Dengue Fever

The Aedes aegypti type of mosquito likes humans.  It likes to lay its eggs in artificial water containers, like in flower pots or old truck tires lying on the ground in the rain, rather than in puddles or ponds.  It likes to feed on humans, not on other animals.  Scientists call it “domesticated,” like dogs and cats.  It’s nice to have friends.

The Aedes aegypti type of mosquito likes Spring Break.  They live between 35 North latitude and 35 South latitude, and below an elevation of 1000 meters.  So, warm to hot places close to the shoreline.  So, all your favorite resorts: Panama City, Florida; South Padre Island, Texas; Cancun, Mexico; Lagos, Nigeria, Jakarta, Indonesia; “Soi Cowboy” in Bangkok, Thailand (if that’s how you roll).

The Aedes aegypti type of mosquito likes Capitalism.  The mosquitoes broke out of Africa between the 15th and the 19th Centuries as a side effect of the massive expansion in the slave trade.  In the many days ago, ships carried their drinking water in wooden barrels.  Probably the A. aegypti were passengers in the holds of the ships.  Slave ships crossing the Atlantic to the Caribbean carried the skeeters to the Americas.  Probably ships trading between the Americas and the Far East carried them to Asia.  Then the range of A. aegypti greatly expanded between 1960 and 2010 because of global warming (not stuck between 35 N and 35 S any longer), the growth of towns and cities[1], and increased international migration/travel.

Other than the fact that they are kind of hard to keep as pets (try buying a mosquito leash), the big problem with A. aegypti is that they carry dengue fever.[2]  (“Dengue” is a Spanish word that may have begun as an African word brought to the Americas by slaves.  Nobody knows what it means.)  The symptoms are fever around 103 degrees, torrential sweating, headaches that make you feel like your eyes are going to pop out of your head, muscle and joint pain, and an ugly rash.  It used to be called “breakbone fever” if that gives you a clue.

The first recorded dengue epidemic washed over Asia, Africa, and North America in 1779-1780.  One of the places hit hard by dengue was Philadelphia, because an unusual weather pattern had pushed the range of the A. aegypti farther north that summer.  There weren’t a lot of world-wide epidemics after that, but dengue kept killing people on a smaller scale all the time.  Once Western people started building empires in Africa and Asia in the 19th Century, dengue and other tropical diseases came to their attention.  Europeans used to call Africa “the white man’s graveyard.”  Generally, disease posed a greater danger than did native resistance.  So, scientists and sawbones got busy trying to deal with diseases.  In 1906 doctors confirmed that A. aegypti transmitted dengue; in 1907 doctors confirmed that dengue came from a virus.

Dengue evolved (I’m not sure that this is the correct term for a virus) in some fashion around the time of the Second World War.  Dengue hemorrhagic fever and dengue shock syndrome began to be identified in Asia and the Americas.  You got deader sooner.

Dengue now is endemic (never goes away, but never kills everyone, in a specific place) in more than 100 countries.  Between 50 million and 100 million people get it every year.  On average, 25,000 of them die each year.  Scientists haven’t come up with a way to prevent infection (a vaccine).  Until they do, the chief method is to reduce the skeeter habitats.  Failing that, they kill them with bug spray.  That’s fine with me, but don’t tell PETA.

[1] Towns and cities have in-door toilets instead of out-houses or lush shrubberies where you squat in the nightime.  A.aegypti just loves the stagnant water found in toilet tanks as a place to lay their eggs.

[2] To be fair, they also carry yellow fever.

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