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Archive for February, 2010

Changing Climate, Changing Infections

I will state my bias up front.  I am convinced by the preponderance of data in favor of man made global warming.  At the most simplistic level, I can’t see how converting humongous tons of fossil fuel into C02 and dumping it into the the atmosphere cannot have effects on the climate.  To my mind its like determining vaccine efficacy or evolution.  Plausible mechanism(s), good basic science, multiple studies using different lines of evidence that all come to the same conclusion.  There are lots of fine points and nuances to be worked out, but the basic truth is reasonable and well defined. Infectious diseases lend some validation to the concept that world is warming, since with global warming will come a variety of infectious diseases.
It is one big IF THEN statement.  IF global warming, THEN infections.  Of course the if the IF is not true, then the THEN doesn’t follow.
There is the weather, which the Action Channel News never seems to get right, and I will spare you the Mark Twain quote even though I think he is our best writer ever,  and there is the climate, the summation of weather over time.
Interestingly, infections have probably altered climate for short periods of times.  Through history humans burned trees releasing C02, chopped down forests for agriculture and raised animals, releasing methane.  As humans populations increased, both C02 from burning and methane from animals increased as well.  Every now and then large numbers of people have died off.  It happen when Columbus et. al. brought infections to the New World and when plague came to the Old.  People died.  Maybe 90% in the Americas (estimates vary widely) and 2/3′s of Europe died.  As a result, burning and agriculture decreased, decreasing emissions and forests grew back, sequestering C02.  And temperature rise slowed or decreased (http://stephenschneider.stanford.edu/Publications/PDF_Papers/Ruddiman2003.pdf).
“Abrupt reversals of the slow CO2 rise caused by deforestation correlate with bubonic plague and other pandemics near 200-600, 1300-1400 and 1500-1700 A.D. Historical records show that high mortality rates caused by plague led to massive abandonment of farms. Forest re-growth on the untended farms pulled CO2 out of the atmosphere and caused CO2 levels to fall. In time, the plagues abated, the farms were reoccupied, and the newly re-grown forests were cut, returning the CO2 to the atmosphere…Moreover, if plague caused most of the 10-ppm CO2 drops… it must also have been a major factor in the climatic cooling that led from the relative warmth of 1000 years ago to the cooler temperatures of the Little Ice Age.”
Like all good scientists, he notes the problems with his conclusions
“A more complete assessment of the role of plague- driven CO2 changes in climate change during the last millennium would require a narrowing of uncertainties in both the spatial and temporal occurrence of plague and in the amount of farm abandonment (and reforestation), as well as a resolution of the inconsistencies among the CO2 trends from different Antarctic ice cores.”
This kind of study will never be reported in the Atlantic; too much nuance.
It is not the correction for global warming I would suggest, an Earth Abides die off of humans.  But it is an fascinating association between infectious human deaths and global warming.
As the weather changes, for a week, a season, or a over longer period of time, the incidence and distributions of  infections change.  Infections could increase or decrease due to something as simple as temperature or humidity.
Or it could be more complex.  Increase rainfall could lead to more food, which could lead to a boom in the rodent population leading to more interactions of humans and mice and the next thing you know you have bubonic plague in India or Hanta virus outbreak in the four corners of the US.
The daily weather makes a difference in infection risk.  My favorite example is Legionella pneumonia, which increases shortly after thundershowers and humid weather.  It explains why we do not have a lot of Legionella in the NW despite all the rain; it is rarely hot and humid.
In Philadelphia  Legionella
“Cases occurred with striking summertime seasonality. Occurrence of cases was associated with monthly average temperature (incidence rate ratio [IRR] per degree Celsius, 1.07 [95% confidence interval [CI], 1.05-1.09]) and relative humidity (IRR per 1% increase in relative humidity, 1.09 [95% CI, 1.06-1.12]) by Poisson regression analysis. However, case-crossover analysis identified an acute association with precipitation (odds ratio [OR], 2.48 [95% CI, 1.30-3.12]) and increased humidity (OR per 1% increase in relative humidity, 1.08 [95% CI, 1.05-1.11]) 6-10 days before occurrence of cases.”
I ask the housestaff to look for Legionella after thundershowers and I usually get a case or two, although it may just be due to increased diagnostic testing.
Can you catch a cold when the weather is cold? Maybe.  It has been a topic of interest for years (http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2279651/)
“The average outdoor temperature decreased during the preceding three days of the onset of any RTIs, URTI, LRTI or common cold. The temperature for the preceding 14 days also showed a linear decrease for any RTI, URTI or common cold.  (http://www.ncbi.nlm.nih.gov/pubmed/18977127).”
More interesting are the infections associated with El Nino oscillations, where the ocean temperatures vary on a 3 to seven to year cycle, leading to alternating wet and dry weather.  As a result
“In North America, El Niño creates warmer-than-average winters in the upper Midwest states and the Northwest, thus reduced snowfall than average during winter. Meanwhile, central and southern California, northwest Mexico and the southwestern U.S. become significantly wetter while the northern Gulf of Mexico states and Southeast states (including Tidewater and northeast Mexico) are wetter and cooler than average during the El Niño phase of the oscillation. Summer is wetter in the intermountain regions of the U.S. The Pacific Northwest states, on the other hand, tend to experience dry, mild but foggy winters and warm, sunny and early springs.”
