Tuesday, May 5, 2009

Swine Flu: The Facts

Renowned Doctor Discusses Virus & Addresses Concerns

In an attempt to set the record straight about misconceptions regarding the swine flu, I requested an interview with Stephen S. Morse, Ph.D., one of the country's foremost experts on viruses and biological agents. Dr. Morse serves as Director of the Center for Public Health Preparedness at Columbia University. His professional interests include epidemiology of emerging infections (a concept he originated), international cooperation for infectious disease surveillance, and defense against bioterrorism. Dr. Morse recently returned to Columbia from four years in government service as Program Manager at the Defense Advanced Research Projects Agency (DARPA), Department of Defense, where he co-directed the Pathogen Countermeasures program and subsequently directed the Advanced Diagnostics program. Before coming to Columbia, he was Assistant Professor (Virology) at The Rockefeller University in New York, where he remains an adjunct faculty member.

G-Man: FOX News and MSNBC have featured medical experts who talked about the virus in standard medical jargon. I’d like you to break it down in layman’s terms so everyone will be able to follow you, doctor. What exactly is the swine flu?

Dr. Morse: The flu subtype called “H1” (after a key surface protein) has been found infecting both humans and swine. The notorious 1918 pandemic virus was a “swine”-like H1 flu. Its “offspring” circulated worldwide in the human population as the seasonal flu viruses, until H1N1 was displaced by the 1957 pandemic. H1N1 reappeared in 1977, and has been circulating (at low levels) in the human population since then.

Like humans, pigs can get the flu, and can sometimes carry the virus for long periods. H1N1 is one of the commonest subtypes in swine (as well as in wild waterfowl, which is where most influenza viruses usually live). The virus we’re seeing now is a variety of H1 that has not been identified before, in either humans or swine. It was called “swine” for convenience because it was clearly not a human H1 variety. However, further analysis of the virus suggests that it probably did originate in swine. Wherever it started, it is now spreading in the human population, from person to person. Most cases have been exactly like the usual influenza, but often relatively mild.

G-Man: Is it common for a virus to mutate from three different sources (like a pig, bird and human) or is this an anomaly?

Dr Morse: Yes. Flu viruses infect several different species of birds and mammals, and often swap genes. In this case, some experts believe that all, or most, of the viral genes have been in pigs for 10 years or more. This includes the avian (bird) origin genes in this virus, which have apparently been in pigs for all this time.

G-Man: What does the virus do to cause death?

Dr. Morse: We don’t know whether this virus is the one responsible for the deaths reported in April from Mexico. The virus grows in the upper respiratory tract. In general, only a small percentage of people infected with influenza may become severely ill and die. Usually, the people at greatest risk are the very young, the elderly or people with certain medical problems. Having the flu can cause additional stress on breathing and the heart that some of these individuals may not be able to withstand. Or some individuals may succumb to a secondary bacterial pneumonia after their respiratory tract’s defenses have been weakened by flu. More rarely, influenza itself can get into the lungs and cause a fatal pneumonia. In 1918, young, healthy adults also died, which is extremely unusual. We think death was caused by the body’s defense systems over-reacting and adding to the damage. Some scientists have suggested that secondary infections also played a role in these deaths, and may have been responsible in at least some cases.

G-Man: Students that were infected at St. Francis Preparatory School in Queens (NY) were treated and said to be doing well. They appeared to have a less severe strain. When looking at the cases in Mexico, could we be dealing with two different strains of the virus?

Dr. Morse: The St. Francis students appear to have recovered even without special medical treatment. What they had was a mild flu, just like the regular flu but with milder symptoms. The flu virus seems to be the same in California, Texas, and other places, where we’ve also been seeing mild disease so far. There were mild cases like this in Mexico, as well as the more severe. What caused the more severe cases – for example, changes in the virus or a different disease – is still being sorted out.

G-Man: Once a person becomes infected, how long do they have before the virus becomes potentially fatal?

Dr. Morse: Flu is only very rarely fatal. In fatal cases, the time it takes varies with the virus and the person. Most specialists recommend that people with very severe cases should get medication within 48 hours after onset of disease.

G-Man: If an infected person has other maladies, such as diabetes or hypertension, is the virus likely to attack their system, or possibly kill them, at a faster rate?

Dr. Morse: They may be at greater risk of death. Even then, only a small percentage of this group would die.

G-Man: If the infected person is on certain medications, could those meds counter the effects of the treatment(s) used to combat the swine flu?

Dr. Morse: Not usually, but it depends on the medications.

G-Man: The virus appears to be spreading rapidly throughout the country and the world. Honestly speaking, what percentage of the U.S. population do you suspect could be infected within the next six months?

Dr. Morse: It is currently impossible to predict. We can try to model (calculate) it mathematically, but there are too many variable factors for accurate estimates. In a pandemic, generally about 40-50 percent end up becoming infected.

G-Man: Is there any real way to contain this virus or track its origin?

Dr. Morse: Once it becomes available (in several months after the outbreak begins), vaccine will usually contain the epidemic. Until then, there are ways to reduce spread of the flu – stay home if you have an illness that feels like the flu, and, for those not yet sick, wash your hands, cover your coughs and sneezes, and try (if possible) to keep several feet away when someone is coughing or sneezing. In more severe situations, antiviral medication (like “Tamiflu”) can be given to the contacts (such as household members) of infected people to prevent further spread. This should usually be saved for situations where it will be most useful, to delay the virus’ developing resistance to the drug and to prevent depleting the supply of medications.

Tracking origin is difficult, but may be possible. We work backward to find the earliest cases, and if virus samples are available, compare the virus’ genes on a sort of “family tree” to see which is the closest to being the ancestor of the others.

G-Man: Michael Chertoff, former head of the Department of Homeland Security, as well as members of the 9/11 Commission, told members of the House and Senate that a chemical and/or biological attack by terrorists on American soil was “imminent”. Just last month, on April 22, CNN reported the following: “Missing vials of a potentially dangerous virus have prompted an Army investigation into the disappearance from a lab in Maryland. The Army's Criminal Investigation Command agents have been visiting Fort Detrick in Frederick, Maryland, to investigate the disappearance of the vials. Christopher Grey, spokesman for the command, said this latest investigation has found ‘no evidence of criminal activity.’ The vials contained samples of Venezuelan Equine Encephalitis, a virus that sickens horses and can be spread to humans by mosquitoes. In 97 percent of cases, humans with the virus suffer flu-like symptoms, but it can be deadly in about 1 out of 100 cases.” Doctor, if terrorists were able to gain access to these vials, would it be possible for them to develop a variation of swine flu virus, or any other type, from the Venezuelan Equine Encephalitis virus?

Dr. Morse: No. It’s theoretically possible, but extremely difficult, and it would be hard to ensure getting the desired results.

Photo Credit: Stephen S. Morse, Ph.D.