Dengue Fact Sheet – May 2014 Update

  • Dengue Hemorrhagic Fever rates have been more than 50% of confirmed Dengue cases in Yucatan & across Mexico for the past 2 years.  (Likely due to secondary infections.)
  • 2.5 billion people – two fifths of the world’s population – are now at risk from Dengue.
  • 50 million new Dengue Virus infections occur annually.
  • Dengue Virus is transmitted only through being bitten by female Aedes aegypti (silent) mosquitoes in the Americas.
  • Infection by 1 of 4 Dengue strains gives protection against only that strain for 4 months.
  • Infection by the other 3 strains are possible during the meantime, and re-infection by the first strain is possible after 4 months.   There is no such thing as “Dengue H.”
  • All four Dengue Virus strains (DV-1, … , DV-4) are  circulating-in  and  endemic-to  the Yucatan Peninsula.
  • Prior Dengue infections  almost universally interfere with our subsequent immune responses to new Dengue infections, (see ADE theory), with each new  subsequent infection producing more severe symptoms, increasing the chances of possibly fatal Dengue Hemorrhagic Fever (DHF) symptoms or Dengue Shock Syndrome (DSS). (See Subneutralizing Antibodies)
  • Dengue infections take several forms:  No noted symptoms, mild symptoms like just a rash, flu-like symptoms, distinctive pain behind the eyes, high fevers (104ºF or 40ºC), or light bleeding from the nose or gums,  which sometimes transitions to:
  • Potentially fatal Dengue Hemorrhagic Fever (DHF) symptoms with bleeding from the eyes,   under the skin,  shock,   and vomiting congealed blood (looks like coffee grounds),  and abdominal pain with bleeding into the Gastro-Intestinal Tract.
  • if you suspect a Dengue infection, do NOT take aspirin or NSAIDs (Alleve, Motrin, Advil, etc) or blood thinners like Warfarin/Coumadin, because blood thinners (like NSAIDs) can trigger catastrophic DHF bleeding. Use Tylenol for pain and reduce high fevers (>104ºF or 40ºC) with cool compresses or lukewarm baths.  People taking blood thinners like Coumadin (warfarin) or Methotrexate should contact their physician to see if they should temporarily stop taking their meds.
  • There can be up to 3 week delay between the mosquito bite and onset of Dengue symptoms.  There are anecdotal reports of as little as 4 days between being bitten and the onset of symptoms.
  • The key days for getting the Dengue “NS-1 test” are DAYS 1 -4 after onset of fever/symptoms.
  • PRIMARY DENGUE INFECTIONS (First-Time Offenders): It is helpful to get tested for Dengue between Days 1 – 4, for NS-1 & platelet counts, so you know to pay special attention between Days 4-7 for DHF or DSS symptoms.
  • SECONDARY DENGUE INFECTIONS (Infected people who have already had a prior Dengue Infection): In contrast to the NS-1 test, some commonly-used other lab-tests  do not detect Dengue until Day 10 after onset of symptoms, because prior Dengue infections heavily interfere with the patient’s immune response to the new infection.
  • Yucatan has several labs in Yucatan that do this testing. Contact the State Secretaria de Salud (INDRE) lab for information.
  • The Dengue carrying mosquitoes Aedes aegypti (A. ae) need only a teaspoon of water that doesn’t evaporate for one week to convert eggs to free-flying adults at Yucatecan temperatures.
  • They (A. ae.) prefer clean water residues, like rain water in tinacos, flower pots, rubbish piles, old tires, old pipes, junk, rain water in unattended swimming pools, sink & floor drains, etc.
  • The best methods for reducing Dengue risks is to kill or exclude mosquitoes (using screens) from living areas. When outside wear long pants and socks or use a repellent.
  • Dengue’s transmission cycle can be broken by mosquito breeding controls:  seal or invert containers, put mosquito eating fish into ponds or fountains or treat with ammonia, chlorine, or copper,  and  eliminate even small amounts of water that stands for a week or more.
  • The adult A.ae. mosquitoes live roughly 1 month “in the wild” (normal conditions). Under better conditions, (like a nice laboratory with 3 hots and a cot), they live for 6 months.
  • Once an A.ae. adult female gets Dengue virus, they can transmit it through biting humans for the rest of their little lives: 1 month – 6 months.
  • Mosquito traps (that emit CO2 from propane) or the UV light+fan ones work well at trapping just mosquitoes, while the exterior ones that use a UV light attractant can kill lots of many many types of bugs. (reducing bat populations)
  • Dengue Transmission occurs as a chain of events.  Break just one link of the chain and Dengue transmission ends.
  1. Uninfected female A. ae. finds febrile Dengue infected Human.
  2. Female A. ae. bites the febrile Dengue Human.
  3. Female A. ae mosquito hides and rests for 3-4 days.
  4. Dengue virus moves into the A. ae. mosquito’s salivary glands.
  5. Female A. ae. mosquito lays eggs in water.
  6. The now Dengue-infected female A. ae. mosquito finds human and bites human.
  7. Mosquito eggs hatch and develop into adults in 7 days at Yucatan temperatures.
  8. Newly hatched female mosquito has sex with male mosquitoes.
  9. Infected female goes in search of new blood meals, possibly infecting the person she bites.