Changes due to the El Nino lead to changes in the incidence of a huge variety of infections: an example, I think, from WHO.
Climate change will affect the distribution of disease vectors such as insects and snails.  Vectors may thrive with increased temperatures or they may die off, but more likely the vectors, like mosquitos, will move.  It has been estimated that half of everyone who has every died has died from a mosquito borne illness (I admit I heard this numoerous times at ID lectures but do not have reference, at least there is a solution . http://mashable.com/2010/02/12/mosquito-death-ray-video/).  As it gets warmer, mosquitos can either go up in elevation or North.  It seems that they are doing both.
- Dengue has appeared at higher altitudes than previously reported in Costa Rica (at 1,250m),and in Colombia and India (at 2,200m).The previous range was temperature limited to approximately 1,000 metres above sea level.
- In Mexico, the dengue vector (Aedes aegypti) has been detected at 1,600 metres; transmission of dengue was unknown above 1,200m before 1986. There have been cases of dengue near or above the altitude or latitude limit of transmission and would be vulnerable to the small increases in temperature that have occurred across these regions.
- Other examples of climate-related changes in the prevalence or distribution of pathogens and their vectors include the resurgence of Mediterranean spotted fever in Spain and Italy, the recent epizootic of African horse sickness in Iberia,the resurgence of plague in parts of southern Africa,increased incidence and geographic spread of algal blooms, outbreaks of opportunistic infections among seals,and the spread and establishment of pathogens and vectors in Switzerland.  http://archive.greenpeace.org/climate/impacts/erwin/3erwin.html
- Dengue has, by serology, infected 40% of the populations of Brownsville Texas, as the disease slowly moves north.
“In the fall of 2004, during a period of endemic dengue transmission, a cross-sectional survey was conducted in these two cities,4 and dengue incidence and prevalence were measured. In Brownsville, the incidence was 2%, which, if extrapolated to the 2005 population of the city (using the 95% confidence interval), projected between 837 and 5,862 recent infections. Similarly, the prevalence was 40%, with a range from 56,948 to 75,372; these values are relatively similar to those obtained from Brownsville in 2005. http://www.ajtmh.org/cgi/content/full/78/3/361″
More than mosquito born illnesses are changing in prevalence.  Hanta is increasing in Belgium.  There has been increased temperature which has lead to increased broadleaf trees, with increased seeds, with increased voles, which carry Hanta, which infected humans to cause renal failure (http://www.ij-healthgeographics.com/content/8/1/1).
Oceans are getting warmer and supporting infections.  Vibrio was not found in Alaskan oysters as the water was too cold.  The water temperature was always less than 15 C.  No longer.  The mean temperature has increased each year since 1997  and now supports the growth of V. parahaemolyticus with resultant outbreaks (http://content.nejm.org/cgi/content/abstract/353/14/1463).  Many other infectious diseases are increasing as well http://www.thebulletin.org/web-edition/columnists/laura-h-kahn/the-threat-of-emerging-ocean-diseases.
However, not all is doom and gloom.  Some infections may fade with global warming. For example, RSV may be disappearing as England warms.
“The seasons associated with laboratory isolation of respiratory syncytial virus (RSV) (for 1981–2004) and RSV‐related emergency department admissions (for 1990–2004) ended 3.1 and 2.5 weeks earlier, respectively, per 1°C increase in annual central England temperature ( and .043, respectively). Climate change may be shortening the RSV season. http://www.journals.uchicago.edu/doi/abs/10.1086/500208.”
Diseases that may increase in the US or become endemic again include malaria, dengue, and Leishmaniasis.  A 4 degree rise in temperature could allow dengue to exist as far north as Winnipeg and malaria to be in all of Europe. Seems to be a good trade off to me: more dengue and malaria, less RSV.
Good times for an infectious disease doctor.
These studies are representative of the literature, not a comprehensive review of the topic.  Personally, I find this adjunctive data compelling  support of global warming, at least over recent times (deliberately worded to not commit to the meaning of recent.)  This does not include all the other potential interactions between human behaviors and changes in the weather to result in an increase in infectious diseases.  Even simple local changes can lead to the unexpected increase in the risk of diseases.
“Adjustable rate mortgages and the downturn in the California housing market caused a 300% increase in notices of delinquency in Bakersfield, Kern County. This led to large numbers of neglected swimming pools, which were associated with a 276% increase in the number of human West Nile virus cases during the summer of 2007.”   http://www.cdc.gov/eid/content/14/11/1747.htm
All the neglected pools became mosquito breeding grounds, and the disease spread was exacerbated in part by a drought that altered bird populations from resistant finches to susceptible sparrows that were not immune to west nile, allowing the disease to spread.  The result, I suppose, of failed flock immunity.
Imagine how war, human migration, starvation will interact with climate change to increase or alter the spread of malaria, Tb and some infection that no one can predict.  If H1N1 proved anything, it is whatever new infection will sweep  across the county, it will not be the infection we predict. Who would have thought in 1989 that the next decade would see West Nile virus, never seen the the US, arrive to the continent in a migrating goose and become endemic.
Maybe its just the weather, the season, or the climate.  I think these are a few interesting infectious disease associations that lend credence to climate change.

