Archive for the ‘Infectious Diseases’ Category
But one thing remains true: “People have a very weird perception of large numbers,” [Dr. Brockmann] said. “If you have 2,000 cases of flu in a country of 300 million, most people think they’re going to be one of the 2,000, not one of the 299,998,000.”
I think people have a wierd perception of risk, and that is often influenced by media attention. Which reminds me of a memorable article from the New York Times Op-Ed page in 2003 – remember West Nile Virus? “Never Bitten, Twice Shy – The Real Dangers of Summer” by Ropeik and Holmes.
Yes, the graphic is not perfect (see this critique at Edward Tufte’s blog), but does get across the idea that risk perception is not always influenced by the facts. And is expanded in this article in Health Affairs “Dealing with the Dangers of Fear: The Role of Risk Communication” by Gray and Ropeik.
Ok, but what about the facts? The fast moving breaking news often plays fast and loose with the truth, and can spread alarming information. Early reports of the swine flu in Mexico seemed to have extremely high mortality reports, especially among young adults. Now, with new evidence of confirmed cases, the virus is looking alot milder. When I first read that influenza virus could survive for 10 days on money, I thought it was another casualty of the truth, as the avian-human-swine flu reported in a press briefing by the CDC. However, in this case, the facts seem to check out (Survival of Influenza Virus on Banknotes, Thomas et al), unlike the potluck origins of the swine flu which ProMED reported to be, upon closer examination – just swine flu.
More on risk perception:
Here’s a conversation with David Ropeik in the New York Times, and he wrote a book with George Gray – Risk: A Practical Guide for Deciding What’s Really Safe and What’s Really Dangerous in the World Around You
Reckoning with Risk: Learning to Live with Uncertainty – Gerd Gigerenzer
Thermal scanners purchased after the SARS outbreak have been mobilized for border screening. Super-cool, but do they work to stop the spread of an epidemic?
The New York Times led with this image, but now the story link has been updated. Here’s the original text by Donald G. McNeil, Jr. on border controls:
Given extensive human-to-human transmission, the World Health Organization raised its global pandemic flu alert level on Monday, but it recommended that borders not be closed nor travel bans imposed, noting that that the virus had already spread and that infected travelers might now show any symptoms.
However, many countries are tightening border and immigration controls, and on Tuesday Britain advised against any nonessential travel to Mexico. Japan announced that it would no longer allow Mexican travelers to obtain visas upon arrival. The United States, France and Germany have also warned against nonessential travel to Mexico.
Here’s my understanding of how it works: the thermal scanner camera detects infrared radiation (IR). Basically any object emits IR which intensifies as it gets hotter. The camera has a sensor which detects IR and converts it into a temperature reading. In this system it does it visually.
However, when you first get flu, you don’t have a temperature, and the thermal scanner only measures skin temperature on your face, so an early fever (which raises your core temperature) is also not detectable.
So – does it work? Work done by Bitar et al as a followup to SARS control was published in February 2009: International travels and fever screening during epidemics: a literature review on the effectiveness and potential use of non-contact infrared thermometers In the early stages of a pandemic when less than 1% of people will be feverish, fever screening at the border is of limited use – from the paper “When we fixed fever prevalence at 1% in all studies to allow comparisons, the derived positive predictive value varied from 3.5% to 65.4% ” So thermal scanners aren’t very useful when very few people have fever.
However, check out this view from William Saletan in Slate: Heat Check – Swine Flu, Body Heat and Airport Scanner
On another note, I’m wondering why journalists don’t seem to have quick access to infectious disease specialists. In the New York Times, an environmental health epidemiologist is quoted in the debate, and here in the Cape Times, a sociologist who now specializes in the public understanding of biology. Where are the infectious disease experts? Maybe the CDC needs to draw up a list of media contacts among their top virologists and infectious disease specialists. Maybe part of science education should be a course in writing on science for the public, as well as how to write (and read!) papers.
Swine flu is in. In the rush to cover this latest possible pandemic, newswires are alive with activity, blogs and social networking sites are buzzing, and the CDC and WHO are back in the limelight. This despite the fact that the number of cases are limited (only 40 confirmed infections have occurred in the US).
