Salmonella & Parasites: Food Contamination in Mexico


Here are a few observations from nationwide studies conducted by the US CDC, NIH, Mexican hospitals, and Mexican Medical Schools that suggest why both tourists and ex-pats NOB hygiene habits don’t work so well here in the Tropics.         http://www.cdc.gov/eid/content/14/3/pdfs/429.pdf
http://www.journals.uchicago.edu/doi/abs/10.1086/498508

Over 40% of Yucatecans have no bathroom / septic system facilities,   25% are basically illiterate, and across Mexico:Figure 1.http://www.cdc.gov/eid/content/14/3/images/07-1057_1b.gif

These study results showed that meat sold in typical Mexican grocery stores had equivalent or higher levels of salmonella contamination than was found in local animal intestine fecal samples. Detailed analyses of the salmonella genotypes pointed to butchering practices as the most likely source of the contamination. These results for Mexico sure seem troubling, but are actually roughly 3X less contaminated than US chicken, 83% of which nationally was found to be contaminated by either Salmonella or Campylobacter. (http://www.consumerreports.org/cro/magazine-archive/2010/january/food/chicken-safety/overview/chicken-safety-ov.htm)

So, if US chicken et al have similar or higher levels of commercial raw meat contamination, why would there be higher risks of getting food poisoning , worms, amoebas, or parasites in Mexico?

The CDC/Horan authors go on to say: “…in the other states (like Yucatan), Salmonella spp. infections are probably acquired by other modes of transmission aside from contaminated food, such as from person to person or by contact with animal feces. In settings with greater fecal-oral transmission, asymptomatic infections would not directly reflect contamination rates in the retail meat.”

It is worth noting that these Salmonella were also resistant to common antibiotics (except Cipro) in about 15% – 20% of the cases.

And then they put a nice bow onto this little present describing typical Yucatecan households:
Population >15 yr. old, who are illiterate or with incomplete primary education: 40.1%
Households with no toilet or latrine: 24.6%
Households with no sewage system: 40.8%
Percentage of kindergartners with endemic salmonella infections” 16%
(Sonora, Michoacan, & San Luis Potosi were only nominally better.)

Before we criticize too heavily, how many people with NOB habits wash their hands for 20 seconds of vigorously rubbing soapy suds on our hands? How many (likely illiterate) food service workers know what’s needed to stop salmonella transmission?

How many expats and visitors from NOB know how to properly disinfect fruit and veg, counters, cutting boards, floors, etc?

Past NIH tests of fecal coliform contamination of commercial fruits and veg, in Mexico City consistently found high levels of salmonella in almost all samples, due to the use of “organic” (fecal) fertilizers and contaminated irrigation water. http://www.ncbi.nlm.nih.gov/pubmed/17061512

So, just what works, and what doesn’t, if you want to keep yourself and your family safe and healthy?

The NIH study evaluating Mexican vegetable contamination found that the silver colloid based disinfectants (like microdyne, biodyne, etc) lowered fecal coliform (pooh bacteria) counts, but did not eliminate them, and these same silver colloid products did not remove salmonella typhi risks in any samples. They found that bleach-based disinfectant solutions** were effective against all three major families of microbial contaminants tested (killing fecal coliforms, salmonella, and various pathogenic mesophillic microorganisms).

After having Walmart/Chederaui/Soriana/Mega-Commercial meat sometimes go bad in as little as 2 days, I started watching meat handling practices at these stores, checking out different stores to try to find a good one, and I found that employees routinely pack and un-pack the cases, leaving the meat sit out warm in carts 1 – 2 hr at all of these stores.

I really hate food poisoning, after a number of really wicked bouts in Ukraine after the break-up of the Soviet Union, so, I began feeling the packages in the cold cases of each store, and often find the meat warm – room temp – to the touch. The meat department in every single store mentioned has smelled absolutely awful at least once in the past 3 years, much worse than anything I’d experienced in 40 years of shopping in the States. We’ve had similar issues with the Deli sections of the aforementioned stores, with occasional ham and bacon going bad within 24 hrs of purchase. The only reliable solution we’ve found is to buy meat that is still frozen, as it is sold at Super Aki. Some people rely on fresh-killed meats from local butchers, but all it takes is one fly to land on that, blow a few of their regurgitated bubbles, and even that meat has surface contamination.

