Mike the Mad Biologist

Salmonella Poisoning Is Rampant

A recent article in MMWR Weekly with the unassuming title of “Preliminary FoodNet Data on the Incidence of Infection with Pathogens Transmitted Commonly Through Food — 10 States, 2008” is incredibly disturbing.

The incidence of reported (more about that in a bit) Salmonella was 16.20 cases per 100,000 people. If we use a population size of 300 million, that means (Mad Biologist takes off shoes to do big number arithmetic) roughly 48,600 people had food associated Salmonella infections.

But it’s probably higher than that, although I have no idea how much higher. For a Salmonella infection to make its way into the FoodNet surveillance system, the following has to happen:

  1. The illness has to be severe enough for the infected person to seek medical attention. A huge number of infections will be missed, particularly if they clear up (e.g., you spend all night being sick, but feel better–or at least stop vomiting–so you never seek medical help).
  2. If the person winds up at a doctor’s office or a hospital (or clinic), a sample has to be taken and analyzed. Again, this doesn’t happen that often, particularly if the patient starts to feel better (due to rehydration, for instance).
  3. The laboratory doing the testing has to be part of the FoodNet network (and report it). This is probably the best step, in that, in the ten FoodNet states, coverage is pretty good, and reporting is pretty reliable.

Like I said, it’s hard to know how underreported this is (for the reasons above), but it’s pretty clear it has to be much higher–and this is only one organism. If you include all of the agricultural-associated organisms (and no viruses are measured), the numbers increase three- to four-fold.

But, don’t worry, there’s very little transmission of bacteria through the food chain. At least, that’s what the ag lobby tells me about antibiotic resistance

Cited article: Vugia et al. 2008. Preliminary FoodNet Data on the Incidence of Infection with Pathogens Transmitted Commonly Through Food — 10 States, 2008. MMWR Weekly 58(13): 333-337.

Comments

  1. #1 Edward
    April 17, 2009

    I’m fairly curious myself about underreporting of Salmonella. I’ve been told that normal healthy adults can carry the disease with only very minor symptoms. However, I’ve never seen the data to back it up. I’d be curious if anyone has done a population survey for Salmonella infection. Also, there was something about person-to-person transmission being underreported – but it’s been 10+ years since I look at this.

  2. #2 rpsms
    April 17, 2009

    Perhaps a related tangent to your ag lobbyists:

    I once asked my printer to provide samples of varnish techinques and he provided me with materials they printed for Hatfield. They are a huge pork producer in Pennsylvania. Based upon their company literature, they are also extremely Jesus oriented so they may actually have a religious problem with the very idea of antibiotic resistance.

  3. #3 Rob Jase, RS
    April 17, 2009

    At last, a subject I can actually contribute to! Twenty years in public health finally comes in handy.

    Here’s the set-up – let’s say there is a outbreak of suspected foodborne illness and the health dept. is notified.

    All the persons potentially exposed have to be identified.

    This is all well & good if its a nice group such as a catered party but if its the general public its impossible, there is simply no way to identify everyone that’s eaten at a restaurant over a several day period.

    We’ll add in the food service people later, all 6 or so of them.

    But let’s take the catered party to make things easier.

    Say 100 persons attended and 80 got sick. Those people will be contacted and advised to get stool samples for testing. With a little luck, based on my experience, maybe half will do so. That gives us 40 stool samples.

    Of those some will be from persons who have already stopped shedding viruses, some will be from persons who improperly collected their samples, some will be insufficient for testing. That maybe leaves 30 samples.

    Viruses aren’t all that cooperative to being cultured but with a bit of luck maybe half of those 30 will work out right and we will get 15 confirmed cases. A higher percentage will be gotten for the food service staff because they will be forced to cooperate so we can add maybe 3 more confirmed cases.

    So out of the 106 actual cases only 18 can be confirmed – that’s all that are counted because unconfirmed cases cannot be counted (no virus found, no confirmation).

    None of this is very comforting but that’s how it is.

  4. #4 Edward
    April 17, 2009

    This is what the CDC has to say on the number of cases:

    “Every year, approximately 40,000 cases of salmonellosis are reported in the United States. Because many milder cases are not diagnosed or reported, the actual number of infections may be thirty or more times greater.”

