Swine flu--still spreading

As expected, new potential cases are being investigated in several states, including an additional possible case in Northern California, 2 potential cases in Indiana, a potential case in Ohio and another in Michigan [updated: and some in Massachusetts too]. New York has also confirmed 20 cases now, and 17 more are suspected (check here for additional information--updated as new cases come in and are confirmed or ruled out). Around the world, four in France have apparently tested negative, as have two potential cases in Australia, while 2 in Scotland have been confirmed positive. In Mexico, the current numbers put it at over 100 deaths and above 1600 suspected cases (again, not all of those laboratory confirmed).

(More on these after the jump...)

It's difficult to be in the midst of this, to know a lot about flu and all the worst-case scenarios, while at the same time to provide some balance and trying to avoid over-hyping anything. According to a CDC conference call PalMD is twittering (tweeting? I'm new at this), there are 40 confirmed US cases, most of them mild, so that's something to keep in mind for now. And around the web, there are reminders that (cue the Battlestar Galactica themesong) all this has happened before, and will happen again (so say we all). However, that doesn't mean that the wait for more data is any less frustrating or scary for those in the midst of it, particularly those living in or near affected areas.

I say this especially because one of these affected areas--the case being investigated in Wood County, Ohio--is where most of my family lives, including my pregnant sister and her sons (ages 3 and 1), and her husband who has diabetes (can you find a family with more risk factors combined?) So I am incessantly refreshing my browser, looking for updates and more information. I remember doing this as a graduate student during the SARS outbreak and combing the internet for the latest news, but this one hits home in more ways--being so close to some of the world's experts on swine flu; doing research involving swine myself; and having this in my hometown backyard. Despite all this, I remain in the concerned-but-monitoring-the-evolving-situation stage, and my logical self even resisted telling my sister to take her family and head for a remote cave somewhere. However, she's already well aware of my advice on handwashing...and hopefully heeding it.

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Your coverage of this swine flu issue is really appreciated. It's been difficult to get scientific, in-depth, un-hyped information on the MSM. Also, you get a gold star on your geek card for tying BSG into the swine flu epidemic - excellent use of the quote.

We keep hearing that the effects of the flu seem to be milder here in the U.S. than in Mexico. Granted, this is more anecdotal than it is data-based, but for the purposes of my question I'll treat it as true. I haven't seen any coverage of why this might be true, except for some people saying that it's possible that the flu could lose some of its virulence as it's transmitted (doesn't sound all that plausible to me). Could the apparent difference in harm be due to differences in general health of the populations being affected - that is, perhaps the people in Mexico aren't quite as healthy as the U.S. citizens that have picked up the bug? Also, another thing I haven't heard mentioned is latent (or active) TB infections, which (I believe) are much more prevalent in Mexico.

My point here is that it seems like everybody is waiting for the other shoe to drop here in the U.S., Canada, and the U.K. - that we'll start seeing significant numbers of people die, and infection rates climb - but perhaps our populations just aren't as primed for this type of opportunistic infection as, perhaps, the population of Mexico.

If the US has a population of 300+ million and 36,000 flu related deaths per year (according to the CDC), then with a population of 110 million Mexico probably has about 12,000 flu deaths per year or 1,0000 per month.

According to this morning's WaPo, there are 103 official deaths from the flu in Mexico, with all of the victims being aged 25-50. The article goes on to note that "President Felipe Calderón said Sunday that of the 1,324 patients with flulike symptoms as of Saturday, 929 have been treated and released from the hospital."

So trying to tease out rough numbers in a fast moving situation, Mexico is officially counting 103 deaths (let's use a timeframe of a month) with roughly 1,324 patients hospitalized and 929 of those treated and released already.

In a typical month historically, Mexico probably has about 1,000 deaths from the flu and while the majority of those patients are probably outside of the ages of 25-50, not all of them are . . . . if just 10% of the flu related deaths in a typical year in Mexico are in the 25-50 age bracket, that's 100 flu related deaths per month aged 25-50.

