Dengue is a mosquito-borne viral infection which can cause a severe flu-like illness. The infection spreads through the bite of infected Aedes mosquitoes (Ae. aegypti or Ae. albopictus). There are 4 Dengue virus strains (DEN 1, DEN2, DEN3, and DEN4) commonly associated with dengue infection. Among these, DEN 2 is more commonly associated with outbreaks.
As there has been a sudden rise in the cases of Dengue infection these days, here is a quick guide to know the symptoms and to prevent transmission of the virus. This guide will also help to identify what and when to get tested if you suspect dengue-like symptoms.
Signs & Symptoms Of Dengue
The symptoms of dengue usually appear 4-10 days after being bitten by an infected mosquito. The most common symptoms associated with dengue fever may include:
– Fever as high as 104℉ or 40℃
– Severe headache
– Eye pain, typically behind the eyes (Retro-orbital pain)
– Muscle, bone, or joint pain
– Nausea and vomiting
– Loose motions
– Decreased appetite
– Swollen glands
The fever can last for 5-7 days, but it may lose intensity around the 3rd to 7th day of illness. If the symptoms still persist with marked fatigue and generalized weakness, this could be an indication of the beginning of the critical phase (rapid decrease in the platelet count).
It is important to know that in some cases people may not develop any symptoms or illness even after getting the virus. Still, it is advisable to consult a doctor or carefully analyze the symptoms.
Many of these symptoms are similar to COVID, and other flu-like illnesses. It’s best not to ignore any symptoms. Get in touch with an expert immediately.
How To Diagnose Dengue?
A blood test is generally advised if a person is down with fever, muscle pain, and weakness or has any other symptoms of dengue. A lab test is the only way to confirm dengue infection. However, the type of Dengue test may depend on the time of infection and the appearance of the symptoms of dengue fever. Therefore, before you consider a blood test for dengue, you must know about the different types of blood tests available.
Dengue testing is divided into 2 categories:
A) Direct Tests: Tests identifying the virus by antigen / genetic signature. These include a nonstructural protein 1 (NS1) antigen test done through ELISA, and a dengue PCR test done using RT-PCR technique. These tests are 99-100% specific with the latter having higher sensitivity.
B) Indirect Tests: Tests related to the body’s response against the virus. These include IgM and IgG antibodies against Dengue virus measured by ELISA technique.
Here is a quick read which can guide you about the different tests suggested to identify dengue infection.
A) Direct Tests
1. Dengue NS1 Antigen
This test is performed early in the course of infection, usually within the first 5 days of the onset of symptoms. This is because NS 1 antigen starts to appear from the very first day of dengue infection and may be present for up to 5-7 days. Thereafter, it starts disappearing from the body and may therefore indicate false-negative results.
2. Dengue RT-PCR test
This test is also used to detect dengue virus in the early course (first 5 to 7 days) of the infection. It detects the viral genome (the genetic material of the virus) in the blood. This test is around 90% sensitive and 95% specific against the infection. This is the most sensitive and specific test suggested to be taken in the initial phase of the infection.
The dengue PCR test should be done within 5 days after the symptoms start to appear.
B) Indirect Tests
1. Immunoglobulin M (IgM) test for Dengue
This test detects IgM (antibodies) in the blood, which appear in the initial phase of the disease, and signifies acute infection or recent infection. It is advised to undergo a dengue antibody IgM test if you experience the symptoms of dengue continue for more than 5 days. It is usually done after the 4th day of the occurrence of the symptoms as the antibodies start developing after 4-5 days of infection.
-In the 1st week of the onset of symptoms, dengue PCR test and NS1 antigen are recommended.
–Between the 3rd to 9th day, a combination of NS1 antigen/ PCR and IgM antibodies is recommended.
2. Immunoglobulin G (IgG) test for Dengue
The test is used to detect infection in the later course of the disease because the level of IgG which is to be monitored in the test tends to increase slowly. Usually, IgG antibodies are detectable in low quantities starting around 14-21 days of the infection, after which they slowly increase. These antibodies can remain in the blood for around 90 days and in some cases may remain for the rest of your life.
