Time to learn more about this old acquaintance of Brazilians!


About 75% of the people infected with the dengue virus do not present symptoms (1).



Main symptoms (1,2)


  • High fever (40ºC));
  • Extreme fatigue;
  • Headache, pain in the muscles, joints and behind the eyes;
  • Redness in the skin (rash), which may or may not be accompanied by itching in the first few days (2).;
  • Lack of appetite, nausea, vomiting and diarrhea.


In general, the symptoms appear between two and seven days after the bite of an infected mosquito. In some patients, the process takes longer and may take up to 15 days. Still, it may be the case that not all symptoms appear.



Warning signs (1,3)


  • Bleeding;
  • Intense vomiting;
  • Increased liver;
  • Low or convergent blood pressure (when the maximum equals the minimum, for example, 100/87, being 120/80 the usual);
  • Somnolence;
  • Temperature drop;
  • Rapid reduction in platelet count;
  • Severe irritation;
  • Decreased sweating;
  • Breathing difficulty..  


In some cases, dengue may also be accompanied by clinical manifestations of the nervous system, such as delirium, depression, psychosis, dementia, paralysis and encephalitis, among others.


In more severe cases, the patient may worsen rapidly, go into shock and, if untreated, die within 12 to 24 hours.


Fast medical care is key to avoiding the worsening of the clinical condition!



How to be sure it is dengue?


The symptoms of dengue can be easily mistaken for those of other diseases. Therefore, it is essential to perform exams. Some are called nonspecific exams because they can give altered results in various types of diseases. Others are more specific for dengue (3).



Tourniquet Test (3)

The patient's arm is pressed using a sphygmomanometer (that part of the device that measures blood pressure that tightens the arm). The number of petechiae - red dots - that appear is then counted.



Counting platelets (3)


A simple blood test that counts platelets, the blood elements responsible for clot formation. In the case of dengue, the platelets fall abruptly from the onset of symptoms.



Hematocrit (3)


The patient's blood is checked to determine the volume occupied by the red blood cells. In cases of dengue, the hematocrit may increase, especially if there are complications, since the plasma - the liquid part of the blood - may leak from within the circulatory system.





This test looks for the presence of antibodies against the dengue virus in the blood of the patients. The presence of these antibodies indicates whether the person has had, in the past or the present, contact with any of the virus types.


In addition to providing answers to dengue cases individually, the ELISA allows the health system to verify which type of virus is causing a given outbreak. A disadvantage of the test is that it cannot be carried out at the early stage of the disease because the human body, after infection, takes at least five days to produce antibodies.



Fragments of the DENV virus (4)


This test, which is faster than ELISA, searches the blood not for antibodies, but for a dengue virus protein (called NS1), produced in large amounts between the first and seventh days of infection. The obvious advantage is that the diagnosis can be made earlier. The disadvantage? The price. As the test is very expensive, it is not available in all health facilities. Besides, you cannot distinguish between the different types of dengue virus.



Real-time PCR (3, 4)


One test that helps confirm the type of virus that is causing an epidemic is the real-time polymerase chain reaction (RT-PCR). Do not be scared by the complicated name! Its purpose is to identify, in the patient's blood, the genetic material of the virus. It is a very sensitive test, capable of detecting even small amounts of virus RNA and discriminating the type. On the other hand, it is an expensive and complex test, because it requires equipment and workers with sophisticated knowledge.



Taking care of those with dengue (3)


In mild cases of the disease, treatment includes rest, fluid intake and fever and pain relief medicines, preferably without acetylsalicylic acid. Between six and ten days after they begin, the symptoms usually disappear. But it is very important to seek medical attention: dengue fever can worsen rapidly, and agility in treatment is key in these cases.



The history of an old acquaintance


Dengue takes our sleep today, but it is not a new problem.



An ancient disease


The first historical reference to dengue-like disease dates back to the Qin Dynasty (221-206 BC) in China (5). There are also reports of similar outbreaks in the seventeenth century. But it was in 1779 that the first more concrete account of dengue came to light: an outbreak in Jakarta, Indonesia (5). The following year, an epidemic would also hit Philadelphia in the United States (5). A hundred years later, dengue fever was already a famous disease, common in coastal regions, ports and cities.


In the 1920s, hemorrhagic forms of the disease were recorded in areas where it was not endemic. However, only in 1950 was the dengue hemorrhagic fever recognized as a new and more severe form of the disease (1). In 1958, in Thailand, the first epidemic of dengue hemorrhagic shock was observed (1).


The comprehension of dengue by science took a leap with the isolation of the virus, realised separately by Albert Sabin (6) in the United States, and Susumu Hotta (7) and Ren Kimurao, Japan, during World War II. Types 1 and 2 were isolated first and later also types 3 and 4. In Brazil, type 1 was first isolated in 1986 by the Department of Virology of Fiocruz (8), which, in turn, also isolated types 2 (9) and 3 (10). Type 4 was isolated in 2008, in Manaus (11).



Dengue fever in the Americas


The first reports of dengue-like disease in the Americas are outbreaks in Martinique and Guadalupe in 1635 (5) and Panama in 1699 (5). But the first epidemic described in more detail was that of 1780, in the United States (4). In Brazil, the first outbreak was reported in 1845 (5).


At the beginning of the twentieth century, America faced a dengue pandemic that began in the United States and Panama, spreading throughout the Caribbean (5). In parallel, other countries, such as Cuba and Brazil, were fighting a battle to eradicate Aedes aegypti, motivated by the presence of yellow fever (12, 13), also transmitted by the same mosquito that today transmits dengue fever.


Despite the efforts of several governments, the vector has never been completely eliminated from the continent and, therefore, dengue has continued to spread throughout the Americas.



