- Dengue Hemorrhagic Fever rates have been more than 50% of confirmed Dengue cases in Yucatan & across Mexico for the past 6 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.
- 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.
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How to best control mosquitoes?
The last 120 years of mosquito control efforts show one proven method, that works both short-term and long term:
~ Eliminate Aedes ae. “Dengue” mosquito breeding sites. ~
Since Aedes ae. “Dengue” mosquitoes LOVE just a tablespoon of fresh rain water, we must eliminate (or treat**) or cover all standing water, inside & out. … Bits of plastic rubbish, old bags, bits of old crockery, piles of yard waste (like palm frond bases that hold water), fountains, the over-flow dishes under plants … and even flower pots (with no drain hole in the bottom)
… even unused toilets & floor drains … (cover them tightly)
… anything that holds water for 7 days or more … breeds whole new crops of mosquitoes in just 1 week at our temperatures.
**Clean up our back yards & the insides of our homes … Clean up the vacant lots .. treat “drained” fountains, swimming pools, and old tires with Abate … Treat floor drains with either mineral oil or ammonia …
If it holds even a tablespoon of water … it puts us, our families, and our neighbors at risk.
Notice that elimination of Aedes ae. “Dengue” breeding sites can be challenging for old fountains, drained swimming pools, and old tires etc that accumulate rain water. … Active fountains & pools with sufficient free-chlorine disinfectant levels KILLS mosquito larvae … but all other standing water encourages them to breed.
Solutions for standing water? Use Abate pellets or pucks (if you can find them) …. otherwise … Use the blue crystals of copper sulfate….
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Medical Tests for Dengue?
There are at least 3 different tests for Dengue used by hospitals & doctors world wide. The Gold Standard is RT-PCR testing, that actually measures the DNA from Aedes ae. “Dengue” mosquitoes, because it is both ACCURATE and sensitive. … NOTE that the other tests (antibody based testing) have HIGH RATES of both false positive error rates & false negative error rates.
If your doctor tests you “for Dengue” … and you get a “negative” … “No Dengue infection” result while you have an active fever, DO NOT BELIEVE nor TRUST that result. He is likely using the cheap antibody ELISA testing (IGG or IGE tests).
It can take the not-very-sensative … repeated IGG or IGE tests … to give an accurate result. 😦
Here’s some basic information on how current medical testing works with Dengue (CDC plots):
If you think you may have Dengue, what tests work?
… aka Things the Medical Doctors do not tell you. 😉
Notice from the curves that ONLY RT-PCR testing for the Dengue virus is reliable for first time Dengue infections, especially when testing before Day 8 of fever.
For anyone needing testing when they have a fever, the RT-PCR testing is the most sensitive and most accurate, particularly during the first 7 days of fever.
“IgM tests” ~may~ start to work around day 5 of fever, but a “Negative IgM” result does not mean anything, until after Day 7 of fever …. Patients with negative IgM results before Day 8 of illness, and absent or negative NAAT or NS1 results … are overall considered unconfirmed cases. … For these “Negative IgM” results cases, a second sample should be obtained after day 7 of symptoms for additional serologic testing.
Unfortunately, because IgM tests also respond (falsely) to other flaviviruses, it really takes 2 successive IgM positive results AND positive PRNT test results to confirm some ambiguous, difficult to interpret IgM results.
That’s why the “RT-PCR” tests for the Dengue virus (though more expensive$$) are generally better, because the IgM test too often gives such ambiguous results before Day 8 of fevers, and even sometimes gives ambiguous results after Day 8.
and YES, many local Yucatecan Doctors still use the IgM testing, even with it’s substantial potential~possibilities for ambiguous results. 😦
Finally note: IgG test results say if you had a prior Dengue infection in the past.
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).** Then note that over 600 Dengvaxia patients have died after getting the vaccine … because Dengvaxia vaccine has been found to cause FAR WORSE DENGUE FEVER SYMPTOMS in patients who get their first Dengue infection after receiving the Denvaxia shot.
=> Dengvaxia is now proven to CAUSE BIG PROBLEMS for patients who have never had Dengue.
and also note … As of Oct. 2019, with the Philippine Govt. now banning the use of Sanofi’s Dengvaxia – because of the harm to children, because it causes WORSE DENGUE SYMPTOMS in patients who never had Dengue – leading to the deaths of over 600 children.
Then consider that, even if you already had Dengue at least once … you still 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).
**Then consider that even for people who have had prior Dengue infections …. the vaccine is still 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.
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Feel free to copy with proper attribution: YucaLandia/Surviving Yucatan.
© Steven M. Fry
Read-on MacDuff . . .