The world is scared of COVID19. Brazilian health professionals too. But today I bring something else that has haunted Brazil for years. It’s dengue. Even with the COVID19 pandemic, the mosquito Aedes aegipty doesn’t give us a break.
Dengue is an arbovirus of the flavivirus genus, which is transmitted by the Aedes aegypti mosquito, and has 4 well-established serotypes: DENV-1, DENV-2, DENV-3, and DENV-4.
Dengue is an infectious viral disease which causes a feverish syndrome. Only in January, February and March, there are 94,149 probable cases of dengue in Brazil. In 2019, there were 1,527,119 cases. The intense summer, high temperatures, and rain helped with the proliferation of the vector last year. And, there was also a change in the serotype. Dengue has 4 circulating serotypes. Here in Brazil, the most common had been 1 and 4; however, the circulation of serotype 2 increased – linked to greater severity and hemorrhage. We cannot concentrate all efforts on COVID19 and forget about some diseases that continue to attack our population.
Deaths from dengue are preventable, except for fulminating cases. Many deaths from dengue are consequences of an error, it may be the delay in seeking health care, the lack of access to the network, and the difficulty in identifying the seriousness of the cases.
The fight to stop the transmission of dengue requires a collective effort because it is transmitted by insects, and that is where exactly the Aedes aegypti mosquito, the great star of dengue, comes into play. The Aedes aegypti mosquito thrives in standing water. The female is responsible for carrying the dengue virus. In addition to dengue, this mosquito can transmit urban yellow fever, Zika, and Chikungunya.
Then, a patient with a high fever, retro-orbital pain, myalgia, prostration, headache, and maculopapular rash arrives and a recent trip to tropical regions (like Brazil!) … think, it could be dengue!
“As per WHO guideline 2009, dengue patients can be further categorized on the severity basis that includes severe dengue patients, dengue patients with few warning signs, and dengue patients with no warning signs. Dengue hemorrhagic fever which is most severe out of these three categories mainly occurs in 5% of total dengue patients”.(2)
Although there is a test called NS1 (viral antigen research) widely used in Brazil for the diagnosis of dengue, with a sensitivity of 70% and specificity of 95%, it is not a good test to rule out the suspicion of Dengue even if it comes negative – and this pattern is repeated in all the other methods like Viral Antigen Research (NS1), Genetic Amplification Test (RRT-PCR) and Tissue immunohistochemistry. It must be done until the 3rd day; after that, its accuracy drops a lot. Moreover, if the patient has had dengue before, its diagnostic value drops. (4)
Regardless of this issue of time, some tests valid for patients are blood count (presence of atypical lymphocytes and thrombocytopenia) and those that demonstrate organ dysfunction, such as TGO and TGP, urea and creatinine) to monitor the severity of the case and guide your treatment. Hemoconcentration, evidenced by the progressive increase in hematocrit (Ht) is the main laboratory finding in the identification of capillary leakage so it can show the severity of the patient.
Do not freak out! If your patient has no alarm signs and no special conditions, treatment can be done on an outpatient basis, advising the patient on the warning signs and the importance of hydration. There is no specific antiviral treatment available in the market yet. Generally, treatment includes the mechanism of controlling fever and pain with paracetamol rather than aspirin (aspirin may promote bleeding), and increasing fluid intake ³. (Look for the specific protocol of your country for the treatment of dengue). And avoid using medications that affect the coagulation cascade, such as non-steroidal anti-inflammatory and acetylsalicylic acid.
Staging and start hydrating!
You may be asking yourself, why do some people develop dengue more seriously and others don’t?
Halstead’s theory states that the disease is becoming more and more severe as the patient becomes infected with different serotypes of the causative virus.
The idea is that in the first infection, the organism can defend itself by producing a series of antibodies that are specific to that invading serotype. But if reinfection with another type of virus occurs, these antibodies may even bind to the pathogen, but they are not effective in stopping them. And this connection also favors the entry of viruses into cells, which enhances their multiplication and, consequently, the patient’s clinical condition.
This is the most accepted theory. There are others, such as the theory of multicausality, which claims the severity of the disease is associated with the interaction between several factors, ranging from the pathogen’s virulence to environmental conditions and also from the disease itself and patient being infected (such as previous comorbidities, age, among others).
Here in Brazil, we have a popular saying “It’s just a bug!”. We use it as a joke when we go to the doctor and he tells us: “it’s just a viral disease, go home, get hydrated and rest!” Yes, dengue is a viral disease. But it deserves special attention, as it can turn into a serious organ dysfunction if not treated properly !!
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- Giang HT, Banno K, Minh LH, Trinh LT, Loc LT, Eltobgy A, et al. Dengue hemophagocytic syndrome: A systematic review and meta-analysis on epidemiology, clinical signs, outcomes, and risk factors. Rev Med Virol 2018; 28(6): e2005.
- Rinku Rozera1, Surajpal Verma1, Ravi Kumar1, Anzarul Haque2, Anshul Attri1 Herbal remedies, vaccines and drugs for dengue fever: Emerging prevention and treatment strategies. Asian Pacific Journal of Tropical Medicine. 2019
- CRUZ, Jaqueline. Avaliação de Testes Diagnósticos para a Identificação da Infecção pelo Vírus da Dengue em Pacientes com Síndrome Febril Aguda. Dissertação (Mestrado em Biotecnologia em Saúde e Medicina Investigativa) – Fundação Oswaldo Cruz, Salvador, 2014.
- Ministério da Saúde. Dengue: Diagnóstico e Manejo Clínico. 5a ed. Brasília: Ministério da Saúde, 2016.