“Conversation about the weather is the last refuge of the unimaginative.” – Oscar Wilde

I will state my bias up front.  I am convinced by the preponderance of data in favor of man made global warming.  At the most simplistic level, I can’t see how converting humongous tons of fossil fuel into CO2 and dumping it into the the atmosphere cannot have effects on the climate.  To my mind its like determining vaccine efficacy or evolution.  Plausible mechanism(s), good basic science, multiple studies using different lines of evidence that all come to the same conclusion.  There are lots of fine points and nuances to be worked out, but the basic truth is reasonable and well defined. Infectious diseases lend some validation to the concept that the world is warming, since with global warming comes a variety of infectious diseases.

It is one big IF:THEN statement.  IF global warming, THEN infections.  Of course  if the IF is not true, then the THEN doesn’t follow.

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Posted in: Public Health, Science and Medicine

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Why You Can’t Depend On The Press For Science Reporting

I admit that the title of this post is a little inflammatory, but it’s frustrating when reporters call for input and then proceed to write unbalanced accounts of pseudoscientific practices. A case in point – my last post described a conversation I had with a reporter about energy medicine. My interviewee was very nice and seemed to “track” with me on what I was saying. I did my level best to be compelling, empathic, and fair – but in the final analysis, not a single word of what I said made it into her article. For fun, I thought you’d like to compare what I said, with the final product.

Here’s an excerpt from the article:

Disease has always been with us, but modern, Western medicine is only a few hundred years old.

Before germ theory and pharmaceutical research, the human race devised countless strategies to relieve pain, banish illness and prolong life. Southern Marylanders are keeping a few of these ancient disciplines alive, insisting they have much to teach us, even in a scientific age. (more…)

Posted in: Energy Medicine, Science and the Media

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Dr. Amy Tuteur has decided to leave Science-Based Medicine

The editors and crew at SBM have an announcement that needs to be made. This morning, Dr. Amy Tuteur tendered her resignation and will therefore no longer be a blogger at SBM. Some of you might already be aware of this development because Dr. Tuteur has already announced her decision on her own blog. That is why we considered it important to post an announcement here on SBM as soon as possible.

