- 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, and sometimes fatal Dengue
- Hemorrhagic Fever symptoms with bleeding from the eyes, under the skin, shock, 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 or the diagnostic laboratory at Hideyo Noguchi Hematology lab. Testing costs roughly $400 pesos. UADY’s Hideo Noguchi lab sees patient between 7:00 – 9:00 AM – located just north of Merida’s zoo on Av. Izaes & C59.
- 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.
- Uninfected female A. ae. finds febrile Dengue infected Human.
- Female A. ae. bites the febrile Dengue Human.
- Female A. ae mosquito hides and rests for 3-4 days.
- Dengue virus moves into the A. ae. mosquito’s salivary glands.
- Female A. ae. mosquito lays eggs in water.
- The now Dengue-infected female A. ae. mosquito finds human and bites human.
- Mosquito eggs hatch and develop into adults in 7 days at Yucatan temperatures.
- Newly hatched female mosquito has sex with male mosquitoes.
- 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.
* * * *
Feel free to copy with proper attribution: YucaLandia/Surviving Yucatan.
© Steven M. Fry
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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.
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
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.”
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
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.
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
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.
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
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.