Travel Health: Dengue Fever

Can you be immunized, what are the symptoms and how is it treated? We look at what tropical travelers need to know about Dengue Fever.


When it comes to Dengue Fever, prevention is better than treatment.  Don't get bitten by one of these tiny, dangerous and very common creatures! Photo ©

What is Dengue Fever?

Nicknamed "breakbone fever", for its severe muscle aches and fevers, dengue is the fastest-spreading, mosquito-borne disease in the world. The World Health Organization (WHO) estimates 50 - 100 million people are infected annually, with half a million hospitalized with Dengue Hemorrhagic Fever (DHF). Seasoned travelers will be familiar with Dengue as the disease is prolific in tropical and subtropical countries in Asia and Latin America.

Dengue Sero-Types

Part of the Flavivirus group, dengue is divided into four serotypes, numbered 1 - 4. When a person is infected with dengue for the first time, the patient suffers the typical "dengue-like" symptoms. All four strains can be present in the same geographic area, at the same time.

The real risk begins when the same person gets infected again, with a different strain of dengue. This is what leads to a more severe illness and progression to DHF, where mortality rates can reach 50%. The third time a person gets Dengue... well, you get the picture. Unfortunately, the first Dengue infection frequently goes unnoticed or is attributed to an "influenza-like" virus.

Symptoms of Dengue Fever

Symptoms of Dengue include muscular aches and pains, fevers, headache, nausea, vomiting and often is accompanied by a fine petechial or "pinpoint" rash. Severe cases can progress to DHF where the victim suffers from massive bleeding, frequently from IV sites, gums, and rectum. People generally progress to DHF when they have been previously infected by Dengue, earlier in their life.

Basically, the more times you get Dengue, the greater your risk of death.

Dengue Fever Re-Infection

The concept that multiple, subsequent infections of Dengue lead to a worse disease is exactly the difficulty vaccine researchers are dealing with.

Researchers are still not sure what causes the second infection of Dengue to be more severe, but it appears confusion of the immune system is to blame. When the body encounters something foreign and deemed a threat, like a virus, it produces antibodies to attack the invader. These antibodies often travel with white blood cells riding alongside, ready to attack the virus, bacteria, etc.

When Dengue Virus is first encountered by the immune system, this is exactly what happens and the body generally defends itself well. A few copies of the successful antibody are then stored, in case the body runs into that same virus again. When the second and different strain of Dengue is encountered, the antibodies and white blood cells go to attack. However, this new virus is just a little bit different, and the antibody has trouble attaching properly. Unfortunately, the antibody can attach just well enough to allow the virus access to its white blood cell passenger, introducing the virus to a whole new type of cell and a great opportunity to rapidly reproduce.

Is There a Vaccine?

If drs vaccinate a person against dengue, are they increasing the patient's chances of going right to DHF and skipping their first (safer) infection? This is why researchers are not yet producing a vaccine for the public, yet.

A vaccine was developed in 2015, and the Philippines rolled out a Dengue vaccination program in 2016, however, there are still issues to overcome with the vaccine in terms of side effects. The vaccine's manufacturer publicly warned government health authorities across the world that the vaccine would induce severe hemorrhagic for anyone who was immunized and had not contracted Dengue previously. The Philippines government then ceased the program.

Presently, there is no publicly available safe vaccine so mosquito control and bite prevention are the only methods to prevent dengue.

Dengue Fever Risk Factors

The WHO estimates that there are 2.5 billion people living in areas at risk. That's approximately 40% of the world’s population. In 1970, there were only nine countries with Dengue Fever, and that list has grown to more than 100 countries. With the Aedes mosquito acting as the vector or carrying agent, it's is to see the explosive growth the mosquito species has had and its success in spreading the disease.

Researchers are attempting to link increased global temperatures and rainfall with the increased dengue activity. The idea that warmer weather leads to increased mosquitoes and mosquito breeding grounds are nothing new, especially combined with standing water which allows the mosquitoes to have an ideal breeding ground.

Dengue Fever Prevention

the best way to avoid Dengue Fever is to not get bitten by mosquitoes. Use a multi-step approach of using a mosquito net, if sleeping outdoors or with open windows, applying insect repellent to the skin, and wearing permethrin-treated clothing and long sleeves and pants when outdoors.

Avoid areas with standing water such as upturned canisters, flower pots, tires that may contain water and lakes or large puddles.  Public health campaigns focus on the destruction of these standing water breeding grounds and implementing proper water storage options to at least try to eliminate or decrease the Aedes mosquito population. 

Travelers headed to areas with Dengue Fever activity should travel prepared. Caution should also be used when looking at the time of year, especially during rainy seasons.  Dengue should not be going away anytime soon and savvy travelers need to be aware of it and start getting used to taking proper precautions.

While Dengue Fever is a very frightening disease, it shouldn't stop you exploring the world. With the proper planning and by taking the right precautions, you should still travel to amazing tropical destinations.

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  • christy said

    are all mozzies the same? do they all carry the same risk?

