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Dengue Fever Information

For people who live, work or travel extensively in the tropics
Especially those who have had Dengue and are worried about getting it again,
as subsequent infections can have a much more severe reaction

By Art Ludwig, from an interview with Enid Garcia, Center for Disease control, Puerto Rico, Jan 11 2003


Summary: Dengue hemorrhagic fever is not particularly difficult to treat, nor that dangerous if your treatment is good. This document describes hard to find info for good monitoring and treatment. Print it out and take it with you to areas where dengue is endemic, for peace of mind to and as a quality control checklist for proper treatment in of dengue. Please link to this page to make it easier for others to find.



Hundreds of mosquito and sand flea bites on feet

Lots of bug bites in the photo above-one of these might be the very mosquito bite from which I contracted dengue fever.

My wife and I came down with Dengue fever while working on water, sanitation and health care for an  Indigenous community in Michoacan, Mexico.

Search on the internet and it is easy to find out that if you've had dengue before, you're at higher risk for contracting dengue hemorrhagic fever (DHF) and dying a gruesome death.

Numerous authorities give the excellent, but difficult to follow advice that boils down to:

"...avoid getting bit by the dengue transmitting mosquito."

Well...the dengue mosquito bites primarily during the day, but if it's still hungry, it will bite at night, too. So, unless you leave and never come back, or you're in a bee keeping suit with DEET all over it, day and night (unlikely, considering most places where there is dengue it is hot), there is a good chance you might get bit again.

So what to do—short of never living in/ visiting/ working in any tropical place ever again?

What if you do get bit again, despite precautions?

It was very difficult to find out what the actual odds of getting DHF are, and what to do if you do get dengue again. A few days search was almost fruitless, until I reached Enid Garcia at the Center for Disease control in Puerto Rico. In stark contrast to the other sources, she is a veritable font of excellent, practical information and advice.

Here's some general info on dengue, followed by the information she shared with me:


General info on Dengue

Dengue is the most important mosquito-borne viral disease affecting humans; its global distribution is comparable to that of malaria, and an estimated 2.5 billion people live in areas at risk for epidemic transmission (1997 numbers).

Each year, tens of millions of cases of dengue fever occur and, depending on the year, up to hundreds of thousands of cases of DHF. The case-fatality rate of DHF in most countries is about 5%; most fatal cases are among children and young adults.

Dengue and dengue hemorrhagic fever (DHF) are caused by one of four closely related, but antigenically distinct, virus serotypes (DEN-1, DEN-2, DEN-3, and DEN-4), of the genus Flavivirus. Infection with one of these serotypes does not provide cross-protective immunity, so persons living in a dengue-endemic area can have four dengue infections during their lifetimes.

(Note: it is the subsequent infections which are much more severe)

Dengue is primarily a disease of the tropics, and the viruses that cause it are maintained in a cycle that involves humans and Aedes aegypti, a domestic, day-biting mosquito that prefers to feed on humans. Infection with dengue viruses produces a spectrum of clinical illness ranging from a nonspecific viral syndrome to severe and fatal hemorrhagic disease. Important risk factors for DHF include the strain and serotype of the infecting virus, as well as the age, immune status, and genetic predisposition of the patient.

Much more general info on Dengue



The greywater from  most homes in the village where we we worked was feeding festering black puddles..

The Washwater which used to feed this black puddle was rerouted into irrigation furrows which water and feed about 20 fruit trees. Because the water is spread over a wide area, it never stays on the surface long, so it doesn't stink or breed vermin.

Gray water garden beds and trenches

A new greywater system to treat water from between five and two hundred showers a day (it used to go into a pig wallow on the side of the river).

Though my California Department of Health Services brainwashed brain initially rebelled against the idea, the locals prefer clean-swept ground to mulch and don't mind looking at greywater. I worked with them to re-form the irrigation field into a series of beds surrounded by canals. The only difference in the maintenance compared to what they normally do is to adjust the levels in the trenches so the wetted area is even (this photo taken before the upper right trench was lowered and the upper left trench area raised).

For more info see Oasis greywater-book, our book on greywater systems

Dengue symptoms

Once an infected mosquito has bite a susceptible person, the virus has an incubation period of about 4 - 7 days in the body, prior to the development of symptoms. Dengue may produce very mild or severe illness. The disease is characterized by sudden onset of fever (at or over 38°C during the first 3 to 5 days), headache, general malaise, bone pain, and muscular pain. Also some people may present with vomiting or diarrhea, a generalized rash and in some persons, hemorrhagic manifestations that are usually very mild. The symptoms may last from 5 to 7 days. A small proportion of patients may develop low platelets, low blood pressure and severe bleeding requiring hospital care (Dengue hemorrhagic fever or DHF).


What are odds of getting and dying of hemorrhagic or shock dengue if you've had dengue and you get it again?

Precautions for people who've already had dengue

If you are returning to a dengue area after already having had dengue, you're at greater risk.


Small dengue clinic list

This list is of equipment for monitoring for possibly emergent DHF in a non-hospital setting, to determine if hospitalization is necessary or not:


Monitoring dengue patients for onset of DHF

Usually people who develop DHF do so after the fever goes down. It is most critical to monitor closely during the 24-48 hours after the fever goes down. In mild cases of DHF changes in vital signs are minimal and transient, patients recovering spontaneously or shortly after a brief period of time. In more severe DHF cases the disease might progress rapidly into a stage of shock. If you can, get a platelet count, blood pressure, and hematocrit at the onset of regular dengue symptoms, as a baseline.

Patient follow up


Criteria for hospitalization


Shock related symptoms

Dengue shock symptoms which indicate that the patient should go to a hospital immediately:

If you have the equipment & know-how, it could benefit a severely dehydrated patient to provide IV fluids during transport if it is a long way to the hospital.



You need to send blood to a well-equipped laboratory for dengue testing.

Virologic testing

Virologic testing (to see which of the four serotypes of dengue you've got) has to be done during the acute stage (1-5 days) of the illness to isolate the virus. Afterwards it won't be easy to determine which serotype it was.

The public health service in some countries do virologic analysis by area and outbreaks. Thus, if you've been infected, you might be able to find out the likely serotype by asking around, even if it is too late to test yourself.

Serologic testing

Serologic testing is to see if you have develop antibodies against dengue virus. This will let you know your risk factor for subsequent infections.

IGM testing will give let you know if you've had dengue or not, within 30 days of infection.

IGG testing will let you know if you had dengue in the past (long term immunity)

If you think (or know) you've been exposed to dengue years before, IGG testing will show if you still have the antibodies, and thus are at greater risk of contract DHF from a subsequent infection—this is the most critical information.

Infants exposed to antibodies via pregnancy or mothers milk


At the hospital

Should you fly to a hospital in an industrialized country?

The care for dengue is relatively simple, and hospitals in endemic areas are probably more experienced with dengue than most hospitals in overdeveloped countries.

If the facility is reasonable, the personnel reasonably competent, and the patient reasonably happy, it's probably best to stay put.

An ideal situation might be a local hospital close to an airport.

Adequate follow up in a hospital (or small dengue clinic If there is no alternative):

Before discharge

Good luck!