If you break or interrupt any single link in this chain, Dengue transmission stops.

Here’s some basic information on how current medical testing works with Dengue (CDC plots):

image: showing comparison between primary and secondary infections

=========================
MORE RECENT UPDATES ON DENVAXIA by Sanofi  and WHO  2015 Reports:  
If you read the WHO reports and Sanofi’s most recent 2015 reports on the ‘Dengvaxia’ vaccine, readers may make a different choice,  based on facts.

Consider that the “new”  Dengvaxia vaccine only works on less than 40% of patients for protection against the nastiest strain of Dengue (DEN-2).**

Consider that you may likely need at least 4 shots a year, and possibly 8 shots a year to maintain an effective titer (sufficient blood levels) of Dengue antibodies  (depending on patient’s age and immune system health).

**Consider that the vaccine is  at best  only effective about 70% of the time against just 3 of the 4 varieties of Dengue, (DEN1, DEN3, &DEN4) and it works relatively poorly against DEN2 ( < 40% effective).

DEN2 has been very common in recent past Yucatan Dengue infections.

==========================

* * * *

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

Read-on MacDuff . . .

26 Responses to Dengue Fact Sheet – May 2014 Update

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  5. Dean DeVolpi says:

    I live in the baja where normal rainfall is about 2-3 inches of rain a year. Untill recently we had about 1/2 inch of rain in 2 years. With that little rain we have the dengue AE mosquito here so one can assume it is not from teaspoons of rain sitting because do not have even a drop. See my website http://www.la-ventana.info. Though people say they need clean water to breed we have found them in the tens of thousands breeding in septic systems. So very simple put 10 cents screening material on your septic tank vents and roof vents with a piece of wire, make sure septic tank does not have any cracks. I have reports of people seeing clouds of mosquitos fling out of these tubes or cracks at dusk. I would love to find some funding to build a one way trap for these septic vents as I have drawn up on my site.

    • yucalandia says:

      Dean,
      Good advice on using milañaque (screening) to cover vents on sumidoros. Aedes Aegypti do not have an absolute need for clean water for breeding, but they definitely prefer it. They do not use sumidoros here in Yucatan, but they do breed in our alcaltadores (french drains in the streets).
      Stay safe,
      steve

      • Dean DeVolpi says:

        The issue is only recently have scientists believed they breed in septic systems dirty water…. only recent tests done like the one in 2009 in areas with high rainfall have shown septic tanks have the AE living there. This was the first study I have seen that conclusively shows even in areas with high rainfall that septic tanks are a significant problem, please see the links on my website. If you are in an area that uses septic systems here is a quote from the formal research:
        title:
        Unusual productivity of Aedes aegypti in septic tanks and its implications for dengue control. Barrera R, Amador M, Diaz A, Smith J, Munoz-Jordan JL, Rosario Y.
        ” We calculated that septic tanks could produce > 18 000 Ae. aegypti and approximately 170 000 Cx quinquefasciatus adults per day. Septic tanks are likely to be common and widespread in suburban and rural Puerto Rico, where, apparently, they can contribute significantly to the maintenance of island-wide dengue virus endemicity.”