  • Erik said

    Very good question! Mosquitoes transmit disease to roughly 700 million people in just one year. They are by far, the most dangerous insects on the planet. The three types of mosquitoes to know are Aedes, Culex and Anopheles. <br><br>Mosquitoes are basically the same, when it comes to disease spread, with a few variations in biting habits and living preferences. Some mosquito species are known to be "day biters" while others prefer the typical dusk/dawn time. Other species prefer to live in more urban environments versus a rural or forest area.<br><br>Overall,a small precentage of the 3,500 different species are capable of carrying diseases that infect humans. Perhaps the most important thing to know about mosquitoes is that they are capable of carrying disease and steps should be taken to reduce bites. <br>

  • PAul said

    While I would agree with most of what the previous poster said, he didn't really answer the question which was "are all mossies the same and do they carry the same risk?" Well the answer to that is NO!<br><br>They are not really teh same with regards disease spread as different pathogens are carried by specific subsets of mossies. For example, dengue and yellow fever are transmitted by Aedes mossies, West Nile by Culex and malaria by Anopheles. The term "mosquito competence" refers to the ability of one mosquito species to transmit a particular pathogen and this isn't the same across all the different types of mossies.<br><br>But I would certainly agree with the comment about taking precautions against being bitten at all!

  • Faaloloi Teo said

    Well we should try to eliminate the growth of dengue fever by preventing the adult mosquito from laying eggs. This would mean that community participation is needed to reduce number of breeding sites within the community.<br>Also, the utilization of bio-control predators are to be study for the population control of immature mosquito species.<br>

  • RAVI said


  • Sarita said

    I have had second exposure to dengue fever which occurred in Sri Lanka (DHF), after previously having it in Bolivia (four years prior - although misdiagnosed at the time as typhoid fever). I am considering travelling to South East Asia again - is there information on where each of the four serotypes are located, and, after now having dengue twice, is it safer to go back to an area which contains mosquitoes carrying the same serotype that I was last exposed to or does it not work like that? I don't want to take any unnecessary risks but, conversely, don't want to be constrained to being an armchair traveller for the rest of my life in fear of a further dengue attack. Many thanks in advance for any advice given.

  • marshall said

    im doing a report and i need to know what body system the virus attacks. can any one help me out

  • pip said

    Question 7 and Question 10:
    I'm with you. I got DHF in Thailand (or Cambodia I can't really be sure) in May 2012. I had a full on fit and muscle seizure on a bus and then was hospitalised for 10 days. Between these two incidents about a week past during which I failed to get any decent medical attention. I don't know if this is why I ended up with the worst form of Dengue you can get but I certainly would advise you both to get decent insurance and be ready for the warning signs. If a dengue sufferer can get excellent medical help straight away in THEORY it should be survivable, even if it's hit number 2 or 3.. or who knows, maybe even 4.

    I don't know what's worse... dying of DHF or only going to the North Pole on holiday from now on. I desperately want to do South America but we need to fully understand the risks.

    Does anyone know? Do the serotypes mix and match or are they specific to certain regions?

    I'm going to keep researching and come back with any info I find. Perhaps we need to see how many people survive dengue 4 times.

    Good luck travellers.

    PS. My insurance was with WorldNomads, and they literally saved my life. Excellent support and in a time of literal crisis they were amazing.

  • Jake said

    Stop worrying about it so much go buy some insect repellant n a box of tissues for ur tears

  • M said

    Looking for answers too. Got dengue fever 4 days after returning from sri lanka in 2005. Not sure what type i had since i was misdiagnosed by US doctors for months. It was the worst 2 months of my life for sure. Had the high fever, nausea and throwing up for days, purple rash on legs for weeks, bruised easily, etc. Has anyone who had it twice had the rash amd the easily bruising the first time too? I know the say it's alway worse the second time. The first time seemed really bad for me already so concerned about the risk since i'm planning to go to SL next month. Is early detection and care key to surviving the second time or is it all up to luck?

  • PhilSylvester said

    M, we actually went back to the good doctor with this question.... his answer is presently on the front page of the WorldNomads safety hub, but here's a direct link:
    I think you'll find it answers your questions (at least a bit better).
    good luck
    Phil at the safety hub

  • brooke said

    my dad just got dengue fever and he was bitten twice is he still safe or no?

  • harell said

    Hello, i have dengue the third time due this date, the first is the worst where i almost had blood tranfusions, second just have minor bleeding in nose but just pass away in a week, i have never been sent to hospital, i even attended school, third is what i am experiencing right now it started 4 days ago when i had chills and high fever and runny nose but right now i am feeling better, what do you mean getting more dengue can have greater risk of death? Is it by having more types or more instances of the same type?

  • Kat said

    I read that one needs to be hospitalized if platelets are below a certain level. How would I know if my platelets are too low? Would that only happen if there was outer bleeding? I have Dengue now but am feeling better so I don't feel I need to go to the Dr. I just wonder is it possible to be feeling better but still have low platelets or to still be at risk for more severe complications?

  • VB said

    I have just recovered from dengue which turned into dengue hemorragic Fever (DHF). I live in Myanmar but traveled to Sri Lanka. One Dr said that I had had it before but I never went to the Dr about it and thought it was flu or something but the next Dr said this was the first time since my blood test after the fever hit showed negative!

