British researcher Ronald Ross found out that mosquitoes transmit the tropical disease malaria. He showed that the Anopheles mosquito carries one-celled parasites that cause malaria. Today, 200 million people a year still catch malaria, and about half a million of them die because of it. But thanks to Ross' findings, researchers were able to develop treatments to fight the disease.

Robert Koch discovered the tuberculosis pathogen, the bacterium mycobacterium tuberculosis. Tuberculosis is still a globally widespread infectious disease. Treatment is possible but protracted, even though there are antibiotics for the illness today. There is also a vaccine which protects children, but not adults.

French surgeon Alexis Carrel succeeded at transplanting blood vessels and entire organs. He developed a suture technique with which he could stitch torn blood vessels back together. He also discovered how to store organs outside the human body. Today, doctors transplant roughly 100,000 organs every year.

Dutch doctor Willem Einthoven developed the electro-cardiogram (EKG) to a point where it could be used in hospitals and doctor's offices. An EKG records the heart's electric activity. The data it provides helps doctors recognize an irregular heart rhythm and other heart diseases. It's a wide-spread method in modern medicine.

Austrian physician Karl Landsteiner discovered that mixing the blood of two different people often - but not always - led to clotting. He soon found the cause for that phenomenon: the different blood types A, B and O (which he called C). Later, his colleagues also discovered the blood type AB. Because of these findings, safe blood transfusions became possible.

Three Nobel Prizes went to the discoverers and developers of antibiotics, among them Alexander Fleming (1945), who discovered penicillin. Today, antibiotics are still some of the most commonly used drugs and often save lives. New kinds of antibiotics constantly need to be developed, however, as bacteria become resistant to the medicines.

The chemical compound DDT kills insects but hardly affects mammals, as Swiss chemist Paul Hermann Müller found out. Following that discovery, DDT became one of the most used insecticides worldwide. But then it turned out that DDT was damaging to the environment, especially to birds, and its use is now frowned upon. But it is still being used is places where mosquitoes are known to carry malaria.

German physician Werner Forssmann received the Nobel Prize together with two colleagues for the development of cardiac catheterization. Forssmann conducted the procedure for the first time on himself. It calls for inserting a tube into an artery in the hand, bend of the elbow or the groin, and pushing it up to the heart.

When you wanted to see the inside of a human body, there used to be only one way: X-rays. But by now, doctors have superior methods. One of them is computed tomography (CT), which also uses x-rays, but takes detailed pictures of the body's "layers" as if it were cut into slices. The discovery was followed by that of magnetic resonance tomography (MRI), which works with harmless magnetic fields.

Thanks to Harald zur Hausen from the German Center for Cancer Research, we know that the human papillomavirus can cause cervical cancer. This knowledge helped the development of vaccines against the virus. Girls and women can now be vaccinated against the viral type of cervical cancer.

Robert Edwards developed the in-vitro fertilization. The first baby that was created this way was born in England in 1978. Advancements improved the method's success-rate further. Globally, several million in-vitro babies have been born.

We all have natural defenses against tumors in us. We only need to release the natural brakes in the immune system. James P. Allison and Tasuku Honjo have laid the foundation for a cancer treatment in which tumors which have already formed metastases recede. At the end of the therapy, many patients remained cancer-free — a huge breakthrough.

William Kaelin, Peter Ratcliffe and Gregg Semenza discovered how cells sense and adapt to the availability of oxygen. When oxygen level change, cells undergo shifts in gene expression. Responses include cell metabolism, tissue remodeling and heart rate. It plays a role at high altitudes and has medical implications from exercising to pregnancy, altitude sickness and wound healing.