The Checkout

Tracking Outbreaks Five Days a Week

Last month's deadly E. coli outbreak in fresh bagged spinach is beginning to fade from public memory. Spinach is back on supermarket shelves and in salad bars, even as a team of about two dozen California state and federal investigators continue to work around the clock searching for the source of the outbreak.

The all-out intensity of the effort is warranted given that the outbreak has sickened 200 people and killed at least three. It provides a contrast, however, to the system that is supposed to be the front line for detecting outbreaks of foodborne illness--an even bigger issue these days with the potential threat of a terrorist attack on the food supply.

The system that health officials rely on to track outbreaks is called PulseNet. It's a network of public health labs run by the Centers for Disease Control. State and local labs that suspect an outbreak submit information such as the genetic makeup of whatever nasty bug is making the rounds into the network's database. That allows federal health officials to link clusters of illness in different locations across the country.

But the spinach outbreak highlighted one potential flaw in the PulseNet system. Wisconsin was among the first state to realize early on that we may be in the midst of a nationwide outbreak. A state epidemiologist dutifully punched in data on their cluster of cases into PulseNet, where it landed at 5:14 p.m. on Friday, Sept. 8.

PulseNet was already closed for the weekend. The discovery of the outbreak had to wait until Monday.

It then took federal health officials a few more days to put the pieces together and call in the Food and Drug Administration, which put out its warning to consumers to avoid all fresh spinach on Sept. 14.

Blogger James Prevor takes on the question of why PulseNet, our nation's first alert for outbreaks of foodborne illness isn't a 24/7 operation after the LA Times reported details of the spinach outbreak, including the information about the weekend closure of PulseNet.

Peter Gerner-smidt M.D., Ph.D., Acting Chief, Enteric Diseases Laboratory Response Branch, Center for Disease Control & Prevention, told the Perishable Pundit that the PulseNet lab and database at CDC is shut down during the weekends because the state labs are, too, and they don't submit data.

After federal health officials figured out they had an outbreak on their hands, Gerner-smidt said, PulseNet checked for submissions that came in during weekends. He argues that any delay doesn't substantially add to the time it takes to recognize an outbreak, which averages about two weeks--the time between when a person comes down with an E. coli O157:H7 infection and when the genetic info about the bacteria makes its way to PulseNet.

Gerner-smidt's disheartening kicker, though, is this: "It would increase the cost of the PulseNet system considerably if the public health labs and CDC were to work routinely on weekends... funds that are not available."

Would those 48 hours have made a difference and even prevented people from getting sick?

The family of June Dunning wonders whether health officials moved fast enough.

Dunning, 86, of Hagerstown died of E. coli the day before the FDA issued its warning against eating spinach. Moving up the warning two days earlier wouldn't have helped her since she ate fresh bagged spinach two weeks before she died. But word of an outbreak might have kicked health officials into gear more quickly. Genetic info on the strain that infected Dunning didn't reach PulseNet until she had passed away, even though she was told she had been infected with E. coli as early as Sept. 8.

Knowledge that her case could be part of a larger outbreak might have changed the way her tissue samples were handled. Her death is still being investigated for links to the outbreak, but it may never be conclusively linked because of problems completing a genetic test on the bacteria that infected her. State officials have declined to comment on her case.

Prevor suggests at the very least, PulseNet should stay open during the week long enough to receive data from labs in the central and western time zones.

What would make you feel safer? Should PulseNet stay open longer?

By Annys Shin |  October 19, 2006; 9:00 AM ET Consumer News
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Please email us to report offensive comments.

More to the point: How much more are you willing to pay for each item of food in order for PulseNet & the state labs & everything else in the chain to run 24/7. Blaming the corporations and the farmers is short-sighted; all of us have made it clear that we want cheap food, not necessarily good food, and we're now paying the price. Starvation is not an issue for the vast majority of americans, but we still try to chisel every last cent out of our food bills.

Posted by: John | October 19, 2006 10:08 AM

I've been eating Wisconsin spinach quite happily for a few weeks now. Unfortunately, without co-ops and farmer's markets it's difficult to find local produce. If Americans bought local, these outbreaks would be a lot more localized and cost a lot less to monitor.