      • yucalandia says:

        Dean,
        Interesting that they calculate and estimate 10X more quinquefasciatus mosquitoes than Aedes Aegypti per day for Puerto Rican sumidoros. Our research groups here in Yucatan actually capture mosquitoes using high velocity vacuum backpack fan systems and the researchers actually count physical mosquitoes in homes, alcaltadores, and patios.

        Fortunately, septic systems in Yucatan are typically NOT mosquito breeding grounds.
        In 27 years of coming to Yucatan, and 6 years living here, we’ve seen no mosquitoes in from our septic systems, nor from our families systems, nor from friend’s home’s septic systems.

        The UADY Centro de Investigaciones research group and laboratory has been studying Aedes Aegypti mosquitoes and Dengue here in Yucatan Peninsula since 1983, They also report that they focus their sampling efforts on homes and patios, not on septic systems. I tend to trust decades of actual scientific field results over calculated results that are based on scientist’s beliefs.

        What are the actual numbers from measurements of mosquitoes in sumidoros in your town in Mexico?

        How do those numbers compare to home and garden collections on the same properties?

        I mention these things, because you quote only the older 2008 preliminary study results from one small town in Puerto Rico, while the same research group reported that almost all of the mosquitoes that they actually caught came from homes and gardens.

        The research picture becomes even more interesting when reading this groups’ 2010 detailed follow-up study on mosquitoes in actual septic tanks. The actually found only mosquito larvae in less than 1 in 5 tanks, and even those tanks contained just 10.3 larvae per septic tank per day.

        Do you consider the actual measurement of 10.3 Aedes Aegypti larvae per day a good confirmation of their preliminary calculations of 18,000 AE mosquitoes per tank per day? I calculate a rough 1800 X too large of estimates, when comparing the ultimate reality with their preliminary guesses.

        Why report only the calculated estimates, and not report the actual field measurements conducted by the same group at the same locations?

        Read http://www.ncbi.nlm.nih.gov/pubmed/20374477 for the actual results vs. http://www.ncbi.nlm.nih.gov/pubmed/18380655 for the preliminary guesses. Since some septic tanks remain wet, even during dry seasons, it becomes a simple preventative measure to block air openings with a little screen / mesh, in a wet septic systems, to prevent carryover of mosquitoes from one wet season to the next.

        On another note: Is your website OK?

        Mozilla Firefox identifies it as a “risky site”, with a security certificate that “has been stolen from another website”. From your earlier comments, it appears that you are trying to sell a system to control mosquitoes from septic systems, using inflated estimates, while actual publicly reported research results by the same research group, published in the same journal seem to clearly overturn the initial preliminary estimates.

        Which is the more reliable information:
        The actual field measurements (10.3) or preliminary calculations (18,000) based on beliefs?

        10 mosquitoes per day is fortunately a small number when compared to common backyard breeding sites like individual dog dishes, flower pots or plastic waste – and they are easily prevented by blocking tank openings to the air with a little window screen.

        Thanks for the helpful tip!
        steve

  6. Dean DeVolpi says:

    sorry it lists my site as risky because I own the domain and yes forward it to a public forum hosting service that is free. There is not one product on my website that I sell or make a commission on….. I am hoping to raise money to develop a one way trap that attaches to septic pipes to give away in developing nations. I have submitted funding requests to several organizations, but no luck yet.

