Dengue Fact Sheet – May 2012 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, 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.

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

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