The thrill of discovery came early in Sunil Shaunak's medical career. While at Duke University in the mid-1980s he remembers looking down a microscope and seeing the virus that eventually explained the AIDS epidemic.
Now, after 27 years of treating and researching infectious diseases at the Royal Postgraduate Medical School and then in the department of medicine at Imperial, he reflects on a career that has seen AIDS change from a deadly disease to one whose treatment is as routine as that of diabetes.
But infections still take a huge toll on human lives. "Even though doctors have a powerful arsenal of antibiotics, antivirals and antifungals at their disposal, patients are still dying," Professor Shaunak says. The reason, he asserts, is the over-reaction of the patient's immune system to the threat, which doctors call septic shock.
When the body is attacked by a dangerous microbe, cells of the immune system sound the alarm by releasing cytokines - powerful chemicals with a mission to seek and destroy the invader.
But some infections like E. coli and salmonella unleash such an excessive cytokine storm that the patient's blood pressure crashes catastrophically, multiple organ failure develops and death is often the result.
"It's a catastrophe that unfolds in front of your eyes," says Professor Shaunak. "We do a good job of killing the bug but we do nothing to control the excessive immune response of the patient," he adds.