While we are sorry to see Dr. Tuteur go and wish her well in whatever future endeavors she decides to pursue, over the last several weeks it had become clear to both the editors of SBM and Dr. Tuteur herself that, although Dr. Tuteur had routinely been able to stimulate an unprecedented level of discussion regarding the issues we at SBM consider important, SBM has not been a good fit for her and she has not been a good fit for SBM. Over the last few days mutual efforts between the editors and Dr. Tuteur to resolve our differences came to an impasse. Unfortunately for all parties, that impasse appeared to be unresolvable and resulted in Dr. Tuteur’s decision to leave SBM.

As a result of Dr. Tuteur’s departure, we will be adjusting the posting schedule in order to cover her normal Thursday slot. Final decisions have not been made yet, but we expect that every weekday will continue to be covered, with at least one post per weekday. 

Posted in: Announcements

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Homeopathy Gets a Reality Check in the UK

The House of Commons Science and Technology Committee (STC) has released a report, Evidence Check 2: Homeopathy, in which they recommend that the NHS stop funding homeopathy. The report is a rare commodity – a thoroughly science-based political document.

The committee went beyond simply stating that homeopathy does not work, and revealed impressive insight into the ethical, practical, and scientific problems caused by NHS support for an implausible and ineffective pseudoscience.

The STC formed in October of 2009, and this is their second report. The goals of the STC itself are significant step forward:

The purpose of Evidence Check is to examine how the Government uses evidence to formulate and review its policies.

We certainly can use more of that.

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Posted in: Homeopathy, Politics and Regulation, Science and Medicine

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Chronic Fatigue Syndrome and Retroviruses: Jumping the Gun

When I first heard that a retrovirus had been identified as a possible cause of chronic fatigue syndrome, I withheld judgment and awaited further developments. When I heard that two subsequent studies had failed to replicate the findings of the first, I assumed that the first had been a false alarm and would be disregarded. Not so.

 It’s a classic case of wishful thinking outweighing good judgment. One unconfirmed report of an association between the XMRV virus and chronic fatigue syndrome (CFS) resulted in a rush to test for the virus, speculation about possible implications, and even suggestions for treatment. And the subsequent negative studies did little or nothing to reverse the trend. 

XMRV is Xenotropic murine leukemia virus-related virus. In the past, there were reports that this retrovirus was associated with prostate cancer, but then other reports found no link. In 2009 a study was published in Science, “Detection of an Infectious Retrovirus, XMRV, in Blood Cells of Patients with Chronic Fatigue Syndrome” by Lombardi et al., reporting an association with CFS:

we identified DNA from a human gammaretrovirus, xenotropic murine leukemia virus–related virus (XMRV), in 68 of 101 patients (67%) as compared to 8 of 218 (3.7%) healthy controls. (more…)

Posted in: Basic Science, Science and Medicine

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The fall of Andrew Wakefield

I must admit, I never saw it coming.

At least, I never saw it coming this fast and this dramatically. After all, this is a saga that has been going on for twelve solid years now, and it’s an investigation that has been going on at least since 2004. Yes, I’m referring to that (possibly former) hero of the anti-vaccine movement, the man who is arguably the most responsible for suffering and death due to the resurgence of measles in the U.K. because of his role in frightening parents about the MMR vaccine.

I’m referring to the fall of Andrew Wakefield
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Posted in: Medical Ethics, Neuroscience/Mental Health, Vaccines

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Rom Houben: Not communicating through facilitated communication

The news is finally filtering out to the rest of the world.

As Steve Novella and my good buddy pointed out a few days ago (and as Steve pointed out in an interview on NPR), Dr. Steven Laureys admitted that Rom Houben, the unfortunate victim of a car crash that left him in what had been diagnosed as a persistent vegetative state, was in fact not able to communicate through the woo known as facilitated communication. This came as no surprise to anyone who has followed FC over the years. In fact, what had come as a surprise is that Dr. Laureys could have been so easily taken in by pseudoscience that had been so thoroughly debunked in the 1990s. To his credit, though, after a period of initially stubbornly defending FC, he relented and allowed objective testing, and the result was predictable. It took a few days, but the English language world is learning of the failure of FC in Houben’s case:

The sceptics said it was impossible – and it was. The story of Rom Houben of Belgium, which made headlines worldwide last November when he was shown to be “talking”, was today revealed to have been nothing of the sort.