    There is nowhere where I said that every single septic system breeds them, some are built differently. See my explanation below.

    I have two testimonials that people here in baja have seen thousands of mosquitoes, literally a cloud coming out at dusk from two different locations. So I do consider that accurate. On my site that you did go to which sited the burke et al documents, have read them and many more that i cited. And many more from India, australia, sonoma, countay, usa, that have determined mosquitos breed in septic systems. None claim every single septic system is a breeder.

    I found it 14 years ago when building a septic system here in baja mexico. I was gone when the system was built and had a cleanout inspection on the first two tanks put in to make sure it was correct. When I opened it mosquitos flew out at me. And my location had mosquitoes. I immediately covered the vents with screen and in about 30 days I no longer had mosquitoes at all for several years (now i have neighbors with neglected pools). I repeated this a few years later at a large campground near me. They had such a horrible case of mosquitoes. And I was getting them where I live. So we put screens on the two different septic systems and in a few days there was a huge noticeable difference. and in a week almost no issues. and a month none. I have repeated this down there in that campground several times in a few years when the screens come off.

    Now why some septic systems do not breed them can be a lot of variables. Is there a vent tube, some are built without vent tubes. Is the vent tube at the tank or at the house? the length and diameter of the vent tube. Are chemicals present in it. There are many variables that I have not seen any research on.

    What I can tell you is just pure common sense when you sit and try to explain. From the start I mentioned we are a desert with 2-3 inches of rain as a norm and those come generally is a 3 day period. Yet we have a AE mosquito problem and dengue sometimes. And as I noted we just ended a 2 year drought and there are mosquitoes, those conditions are really not explainable other than breeding in septic systems. And as I noted I have seen it with my own experiments.

    I hope I have explained a bit better, not all septic systems do, and it is not something that has been studied. As I mentioned the scientific community and you had been claiming mosquitoes can not breed in septic systems, and only the 2009 is the first time they actually began to test and they found some can be massive breeders. which here in the baja we have seen with our own eyes.

    Now back to my trap I want to design, since egg laying mosquitoes do fly into septic systems it is a natural lure. If a tap is made for this size AE mosquito we could put a dent in population. Kind of a trap like the flys and bee ones, they can enter but can not get out.

    • yucalandia says:

      Dean,
      Good points about using 10 cents of screening to block septic tank openings to the air to stop mosquito breeding.

      On the matter of your previous claims of 18,000 Aedes Aegypti mosquitoes per septic tank, I think most scientists and readers find that inappropriately presenting wild, exaggerated, over-estimated claims does not inspire confidence or trust.

      Since you have read so many research articles on this, why make 2000 X exaggerated claims?

      Yes, water in underground tubes, culverts, septic tanks can serve as reservoirs for generic mosquito populations during dry seasons. Still, this does not justify reporting over-blown numbers about Dengue carrying Aedes Aegypti mosquitoes.

      Again: How many Aedes Aegypti mosquitoes did you or others identify in your septic tanks?

      Aedes Aegypti mosquitoes are very easy to identify with the naked eye – with distinctive black and white banded legs and a glossy black body with distinctive white polka dots. Check out the top of this article to give you a solid image of what they look like.

      Best of luck with your invention,
      steve

      • Dean DeVolpi says:

        We only have the AE mosquito here. I have pictures of them on my site, and as we know they are ankle biters in general, active early day and evening and rare at night and we have had severe outbreaks of dengue. I have never seen anything but a AE mosquito in my small area in southern baja. Again I have two people I have discussed this with that have seen clouds of mosquitos coming out at dusk one from a crack in a septic tank and the other from a vent tube. That really is the potential, remember they even warn you that a bottle cap of water is a potential breeding ground of the AE. A septic tank is what multiple of that. 1 cubic meter vs 1 cc, well that ratio is 1 million to one for a rough guestimate.

        Now I “believe” the mosquitoes here in the desert return everyday for the humid conditions they need to survive. This is why I believe we see such high numbers in certain conditions.