    I was at home dealing with the extremely high fever and really should have gone back to the Dr because it progressed to hemarragic fever and I had to fly to Bangkok for treatment. My second visit had the Dr worried and he retested me and it was positive for DHF and very low platelets. Bruising and red 'stains' on my skin were quite scary when you realize what is causing it.

    I do think that travelers should do everything to prevent being bitten but being able to know if it is Dengue would be crucial as well. The infections after DHF are nothing to laugh at or 'grab your tissues' for (I'm thinking Jake has not had it :) and travelers need to be aware of this.

    I was told the Dengue mozzie tends to be urban not rural which means you will find it in cities, not necessarily out in the boonies! But get the health care if you are going into infected areas as said by Pip. IF it progressed to DHF, you will probably need a hospital and the health coverage will take care of you. At least in those countries, they know how to diagnose it properly!

    The Dr from the CDC in Bangkok told me that I would be immune now for about a year... so if your traveling occurs quickly (not more than a year between), you might be OK :)

  • Juda said


    I am a second year medical student and I just wanted to give a quick medical input on the topic.
    Unfortunately I do not have any geographical advice to give, however I would be able to help with the medical aspect.

    There are 4 main types of Dengue- when one gets bitten by the Aede's mosquito (there's a chance that the mosquito is carrying the virus- Flavivirus- positive single stranded RNA virus, and there's a chance it doesn't carry it- for this case we'll presume it does) then the body will react by producing "immediate attack complexes" (aka macrophages and cytokines) that will cause a lot of inflammation and increase Fever! could also manifest bone pain. Next step the body will make "memory attack complexes" (IgG's) to protect the body from future next attack of that virus.

    Remember we said there are 4 types of that virus- if the next attack happens and the virus is THE SAME strand of dengue- then the body will be able to get rid of the virus with no problem. HOWEVER, if the other 3 strands were to infect the same person (75% chance) then the body will be fouled into thinking that it's the same strand and try to kill the virus with the same "memory attack complexes" and miserably fail. This will result in consequent attack by the initial "immediate attack complexes" which will result in massive release of signals to the body to do all sorts of inflammatory actions including: vasodilation (dilation of blood vessels) causing blood to rush out of the vessels and potentially cause massive reduction in blood pressure. This could subsequently cause hypovolemic shock and death if not treated right away.

    I myself have actually just recovered from Dengue fever and had a personal scare when we learned about the topic in class not long ago.

    I hope this helps,


  • Anna said

    “In about 1 percent of cases, dengue advances to a life-threatening cascade of immune responses known as hemorrhagic or shock dengue. This potentially mortal condition generally happens only after a second dengue infection."

    Please note, it's *only* 1% of the cases, most commonly after a first infection, but not necessarily - even if the 1st and the 2nd are of different strains (which is basically a given since people are usually immunized for life after an infection). Rio de Janeiro has all 4 types of dengue, population is not dying plague-like of hemorrhagic dengue.

    Take precautions, avoid peak mosquito time if you can, and you will most probably be fine

    (yes, most probably, as you most probably won't die of a plane crash on your next travel. Life has risks and shit happens, but if you can't take any risks, you won't leave your bed - because, you know, you might trip on your carpet, fall, hit your head and die :P)

  • Pip said

    Hello folks. I am STILL trying to get an answer about whether or not you can get DHF more than once. Despite contacting several hospitals and doctors I cannot get an answer out of anyone. Surely SOMEONE must know. Why is there no information about it? Are we DHF suffers now immune or are we in line for a gruesome death? If I have to read another article that warns of secondary infection leading to DHF I'm going to scream. We all know that, it's EVERYWHERE online. What about DHF? Has anyone ever contracted it twice/three times/four times?

  • manos said

    Stay away from asia!if you think that cause you have not got dengue yet you are safe the first time you are mistaken by far.
    First you must make a test to make sure you were not infected previously.
    Second.i got dengue last year in manila philippines for the first time.It made complications and developed to dengue hemmoragic fever.I had to b hospitalised for days with no quarantee for my life.Thank God there are plenty of more beautyful absolutely safe and cheaper places in the rest of the world.Not to mention the rude behavior especially of the compare to the western hospitality.Whole europe has so much to show.From spain italy to the 3500 Greek islands paris praque budapest turkey cyprus etc.everyone of each unique.Every place in europe or america is looks everywhere more than less same.And from culture archaeology not much.You may not take all these under serious consideration now and believe it ll not happen to you.well dengue has developed to epidemic the last years and unfortunately no warning to travelers cause lot of money behind obviously.When you ll get it and you will not know if tomorrow you will be alive you will regret you traveled and you will remember me but it will be too late.God bless!Ashe vaccine of sanofi it will not protect you absolutely and no quarantee for the second time infection.PEOPLE!ITS JUST NOT WORTH THE RISK.

  • said

    Dengue can kill human being in case of ignorance. According to experts one can bit danger of dengue with timely cure and hygiene lifestyle.

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