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Sprouting Outbreaks

The next sprout-based outbreak is upon us, again in Europe. Fenugreek seeds imported from Egypt have been identified as the source of an E coli outbreak in France this month.

According to a Wall Street Journal article, there is some evidence that Fenugreek from the same source were imported to Germany over the last couple years, and that the Fenugreek sprouts could be related to the German E. coli outbreak as well.

Back in the US, sprouts from an Idaho-based company were recalled last week. These sprouts have been linked to a 5-state outbreak of Salmonella enteritidis (states include Washington, Idaho, North Dakota, Montana, and New Jersey).

So, why the sprouts? Be they alfalfa or fenugreek or bean, these seemingly healthy raw-food options are the disease harbinger of the salad bar. In their US outbreak press release, the FDA warns that susceptible groups (elderly, infants, immune compromised…) should avoid eating any sprouts altogether, ever. According to FoodSafety.gov and others, there are a few reasons that sprouts pose a higher risk than your average raw food:

  • Aflalfa fields may be fertilized with manure, which can contaminate seeds later used for sprouting
  • Seeds not contaminated in the field may be contaminated during storage
  • Bacterial contaimination of a seed intended for sprouting can survive if proper control techniques are not practiced during harvest and storage
  • Sprouts require warm, moist conditions to germinate — also a favorite habitat of bacteria

CDC recommends cooking sprouts before consumption (yuk!), and others note that home grown sprouts are not necessarily less contaminated. For many people in the know, sprouts are off the table.

Techie-Track

Here’s another neat and delightfully unexpected use of technology to help epidemiologists track disease and investigate outbreaks. Yes, everyone’s talking about new uses for social networking, but because the affluent of the human race are quickly becoming attached at the palm to their mobile devices, why not put social networking to use for outbreak investigation?

The story from the New York Times:

 In February, there’s a party at the playboy mansion for attendees of an annual conference – food, music, dancing, etc. Conference attendees scatter home to their various locales. A couple days later one of the attendees is feeling terrible with cough and fever, posts his status update on Facebook, and asks if any other attendees are feeling the same thing. Before you know it, 80 cases have been identified, the diagnnosis is suspected to be legionellosis, the hypothesis is that it was caused by the articificial fog machine, and the Wikipedia legionellosis page has been updated with their outbreak. All this without the involvement of a single health official or epidemiologist!

CDC put an EIS officer on the case, who aptly contacted cases and dispensed advice through Facebook, and also directed them to CDC’s online questionnaire. Results of the study have not yet been published.

Summer swat

The mosquitoes out in force in our neighborhood. We have considered renaming our daughter “Mosquito Bait” – you can literally hear and see the swarms when she steps outdoors on a warm day. While the parental side of me sprays the kid from head to toe in 7% DEET or some herbal remedy (sometimes both) and attempts to drape her in netting, the epidemiologist side runs through the potential diseases that could be transmitted. Arboviral diseases top my mental list, but a few notches down is dengue. Not for any good reason, mostly because I like tropical diseases.

 Typically we think of dengue as an imported disease – but if conditions are right, imported diseases can decide to stay. You may have heard about the locally acquired cases of dengue in the Florida Keys in the last year or so (66 cases in 2010). Recently NPR did a nice story on the mosquito issues in the Keys.

The mosquito vector for dengue is Aedes species the so-called “tiger mosquito,” named because of the white striping on the insect’s legs. Aedes has been present in Southern US states for a while, but the population has been growing since the late 1980’s and is currently widespread. The graphic shown here is from the USDA invasive species information center, and depicts the range of Aedes albopictus in 2000 (link from graphic).

Ever take a moment to try and identify a mosquito that’s about to take a bite out of you? If so, you should definitely look into tropical field research – it’s great fun (if a little itchy).

 

The Big Picture

I have to confess that, back in the early days of grad school when I fell in love with epidemiology, I had a bit of geeky wistfulness about not choosing space science. But I was really committed to going the route of studying diseases, and since there are no populations suffering disease in space (anyone beg to differ?) I made my choice and lived happily ever after. Today’s rising epidemiologists, however, could probably find a way to combine space science and epidemiology. The most major case in point: NASA has a series of projects using space technology for public health applications, mostly for monitoring environmental conditions on earth and predicting upswings in vector-borne illnesses.