        Now why are not ALL septic systems breeders? Some do not have vents and no cracks, some vents may be to small or too long for them to fly, the effluent to liquid ratio could be to low? Many factors that to date no-one has studied mainly because there is plenty of people including health organizations that do not believe they breed in septic systems, the two or so actual studies are relatively new.

        I have a large campground near me and when they have a mosquito problem I take screen down there and we fix the septic vents and within 3 days there is a huge difference and within a week almost no problems. I have repeated this 3 times in 10 years.

    • yucalandia says:

      Dean,
      Good points about using 10 cents of screening to block septic tank openings to the air to stop mosquito breeding.

      On the matter of your previous claims of 18,000 Aedes Aegypti mosquitoes per septic tank, I think most scientists and readers find that inappropriately presenting wild, exaggerated, estimated claims does not inspire confidence or trust.

      Yes, water in underground tubes, culverts, septic tanks can serve as reservoirs for generic mosquito populations during dry seasons. Still, this does justify reporting over-blown numbers about Dengue carrying Aedes Aegypti mosquitoes.

      Best of luck with your invention,
      steve

      • Dean DeVolpi says:

        I really need to respond to your request of evidence, because I think it is important for people to understand the magnitude of what a septic tank can produce. Obviously you were not able to read the research I found on my site because you were concerned with the browser warning and you did not have the time to contacted me directly. So below I am listing the research that was done that shows yes 18,000 a day is possible just for the AE dengue causing mosquito. It follows, they tell people just a lid to a coke bottle is a breading ground, and should be cleaned up. That volume is so small and a septic tank is how many tens of thousands larger.

        The research I was citing is below. Also I have anecdotally unscientifically verified this from two people in Baja who have said they witnessed clouds flying out. One, a cracked septic tank that literally a cloud of mosquitoes would fly out in the evening. The second, told me they could see their neighbors septic vent a cloud of them flying out. To generate a cloud would require thousands.

        here is the specific research I was giving data from. NIH
        http://www.ncbi.nlm.nih.gov/pubmed/18380655
        “Geographical Information Systems identified significant clustering of adult mosquitoes, which led to the discovery of underground aquatic habitats (septic tanks) that were producing large numbers of Ae. aegypti and Culex quinquefasciatus (Say) in the treated town. We calculated that septic tanks could produce > 18 000 Ae. aegypti and approximately 170 000 Cx quinquefasciatus adults per day. Septic tanks are likely to be common and widespread in suburban and rural Puerto Rico, where, apparently, they can contribute significantly to the maintenance of island-wide dengue virus endemicity.”

  7. Dean DeVolpi says:

    yes my site is safe to go to… email me directly and I can discuss with you. dean@mykeyo.com is another site I have that is forwarded.

  8. Dina says:

    Dear Steve,

    Thank you so much for taking so much time and effort into researching Dengue. My 5 year old son was diagnosed with dengue exactly 3 weeks ago, and he was in the hospital for 1 week with his lowest platelet count being 58. I have read so much on Dengue, but nothing as comprehensive and informative as your research. We live in Indonesia, and for a country that has seasonal Dengue epidemics, there is little information and awareness. Doctors are not as considerate and tend to say “he’ll be home tomorrow”, without telling us what was happening. So for a terrified mom, thank you for a little peace. My son is still in recovery, he gets tired very quickly, and the skin on his hands, elbows and knees are peeling. He had a nose bleed last night, which was what brought me to your website….and it probably is not related…but as a very paranoid mom you know how it goes. I thank you again, and wish you much luck and success!