So, I'm starting to have a hard time seeing this flu in its current incarnation (which I think I had and recovered from with no problems, though Relenza gets a H/T after the 2nd day) as anything more than a unique strain of Type A H1N1, suggesting that any prior flu vaccinations and natural exposures provided little or no protection and so this flu kicks like a country mule, as they say back home, but doesn't do any more lasting damage than THAT.

Isn't that a serious problem with the current CDC approach, which misses nearly all of the mild/moderate cases of swine flu and even misses most of the severe cases not requiring hospitalization? Because deaths and hospitalizations are high profile events that get attention and testing the numerator in the ratio is accurate, but the denominator is wildly, grossly completely understated to the point of meaninglessness.

I think the key to understanding the difference between Mexican and American/European swine flu behavior is simply that the Mexican numbers are total nonsense. First of all, they don't have the means to recognize swine flu by DNA, so they have to send samples to labs in other countries. Now we have more "confirmed" cases in the USA than in Mexico simply because the USA are capable of doing more proper testing!

Because the Mexicans do not have useful verified numbers, they are now declaring every severe pneumonia case (and possibly other similar illnesses) to be a swine flu case - that gives a minimum of 2,000 suspected infections, and the deaths in those give the suspected death toll of currently 149.

So that means that, unless 100% of swine flu victims develop pneumonia, there are potentially MANY more infections than have been reported! If say 5% of infected people develop pneumonia, then there are really 40,000 rather than 2,000 infections in Mexico. This means the disease will be much harder to contain, but it also means that the mortality is MUCH lower than reported.

On the other hand, it can also mean that other diseases are being mistaken for the swine flu.

And then we have some people who claim to be doctors in Mexico and who say there are more deaths than have been reported: http://news.bbc.co.uk/2/hi/talking_point/8018428.stm (on Sunday someone wrote there are probably 200 rather than the 20 reported cases)

So you can look at it any way you want and the Mexican numbers are very inconclusive, and at least mortality is probably lower than reported especially if you compare with the numbers from other countries.

Just want to echo thanks on your coverage/analysis of this--folks here in NYC are starting to panic over the Queens cases, and real, rational info is surprisingly hard to find.

Certainly Mexico, like many other less prosperous countries, has its share of illnesses. Mexico City in particular has some of the worst air pollution in the world, hence a variety of respiratory illnesses. And the poor in that city do not have adequate health care and so may suffer from many untreated or undiagnosed illnesses.

On the other hand, let's note that China and Southeast Asia, the usual breeding grounds for new flu variants, also have more than their share of health problems and poverty, yet I do not recall that flu in those areas was particularly more virulent than it was when it arrived in the richer nations.

I share Tom's concern that the numbers coming out of Mexico are "total nonsense." What the press is doing with them simply compounds the problem. Much of the panic out there is being fostered by coverage such as that of CNN. CNN has waged a continual media blitz against Mexican products, Mexican truck drivers, Mexican immigrants, Mexican drugs, Mexican what have you. Now its Mexican swine flu. CNN and other networks have pushed the Mexican authorities to give answers to questions when they lack the technical resources in Mexico to answer them definitively. And so, even well informed sources (such as this blog) talk of "suspected cases." You can make too much of "suspected cases." CNN does -- time and again.

This rather reminds me of the treatment Haiti received in the early days of HIV. Haiti was initially viewed as the probable source of HIV, Haitian Americans were shunned and discriminated against, and travel to Haiti came to a near standstill. Until the data was looked at more carefully.

By Paul Heikkila (not verified) on 27 Apr 2009 #permalink

New Zealand's Science and Media Centre also has some useful coverage, see:


There are several long articles with scientists observations/remarks that some here might find worthwhile.

NZ had one of the earliest groups of people outside of the Americas with likely positives, a group of foreign language students returning from a visit to Mexico. They have tested positive for influenza A and confirmation if they carry the current swine flu is underway. These people are currently under home quarantine.