    So that is 1,200,000 or more cases in the US per year.

    It also appears to be the case that a large number of humans are asymptomatic carriers. Salmonella in and of itself is sufficient reason to always wash your hand before eating or preparing food.

    Also, 15-20% of chickens in the US are contaminated with Salmonella – which is why you should always make sure your chicken is completely cooked.

  5. #5 nails
    April 17, 2009

    rob- there are antibody tests for salmonella that are performed on blood samples. That cuts down on a lot of the problems with stool samples.

    It seems like everyone tests for cdiff and giardia when patients have stool issues, and test for h. pylori when people have stomach issues. I don’t think I have seen a salmonella test ordered on a patient in the couple of years I have worked in a lab. I would wager that salmonella is not tested for as often as it should be. Of course it would take a really in depth analysis to say that for sure, its just my impression based off of work.

  6. #6 Lion Dancer
    April 17, 2009

    One word…irradiation.

  7. #7 Rob Jase
    April 18, 2009

    OOps! Sorry about the brain fart, Salmonella is not a virus.

    nails – the blood tests sound good but there will be still be the problem of getting folks in to be tested. I admit I’d rather do a blood test than stool sample myself.

  8. #8 LK
    April 18, 2009

    Antibiotics are not indicated or recommended for routine salmonella cases — actually makes people worse. On the other hand, we do and must treat for cdiff and giardia.

  9. #9 alufelgi
    April 19, 2009

    In my opinion the largest threat for California are cataclysms and ecological catastrophes. Not important is how many money we have because one tragedy can us take all.

  10. #10 Marion Delgado
    April 19, 2009

    The meat industry contributes to this in 2 ways, first by selling poisoned water cheaply to be sprayed on vegetables, second by using last-line-of-defense antibiotics without a disease present to gain water weight, as well as to keep animals chugging along in unsanitary conditions, instead of fixing them.

  11. #11 Max
    April 19, 2009

    Not to make like of 50k to 1.5M cases every year, but is the word rampant really appropriate? Also, is this an increase in recent years in per capita cases?

  12. #12 cam balkon
    April 20, 2009

    I guess that monkeys are using tools as sticks in much more natural way than we, that’s why during those tests their SPOC expanded. Maybe humans’ SPOC would respond to special kind of well-known tool as fork, as we uses it habitually?
    The fact that Sci-cat (as any other animal) knows she is out of reach may imply that there is another(?) part of brain that specialises in estimating range of external object’s movement. That’s why we ‘know’ the safe distance from aggressor – which means: out of their reach.

  13. #13 drdra
    April 20, 2009

    The current estimates are between 1 and 2 million cases (there is a citation for 1.4 million estimated cases which I can dig up if you like) of salmonellosis in the US annually, and these are associated with 500-600 deaths. In previous years Salmonella was second only to Campylobacter (estimated 2.4 million cases annually in the US)- in bacterial foodborne diseases- virtually all chicken in the US is positive for campy.

    Nails- blood testing for antibodies is only evidence of an exposure at some point and is not as good as stool culture or blood culture (in kids) for Salmonellae.

    Antibiotics are not indicated for salmonellosis in otherwise healthy individuals, but are indicated in particular cases (kid w/ positive blood culture!! for example). I’m not aware that this is because antibiotics make salmonellosis worse- I don’t believe that’s the case- they simply don’t decrease the severity or duration of disease, nor do they decrease the length of fecal shedding… at least that is what I’ve read.

    Finally- once clinical signs are resolved in people- non-typhoidal Salmonellae can be shed for prolonged periods of time in feces- in humans the mean time for this is something like 5 weeks in people.

  14. #14 resimleri
    April 20, 2009

    I think the reason for our special friends not being too insulting on SBM is that the posts there are signed with a real name. It’s one thing to insult someone anonymously who’s also using a pseudonym, and another to do it to a “real person”. It’s the hidden fear that someone might expose THEIR identity too.

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  16. #16 Cynthia
    April 22, 2009

    Salmonella Sickens Scores of Students at Massachusetts School: http://www.newsinferno.com/archives/5710#more-5710

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    October 26, 2009

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