You can get an IgG antibody test for dengue after 14-21 days of infection or even later as these antibodies remain in the blood several months post infection. The presence of IgG antibodies signifies previous infection, recovery after dengue or post vaccination against dengue.
3. Complete Blood Count
Dengue is frequently associated with decreased platelet count (normal platelet count lies in the range of 1.5 to 4 lacs). Therefore, platelet count should be monitored carefully and regularly, especially when the fever comes down.
If a patient is positive for dengue-specific antigen, a decrease in platelet count and a decrease in total white blood cells (WBC) count may be seen. But, it is important to know that diagnosis of dengue does not depend solely on platelet counts.
The above-mentioned lab tests can help diagnose and confirm a dengue fever. But it is possible that some of these tests may miss a diagnosis in a few people if the tests are not performed during a specified time of illness. While Dengue RT-PCR remains the most sensitive and specific test for dengue, a combined NS1 antigen & IgM are also useful in detecting early infection.
How To Treat Dengue?
There is no particular treatment available to completely eradicate dengue infection from the body. In order to better manage dengue, the focus is kept on improving the symptoms and ensuring sufficient rest. Fever can be treated with antipyretic drugs like paracetamol to bring down the temperature and also relieve body aches. Medicines such as aspirin, ibuprofen, etc. should be avoided as they may increase the risk of hemorrhage. Antibiotics or Antivirals are not required as these generally have no positive effect in managing dengue fever.
Here are some suggested ways to manage dengue fever:
Drink plenty of fluids to stay hydrated. This is advised to relieve the symptoms until the infection has gone. Eat a healthy diet in addition to taking sufficient rest.
Don’t forget to take doctor’s advice if you notice that the condition is getting worse or if symptoms like uncontrolled fever, loose motions, cold clammy skin, decreased blood pressure, decreased appetite, feeble pulse, pain in the abdomen, or dark stools (charcoal or tar colored feces) appear.
Most patients with dengue fever generally experience mild illness and may not require hospitalization. They can be treated at home by following strict dietary guidelines and guided course of medication. Keep track of the symptoms as in some cases aggravation of symptoms may also be observed pertaining to potentially serious complications. These aggravated or continued symptoms may indicate severe dengue or dengue hemorrhagic fever, which may require hospitalization.
How To Stay Protected Against Dengue?
As dengue is caused by a mosquito bite, the best way to prevent dengue is to stay protected against mosquitoes. Here are some simple and effective ways to prevent mosquito bite and its disease following partner dengue:
– Use mosquito repellents: Some people may be more prone to mosquito bites than others. Applying a thin, even layer of mosquito repellent on exposed areas of the skin will keep the mosquitoes away. Explore our range of mosquito repellents to protect yourself.
– Use an insecticide-treated mosquito net or spray insecticides: Placing an insecticide-treated net on your bed while sleeping can save you from mosquito bites. Do make sure that there are no holes in the net. Also, treat your house with insecticides once or twice a year to prevent the breeding of mosquitoes.
– Protect windows with nets: Cover your doors and windows with mosquito mesh to stop mosquitoes from entering the house. Keep your doors and windows closed during dusk and dawn, the time when mosquitoes are most active.
– Cover yourself with clothing: To avoid mosquito bites, you can wear full-length, loose-fitting pants and full-sleeved shirts. Avoid wearing short clothes and half-sleeved shirts.
– Look out for water pits: Aedes mosquitoes harbors in fresh stagnant water; therefore, it is necessary to remove water that gets collected in spots such as AC trays, room coolers, potted plants, flower vases, water containers or tanks, and clogged drains. Clean dark corners/rooms, behind the curtains, and dust bins, as all these factors can act as breeding grounds for mosquitoes.
Remember, the best way to manage the spread of dengue infection is prevention. Prevention is always better than cure. Let’s do our bit to prevent it!
(The article has been reviewed by Dr. Pragya Rani, Microbiologist, Tata 1mg Labs)
1. Dengue/Severe dengue frequently asked questions. Dengue Control. The World Health Organization (WHO). https://www.who.int/denguecontrol/faq/en/index2.html
2. Symptoms and Treatment. The Centers for Disease Prevention and Control (CDC). US. https://www.cdc.gov/dengue/symptoms/index.html