    Regards,
    Dina

    • yucalandia says:

      Good Morning Dina,
      You’re very welcome.
      You have our best wishes for his continued recovery and good health.
      Do you know when he was bitten? Are you able to limit his chances of being bitten again and getting a second infection?
      Best of luck,
      steve

  9. Dina says:

    Hi Steve,

    Actually I do. My son and 3 other classmates got dengue at around the same time (my son’s day 1 was wed, the other kids were on thurs), which probably means he got it from school. They fogged the school the weekend after all 4 children were admitted into the hospital. In fact they found mosquito larvae in the water dispenser drip guard. Now I send him to school with lotion repellent, anti mosquito stickers and an leg band…how’s that for triple protection…and of course silent prayers hoping he will be safe. I keep pushing the school to inform the parents about dengue and other diseases. People here still think dengue is airborne, and talking to a dengue infected person means you might catch it too, they are also are unaware about clean stagnant water as a perfect breeding ground.

    Thank you for your well wishes, and I sincerely hope a vaccine will be approved soon.

    Best wishes,
    Dina

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  12. eric chaffee says:

    Hi Steve,
    I have an eye-popping eyewitness story to tell about mosquitos breeding in septic systems in Yucatan. I friend had a small screened room built while he was away. The builders didn’t notice that inside this sitting room, screened on three sides, was a breather vent for the septic system. When my friend returned, I was on hand when we both discovered that he had a cage filled with a huge cloud of mosquitos! (No, we did not count them, but it was impressive.)

    I’m a big believer in screening. I have tightened my premises, thoroughly excluding these invaders — including one 4″ rain drain tube that transports rooftop water thru a patio room, an addition housing an interior breather, which breather I’ve covered with screen — as skeeters could and did fly down the rooftop drain, emerging into the interior of the house thru that breather. Even toilet traps have potential for becoming breeding pools, if they offer unfettered access thru a rooftop breather! These tubes need to be covered with plastic screen. (Don’t use metal mesh, as it will rot.)

    Screens can be an important aspect of control. If homes lack thorough screening, biting insects have access to the blood they need to continue this plague. We all need to tighten our dwellings! I’ve written a blogpost on the topic of reducing breeding by covering neglected swimming pools at my site, MeridaGOround, presently linked with this comment. (my blogpost is not a “sticky” post, so later readers could simply search my site for the word MOSQUITOS.)

  13. eric chaffee says:

    Thanks! YuctanLiving is preparing to run and link my blogpost on caring for pools while absent. I hope it launches a lively discussion.

  14. Dean DeVolpi says:

    Hi Steve

    It is me again, Though I was denied funding for my concept of a one way mosquito trap in 2003 by the gates foundation, I tried a few times without any funding to do it. I have very encouraging news for this summer. Long story but I call myself a Manny for two Mexican kids I teach English/math and inventing to, Right now they are 8yo and 10yo and have been doing this with them for about 5 years fulltime. Anyway they are now getting top grades in math so last year for a reward gave them iguanas one term and water turtles another on. I had to clean out the turtle container every week or two and realized i can make use of these larvae. With these I designed testing to make a trap that allows a mosquito to enter but can not get out, 98% effective. I found they were much smarter than one would guess, it took me 3-4 iterations to hit a 98% level over about 4 months. Then I made units to see if I could do the same in the “wild”. I have achieved this in a very small test. The cost of these for people to do it themselves is 10-30 cents. The problem is I am an engineer and I can make them. The question is can others duplicate my results. Because my trap is like what the industry says is a ovi trap, I am effective only on mosquitos that have bit a human, and wants to lay eggs which is the important time to get them. The reason I could as a non expert on mosquitos do this is because as I have mentioned before here in the baja we only have the AE mosquito so I did not have to be an expert at determining what is in my trap, basically ideal real world lab conditions. I would like to ask a favor of you. Can you be a beta tester for me if you have a AE mosquito issue in your region. I can not make a claim it works on any other mosquito, just the AE one. Please do not make this public at this point till I have independent verification.

    • yucalandia says:

      Hi Dean,
      Yes, I’d be glad to test it on our assortment of Aedes aegypti, Aedes albopictus, and about 20 other types of mosquitoes.

      I’ll send you an email with my email address.

      Thanks!
      steve

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