Dengue Fever – it’s here again!


We are in the wet season.  There is no doubt about that.  As I write it is bucketing down outside, but being tropical rain, it is warm and all over in a couple of hours.  But there will be many puddles of water left – the ideal environment for the Aedes aegypti mosquito to breed.  Aedes aegypti is not some opera (that’s Aida), but is the name of the main mosquito carrying the Dengue virus.  The other is Aedes albopictus.

We see many westerners with Dengue Fever.  These are not an isolated group that caught it from drinking out of damp glasses in the same bar.  And if you don’t think Dengue is important, there were 70 fatalities last year.  That’s more than died from the SARS epidemic that had people cringing in their homes afraid to go out without a gas mask.

So, despite my previous pleas (and those of the Public Health Department), Dengue Fever and its potentially fatal variant, Dengue Hemorrhagic Fever (DHF) is still with us.  The latest figures have now prompted me to repeat my advice on this subject.  This is an important ailment, that can be avoided.

However, first you should understand a little more about Dengue.  It was first described in 1780 by a Benjamin Rush in Philadelphia (so it didn’t start here), when the name Break Bone Fever was applied, with the symptoms of pain in the bones and rise in temperature.  The name “Dengue” came in 1828 during an epidemic in Cuba.  The new name was a Spanish attempt at a Swahili phrase “ki denga pepo” which describes a sudden cramping seizure caused by an evil spirit!  Let me assure you that the local brand of Dengue Fever owes nothing to spirits, evil, bottled or otherwise.

Like Malaria, the virus is carried by mosquitoes.  The virus itself is related to Japanese encephalitis, Murray Valley encephalitis and Yellow fever, and there are four “serotypes” or subgroups of it.

The mosquito lays its eggs in water containers, preferring the clean water found in water tanks and pots, in the saucers under pot plants and even under the pet’s food dish.  Inside discarded car tyres is another favorite spot.  These mosquitoes are not of the adventurous type and feed during the day and spend their time within 200 meters of their hatchery.  Consequently, the eradication of any local breeding areas becomes very important towards maintaining your own health, as you can see.  Keep your home free from standing or lying water for a radius of 200 meters and you’re looking good!

Simple Dengue (if you can call it that) has an incubation period of around four to seven days and then the full blown symptoms of high fever and headache begin.  The headache is usually behind the eyes and is made worse by eye movement.  From there the pains progress to the limbs with acute muscle pains, which gave it the old name “Break Bone Fever”.  Interestingly, some patients complain of a metallic taste in the mouth.  (Please don’t ask – I have no idea why!)

On the other hand, Dengue Hemorrhagic Fever (DHF) can certainly be fatal.  It appears that Serotype 2 may be the culprit here, but does not usually produce DHF unless you have been previously bitten by Serotypes 1, 3 or 4.  In addition to the symptoms of Classical Dengue the skin begins to bruise very easily as the blood hemorrhages into the skin.  Children are also more susceptible to this than adults.  This also becomes much more of an emergency and might need to be treated in the Intensive Care Unit (ICU) of your favorite hospital.

With our ability to treat the viral ailments being very limited, the defense against the Dengue virus lies in the preventive measures.  The other precautions are to wear long trousers and long sleeved shirts, especially at sun up and sun down, when the mosquito is at its most ravenous.  The other factor to remember is “D” for Dengue and “D” for DEET.  DEET is the magic ingredient in mosquito repellents, so when you go to buy some, check the label – if it has DEET, then get it.  And then remember to use it!