To confirm the diagnosis of dengue, in addition to evaluating the symptoms presented by the person, laboratory tests are carried out, such as blood count, virus isolation and biochemical tests, for example.
After carrying out the tests, the doctor can check the type of virus and, thus, recommend the most appropriate treatment for the person. Therefore, if a fever appears accompanied by two or more of the symptoms mentioned above, it is recommended to go to the emergency room so that diagnostic tests can be carried out and, thus, treatment can begin.
Dengue is a disease caused by mosquito bites Temples of the Egyptians infected, which is more common to appear in summer and in wetter regions due to the ease of development of the dengue mosquito. See how to identify the dengue mosquito.
1. Physical examination
The physical examination consists of the doctor’s assessment of the symptoms described by the patient, which are indicative of classic dengue:
- Intense headache;
- Pain in the back of the eyes;
- Difficulty moving joints;
- Muscle pain throughout the body;
- Dizziness, nausea and vomiting;
- Red spots on the body with or without itching.
In the case of dengue hemorrhagic fever, symptoms can also include excessive bleeding, which usually manifests itself as red spots on the skin, bruising and frequent bleeding from the nose or gums, for example.
Symptoms normally appear 4 to 7 days after the bite of a mosquito infected by the virus and begin with a fever above 38ºC, but after a few hours it is accompanied by other symptoms. However, dengue symptoms can easily be confused with those of other febrile illnesses, such as Zika or oropouche fever.
Read too: Oropouche fever: what it is, symptoms, cause and treatment
Therefore, if blood is suspected, it is important to seek medical help so that more specific tests can be carried out to confirm the diagnosis and start treatment quickly, since in more serious cases the dengue virus can affect the liver and heart.
Don’t ignore your symptoms!
Online symptom test
To find out your risk of having dengue fever, select the symptoms that may be present in the following test:
The symptom test is a tool that only serves as guidance, not serving as a diagnosis or replacing consultation with a general practitioner or infectious disease specialist.
2. Loop test
The loop test is a type of quick exam that checks the fragility of blood vessels and their tendency to bleed, and is often carried out in cases of suspected classic or hemorrhagic dengue fever.
This examination consists of interrupting the blood flow in the arm and observing the appearance of small red dots, with a greater risk of bleeding the greater the number of red dots observed. Understand how the lasso test is performed.
Despite being part of the tests recommended by the World Health Organization for diagnosing dengue, the loop test can provide false results when the person is taking medications such as Aspirin or Corticosteroids or is in the pre or post menopause phase, for example.
3. Quick test to diagnose dengue
The rapid test to identify dengue is being increasingly used to diagnose possible cases of infection by the virus, as it takes less than 20 minutes to identify whether the virus is present in the body and for how long due to the detection of antibodies, the IgG and IgM. This way, it is possible to start treatment more quickly.
However, the rapid test also does not identify the presence of other diseases transmitted by the Dengue mosquito, such as Zika or Chikungunya, and therefore the doctor may order a normal blood test to identify whether you are also infected by these viruses. The rapid test is free and can be done at health centers in Brazil by anyone and at any time, as it is not necessary to fast.
4. Virus isolation
This test aims to identify the virus in the bloodstream and establish the serotype, allowing differential diagnosis for other diseases caused by the bite of the same mosquito and which present similar symptoms, in addition to allowing the doctor to initiate more specific treatment.
Isolation is done through the analysis of a blood sample, which must be collected as soon as the first symptoms appear. This blood sample is sent to the laboratory and, through molecular diagnostic techniques, such as PCR, for example, it is possible to identify the presence of the dengue virus in the blood.
5. Serological tests
The serological test aims to diagnose the disease through the concentration of IgM and IgG immunoglobulins in the blood, which are proteins that have their concentration altered in cases of infection.
The concentration of IgM increases as soon as the person comes into contact with the virus, while IgG increases later, but still in the acute phase of the disease, and remains in high quantities in the blood, therefore being a marker of the disease, as It is specific to each type of infection.
Serological tests are normally requested as a way of complementing the virus isolation test and the blood must be collected approximately 6 days after the onset of symptoms, as this makes it possible to more accurately check the concentrations of immunoglobulins.
Read too: IgG and IgM: differences and what a reactive result means
6. Blood tests
The blood count and coagulogram are also tests requested by the doctor to diagnose dengue, especially dengue hemorrhagic fever. The blood count normally shows variable amounts of leukocytes, and there may be leukocytosis, which is an increase in the number of leukocytes, or leukopenia, which corresponds to a decrease in the number of leukocytes in the blood.
Furthermore, an increase in the number of lymphocytes (lymphocytosis) is normally observed with the presence of atypical lymphocytes, in addition to thrombocytopenia, which is when platelets are below 100,000 /mm³, when the reference value is between 150,000 and 450,000 /mm³.
Read too: CBC reference values
The coagulogram, which is the test that checks the blood’s ability to clot, is normally requested in case of suspicion of dengue hemorrhagic fever and an increase in prothrombin time, partial thromboplastin and thrombin can be observed, in addition to a decrease in fibrinogen, prothrombin, factor VIII and factor XII, indicating that hemostasis is not happening as it should, confirming the diagnosis of dengue hemorrhagic fever.
7. Biochemical tests
The main biochemical tests requested are the measurement of albumin and the liver enzymes TGO and TGP, indicating the degree of liver impairment and being indicative of a more advanced state of the disease when these parameters are measured.
Normally, when dengue is already at a more advanced stage, it is possible to observe a decrease in the concentration of albumin in the blood and the presence of albumin in the urine, in addition to an increase in the concentrations of TGO and TGP in the blood, indicating liver damage.
