With the recent rains, it’s time to remember that the mosquitoes around your home may carry Dengue Fever risks, so, it’s important to eliminate Aedes aegypti mosquito breeding sites.

Aedes aegypti mosquitos are superbly adapted to urban life, breeding in as little as a tablespoon of water that doesn’t dry out for 7 days. During rainy times, the female Aedes ae. mosquitoes lay eggs at water’s edge. When the collected water spot dries out, the eggs remain – stuck to the side of the container, or bit of trash, or bit of plastic … remaining viable for years … waiting for the next rain to rehydrate the eggs, and to create whole new generations of Aedes ae. Dengue virus carrying mosquitoes.

This means that NOW is the time to check your patio, front yard, back yard, and even up on the roof for things that collect just 1 tablespoon of water … and to eliminate that standing water. Buckets, crockery, plastic containers can simply be turned upside to eliminate standing water mosquito nurseries.

Fountains, wash basins, bird baths that hold standing water can be treated with either Copper Sulfate, or Abate.

So, now’s the time to check around outside our homes for even a tbs. of standing water that persists for 7 days here … to eliminate A. aegypti mosquito breeding sites, where the eggs hatch out into larvae, that can become free flying adults in just 48 – 72 hrs.

Dengue Fact Sheet:
https://yucalandia.com/science-health-issues/dengue-fact-sheet/

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Clever readers might realize that we did not address whether the A. aegypti mosquitoes emerging with these latest rains are infected with Dengue virus. At this point, the answer is that we don’t know.

It’s curious that some A. aegypti eggs carry Dengue virus, as they sit dry, clinging to the sides of dried out rainwater collectors for up to 450 days. … aka A. aegypti. nurseries.

The key term in the processs is “vertical transmission”.
Aedes aegypti eggs sometimes carry the Dengue Virus. Infected female A. aegypti mosquitos can pass the virus directly to her offspring. As a result, the developing larvae and the newly hatched mosquitoes can already carry the virus before they ever bite a human.

A single A. aegypti Dengue infected female mosquito can produce over 1,000 offspring, via Dengue virus infected eggs.

In warm conditions, the newly hatched A. aegypti larvae can emerge as free flying adults in as little as 72 hrs after rehydration.

I can’t find any citation for what percentage of A. aegypti eggs carry Dengue Virus, so I let the matter lie. I do know that Dengue rates in Yucatan were low last Fall, with just 192 total confirmed cases for all of Yucatan State in all of 2025, which is the other reason I left the issues unmentioned. (preferring to NOT raise any unnecessary alarms).

Here’s what older (brownish) A. aegypti eggs look like … roughly 4 mm in length.

https://www.ioc.fiocruz.br/en/dengue/textos/oportunista.html

October 19, 2019
Curiously, we got an anxious PM (FB chat) message & phone call from an expat here in Merida, from Clinica de Merida, whose daughter was admitted just last night for a 40.6ºC (105ºF) fever … needing a transfusion of platelets … aka plaquetes …**

So … Dengue Fever infections are being transmitted ~now~ in Merida. … Take precautions …

This is the Worst Dengue Year in Nearly a Decade. It May Get Worse from Here.

Educate yourself on how to protect your families from Dengue risks … See the ~”How To Avoid Dengue”~ articles listed below.

**FORTUNATELY, she was not bleeding from nose, eyes, gums or stomach (GI system), and she had no DSS symptoms (no fluid in the lungs, no shock symptoms) … If a family member has Dengue symptoms (high fever, plus possibly achy joints) ~Pay special attention~ to their symptoms on Days #4 – #6, because that’s when the real health risks happen.

Education … and actions … are the keys to staying safe. 😉

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Sidelights:
~ If someone in your household (or neighbors) gets Dengue … SPRAY YOUR HOME carefully to eliminate mosquitoes that may (likely) be infected with Dengue virus to protect your family & friends.

… Past studies show up to 95% of household members get subsequent Dengue infections, when one member is bitten by a Dengue-infected mosquito. … Those Dengue-infected female mosquitoes can easily live ANOTHER 10 to 30 more days – biting other household members & biting neighbors (because the females go back outside to lay their eggs).

~ SPRAY every room carefully with typical mosquito killing ~indoor~ sprays … like H24 … Aedes aegyptii mosquitoes LOVE to hide underneath furniture … in with our clothes (lightly-stinky from our body-odor residues) … and up by the ceiling … So, FOCUS the spraying on those areas … briskly moving-disturbing the clothes when spraying them.

~ Check ALL screens & doors to find & block even small holes that mosquitoes can enter. …. You can cut little pieces of fiberglass screen material, to fold & fit … to block the gaps, openings, tears & spaces …

~ We personally have nylon sheer curtains over our exterior doorways … weighted at the bottom corners (to hold the curtain closed over the doorway) … because the mosquitoes LOVE to ride in on our backs, and fly-in in our wake … as we enter the house.

~ ELIMINATE or treat ALL water that stands more than 5 days. … fresh Aedes aegyptii hatch out & fly in just 7 days of only 1 tbsp of standing water here … Plus: Pay special attention to   flower-pot drip trays,   bits of old crockery,   bits of poly*styrene pkging   or even small pieces of plastic trash & plastic bags …

~ Treating water that stands for more than 7 days? … There are 2 good larvicides that kill all the mosquito larvae in standing water:   Copper Sulfate (-trihydrate or pentahydrate crystals)  ~ works permanently ~ … or Abate (lasts for 3 months) …  Note that after checking 12 different ag-chemical stores & pesticide vendors, there’s no Abate tablets~puck~pellets available in Merida … so use Copper Sulfate. … Just 1 or 2 crystals in a tire kills larvae for years. … AND   for swimming pools or fountains, your chlorine disinfectant is enough … AND for unused (drained) pools or fountains with standing water, Copper Sulfate (‎ CuSO4 – 5H2O ) works GREAT at just 3 ppm (3 mg/L) levels.

For both mosquito & algae control in pools and fountains, just 1½ tablespoons of the pretty blue crystals of ‎Copper Sulfate (… CuSO4-5H2O  or ‎CuSO4 – 3H2O … ) in 30,000L of pool water works great & is very safe   (per WHO, EPA & US State Health Depts).

See this good article for additional ways to protect yourself & your loved ones:
https://yucalandia.com/science-health…/dengue-fact-sheet/

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Yes, I am available for PMs & chats on Facebook … Please read the “Dengue Fact Sheet” (see second link below) … first.

Plus … Two good sites:
https://yucalandia.com/science-health-issues/dengue-what-to-do/chikungunya-dengue-virus-information/

and

Dengue Fact Sheet:
https://yucalandia.com/science-health-issues/dengue-fact-sheet/

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

Read-on MacDuff . . .