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PCR test detects dengue in the early stages

PCR test detects dengue in the early stages

The PCR test or molecular test for dengue is used to determine if a person is infected with the virus. As the symptoms of dengue are very similar to those of other diseases, such as influenza and virus, the test assists in the most accurate diagnosis.

The molecular test for dengue can detect the virus within the first 5 days after the onset of symptoms. Method is able to identify the genetic material of the virus in the blood while it is still multiplying.

The differential of the PCR test is that it can identify which serotype is infecting the patient. There are four types of dengue virus (DEN-1, DEN-2, DEN-3 and DEN-4) and they have different genetic materials. As the test identifies the DNA of the virus, it is possible to make this differentiation.

It is not very common to do molecular examination for the diagnosis of dengue. It is usually done the serology test, which detects the presence of antibodies responsible for fighting the dengue virus in the patient's blood.


Molecular test for dengue


The main indication of the PCR for dengue are people who have symptoms of the disease. The main signs are:

  • High fever with sudden onset (39 ° to 40 ° C)
  • Severe headache
  • Pain behind the eyes that worsens with movement
  • Loss of taste and appetite
  • Nausea and vomiting
  • Dizziness
  • Extreme tiredness
  • Body aches and pain
  • Many pains in the bones and joints
  • Abdominal pain (especially in children).

Other symptoms of dengue may manifest in the hemorrhagic form of the disease. See:

  • Strong and continuous abdominal pain
  • Persistent vomiting
  • Pale, cold and moist skin
  • Bleeding through the nose, mouth and gums
  • Red spots on the skin
  • Behavior ranging from drowsiness to shaking
  • Mental confusion
  • Excessive thirst and dry mouth
  • Respiratory distress
  • Blood pressure drop.


There are no express contraindications for a PCR test for dengue. However, the doctor or doctor can tell you whether you are fit to take the test or not.

Pregnant can do?

There are no contraindications for conducting the PCR test for dengue during pregnancy. for the exam

No preparation is required to take the PCR test for dengue. It is usually done without scheduling, since it is only done when a patient is going to the hospital or clinic to complain of the symptoms.

Before taking the PCR test for dengue, the doctor or doctor can also do the so-called test of the loop. It does not confirm the diagnosis of dengue, but it raises suspicion and may justify the molecular test.

To do the loop test, tying a small stick on the patient's arm to secure the circulation. If red dots appear on the skin, it is a sign that the disease is present, as dengue affects the blood circulation.

How it is done

In a hospital or laboratory, the dengue PCR test is performed by a health professional as follows:

With the patient seated, a rubber band is tied around his or her arm to stop the flow of blood. This causes the veins to become wider, helping the practitioner hit one of them.

  • The professional cleans the arm area to be penetrated by the needle.
  • The needle is inserted into the vein. This procedure can be done more than once until the health care provider hits the vein and is able to remove the blood.
  • Blood collected in the syringe and placed in a tube
  • The elastic is removed and a gauze is placed on the where the health professional inserted the needle, to prevent any bleeding. He or she can press on the bandage to staunch the blood
  • A bandage is placed on the spot.
  • Examination time

The PCR test for dengue takes a few minutes to be performed, and may take longer in cases in which the health professional has difficulty hitting the vein and collecting blood.

Post-examination recommendations

There are no special recommendations following the examination. The patient can do his / her activities normally. Because of the fast, it is recommended to eat a meal as soon as the examination is completed.


The risks involved in conducting the dengue PCR test are extremely rare. At most, there may be a hematoma at the site where blood was withdrawn. In some cases, the vein may become swollen after the blood sample is collected (phlebitis), but this can be reversed by making a compress several times a day.

People who use anticoagulant medications or have coagulation problems may suffer from a bleeding after collection. In these cases, it is important to inform the health care professional of the problem in advance.


PCR results for dengue can be positive or negative. A positive PCR result is considered conclusive and no further testing is necessary.

A negative PCR result may indicate that there is no infection or that the virus level is too low to detect. This can happen if the test is done after the first 5 days of infection, at which time the virus is multiplying and therefore present in the bloodstream. In these cases the blood test for dengue is performed.

If very recent exposure is suspected, the tests may be repeated days later.

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