The Nobel prize in medicine was awarded for drugs against malaria
It is believed that worming suffers a third of the world population, mainly in Africa (South of Sahara), South Asia, and Central and South America. Widely distributed nematodes (roundworms) of the family Onchocercidae. One of the diseases that they cause – the so-called onchocerciasis. The causative agent, Onchocerca volvulus, settles in the lymph nodes of humans where females produce many larvae, called microfilariae. These larvae then migrate under the epidermis of the skin, where they can get to the insect vectors. The larvae enters the human eye, penetrating into all tissues of the visual organ. Inside the eye they cause inflammation, bleeding and other complications, leading eventually to loss of vision. Because midges are vectors live on the banks of the rivers, the disease is called river blindness. There are about 18 million patients with onchocerciasis, of whom about 600 thousand the disease has led to significant loss of vision or complete blindness.
Another famous disease, visivamente, Onchocercidae – the elephantiasis, or elephantiasis, when some part of the body, e.g., leg, enormously increases in size due to the stagnation of lymph, which leads to overgrowth of the skin and subcutaneous tissue. Strictly speaking, elephantiasis is a symptom of Brugia caused by the nematode Brugia malayi, a parasite in the lymph and blood vessels. According to statistics, at present, “clanovima nematodes” infected approximately 100 million people.
River blindness and Brug’s filariasis are just some of a number of diseases caused by parasitic nematodes. The situation with them would be very difficult, if against them there were no drugs. However, these drugs are, and it is for them now awarded half of the Nobel prize in medicine and physiology. One of the current winners, a Japanese microbiologist Satoshi Omura (Satoshi ?mura, born in 1935), has long been engaged in that tried to find in soil microbes new antibiotic substances. As you know, antibiotics are the chemical weapons of fungi and bacteria, used against their competitors, i.e. other fungi and bacteria, and the diversity of these substances is unusually high. The problem is that not always natural bacteria can be removed from its natural environment and grown in the laboratory in order to study in detail, what kind of antibiotics she synthesizes. However, Omura was able to get as many as 50 strains of bacteria of the Streptomyces group, who could potentially become a source of new drugs. The researchers observed that one strain, later named Streptomyces avermitilis, synthesized the substance acting against parasitic worms. (Note that in order to find these 50 strains, we had to analyze thousands of bacterial colonies grown in the laboratory from soil samples.)
Work the Omurov Satoshi and his staff drew the attention of William Campbell (William C. Campbell, born in 1930), specializing in the biology of the parasite. He continued to work with bacterial strains and eventually allocated the active substance called ivermectina – it is very well acted against worms, parasites in domestic and wild animals. After further modifications on the efficiency of molecules has increased even more; the medicine changed its name to ivermectin. Further experiments showed that it is possible to get rid of a variety of nematodes, both from larvae and adults, as well as from ticks, lice and some other parasites. He acts as a nerve poison by disrupting the conduction of impulses in neural chains, so the worm covers the palsy, and he dies. And most importantly – ivermectin can treat not only animals but also people.
But this is only half of the current premium (Omura and Campbell got 1/4 of it), what gave the other half? Here it is necessary to remember about another very “popular” and still, alas, not completely defeated the disease – malaria. Pathogens, not viruses, not bacteria and not even worms and special protozoa called Plasmodium. Them there are about two hundred species, and at least ten parasitic on man. Other species are parasitic on other vertebrates – monkeys, rodents, birds and reptiles. Everyone knows that the vector and intermediate host of the human species of Plasmodium are malaria mosquitoes. However, the life cycle of the parasite is too complex to describe it here. At certain stages he lives in the liver, on the other – enters the red blood cells, destroying them later; maybe also for a long time “to fall asleep” in the body of an infected person, creating the illusion of a cure from the disease. Immune response against Plasmodium falciparum develops very slowly, the parasite due to the peculiarities of the life cycle is inaccessible to immune proteins and drugs, and given the disappointing statistics on malaria (at the beginning of the XXI century the incidence was 350-500 million cases a year, including 1.3–3 million ended in death), it becomes clear why this disease still poses a serious problem.
Previously, the main means against malaria were quinine and chloroquine, but the effectiveness of the treatment with their help, over time, began to decline, and by the end of the 60-ies of XX century it became clear that here you need something else. Trying to find a new medicine, chemist-pharmacist from China The YOYO (Youyou Tu was born in 1930) referred to the recipes of traditional medicine. The animal experiments revealed one promising candidate is an Artemisia, Artemisia annua. That managed to isolate the active component of wormwood called artemisinin. It marked the beginning of a new class of antimalarial drugs. Although key results for artemisinin were obtained in 70-80-ies of the last century, it is used still, however, not alone, but in combination with other antimalarial drugs to the harder parasites to develop resistance to it.
With Amurai, Campbell and The happened classic Nobel history: the elders of the science, already awarded with all conceivable awards, finally won the main prize for scientific works published several decades ago. However, of course, no one can say that their results are obsolete – in the end, these medications still each year save hundreds of thousands of lives around the world.