Fortunately, typical bacterial contamination is only on the outside of meat (though not true for hamburger and ground meats where the grinding process distributes the contamination throughout the meat).   This means that well cooked meat (thoroughly maintained at temperatures above 145ºF for at least 3 minutes) is safe from bacterial, protozoan, and amoebic contamination.   One might also note that the lime juice used to prepare ceviche does not kill worms nor their encysted forms, potentially important as past studies have found roughly 80% of ocean fish have some sort of parasites.

Walk barefoot on the beach, enjoy the surf, eat some ceviche or local sashimi/sushi, & as a bonus: take home some extra “special souvenirs”. (Souvenirs that your local NOB physician likely has no idea of how to diagnose or treat.)

The remaining kitchen/prep problems are solved by immediate careful disinfection** of cutting & handling tools, disinfection of cutting boards, & anything touched by the raw meat, (disinfect using dilute bleach**), followed by thorough hand washing (20 seconds of soapy suds using an antibacterial soap).

http://www.cdc.gov/eid/content/14/3/429.htm from Emerging Infectious Diseases

It’s also worth noting that the high %’s of salmonella on retail meat should also translate to salmonella on the outside of the meat packages. To avoid contaminating your hands, then touching the handle of the shopping cart, and your car’s steering wheel, if you shop for your fruit and veg first, you have a chance to pick up some extra plastic bags. If you slip the bag over your hand, pick out your meat, and then invert the bag over your meat package, you can keep your hands, the shopping cart handle, and your car door handles and steering wheel reasonably clean.

It also helps the clerk if you insert the meat package with the $$$ sticker close to the open end of the baggie, so, they can easily flip back the baggie to scan the sticker. Don’t get me started thinking about other shoppers handling the meat, and then touching the cart handles, which we then touch, and then we go out to our cars and handle the steering wheel…

All of this means that illiterate food service workers very likely transmit low levels of microbes and parasites to unsuspecting diners, and that if you rely on Microdyne, Bacdyne, etc, they just don’t work well, (and no, even though their names imply having iodine as an ingredient: they actually use colloidal silver).      It also says that   short   hand washes also   don’t   work, but learning to   not    touch your mouth, nose, and eyes   does   help.

Post Script to keep things in perspective:
US Turkey was no better in past USDA studies: roughly 50% of US retail turkey had salmonella.
US Chicken has been worse: 65% – 83% of retail chicken tested had salmonella and or campylobacter.
US Beef and Pork were far cleaner @ under 5% with salmonella.

A few final thoughts:
Soap and hot water do not disinfect things nor do they kill microbes.   Soap and water simply remove dirt and grease that offer places for microbes to grow.

To kill microbes (disinfect things) & eliminate the hazards described above it takes either:

  • harsh chemicals (like dishwasher soap) and high temperatures (3 minutes @ 145ºF or 65ºC) or  chemical disinfectants (like dilute bleach solutions**)  or
  • crown ethers (like in bar-glass washing solutions),
  • triclosan,  as in antibacterial soaps,   or
  • peroxide,  or
  • alcohols   like the hand disinfectants popular since H1N1 flu outbreaks.

**Bleach Dilution Schemes:

  • Stored Water Treatment (tinacos etc): 10 mL (1 tsp) bleach per 100 L of non-turbid clear water or 1/4 cup of bleach per 275 gal tinaco makes water microbially safe in 15 minutes.
  • Toilets and Sinks: Apply bleach without dilution via spray or brush for 10 minutes and rinse.
  • Drinking water: 2 drops of bleach per liter of clear water (20 drops per mL) and wait 15 min.
  • Fruits and Vegetables: Wash & scrub thoroughly first to remove dirt, then 10 drops bleach per liter of water and soak for 5 minutes. Rinse thoroughly.
  • Floors and bathroom surfaces (tub & shower): 1/4 cup (60 mL) bleach per gal of wash water and leave it on the surface for 5 minutes before rinsing.
  • Children’s Plastic Toys: Remove dirt first with soap and water, then use 1/4 cup (60 mL) bleach per liter of water and soak for 5 minutes and rinse.
  • Baby Bottles & Nipples:  1 drop of bleach per liter,  soak for 2 minutes and rinse.
  • Other Plastic Objects: Apply straight bleach for 5 minutes and rinse – note that this might cause a permanent bleaching of some plastics.
  • Glasses and Plates: 1/4 cup (60 mL) per gallon of dish washing soapy water, scrub off food residues, and allow to soak for 5 minutes.

