Darwin Day focused on evolution of viruses
Released: February 16, 2007
Eddie Holmes
Emerging diseases are a natural part of the past, present and future. Eddie Holmes, biology professor at Pennsylvania State University's Center for Infectious Disease Dynamics, discussed the historical influences, current and future threats of viruses at University of Wisconsin-Whitewater's annual Darwin Day celebration Thursday, Feb. 15.
Evolutionary biology provides a powerful framework for the study of emerging viruses. "Tracking back the lineage of a virus and understanding where it comes from is important," Holmes said.
Death by infectious disease has been common for hundreds of years. The best example of this is the Black Death of 1347 which killed 25 million people across Europe. Diseases continued to end people's lives across the world, until the 19th century with Louis Pasteur, Robert Koch and Joseph Lister's "germ theory" of disease. They said that viruses were the causes of infectious disease.
"This completely changed the threat of diseases, and the amount of death due to infectious disease went down considerably," Holmes said. "We thought we conquered infectious diseases, but that changed." Infectious diseases once again became difficult to control.
Many bacteria changed and became resistant to antibiotics, including E. coli and tuberculosis. By 1992, more than 50 percent of antibiotics that were given were unnecessary because they were given to people with viruses, and antibiotics are useless against viruses.
Viruses have been and continue to emerge and evolve. Influenza and the human immunodeficiency virus (HIV) are worldwide examples.
Most human pathogens come from other animal species. There is a plague transmission cycle, meaning that plagues have a bacterial cycle. A plague will often start in a flea, the flea will live on a rat and a rat will bite a human. For example, the Severe Acute Respiratory Syndrome (SARS) Coronavirus comes from horseshoe bats.
"HIV completely changed the plane; it shocked everyone," Holmes said. The first cases of HIV were reported in 1981 and since then have grown exponentially. In 2005, 4.1 million people, or 11,000 people each day, were newly infected. At the end of 2005, 38.6 million people around the world were infected with HIV. In some areas of Africa, 30 percent of people have HIV.
"The problem is that the virus makes a DNA copy and becomes a part of you," Holmes said. "It's extremely genetically diverse and evolves extremely quickly - one million times faster than DNA." HIV has a high mutation rate and there is a high production of the virus.
"Every possible mutation is produced every single day; mutation makes it so deadly," Holmes said. The mutations make it easy to track, though.
Where does HIV come from? Did the simian form, SIV, cause HIV? There are conspiracy theories and other thoughts of the origin of HIV, but it may have been from monkeys.
There are two types of HIV. HIV 1 is worldwide with most of its subtypes in Africa and HIV 2 is only found in Africa. A certain type of monkey is known to be the source of HIV 2 and a type of chimpanzee is the source of HIV 1. Hunting and poaching monkeys is a problem in parts of Asia, and the meat is sold at markets.
Influenza is another potentially deadly virus. Every year, 36,000 people in the U.S. die from influenza. Influenza starts in ducks and often transfers to other animals and then on to humans.
Currently, the H5N1 Avian Influenza A Virus is affecting Europe, Asia and Africa. Holmes predicts that the Avian Influenza A virus will eventually make its way to the United States.
"We will see many more diseases in the future," Holmes said. The changing of environments accelerates the evolution of diseases. These changes include deforestation, changing land use, the growth of cities, international travel and war. "Active disease surveillance and global cooperation is essential to understand the evolution," Holmes said.
While those who attended Darwin Day were students, faculty and community members, a large number of attendees were students. This was UW-Whitewater junior Erich Schoeller's third Darwin Day. "The crowd gets bigger every year," he said.
"I really enjoyed hearing about the evolution of viruses more than the history, and he brought up some really important key concepts to understand," Schoeller said. "Eddie Holmes made some good points and made it very understandable for the common person to understand."
Areas across the state also commemorated Darwin Day. In 2009, the 200th birthday celebration for Charles Darwin will take place statewide.- Abby Clark,clarkae12@uww.edu
