Dengue facts

Warning signs

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  1. severe abdominal pain,
  2. persistent vomiting
  3. rapid breathing
  4. bleeding gums
  5. fatigue
  6. restlessness
  7. blood in vomit

Clinical features of Dengue

  • Fever
  • Retro-orbital pain (Pain behind the eyes)
  • Athralgia
  • Myalgia
  • Headache
  • Vomiting

The patient should check their blood if fever lasts for 2 or more days. The doctor suspects dengue when the platelet count is continuously dropping and all patients with platelet count less than 150 000 should be admitted to hospital.

Investigations

The initial diagnosis of dengue fever is based on the above mentioned clinical features. However, there are some simple tests, which can even be done at the bed-side to confirm the diagnosis of dengue.

The dengue NS1 antigen rapid test and the dengue antibody rapid test are two such simple tests.

The NS1 antigen rapid test usually gives a positive result within the first 5 days of dengue infection. However, this test can be positive even up to day 9 of infection.

The dengue antibody rapid test usually gives a positive result after the first 5 days of dengue infection. However, if a patient has had dengue before, this test can yield positive results even before 5 days. Both the tests that have been mentioned can be done without prior processing of the patients’ blood. (i.e. whole blood can be used)

In addition to the tests mentioned thus far, there are other investigations to confirm dengue. However, these are very rarely performed.

First 5 days of illness: do dengue NS1 antigen test
After day 5 of illness: do dengue IgM and IgG antibody test

If my lab test for dengue is negative, does that mean I don’t have dengue?

Both the NS1 antigen test and the dengue antibody test are very accurate. However, the NS1 antigen test can be negative even on day 3 or 4 even if the patient does have dengue. Also, if the dengue antibody test is done too early (day 3 or 4) it will be negative even if the patient has dengue.

Hence, even if a patient’s tests are negative there is still a possibility that he/she could be having dengue, if the symptoms, signs and the full blood count values are suggestive of dengue fever.

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