Notes:
– Only use unscented normal bleach for these purposes: do not use scented or non-splash bleach. (Blanqueador de Ropa)
– NEVER COMBINE BLEACH WITH ANY BASE (higher pH chemical)
– NEVER MIX BLEACH SOLUTIONS WITH AMMONIA PRODUCTS OR DRIED URINE (concentrated UREA),
***because Base + Bleach = Toxic Chlorine Gas***
– Some people report that regular dosing with freeze dried probiotic mixtures of beneficial bacteria and fungi can overseed our GI systems with microbes that put out the “No Vacancy” sign to incoming pathogens.

http://www.ncbi.nlm.nih.gov/pubmed/19681275?ordinalpos=1&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_SingleItemSupl.Pubmed_Discovery_RA&linkpos=3&log$=relatedarticles&logdbfrom=pu for more info on the efficacy of various vegetable cleaning procedures.

There is no joy in Mudville…
(no glee in telling these tales)

But with knowledge, you can improve your chances.
* * * *
Please Continue to Make Comments and Replies to Help Keep This Information Current!
Disclaimer: This information is not meant as legal advice. It is for educational and informational purposes only. Government policies vary between States and offices, and Mexican Government officials have broad discretion in how they individually enforce policies, so, your personal experiences may vary. See a professional for advice on important issues.

*                  *                  *                   *
Feel free to copy with proper attribution: YucaLandia/Surviving Yucatan.
© Steven M. Fry

Read-on MacDuff . . .

16 Responses to Salmonella & Parasites: Food Contamination in Mexico

  1. Pingback: Salmonella Food Contamination in Mexico | Surviving Yucatan

  2. Pingback: Nope, It’s Not Another Blog on “My Life in Mexico” | Surviving Yucatan

  3. Jeanne says:

    Thanks for the excellent information. I have had salmonellas and/or amaebas twice a year for many years, usually after travelling or eating in a restaurtant. It could be a 5+ star restaurtant downto minus 5 stars. Same results. Have been using microdyne and husband says it doesn’t work so have discontinued all salads. Hope to be growing our own organic produce soon but will still have to disinfect with bleach. Also, does a spray or vinegar followed by drying and then a spray of H2O2 work for disinfecting?. Have had many anti-biotics, the only one seemimg to work on the salmonella has been Chloromycetin in huge doses. It works about 50 percent of the time, often leaving me with terrible digestion, candida etc. etc. I have taken many natural remedies which seems to be effective for a week or two. Oil of oregano, olive leaf extract, golden seal, , nutribiotic etc.
    Would appreciate any commentaries. Otherwise am very healthy with no medications even thoughI am nearer to 80 than 70 years old and still work etc. I appreciate your write-up-. thanks. Jeanne

  4. yucalandia says:

    Jeanne,
    Sorry to hear about your on-going GI problems = no fun.

    If you had non-typhoid Salmonella, Ciprofloxen was found to work well in Yucatecan studies in 2006, though non-typhoid Salmonella ‘s have developed some resistance to Cipro in the meantime. Azithromycin (Zithromax) has also been effective against non-typhoid Salmonella infections. http://emedicine.medscape.com/article/228174-treatment

    If you instead had Salmonella typhi or S paratyphi etc, then it may take stronger antibiotics, like Chloramphenicol (nasty stuff). Obviously, consult with your physician before starting such treatments.

    If you have to use such meds, it is often helpful to re-seed/over-seed the gut with capsules of freeze-dried beneficial probiotic bacteria and beneficial fungi (like beet-top molds).

