Planet of the Bugs: The Never-Ending Tale of DNA & Infectious Disease

PRODUCERS: Larry Massett

Humans are in a constant genetic arms race with microbes that make us sick. Can't we all just get along?

New & Noteworthy, 2007
by Jennifer Jongsma

In Planet of the Bugs: The Never-Ending Tale of DNA and Infectious Disease, The DNA Files looked at the ways in which genetic technologies have helped physicians disarm and possibly defeat the infectious diseases that have plagued us for centuries. In 1980, the World Health Assembly declared that smallpox had been eradicated globally. This successful pairing of genetic technologies and diligent public health efforts led to plans to eradicate many other diseases, including polio and measles. Although the global eradication of polio is expected in the next few years, scientists are confronted daily with new infectious threats. Viruses are especially quick to mutate, making them difficult to identify...and even more difficult to treat.

In 2001, Jon Kalish met with Rebecca Stevens, a caseworker for the National Tuberculosis Center in New Jersey. She visited TB patients to make sure they followed their treatment regimen. Patients that do not complete their treatment run the risk of having their TB turn into a multi-drug resistant form, which is much harder to cure. In 2007, a man from Atlanta, GA, who had just learned he had multi-drug resistant TB sparked a worldwide scare when he flew to Europe and back against the advice of the Centers for Disease Control. Travel by air (or any other mass transit) may be a convenient way to quickly reach your destination, but it is also a way for problems in one part of the world to quickly spread to other parts. Also, changes in the environment due to global warming are almost guaranteed to change the behaviors and geographic ranges of infectious diseases. According to Stephen Morse, a microbiologist at Columbia University, warmer temperatures may lure tropical viruses further north. Viruses that have been nearly eliminated in North America, such as yellow fever, could make an unwelcome comeback.

Influenza pandemics are nothing new; however, researchers are trying to make sure they are a thing of the past. Perhaps the most pressing threat is the highly infectious avian influenza A (H5N1) virus. So far, H5N1 virus has only rarely spread from person-to-person. Researchers believe that H5N1 may soon mutate to infect humans. If the H5N1 virus did gain this ability, an influenza pandemic could result, with potentially high rates of illness and death worldwide. Or, the organism might become less lethal as it becomes more infectious, as many viruses do. There is no way to predict which way a virus will mutate. In June 2007, the World Health Organization announced that it is working with vaccine manufacturers to create a global stockpile of vaccine for the H5N1 avian influenza virus.

The title of the 2001 program was right: Our battle against infectious disease probably will never end. Microorganisms like viruses and bacteria have been evolving, and will continue to evolve, just as quickly as we can come up with new ways to destroy them. We simply have to be prepared for the ones we know are out there right now.

Original Program Description, 2001

When scientists announced they had sequenced the human genome, much was made of our new potential to conquer the infectious diseases that have plagued us for centuries.

In this program, we hear from leading researchers in the field of microbiology who are using their knowledge of DNA to disarm and possibly defeat the bugs that harm and kill us.

Our host, John Hockenberry is sick and is looking for ways to banish all germs from his house. He dreams about meeting a spokesperson for the microbes who explains the interdependence between humans and germs.

Not completely convinced, John goes on a quest to find out how genetics might help us understand the relationship between microbes or bugs and humans. He also seeks to learn how we humans are using new genomic sciences to learn about the causes of various infectious diseases, how they make us sick, and how we can contain them.

To do this, he consults with experts in cholera and other food-borne diseases, tuberculosis and influenza.

He visits Rita Colwell, director of the National Science Foundation, who has found Vibrio cholerae, the bug that causes the deadly disease, cholera, in the waters of Chesapeake Bay. She studies how microbes adapt to be more virulent, or less so, depending on the environment they're in.

The University of Georgia Center for Food Safety's Mike Doyle then tells John about his work using chickens that carry Campylobacter, a harmful food-borne pathogen. Out of the thousands of birds he has examined, he's found just a few that do not carry the disease. It turns out they carry protective bacteria that keep the Campylobacter at bay. He hopes to culture these "probiotic" bacteria and use them in chicken feed to inoculate other birds.

Following John's adventures, producer Jon Kalish takes us on a tour of New Jersey's tuberculosis treatment program, called "directly observed therapy," or DOT. We meet a DOT caseworker who risks her own health to treat those at the bottom of the economic ladder. We also meet Dawn Motyka, a general practitioner from California, who tells about the pressure she gets from patients to prescribe antibiotics for viral illnesses like the flu - which cannot be remedied with such drugs.

Epidemiologist Robert Tauxe of the Centers for Disease Control and Prevention (CDC) describes how DNA tracking techniques are used to identify the flu strain hitting our country in a given year. This helps the agency design vaccines and gauge how deadly the virus is before it hits.

Finally, John Hockenberry takes us on a trip to Ellis Island, where European immigrants from the "great wave" (1892-1924) were quarantined if they showed any signs of illness.

Will we, or should we, ever get the advantage over pathogens? Or will the game of move-countermove just continue forever? Perhaps it isn't a matter of winning, but of minimizing damage.