If an influenza pandemic sweeps across the globe, as many public health officials fear, it will take a combination of scientific work and political planning to handle it effectively, said Nobel laureate Peter Doherty at a lecture at MIT on Thursday, May 11.
Even if scientists can create a vaccine against the deadly disease, producing enough for everyone who needs it and distributing it efficiently will be enormous challenges, Doherty said.
"These are not simply scientific problems," he said. "It's really a matter of policy and logistics."
Doherty offered the 2002-2003 SARS (severe acute respiratory syndrome) outbreak as an example of a fairly successful handling of a new infectious disease. In that case, scientists were able to figure out quickly what was causing the disease and take measures to contain it.
Doherty, who has spent his entire professional life studying infectious diseases, won the Nobel Prize in Physiology/Medicine with Rolf Zinkernagel in 1996 for discovering how T cells recognize their targets. He now has laboratories at the University of Melbourne in Australia and St. Jude Children's Research Hospital in Memphis, Tenn.
In his May 11 lecture, titled "Plagues, Pestilences and Influenza," Doherty, a native of Australia, offered some historical background to the current avian flu scare.
A strain of avian flu known as H1N1 is believed to be responsible for the 1918-1919 influenza pandemic that killed 40 million people around the world. Public health officials fear the avian flu strain (H5N1) that is now infecting birds in Asia and Europe could mutate to a form that spreads easily from person to person, leading to another deadly pandemic.
"If it did, we're worried it could be very severe and very dangerous," Doherty said.
Unlike the typical flu, which kills about 36,000 people in the United States each year, mostly the elderly and very young children, the strain that caused the 1918 outbreak was most deadly in young adults. That's because it provoked a very rapid immune response called "cytokine storm," which leads to blood leakage and shock, according to Doherty. "People essentially drowned in their own body fluids," he said.
That quick death actually causes influenza pandemics to eventually burn out, as carriers die before passing on the virus. "Generally it's not beneficial for pathogens to kill their hosts," Doherty said.
Smaller flu outbreaks in 1957 and 1968 also followed genetic mutations in the influenza virus.
Human history has often been shaped by periodic outbreaks of infectious disease, according to Doherty. "Infectious disease has always been a major force in human evolution, particularly after we started to develop villages and cities," he said.
The worst infectious disease outbreak in recorded history, the bubonic plague that struck Europe during the mid-14th century, killed one-third of the continent's population.
Even that long ago, people had a concept of contagion, but they didn't know anything about the existence of microorganisms and how they carry disease, Doherty said. Lacking any knowledge of infectious agents, people came up with their own theories of how diseases spread. Jews were persecuted because they were suspected of poisoning drinking wells, and women believed to be witches were burned.
Ignorance about diseases like rabies probably also gave rise to myths about monsters, Doherty said. "It's almost certain that the Dracula legend arose from rabies," which causes an aversion to light and voracious sexual appetite, he said.
It wasn't until scientists developed the germ theory of disease in the late 19th century that people realized diseases were carried by microorganisms, including bacteria and viruses.
Many of those infectious agents, including those that cause AIDS and Ebola, originated in animal hosts and jumped to humans.
Human behavior and population growth also play a large role in the emergence of new diseases and the spread of familiar ones, Doherty said.
As human populations grow and people encroach further and further into areas that used to be primarily animal habitat, they are exposed to more diseases carried by animals, Doherty said.
And air travel makes it possible for diseases like SARS, which originated from civet cats sold in a Hong Kong marketplace, to rapidly spread all over the globe.
Human behavior, in particular sexual behavior, has been a major factor in the spread of AIDS, Doherty said. With effective health education programs, the disease's spread has been slowed in countries like Senegal and Thailand, while similar efforts have failed in Uganda and other countries due to pressure from religious groups, Doherty said.
"AIDS really exemplifies both the triumphs and limitations of modern science," he said. If AIDS had emerged as little as 75 years ago, scientists would have had no way to figure out what was causing the disease, much less create drugs to treat it and take measures to protect the blood supply, Doherty said. On the other hand, researchers still are not close to creating an effective vaccine to prevent the disease.
Before and after his lecture, which was sponsored by Advance, a networking organization for Australians living abroad, Doherty signed copies of his new memoir "The Beginner's Guide to Winning the Nobel Prize."