Dr Steven Laureys, one of the doctors treating him, acknowledged that his patient could not make himself understood after all. Facilitated communication, the technique said to have made Houben’s apparent contact with the outside world possible, did not work, Laureys declared.

“We did not have all the facts before,” he said. “To me, it’s enough to say that this method doesn’t work.” Just three months ago the doctor was proclaiming that Houben had been trapped in his own body, the victim of a horrendous misdiagnosis, and only rescued from his terrible plight thanks to medical advances.

What was not reported is that skeptics were involved in the testing of Rom Houben. I recently received a statement from the Belgian Skeptics (SKEPP):
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Posted in: Medical Ethics, Neuroscience/Mental Health

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Autism Onset and the Vaccine Schedule – Revisited

This week on Science-Based Medicine I wrote an article about a new study looking at the onset of autism symptoms, showing that most children who will later be diagnosed with autism will show clear signs of autism at 12 months of age, but not 6 months. This is an interesting study that sheds light on the natural course of autism. I also discussed the implications of this study for the claim that autism is caused by vaccines.

Unfortunately, I made a statement that is simply wrong. I wrote:

Many children are diagnosed between the age of 2 and 3, during the height of the childhood vaccine schedule.

First, this was a vague statement – not quantitative, and was sloppily written, giving a different impression from the one I intended. I make these kinds of errors from time to time – that is one of the perils of daily blogging about technical topics, and posting blogs without editorial or peer-review. Most blog readers understand this, and typically I will simply clarify my prose or correct mistakes when they are pointed out.

However, since I often write about topics that interest dedicated ideologues who seek to sow anti-science and confusion, sometimes these errors open the door for the flame warriors. That is what happened in this case.

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Posted in: Science and Medicine, Vaccines

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Longing for a past that never existed

There once was a time when all food was organic and no pesticides were used. Health problems were treated with folk wisdom and natural remedies. There was no obesity, and people got lots of exercise. And in that time gone by, the average life expectancy was … 35!

That’s right. For most of human existence, according to fossil and anthropological data, the average human life expectancy was 35 years. As recently as 1900, American average life expectancy was only 48. Today, advocates of alternative health bemoan the current state of American health, the increasing numbers of obese people, the lack of exercise, the use of medications, the medicalization of childbirth. Yet life expectancy has never been longer, currently 77.7 years in the US.

Advocates of alternative health have a romanticized and completely unrealistic notion of purported benefits of a “natural” lifestyle. Far from being a paradise, it was hell. The difference between an average lifespan of 48 and one of 77.7 can be accounted for by modern medicine and increased agricultural production brought about by industrial farming methods (including pesticides). Nothing fundamental has changed about human beings. They are still prey to the same illnesses and accidents, but now they can be effectively treated. Indeed, some diseases can be completely prevented by vaccination.

So why are advocates of alternative health complaining? They are complaining because they long for an imagined past that literally never existed. In that sense, alternative health represents a form of fundamentalism. Obviously, fundamentalism is about religion and the analogy can only go so far, but there are several important characteristics of religious fundamentalism that are shared by alternative health advocacy. These include:
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Posted in: Science and Medicine

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The Early Course of Autism

Understanding the natural history of a disease is an important framework to have. It not only is critical for prognosis, but also informs us about diagnostic and screening strategies, is important to assessing interventions, and provides clues to causation.

There has been much debate about the early course of autism, specifically the earliest age at which autism may be detected. At present scientific evidence suggests that autism is dominantly genetic, and so researchers expect that there may be early signs of autism even in infancy. Traditionally, however, autism is not diagnosed until age 2-3, when parents bring their children to medical attention, or when signs are detected on routine well-child visits or in day-care.

Retrospective studies, largely involving review of home movies, have suggested that autism can be diagnosed as early as 6-12 months, suggesting that parental report is not an adequate screen because subtle signs are hard to detect without rigorous observation.

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