Pandemics of the 21st Century


In the 2000s, the Americas saw a huge increase in the number of dengue cases caused by the four types of virus, including two major pandemics in 2002 and 2010 (14).


In 2002, more than 1 million cases were registered, 14,374 of which were severe. There were 255 deaths in several countries of the region (15). In 2010, there was a record number of cases on the continent: 1,663,276, including 48,954 cases of severe dengue fever and 1,194 deaths (16) - Brazil accounted for more than 60% of all cases in the region (16).


In Brazil, for the first time the number of cases exceeded one million, being 16,540 cases of severe dengue and 673 deaths (16-18).



A world issue


In the last decades, the incidence of dengue has increased dramatically and the disease has been spreading explosively. Before 1970, only nine countries had experienced severe epidemics of dengue. Today, it is endemic in more than 100 countries (1).


The World Health Organization estimates that about 3.9 billion people - roughly half the world's population - live in areas where they are exposed to dengue viruses (1).



Comparative Table of Symptoms


Dengue, zika and chikungunya have many characteristics in common. It is easy, for example, to confuse its main symptoms. Check, in the table below, how to differentiate one disease from another according to its clinical manifestations (19):









Always present: high and of sudden onset

Almost always present: high and of sudden onset

May be present: low



Almost always present: moderate pain

Present in 90% of the cases: intense pain

May be present: mild pain



May be present

May be present: can usually be seen on the first 48 hours (usually from the 2nd day on)

Almost always present: can usually be seen on the first 24 hours



May be present: light

Present on 50% to 80% of the cases: light

May be present: Light to intense



Not present

May be present

May be present



It is worth noticing, however, that the only way to have an accurate diagnosis is to consult a doctor and take the indicated tests. If you suspect you have symptoms of any of these arboviroses, be sure to seek care!








1. World Health Organization (WHO). Dengue and severe dengue. Fact sheet. No.117. [Internet]. Disponível em: Acessado em: 2017 Jun 05.


2. Thomas EA, et al. Cutaneous manifestations of dengue viral infection in Punjab (north India). Int J Dermatol. 2007 Jul;46(7):715-9.


3. Cunha RV, et al. Manejo clínico do paciente com dengue. In: Dengue: teorias e práticas. Rio de Janeiro: Editora da Fiocruz; 2015. p. 221–45. 


4. Nogueira RMR, et al. Diagnóstico laboratorial da Dengue. In: Valle D, Pimenta DN, Cunha RV da , editors. Dengue: teorias e práticas. 1st ed. Rio de Janeiro: Editora Fiocruz; 2015. p. 205–19.


5. Pimenta DN. A (Des) Construção da Dengue. In: Dengue: teorias e práticas. Rio de Janeiro: Editora da Fiocruz; 2015. p. 23–59.


6. Sabin AB. Research on dengue during World War II. Am J Trop Med Hyg. 1952 Jan;1(1):30-50.


7. Hotta S. Experimental studies on dengue. I. Isolation, identification and modification of the virus. J Infect Dis. 1952 Jan-Feb;90(1):1-9.


8. Schatzmayr HG, et al. An outbreak of dengue virus at Rio de Janeiro - 1986. Vol. 81, Memórias do Instituto Oswaldo Cruz. 1986. p. 245–6.


9. Nogueira RM, et al. Dengue epidemic in the stage of Rio de Janeiro, Brazil, 1990-1: co-circulation of dengue 1 and dengue 2 serotypes. Epidemiol Infect. 1993 Aug;111(1):163-70.


10. Nogueira RM, et al. Dengue virus type 3 in Rio de Janeiro, Brazil. Mem Inst Oswaldo Cruz. 2001 Oct;96(7):925-6.


11. Figueiredo RM, et al. Dengue virus type 4, Manaus, Brazil. Emerg Infect Dis. 2008 Apr;14(4):667-9.


12. Faerstein E, et al. William Gorgas: yellow fever meets its nemesis. Epidemiology. 2011 Nov;22(6):872.


13. Braga IA, Martin JLS. Histórico do controle de Aedes aegypti. In: Valle D, Pimenta DN, Cunha RV da, editors. Dengue: teorias e práticas. 1st ed. Rio de Janeiro: Editora da Fiocruz; 2015. p. 61–73.


14. San Martín JL, et al. The epidemiology of dengue in the americas over the last three decades: a worrisome reality. Am J Trop Med Hyg. 2010 Jan;82(1):128-35.


15. Pan American Health Organization (PAHO) & World Health Organization (WHO). 2002: Number of Reported Cases of Dengue & Dengue Hemorrhagic Fever (DHF), Region of the Americas (by country and subregion). [Internet] Disponível em: Acesso em: 2017 Jun 05.


16. Pan American Health Organization (PAHO). Number of Reported Cases of Dengue and Severe Dengue (DS) in the Americas by Country: Figures for 2010 (to week noted by each country). [Internet]. Disponível em: Acesso em: 2017 Jun 05.


17. Teixeira MG, et al. Epidemiological trends of dengue disease in Brazil (2000-2010): a systematic literature search and analysis. PLoS Negl Trop Dis. 2013 Dec 19;7(12):e2520.


18. Brasil. Ministério da Saúde. Casos de Dengue. Brasil, Grandes Regiões e Unidades Federadas, 1990 a 2016. [Internet]. Brasília, DF; 2017. [Internet] Disponível em: Acesso em: 2017 Jun 05.


19. Lang P. Zika, chikungunya e dengue: entenda as diferenças [Internet]. Agência Fiocruz de Notícias. 2015 [cited 2017 Jun 8]. Available from: