Dengue fever is common and already endemic in tropical climate countries and especially in South-East Asia such as our own country Malaysia, Singapore, Thailand and Indonesia. Beside these regions, dengue fever also exists in countries such as in the Africa and America region. In Malaysia, dengue tends to peak around May to September during the dry southwest and November to March of rainy northeast monsoon seasons. It is even predicted that this year may be the peak of a major outbreak for dengue fever. Dengue causes a wide spectrum of diseases which range from no known symptoms until severe symptoms involving life-threatening conditions or death.
Since symptoms of dengue range from mild to severe, it is best for patients to have any of the dengue symptoms to get diagnosed with dengue fever at an early stage. Common symptoms include high-grade fever for more than 2 to 7 days and other accompanying symptoms such as headaches with pain behind the eyes (retro orbital headache), joint pain (arthralgia), muscle pain (myalgia) and skin rash. As a matter of fact, 80{445e3770af60cba6905512ef5b12d3a66d56543799e55c2370aa296296103393} of people with dengue infection do only have mild infection or even no symptoms at all (asymptomatic). Due to the fact these symptoms or signs may be mistaken for other medical conditions, additional tests are usually done by doctors to help confirm dengue diagnosis.
One of the tests is NS1. The dengue NS1 antigen test is a test that detects the non-structural protein NS1 of dengue virus. This protein can be found in the blood during dengue infection. The protein circulates at a high level the first few days of illness. NS1 antigen assay is an effective tool for diagnosis of dengue virus infection, especially within the first few days. The antigen can be detected 1 day after a person has fever and can persist up to 7 to 9 days of dengue infection. However, NS1 test is recommended to only be used for the first 7 days of dengue symptoms. This is because the accuracy of the result from the test after day 7 may be inaccurate.
The importance of the NS1 test is shown in early detection of dengue virus infection. Detecting the virus in the early phase of the dengue illness can assess the risk for progression of severe dengue such as dengue haemorrhagic fever (DHF) and dengue shock syndrome (DSS), especially in children and young adults as they are at risk for these conditions. Early and accurate diagnosis can provide better patient management and prevent life-threatening complications. It also helps to prevent unnecessary usage of antibiotics since dengue symptoms may be similar to other medical conditions.
Beside NS1 test, another test known as serologic test is often used hand in hand with NS1 test to help determine dengue infection in cases of NS1 test result is questionable. Serologic test uses the principle of detecting the antibodies responsible for fighting the dengue infection, especially IgG and IgM antibodies. Antibodies are substances that are produced by the body when it is fighting against an infection. A positive IgM test is suggestive of recent dengue infection whereas positive IgG test shows the presence of previous dengue infection. IgM antibodies appear after the 5th day of dengue symptoms and stay in the body for 3 months. IgG appears later than IgM and remains in the human body for a lifetime.
Results from these two tests are typically enough to confirm dengue diagnosis. However, these tests are unable to detect dengue serotypes or provide information of dengue serotypes. Information of dengue serotype plays an important role in surveillance purposes and in certain cases of severe dengue. For this specific piece of information, molecular tests such as nucleic acid amplification tests (NAAT) are used.
In essence, a dengue test is used to confirm dengue diagnosis. This is because dengue symptoms are not enough to conclude a person is experiencing dengue infection. Dengue tests may be done by using rapid test kits in the clinic office or be sent as blood samples to be analysed in the laboratory. It is worth noting that there is no cure for dengue. Treatment available helps to support patients and to help them recover. In most cases, mild dengue infections can go away on its own and be treated at home with enough rest and drinking plenty of water. In severe cases, patients may need to be hospitalised and be given fluid replacement therapy through intravenous. Medications such as paracetamol are common to be used by patients to help relieve fever and ache. It is worth noting that there is a condition known as the critical phase where a patient’s symptoms may seem to disappear and the patient appears healthy but this is not true. Critical phases occur on the 3rd to 7th days of the dengue disease and when a patient in this phase is left untreated, the patient may end up with severe dengue or even death. Hence, it is very important for a person with any dengue symptoms to get checked by a doctor.