Contagion news

Dengue in Florida update – CDC researchers presented results of a serological survey conducted in the Keyes at the Conference on Emerging Infectious Diseases this week. They estimated that more than 1000 people have been infected thus far! Is dengue becoming endemic the US again?

Malaria research upswing – The NIH announced that the National Institutes of Allergy and Infectious Disease (NIAID) will be funding 10 new International Centers of Excellence for Malaria Research; $14 million in funding was awarded to 10 universities (9 in the US and one in Colombia). See the press release for the list of universities and the research focus areas.

HIV vaccine research – In other NIAID news, studies have identified not one but two anti-HIV antibodies that were effective in neutralizing the virus in the laboratory. Will a vaccine be far behind?

Modeling infectious…emotions? Harvard and MIT researchers spent some time determining that the emotion of happiness can be modeled in the same way that infectious diseases are modeled. In other words, they are contagious. A little frivolous, perhaps, especially since common sense might have told us the same thing, but geeks gotta have fun too.  I wonder how they estimated transmission probability.

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Malaria vaccine

Textile Art: Malaria infected blood cells

You may have heard some of the news in the past week or two about a newly developed malaria vaccine. Malaria is tricky for vaccine development because of the complexity of the virus life cycle. The parasite changes the way it looks to the immune system as it goes through developmental stages, so even if you have a great vaccine for one stage, it doesn’t help with the other stages. Trying to figure out the best way to target the vaccine is also difficult. Based on what we know of the natural history – that people develop some immunity, but not complete immunity – it may not be practical to expect that a vaccine could generate enough of an immune response to completely squelch the parasite. But you could reduce the parasite load in a given individual, so that transmission to mosquitoes does not occur as easily. This would also reduce symptoms and severe complications. The vaccine has been an ideal, but for decades vaccine success was always something that was another 10 years down the road.

Currently, the Swiss company Mymetics has announced the success of their malaria vaccine Phase Ib clinical trials in Tanzania. The vaccine they developed was a DNA-based vaccine targeted toward 2 separate parasite stages. It was tested among 40 kids over a 12-month period, and the trial was considered successful because of the high rates of seroconversion (70-80%) among the study subjects. Note that Phase 1 trials (see below) focus on safety, not effectiveness. The company is currently preparing for the next study phase.

Clinical trials are the only form of “experimental” epidemiology. The general phases are:

• Phase I: Researchers test a new drug or treatment in a small group of people for the first time to evaluate its safety, determine a safe dosage range, and identify side effects.
• Phase II: The drug or treatment is given to a larger group of people to see if it is effective and to further evaluate its safety.
• Phase III: The drug or treatment is given to large groups of people to confirm its effectiveness, monitor side effects, compare it to commonly used treatments, and collect information that will allow the drug or treatment to be used safely.
• Phase IV: Studies are done after the drug or treatment has been marketed to gather information on the drug’s effect in various populations and any side effects associated with long-term use.

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Ebola!

May was an exciting month for Ebola fans. First, the National Institutes of Health (NIH) announced the unmitigated success of an Ebola vaccine in an animal model. Next steps for this project are trying to determine how to make the immune reaction one that responds to more strains of Ebola.

Then last week, a team of US and Canadian researchers announced a highly successful (again, in an animal model) treatment for Ebola. Read the Reuters article here or catch the NPR story here.

On an ancillary, but interesting note, to coincide with class content on transmission modalities, bush meat anyone? Here is an article about the purported risk of various exotic viruses that could be associated with the apparently thriving bush mean trade.  A few points about this article, other than the fact that it’s just interesting:

1) What a creative mode of transmission!

2) Now pause, for a moment, and think about epidemiologically “effective contacts”

3) What is the route of transmission of exotic viruses (hop over to this week’s disease of the week, hemorrhagic fevers, and peruse others), and finally

4) Does human consumption of bush-meat lead to human infection with “HIV-like” viruses, or other from primates (as listed in the noted article, monkey pox, the Ebola virus, yellow fever and tuberculosis).

Thoughts? Opinions? Take this week’s poll at the Question of the Week, and/or feel free to leave a comment here.

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Entering the Epidemiologic Triangle

The interaction of pathogen, host, and their environment is one of the hallmarks of infectious disease. Unlike chronic diseases, where we deal in risk factors and probabilities, there is at least one certainty for infectious diseases: if a susceptible person (or other host) must come into contact with the agent for infection to occur. Although this process is an age-old process, with our ever increasing zeal for travel, adventure travel, and even eco-tourism, we are placing ourselves as susceptible hosts into an ever increasing array of epidemiologic triangles.

For instance, see this Canadian news article pointing out risks to travelers going to see the World Cup in South Africa. There’s also a free article in this month’s journal Pediatrics about the occurrence of disease among returning travelers, particularly children (using a pretty fun surveillance network called the GeoSentinel Surveillance Network).