    Sidelight: “In general, (a dose of) about 1 million bacterial cells are needed to cause (Salmonella) infection. Low gastric acidity, which is common in elderly persons and among individuals who use antacids, can decrease the infective dose to 1000 cells, while prior vaccination can increase the number to 1 billion cells.”
    http://emedicine.medscape.com/article/228174-overview

    As an older person with lower stomach acid concentration, you may well want to consider getting vaccinated, according to the source listed above and “World Health Organization Communicable Disease Surveilance and Response. Vaccines and Biologicals. Background document: The diagnosis, treatment and prevention of typhoid fever.” http://www.who.int/vaccines-documents/DocsPDF03/www740.pdf. Accessed 10/29/08.

    The other advice would be to follow the precautionary items we listed on Mexconnect:
    The point in the original post was that there are significant and similar risks of GI upset – Montezuma’s Revenge – both North and South of the Border. It seems clear that poverty and illiteracy play significant roles in allowing amoebic parasites, protozoan parasites, worms, and bacterial GI illnesses to spread.

    All these items point to how such illnesses can disrupt a trip but should not terrorize travelers, and that they can be avoided both NOB and SOB with a few practical precautions.

    * Wear footwear on the beach;
    * Wash hands vigorously for 20 sec w/soapy suds before eating;
    * Avoid touching your nose, mouth, & eyes;
    * Use disinfectant wipes on commonly touched surfaces like home & car door handles, light switches, car steering wheels, computer key boards, etc;
    * Disinfect knives, cutting boards, plates, etc that contact raw meat with dilute bleach;
    * Eat only well-cooked meats – avoiding ceviche, sashimi/sushi, carne-crudo;
    * Consider taking anti-parasite meds semi-annually if you live in the Tropics;
    * Avoid restaurant salads in the Tropics;
    * Street foods: eat basically sterile things – e.g. things that go straight from the hot oil into clean paper/plastic to your mouth – served by people who keep the cash handling separate from the food handling (cash is often filthy).

    Much luck,
    steve

  5. cherylcowen@gmail.com says:

    One thing I have found that reduced my Montezuma’s revenge was to carry the anti-baterial hand wipes with me. After I handle money, I clean my hands as soon as I can. Before I eat, I also take out a handy dandy wipe and clean my hands and the space around my plate. You can use them to clean up before you get in the car and spread anything you got from the grocery store. Sams or Costco sell them in the boxes with several hundred per box.

  6. J. Query says:

    Thanks for the excellent information. I have had salmonellas and/or amaebas twice a year for many years, usually after travelling or eating in a restaurtant. It could be a 5+ star restaurtant downto minus 5 stars. Same results. Have been using microdyne and husband says it doesn’t work so have discontinued all salads. Hope to be growing our own organic produce soon but will still have to disinfect with bleach. Also, does a spray or vinegar followed by drying and then a spray of H2O2 work for disinfecting?. Have had many anti-biotics, the only one seemimg to work on the salmonella has been Chloromycetin in huge doses. It works about 50 percent of the time, often leaving me with terrible digestion, candida etc. etc. I have taken many natural remedies which seems to be effective for a week or two. Oil of oregano, olive leaf extract, golden seal, , nutribiotic etc.Would appreciate any commentaries. Otherwise am very healthy with no medications even thoughI am nearer to 80 than 70 years old and still work etc. I appreciate your write-up-. thanks. Jeanne
    +1

  7. yucalandia says:

    Hi Jeanne,
    “. . . does a spray or vinegar followed by drying and then a spray of H2O2 work for disinfecting?.”

    The vinegar helps a bit as a washing agent. Past studies have found scrubbing with a brush and good rinsing removes 97% of contaminants in fruits and veg, except for leafy vegetables like lettuce and spinach. Adding the peroxide spray would seem to help, but its efficacy depends on how concentrated the H2O2 is and the duration of contact time. Lettuce and spinach require special attention – separating each leaf – washing carefully, and then 10 – 15 minutes of contact time with the disinfectant.