The rush of news has been accompanied by a rush to track that news. The WSJ, amongst others, has a tracking website, including a map of infections in North America. Best of all, Google has a map showing how the infection is traveling.
This rush was started by Google Flu Trends, a website that tracks flu-related search queries to estimate influenza levels in different US states. Further studies suggested the same approach might work for other diseases as well.
Analyzing Google Trends
So how has Google Trends, the broader application of the Flu Trends concept, performed in the current scenario? A quick analysis shows that Google search results did in fact increase over the past few days (see chart – source: Google Trends).
A quick analysis shows three items worth mentioning:
- First, while Google Trends does show an increase in search activity on “swine flu,” the first uptick in activity only occurred on April 23. By contrast, the first news stories appeared on April 21 when two cases were confirmed in California.
- Second, Google Trends reports that the majority of search queries were from New Zealand, USA, UK, Canada, and Australia. Only a very small minority were from Mexico. Yet, Mexico is the country supposedly at the heart of the pandemic.
Explaining the Discrepencies
I had used a Google Trends like methodology two years ago to track the evolution of climate change as an issue in news coverage. Having worked on that, I can propose a few general reasons that explain why Google Trends is limited in this case.
First, it appears that Google Trends follows with some time lag, actual infections. This should not be surprising, as people are not likely to search for a disease before having had some exposure to it. This does not mean that it is not a useful tool for tracking diseases over the long term. At the very least, the response time of a system based on GT might be lower.
Second, the current scenario shows that Google Trends is highly susceptible to “noise.” Prior to this outbreak, swine flu was probably not a commonly known disease, and queries on it were extremely rare (if not non-existent). Thus, even the slightest uptick in search activity would show up as a major change. That uptick was provided by the highly charged media coverage of the subject. Given this, one wonders if the search results are more “noise” and less people with a genuine interest in the subject. So, Google Trends is likely to be more accurate where general knowledge of a subject (the baseline) is high, and media coverage (noise) is low.
Finally, and most interestingly, why is it that most of the search results came from the US, while Mexico is more exposed to it? Not surprisingly, this methodology only works where both a large number of the population and media are on the internet.
What Next for Google Trends?
When discussing why most search queries occurred in the US, it is worth noting another fact about the swine flu outbreak – that it has traveled extremely fast. Originating in Mexico, it has been carried to the USA, Spain, and New Zealand. This brings into question the validity of using the geographic source of search queries as a reliable indicator of where the disease actually is.
Still, it may also offer a way to enhance Google Trends. What if Google Trends data was combined with travel data on the number of people traveling from a “hotspot” of an infectious disease. It would be logical to assume that popular destinations, or ones which receive travel groups, would be the most likely next locations for further infections. Thus, a map could potentially be created of not only where the disease is generating interest, but where it might be headed.
Of course, Google does not have access to such data – though at some point it may decide to acquire a travel operator. But the general lesson is simply that to make Google Trends more useful, search query data needs to be looked at together with real-world data (such as travel data or hospital records).
It is still early days for the swine flu outbreak, but some commentators are already suggesting the “social web” has actually created hysteria rather than help track the disease. That may be true, but it is hardly a problem of the “social web.” As a reader on the FP pointed out, “Twitter is only a natural extension of a typical neighborhood.”
So, in this “typical neighborhood,” what the swine flu outbreak has done is illustrate where Google Trends does well – in tracking general interest amongst heavy Internet users. But it also exposes limitations – the methodology is (not surprisingly) susceptibility to “noise” from media coverage and is biased towards countries and issues that are online. This does not mean that the idea itself is flawed. Just that it must be taken with a pinch of salt, and that it needs work – especially interfacing it with real-world data streams – to make it really useful.
First, a bit of housekeeping – we are tinkering with the look of the blog and considering moving it to another platform, if you have any feedback about what you like and don’t like, let us know.
