a disaster which has already occurred on several previous occasions.