Posted by: Gatsby | October 19, 2006 12:08 PM

The question was ask------What would make you feel safer? Should PulseNet stay open longer?

PulseNet is an after the fact mechanism. It merely shows that a problem already exists and has existed for some time. The major effort should be looking back along the chain of events to get to the root of the problem.

As long as places like Salinas Valley use reclaimed sewage water for irrigating these crops (including we are told organic vegetables), the question will remain, has the problem's source really been identified?

Think about what is flushed down the drain. Hospital waste with many serious pathogens, embalming waste (from what did the person die), slaughterhouse waste, industrial waste, pharmaceuticals, etc. Contrary to popular myth, sewer plants can not effectively treat the incoming pathogens or deal with many of these other pollutants. These are released to the environment.

Sewer plants also generate antibiotic resistance and allow for the transfer of virulence between pathogens. It is the acquired genetic information of a virulence factor that makes E. coli o157:H7 so deadly. Sewer plants assure that pathogens that might never come together are brought into ideal conditions for transfer of this genetic information. Is it any wonder that we are seeing an acceleration of newly emerging infectious diseases? Current standards fail to take many of these issues into account. That is where we should be looking.

We dump millions of tons of sewage sludge on farmlands and this washes into streams and is carried by a variety of transport routes to other fields where commodities are grown. The whole system needs a careful reappraisal, not just PulseNet. The abstracts below are illustrative but just the tip of the iceberg.

Dr Edo McGowan, Medical Geo-hydrology

Increased frequency of drug-resistant bacteria and fecal coliforms in an Indiana Creek adjacent to farmland amended with treated sludge

Shivi Selvaratnam and J. David Kunberger
Can. J. Microbiol./Rev. can. microbiol. 50(8): 653-656 (2004)

Abstract: Many studies indicate the presence of human pathogens and drug-resistant bacteria in treated sewage sludge. Since one of the main methods of treated sewage disposal is by application to agricultural land, the presence of these organisms is of concern to human health. The goal of this study was to determine whether the frequency of drug-resistant and indicator bacteria in Sugar Creek, which is used for recreational purposes, was influenced by proximity to a farmland routinely amended with treated sludge (site E). Surface water from 3 sites along Sugar Creek (site E, 1 upstream site (site C) and 1 downstream site (site K)) were tested for the presence of ampicillin-resistant (AmpR) bacteria, fecal and total coliforms over a period of 40 d. Site E consistently had higher frequencies of AmpR bacteria and fecal coliforms compared with the other 2 sites. All of the tested AmpR isolates were resistant to at least 1 other antibiotic. However, no isolate was resistant to more than 4 classes of antimicrobials. These results suggest that surface runoff from the farmland is strongly correlated with higher incidence of AmpR and fecal coliforms at site E.
Key words: drug-resistant bacteria, indicator bacteria, treated sludge, surface runoff.

Hospital effluent: A source of multiple
drug-resistant bacteria
V. Chitnis, D. Chitnis*,†, S. Patil** and Ravi Kant*

The present work was carried out to study the spread
of multiple drug-resistant (MDR) bacteria from hospital
effluent to the municipal sewage system. The MDR
bacteria population in hospital effluents ranged from
0.58 to 40% for ten hospitals studied while it was less
than 0.00002 to 0.025% for 11 sewage samples from
the residential areas. Further, the MDR bacteria
carried simultaneous resistance for most of the commonly
used antibiotics and obviously the spread of
such MDR bacteria to the community is a matter of
grave concern.
Ribeiro [12] and others [13] have found that as these organisms progress further through sewer treatment, the level of resistance and number of transferred plasmids increases. Reinthaler et al [14] found that the highest resistance rates were found in E. coli strains of a sewage treatment plant which treats not only municipal sewage but also sewage from a hospital. Thus, these authors concluded that sewage treatment processes contribute to the dissemination of resistant bacteria in the environment.

13] Nakamura S, Shirota H. Behavior of drug resistant fecal coliforms and R plasmids in a wastewater treatment plant] Nippon Koshu Eisei Zasshi 1990 Feb;37(2):83-90.

Posted by: Dr Edo Mcgowan | October 21, 2006 3:56 PM

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