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Super spreaders

Infectious disease epidemiologists have the term “super-spreader” for people infected with an organism that behave in such a way that they have effective contact with inordinately higher numbers of susceptibles than is usually assumed to occur. For example, in the first HIV investigations in the 1980’s, it was found that the average number of lifetime sexual partners among those with what was then termed gay-related immune deficiency cases was 1100, with some reporting up to 20,000.   If you haven’t read And the Band Played On, an amazing account of the first HIV investigations, the virus’ unfolding epidemiology, and the heavy hand of politics, you really should. Or, if you are inclined, it was also made into a movie. Click on the book image to link to the free text of some of the book on Google.

News in my state gives rise to another kind of super spreader, and something to get you thinking about legal and ethical issues in preparation for our live meeting this week. A medical technician in Denver who was addicted to painkillers would inject herself with painkillers and fill the syringe with saline to be used for patients.  She was infected with Hepatitis C (see today’s disease of the week). She worked at 2 hospitals during the time period she was doing this, potentially exposing 6,000 people who underwent surgery. All of these people are currently being tested.

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Adventures in Eating

Oh the decisions this week! The July issue of Lancet Infectious Diseases reports that you can get MRSA (methicillin-resistant Staph aureus) from man’s best friend. Accarding to the article, dog slobber hosts an array of pathogens, and dog-bites are an increasingly being found as a cause of MRSA infections, especially in children. Here is a news article on the topic; you can also access the journal article through the UNC Electronic Health Science Library. Dogs (and cats too!) can be carriers of the bacteria… and their most likely source of acquiring it in the first place? Their owners. What goes around comes around.

I would be remiss if I did not mention the cookie dough recall. Contaminated spinach or peanuts is one thing, but don’t mess with the cookie dough. Nestle cookie dough has been implicated after a months-long search for the culprit of E. coli O157:H7 infections, occurring mainly in young women. There’s a nice summary of the problem in this NY Times article. Exactly how the cookie dough was contaminated hasn’t yet been determined. Personally, I prefer to get my foodborne illness from homemade cookie dough, it is much preferred over store-bought illness. (This photo is one I took of my most recent batch!).

But this week’s winner is tapeworm. Now I do consider myself an adventurous eater, and I have willingly eaten specialties from a wide variety of cultures, including insects and several dishes where I decided I was better off not knowing what I was eating. But I do draw the line at raw fish, even though I feel chagrined every time I see a 5-year-old happily eating sushi while I resign myself to a noodle dish. But last week ABC news made me feel a lot better, when they published an extremely scientifically rigorous article about the the increase in parasites from raw fish, especially salmon tapeworm. So this week’s disease of the week: Tapeworm infection!

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Factoid Roundup

Influenza money

While swine-origin influenza A(H1N1) and other pandemic-potentialities threaten, in some ways, they are good for the economy. Of course Novavax is sitting pretty because of  H1N1 vaccine development, but the rubber-glove industry is also thriving just now. And some have done quite well for themselves in selling face-masks, particularly a Japanese entrepreneur who sold out of face-masks lined with ostrich antibodies. You read it correctly, ostrich antibodies. He harvests antibodies from ostriches, and affixes them to the face mask. This goes to show you why epidemiologists don’t double as entrepreneurs, we are entirely too practical. See today’s question of the week to answer the ostrich poll.

Boxing money

Sports-epidemiology may already be considered a sub-field of injury epidemiologists, but how about infectious disease? Sports can lead to some delightfully interesting (and gross) modes of transmission. This week’s winner: Hepatitis B among boxers. Perhaps you already know this story (boxing fans?), but here is an article about a match between 2 rivals, postponed because one has hepatitis and the other hasn’t been vaccinated (wouldn’t you think hepatitis vaccination would be required among boxers??).  Truth-finding on this one is tough – I think sports-writers have as much trouble writing about hepatitis as I have writing about sports.

Not for all the money

An article published in Pediatrics showed the results of a record linkage study to show just how risky not getting childhood pertussis vaccination can be. Here is a news story about the findings. Among my own friends and acquaintances, a surprising number are refusing or delaying vaccinations for their kids. Particularly epidemiologists, who understand that risks apply only to populations, not individuals. I respect personal choices, but my kid gets poked. If you need help convincing yourself or colleagues, listen to this link at doitforyourbaby.com.

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Germ phobes, beware!

The Canadian Environment and Plastics Industry Council publicized the results of a study last week showing that reusable shopping bags make a happy dwelling place for yeast, mold, and bacteria including coliforms. You can read the news story here. A little moisture gets trapped, meat and unwashed veggies go in and out of the bags, checkers handle one set of bags after another, spreading everything around… ew!

Does the scenario sound a bit familiar? A couple years ago, an article in the Journal of Environmental Health related finding 25 different species of bacteria on restaurant beverage lemon slices. In reaction to that news, one of our ID Epi students at the time said that her science students had done a project that found high levels of bacterial growth on restaurant soda machines.

This is all an example of us interacting with our environment and the agents there to create potential new modes of disease transmission. The epidemiologic importance, however, at this point is limited, and begs a few questions. Are the bugs colonizing these items, be they lemons or grocery bags, pathogenic? And if they are pathogenic, is anyone ever getting sick?

I’ve yet to read about a restaurant-lemon outbreak, but if you’ve seen one, let me know. In the mean time, wash out your reusable grocery bags every once in a while.

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