    Bacdyne, Microdyne, etc reduce pathogenic bacterial counts, but don’t have significant effects on various Salmonellas. Diluted bleach solutions seem to be the best documented disinfectants for lettuce and leafy veg.

    Do you take Xantac, Prilosec, etc or anti-acids? Older people tend to produce a lot less stomach acid than younger folks, which leaves them more susceptible to GI infestations: only 1,000 salmonella units are reported to infect older people, while 1 million salmonella are required to infect a person with typical stomach acid levels.

    If you do take stomach acid inhibitors/neutralizers, you may be increasing your GI infection risks, which could indicate that you might have to choose between leafy salads in restaurants and taking your stomach trouble medicines.
    Hope this helps,
    steve

  8. Ron says:

    Thanks for the extreme detail

  9. My sister’s IBS turned out to be severe Blastocystis hominis. After rounds of drugs we turned to homeopathic remedies because of the side effects. Look into something called Para 90. It’s a combination of several herbs that drew the parasites right out within days. http://www.para90.com

  10. Pingback: "authentic" mexican pottery - Page 2 - Playa del Carmen, Mexico forum

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  12. justin says:

    Dr. Fry,

    Thank you for this incredibly helpful article (I read the later version at Yucatan Living).

    I have physician friends in Guatemala who use a dilute iodine solution for vegetable washing. And of course, as a kid camping in the era before pumps, I used to use iodine tablets to purify water. I’ve looked online for references to compare bleach vs. iodine for vegetable rinsing but come up empty. Can you shed an light? Advantages and disadvantages? Thanks!

    • yucalandia says:

      Hi Justin,
      Bottom-line: Either Hydrogen Peroxide or Dilute bleach solutions or 5% Iodine** treatments are the only current vegetable/fruit soaking solutions that kill all the different types of Salmonella, Listeria, Amoeba, and some Hepatitis. Both bleach and iodine solutions do kill key species of Salmonella and Listeria. 5% Iodine solutions need to be used at **1-2 drops per liter of soaking solution, with 10 minutes of contact time – with NO DIRT – scrub off all dirt – and get the solution all over the lettuce or other leaves. http://www.ncbi.nlm.nih.gov/pubmed/3100591

      Neither of these 2 approaches kill Paramecia like Giardia or Cryptosporids – as these require boiling…
      http://www.cdc.gov/healthywater/drinking/travel/backcountry_water_treatment.html

      Cryptosporidium oocysts were more difficult to inactivate. Only 10% were inactivated after a 20-minute exposure to iodine according to manufacturer’s instructions; even after 240 minutes of exposure to iodine only 66-81% oocysts were inactivated. These data strongly suggest that iodine disinfection is not effective in inactivating Cryptosporidium oocysts in water. Because this organism is common in all surface waters, it is recommended that another method of treatment be used before ingestion.
      http://www.ncbi.nlm.nih.gov/pubmed/11990150

      Both Bleach and Iodine seems like reasonable approaches, as long as there is NO dirt, and NO fecal contamination issues (Giaria & Cryptosporidia) from fertilizing gardens etc, especially from “organic” approaches that use human night-soil or pig waste.
      steve

  13. justin says:

    Bracing, but helpful. Thank you so much!!

  14. Justin says:

    Dr. Fry,

    I’m back with another question! My family is in Lago de Atitlan now, putting all this into practice, and I have a question about washing vegetables. The other online sources I found, including the article you cite above, say to wash in 100 PPM hypochlorite. I think this would work out to roughly 1.5 tsp/gal, or roughly 8 ml / gal. of regular strength bleach, unless I messed up the math, which I may have.

    You suggest 10 drops / liter, which is roughly 2 ml / gal, right (using a 20 drops / ml conversion which I found). Which seems lower than anyone else.

    Can you shed any light on the discrepancy and which do you recommend?

    Thanks!

    Justin

  15. Justin says:

    Oh – and one other question. The houses where we live have non-disinfected lake water coming out of the tap. Any tips on best practices for hand-washing in that situation? I know hand-washing with soap and potentially contaminated water is better than nothing, but presumably we should do better than that? Just bite the bullet and wash with boiled or purified water? Or use alcohol gel after washing?

    Thanks!

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