Published today in the CMAJ, Early detection of disease outbreaks using the Internet, is worth skimming:
“The Internet…is revolutionizing how epidemic intelligence is gathered, and it offers solutions to some of these challenges. Freely available Web-based sources of information may allow us to detect disease outbreaks earlier with reduced cost and increased reporting transparency. Because Web-based data sources exist outside traditional reporting channels, they are invaluable to public health agencies that depend on timely information flow across national and subnational borders. These information sources, which can be identified through Internet-based tools, are often capable of detecting the first evidence of an outbreak, especially in areas with a limited capacity for public health surveillance.”
The limitations section includes the below list, but I wish they went into much more detail about what the internet is not good for (probably detecting trends among the elderly for example) and more examples of misinterpreting the data. On a related note to using ICTs for surveillance, Jaspal wrote a fairly detail post on Google Flu Trends that you should also check out.
It’s been more than two years since we reported on Seattle as the new Geneva, that is, as the new epicenter of global health activity. An article in this morning Journal-Sentinel (Water-engineering firms see potential, challenge in developing countries) – which includes an exclusive interview with the Acumen Fund’s chief executive Jacqueline Novogratz – suggests that Milwaukee is angling to do the same for water technology:
It’s an issue that almost certainly will preoccupy business leaders in metro Milwaukee in their strategy to brand the region as an international hub of water technology. The metro area is home to scores of water-engineering companies. Gov. Jim Doyle and the University of Wisconsin-Milwaukee this month announced plans to invest millions of dollars for UWM to become a center of freshwater research.
An 2008 article from the same newspaper (Area’s tide could turn on water technology) provides more evidence:
[F]our of the world’s 11 largest water-technology companies have a significant presence in southeastern Wisconsin, according to an analysis of data from a new Goldman Sachs report.
Wall Street has tracked automakers, railroads and retailers almost since there were stocks and bonds. But water remains a novelty. Goldman Sachs Group Inc. didn’t begin to research water treatment as a stand-alone industrial sector until late 2005.
While several large MNCs have shown an active interest in clean water in developing countries (e.g., Procter and Gamble, Vestergaard Frandsen, Dow) open questions remain as to what role large MNCs will play in providing access to safe water for the one billion people who don’t have it.
(Thanks to Dr. Jessica Granderson for sending the link)
Last Thursday, I had the opportunity to view a PhotoVoice exhibition at the University of California, Berkeley organized by Haath Mein Sehat (HMS), a group working to improve access to clean water and sanitation in six slums of Hubballi and Mumbai, including Dharavi.
It was exciting to see a group effectively blend the advocacy elements of PhotoVoice with the design elements of cultural probes. The difference between the two approaches is less in the methods and more in the use of the outputs. In this case, they organized the exhibition to raise awareness and break down stereotypes of slum life, and they are using the photographic corpus to guide the design of both programs and technologies related to their core mission.
What I was most interested in from a design perspective were the instructions given to community photographers and how this tied back to the mission of HMS. The results below followed from the simple prompt: “Represent your daily experience with water”.
I was just sent this information (thanks to Becky!) about a new round of funding for microbicides, which comes on the heels of promising results from a trial of the PRO2000 microbicide candidate. We covered this a couple of years ago and at the time I said – the potential of this drug is revolutionary. With microbicides there was great excitement and hope, then there was failure and now there is some maturity. Okay, maybe I am overstating the case, the take home point is that we still don’t have a product and this is not cheap, easy, or quick. Developing a drug is complicated, involves huge risk, can take decades and is highly uncertain. Let’s review the drug development time line again for those of you not familiar – the graph below gives the most simplistic picture:
The early microbicide discussions took place almost 15 years ago (International Working Group on Vaginal Microbicides, source). Over half that amount of time, from 2000-2007, $1.1 Billion has already been invested in microbicide R&D! It takes anywhere from $200M to $1 Billion to bring a single novel drug to market. Let’s hope one of these compounds works and makes it through phase III. But how much will we have spent? $2 Billion, $3 billion? If it works, it will have been worth the money, however, we must ask if we took the most efficient financial route to get to the end point and if there were better financial models – that is a valid question.