By BioinfoTools (not verified) on 27 Apr 2009 #permalink

As Mark Twain or someone like him once wrote, "there are lies, damn lies and then there are statistics".

Noodling the data again, the WSJ reports this:

"Nearly 2,000 people in Mexico have been hospitalized with serious cases of pneumonia since the first case of swine flu was reported two weeks ago."

Ok. So according to the NCHS and CDC, the U.S. had approx. 1.3 million hospitalizations due to pneumonia in the US 2002 (2001 National Hospital Discharge Survey, NCHS, CDC). The U.S. population is older than Mexico's and so our pneumonia patients probably have a hospitalization rate that's higher than theirs, so let's use 1.3 mil./300 mil. and multiply by the Mexico population of 110 million * 0.5 -- conservatively guessing that their hospitalization rate for pneumonia is half that of the U.S. due to younger age. That gives an annual estimate of pneumonia patients in Mexico hospitalized of about 240,000 people. So the monthly rate in a typical year could be around 20,000 per month or maybe 10,000 per half month.

Why exactly are we supposed to be surprised that there are nearly 2,000 people in Mexico hospitalized with severe pneumonia over the past two weeks, when that number (if accurate) is in line if not lower than typical experience. It's a country of 110 million people, after all.

Sometimes the total cluelessness of the MSM makes my teeth hurt . . . . . .

Last year June 2008 I had a flu like I have never had before. I was staying in a motel in Harlan Iowa. I came back to my room one afternoon and found a cold tablet that the maid had dropped on the floor. The maid was a foreigner and didn't speak English, the owners were Arab but I don't know if the maid was Arab or Mexican.
Driving back to my home in Missouri I had a dull headache but soon had a sore throat mostly one one side, then that night I had a runny nose, fever, tiredness, muscle aches so bad that my skin even hurt. This lasted for about 8 days and on the 8th day I had 2 glands that swelled up in my neck under my ear and one in my lower back.
My doctor gave me antibiotics helped me to recover faster and it did help.
I have never had anything like that before that lasted that long...I'm now wondering if I have this Swine Flu back then.

"This rather reminds me of the treatment Haiti received in the early days of HIV. Haiti was initially viewed as the probable source of HIV, Haitian Americans were shunned and discriminated against, and travel to Haiti came to a near standstill. Until the data was looked at more carefully."

I can't talk about how Hatians were treated during the first stage of the HIV epidemic since I wasn't really around (I was four years old or so) but I think studies on the actual virus circulating in the US have pretty conclusively shown that while HIV originated in Africa, it was brought into the US via a Haitian immigrant.

Hi Tara
I work in the medical field in the uk and have read several of your articles regarding the swine flu - finding them very interesting.
Do you know whether these cases idenitified in the US and further afield have exactly the same genotype as those cases in Mexico and are they mainly in people who have been to Mexico or have had contact with people who have been to Mexico? The reason for asking is it seems from your articles that swine flu has been identified previously in other communities and therefore Mexico might not be the only source of the recent "outbreak".
Many thanks


I wonder if Influenza A/H1N1 is really spreading, or are we just discovering it? Perhaps it's been around a while and we just didn't know enough to look for it, especially if it were a relatively benign condition as it appears to be everywhere but Mexico.

Mexico didn't realize they had it until they sent samples off to CDC. Much of the world lacks the facilities for such tests. It may be much more widespread than it appears to be, but those who have it who have not had contact with Mexico may not be tested for it. We're not doing random testing, are we?

A flu's eye view of this would say nothing much is going on. From the point of view of relatively wealthy humans in the USA unaccustomed to death at an early age the sky is falling (or at least the weather is threatening). If there hadn't been a media frenzy this flu could have gone about its business and none of us would have been the wiser.

By Paul Heikkila (not verified) on 30 Apr 2009 #permalink