Check out some of the projects at the following links:

NASA Applied Science Application Areas: http://appliedsciences.nasa.gov/ApplicationAreas-PublicHealth.php

NASA Center for Health Applications of Aerospace Related Technologies (CHAART): http://geo.arc.nasa.gov/sge/health/chaart.html

Public Health Applications in Remote Sensing (PHAiRS): http://phairs.unm.edu/

June 1, 2011

A rare strain of Shiga-toxin producing E. coli - the O157:H4 strain – is causing outbreaks in European countries, and the first US cases have recently been identified. The strain causes similar symptoms as the more O157:H7, and officials are in wait-and-see mode to determine if it is more or less virulent.

The cucumbers are suspected to have come from Spain, although the place and mode of contamination is still under investigation. Spain is a little upset about being blamed. Read or view the news report at this BBC link.

Updated June 7: From the CDC’s O104:H4 page (http://www.cdc.gov/ecoli/2011/ecoliO104/). How quickly the status changes! There’s a public relations message in all of this…

  • As of June 6, 2011, case counts confirmed by Germany’s Robert Koch Institute* includes 642 patients with hemolytic uremic syndrome (HUS) – a type of kidney failure that is associated with E. coli or STEC infections – and 15 deaths associated with STEC O104:H4 infection.
  • In the United States, one confirmed and three suspected cases of STEC O104:H4 infections have been identified in persons who recently traveled to Hamburg, Germany, where they were likely exposed.
  • At this time, a specific food has not been confirmed as the source of the infections. German public health authorities advise against eating raw sprouts, tomatoes, cucumbers, and leafy salads from sources in northern Germany until further notice.

Outbreaks like these bring home the global village we live in – it’s not that we should not eat imported foods (or export from our own countries), but we should recognize that just as we share the benefits of global trade of products and ideas, we also share the risks.

This week we begin studying modes of transmission and transmission dynamics – foundational concepts in the epidemiology of infectious diseases. Malaria is what first caught my interest for infectious disease epidemiology and definitely ranks as one of my favorite diseases. The malaria parasite is transmitted from person to person (or animal to person) via the bite of the Anopheles species of mosquito. One of the cool things about the malaria parasite (Plasmodium, see malaria “Featured Disease” on this blog for more info) is that the parasite completes part of its life cycle in the human/animal host, and a different part of its life cycle in the mosquito vector. Both creatures are necessary for the propagation of the parasite.

As you may deduce from your studies of the interaction between agent, host, and environment, there are many ways one can go about interrupting transmission of the vector-borne parasite. Drugs reduce the parasite load and treat the individual. Insecticides sprayed on interior walls kill the vectors as they “rest,”  after they have taken one blood meal but before they can infect another person. Bednets prevent transmission from the insect to the person, and insecticide treated nets kill the insect as well. Decades-long efforts toward a vaccine for this challenging multi-stage parasite are also showing some success.

Some scientists promot the sterile insect technique (SIT) for controlling malaria and other diseases transmitted by vectors. This involves releasing a large quantity of sterile male mosquitoes into an endemic area, thus reducing the vector population drastically when females cannot produce offspring. While this technique has its critics, it has been sucessfully used to control disease and reduce insect populations. Read more about SIT in this nice article from the journal Vector-Borne and Zoonotic Diseases.

How Malaria is Transmitted (1943)

Recently, the New York Times published a hard-hitting microbiological Q & A. You know the 5-second rule, right? That’s the one that says any edible item dropped on a floor or other unsavory surface is “OK” if you snatch it back up quickly. It works best if you invoke the rule with an enthusiastic shout of  “5 second rule!” before you eat the escaped munchie (or put it back on your kid’s plate…).

Well, the Times investigative reporter went to the experts at Cornell to ask if this rule really worked. You may be shocked to learn that the answer was, well, not so much. It actually doesn’t matter how long your food sits on a contaminated surface, the contamination happens on contact. The Times article even has a link to the 2007 study published in the Journal of Applied Microbiology, Residence time and food contact time effects on transfer of Salmonella Typhimurium from tile, wood and carpet: testing the five-second rule. Which also answers the question, “Can you get a publication out of an afternoon spent messing around in the lab?” See the news article, which has a link to the full text study, at this link.

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