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How Is Dengue Fever Diagnosed?

Dengue fever is an infectious disease with a fast-spreading rate. Therefore, the diagnosis of dengue fever plays an important role in the early detection of the disease. To diagnose this disease, doctors usually base on the clinical signs of the disease and through tests such as NS1 test, IgG antibody test, IgM test, … dengue treatment suitable for patients.

Overview of Dengue Fever

Dengue is an acute infectious disease caused by the dengue virus. If bitten by a mosquito carrier that carries the disease, the disease can be easily spread. Dengue fever can occur at any age, and children are the most susceptible. The disease causes fever, rash, body aches, hypotension. If prolonged, it can be dangerous and lead to death.

Dengue is an acute infectious disease caused by the dengue virus

State 1

This is the early stage of the disease, the manifestations are often not so obvious that it is difficult to distinguish it from common viral fevers. Patients can have a high fever of up to 39-40 degrees in the first one or two days. Need to go to a hospital or medical center for prompt diagnosis and treatment.

Stage 2

Entering stage 2, the danger level of the disease also increases. This stage usually starts from day 3 to 7 after the sick person has a fever. The patient appeared symptoms such as bleeding under the skin in the arms, abdomen, thighs, legs, … bleeding teeth, nosebleeds. In more severe cases, there may be gastrointestinal bleeding, pleural effusion, cerebral hemorrhage, … In stage 2, close monitoring and treatment are important to limit dangerous complications. Occurs as thrombocytopenia, blood concentration.

Stage 2 is the most dangerous stage of illness
usually starting from day 3 to 7 after the sick person has a fever

Stage 3

Stage 3 is the recovery phase, the patient's health improves. The fever stops, the hemodynamic stabilizes, the appetite, urinating a lot, the platelet tests gradually increase and gradually return to normal.

Diagnosis of Dengue Fever Through Clinical Sign

One of the ways to help diagnose the patient has dengue fever or not is based on the clinical signs of the disease.

When there is mild dengue fever, many people often have no symptoms. Symptoms may appear when an infected person is bitten by a mosquito for 4 to 7 days.

  • High fever, up to 39-40 degrees Celsius
  • Headache
  • Body aches and pains, especially musculoskeletal muscles
  • The sick person feels nauseous and vomiting
  • The eye sockets are sore
  • A rash
  • Swollen glands
Dengue patients with high fever can reach 39-40 degrees Celsius

Most people with dengue can recover in about a week or more. But there are also cases where the condition worsens, the blood vessels are damaged and leaking out, the platelets drop, … This causes dengue – a dangerous form of dengue. High with common symptoms such as:

  • Severe abdominal pain
  • Persistent vomiting
  • Bleeding gums or nose
  • Bleeding under the skin
  • The patient is short of breath and has difficulty breathing
  • The body is tired and restless
  • Skin is damp and cold
  • Blood may appear in feces, urine, or vomit
Some signs of dengue fever

In addition, there is a form of hemorrhagic fever causing internal bleeding such as cerebral hemorrhage, gastrointestinal bleeding. In the case of gastrointestinal bleeding, the patient can have a number of manifestations such as:

  • Low-grade fever
  • Headache
  • No rash
  • Have black blood or stools
  • Tired body
  • Pale skin
  • Bleeding spots appear on the skin

The case of cerebral hemorrhage is often more difficult to recognize. The patient may have symptoms: fever, headache, then paralysis of the limbs or half of the body, coma and can lead to death if not treated early.

When the body shows unusual signs of hemorrhagic fever, it is necessary to immediately go to the nearest hospital or medical center for prompt examination and treatment.

Diagnosing Dengue Fever Through Tests

To accurately diagnose the disease, doctors will conduct specific tests such as:

1. Dengue NS1 antigen test

The Dengue NS1 antigen test is a test based on virus antigen detection.

Dengue NS1 antigen test

Doctors will order to perform tests from day 1 to 5 of illness to determine if the patient has dengue fever or not. If the test result is positive, then the patient has dengue fever and vice versa. However, if the patient has been ill for more than 3 days (from the end of day 3 onwards), the test result may be negative even though the patient has had a fever. This is due to the decrease in the concentration of viral antigens in the blood at the end of day 3 onwards.

2. IgM antibody test

IgM usually appears 4-5 days after a fever. Performing this test helps to determine the presence of antibodies against the dengue virus in the acute phase of the disease. Each different patient will have different levels of antibody production, which determines whether the test result is positive or not.

3. IgG antibody test

For people first infected with the dengue virus (primary form), IgG appears about 10 to 14 days and can remain in the body for many years after that. For people who have had dengue (secondary body), IgG is already in the blood and they will increase in 1-2 days.

If you suspect that the patient is infected with the dengue virus, doctors usually perform all 3 tests above to accurately diagnose:

  • If all 3 tests for MS1, IgM, and IgG are negative, then the patient will not have a fever due to dengue.
  • If the NS1 or/and IgM tests are positive, and the IgG test is negative, the patient has primary dengue infection.
  • If the NS1 or/and IgM test is positive, and the IgG test is positive, the patient has secondary dengue infection.

The timing of the test plays an important role in the diagnosis of dengue fever. In addition, tests may also be performed more than once because each individual's immune response to the virus is not the same.

In addition to the 3 main tests mentioned above, doctors may order several other tests to assist in the diagnosis and monitoring of disease progression such as:

Total blood cell analysis test: to assist in diagnosing and monitoring the condition of the disease and prognosis of the disease.

  • Electrolyte test: helps evaluate electrolyte disorders
  • Liver function test: helps check liver function, detect complications of dengue fever and evaluate the level of damage.
  • Albumin test: helps to evaluate the possible drainage of plasma in patients with dengue fever, early detection, and monitoring of increased vascular permeability.
  • Kidney function test: tests kidney function and assesses the damage caused by dengue complications.
  • CRP test: diagnoses the cause of the fever and evaluates the superinfection caused by dengue fever.

4. Frequently asked questions when testing for dengue fever

When to test for dengue?

When to be tested for dengue plays an important role in the diagnosis and treatment of the disease. Dengue develops into 3 phases, in which phase 2 from day 3 to day 7 is the most dangerous period. In stage 1, the patient usually has a high fever, can go to the hospital to be examined and tested as soon as possible. Prolonged illness can cause dangerous complications for health.

When there are signs of suspicion of having dengue fever, it is necessary to immediately
need the nearest medical facility for early examination and treatment

Does a dengue test need fasting?

Dengue testing does not require fasting. Because the parameters of the disease are platelets and blood concentration is not affected when you eat.

Does a blood test detect dengue?

A blood test is one of the most common dengue tests. The doctors will take blood from the patient and take it for analysis. If the amount of platelets in the blood is lower than required, the bleeding level should be monitored. Elevated hematocrit is a sign of blood concentration due to dehydration. Early treatment is needed to limit dangerous complications.

How much does the dengue fever test cost?

Testing for dengue is usually not too expensive. Virus diagnostic tests for antigens and antibodies usually range from 500,000 VND. Daily total blood tests can range from 100,000 VND to 200,000 VND. However, this is only a reference price, depending on the medical facility as well as the condition of the disease that doctors will advise more other tests.

In some special cases of health or geographical reasons that you cannot go to a hospital or medical facility, you can use home dengue testing at reputable medical facilities to quality assurance.

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The site cannot and does not contain medical advice. The medical information is provided for general informational and educational purposes only and is not a substitute for professional advice. Accordingly, before taking any actions based upon such information. We encourage you to consult with the appropriate professionals.