John Hockenberry: Good morning everyone. If you want to assess the significance of the Swine flu outbreaks around the world, take a look at a map. We've got 50 cases in the United States, many, many more in Mexico. Mexico is the epicenter but it's broadened out from there. There are cases as widely diverse and scattered as New Zealand and Israel. The last few days have been a jumble of numbers and facts about Swine flu. We've tried to keep them in line. Joining us once again is Dr. Richard Wenzel, who's the Virginia Commonwealth University Chairman of the Department of Internal Medicine and an expert on infectious disease. He joins us from Richmond. Dr. Wenzel, first of all, if you look on a map what's the most important thing to pay attention to, the number of fatalities in any particular place or the speed and direction whereby this virus seems to be moving?
Dr. Richard Wenzel: I think two issues. One is we're at least in four continents in terms of how far the virus has spread. And secondly, I think the real key is what's going on in Mexico. Why are people dying there when it looks mild elsewhere? And I think what's really going to be important to know is what's the cause of death there? Is it the virus or is it some secondary bacterial pneumonia?
John Hockenberry: Now is this a problem with information coming out of Mexico, that possibly there are some bottlenecks in getting this information? Or is there something unique about the specific setting where these fatalities occur?
Dr. Richard Wenzel: Well, maybe both. As I look at it from a distance, I mean we have the same virus attacking the same age group in both the United States and Mexico, and the difference is outcome is severe in Mexico, so it's got to be the patients. And then, do they have some unusual susceptibility, we're partially protected? I doubt it. Is it more likely that there's some secondary bacterial pneumonia, that's a possibility. And the last might be, you know Mexico City has horrible pollution, we know that, and pollution has been related to worse outcomes in other countires like England and Ireland and Scotland.
John Hockenberry: Now one of the restraints on Avian flu, apparently in preventing it from being transmitted, was that really people needed to be in contact with infected birds, and really it involved them actually being in the slaughterhouses in some cases. Is it possible that these fatalities in Mexico relate to some proximity to pigs that might increase the viral load and increase their susceptibility to death that wouldn't be the case, say, in New York?
Dr. Richard Wenzel: I think that's unlikely, because most of the people are in the center of Mexico City, a huge, urban metropolis with 20 million people. Aren't living with pigs, outside I would say that's more likely. This is person to person spread of a pig virus that has elements of human and avian genes with it, so it's really not so much pig to man anymore.
John Hockenberry: Now the Centers for Disease Control, echoing some of your head scratching spoke yesterday on this issue of the difference between the spectrum in Mexico and here in the United States. Listen to what Dr. Richard Besser was saying, and I want to get your response here.
Dr. Richard Wenzel: Sure.
Dr. Richard Besser [on tape]: That is a critical question. What we need to understand is why we're seeing a different disease spectrum in Mexico that what we're seeing here. I wouldn't be overly reassured by that. There are many reasons that could explain that and as we gather information we hope to sort that out. I wouldn't rest on the fact that we have only seen cases in this country that are less severe. As we continue to look I expect that we will see additional cases, and I expect to see that spectrum of disease will expand.
John Hockenberry: Dr. Wenzel, I mean if that doesn't occur, if there aren't fatalities elsewhere, is it more of a mystery than actually getting to the bottom of how to treat this particular virus if it does spread and the fatalities do spread?
Dr. Richard Wenzel: Well, if it turns out that all the disease is mild in the United States or New Zealand or Canada and Europe, than we've got to focus on what's different about Mexico, then I would say that there's something unusual there, it's either for some reason they have secondary bacterial pneumonias at a huge rate, and that's always a difficult problem, or maybe the damage to the air weighs locally there. I think the acting head of the CDC was being cautious, but as the numbers expand and we continue to see mild cases, then we have to turn to focus back and see what's different about the patients in Mexico.
John Hockenberry: Before we let you go I want to ask you one question about the incubation of this virus. Do we know what the incubation time is, and how does that inform people like myself in figuring out what preventive measures to take, should we think we possibly come in contact?
Dr. Richard Wenzel: Well usually with flu it's two or three days, but up to a week. So, beyond the week you're safe after exposure to a particular person who's infected, so that's why President Obama is safe from his trip to Mexico. It's well over a week.
John Hockenberry: That's interesting. Dr. Richard Wenzel, thanks for joining us. Virginia Commonwealth University Chairman of the Department of Internal Medicine who's been helping us to understand what's going on in these outbreaks around the world. Thanks so much, Doctor.
Dr. Richard Wenzel: Thank you so much.
