Dengue fever is certainly not a new disease especially in countries with hot and tropical climates. Most dengue fever occur in Asia as it represents 70% of the global disease for dengue. However, parts of America and Africa contribute to a high number of dengue cases throughout the year. It is estimated that 100-400 million infections with 40 000 deaths are recorded annually. Dengue cases steadily increased year by year as a result of many factors including urbanisation, population growth, global trade and climate changes. In Malaysia, dengue tends to peak around May to September during the dry southwest and November to March of rainy northeast monsoon seasons. This year, which is 2023, is predicted to be the peak of a major outbreak for dengue fever.
Dengue is an infectious disease that is transmitted by the Aedes mosquitoes carrying the dengue virus. The only way a person is infected by a dengue virus is when the infected female mosquito bites the person. A mosquito is said to be infected when they bite a person with an already existing dengue virus in the human body.
A person infected with dengue can show various kinds of symptoms and some infections are so mild that they do not even exhibit any symptoms or are known as asymptomatic. Symptoms that mainly contribute to suspicion of dengue infection is when a person is experiencing high grade fever for more than 2 days and may last up to 7 days. Other symptoms associated with dengue are headaches with pain behind the eyes (retro-orbital headaches), joint pain (arthralgia), muscle pain (myalgia), vomiting, nausea and skin rash.
Since symptoms of dengue can also be manifested by other diseases, the only way to make sure the dengue infection or dengue fever is indeed caused by the dengue virus, is by doing some tests. There are 3 tests that is common done by doctors to evaluate the possibility of dengue fever:
1- NS1 test
NS1 test detects the non-structural protein NS1 of dengue virus. It is a protein that comes along with the mosquito bite. In other words, NS1 is an antigen. NS1 test is used for the first 7 days of dengue symptoms. It is not recommended to use the NS1 test after day 7 as the result can be inaccurate. NS1 tests can be done either by rapid test kits or using laboratory facilities. A positive test result means a person is indeed infected by virus infection whereas a negative test result does not necessarily mean a person is not infected by dengue virus. In case of negative test results, further tests such as serologic tests are done to detect presence of antibodies against the dengue virus.
2- IgM antibody test
Antibodies are substances produced by the body that signifies the body is fighting against the infection. Presence of antibodies in the system indicates the infection status. IgM antibodies typically appear after the 5th day of fever and can stay in the body for 3 months. A positive IgM test is suggestive of recent dengue infection.
3- IgG antibody test
Antibodies are substances produced by the body that signifies the body is fighting against the infection. Presence of antibodies in the system indicates the infection status. IgG antibodies typically appear much later than IgM and remain in the body for life. IgG test is usually used to determine dengue infections in a person that has been infected by dengue before. This helps to determine the chances of developing a severe form of dengue.
These 3 tests are the common tests recommended to be done in most cases as it is affordable and easy to be done. These tests can be done through rapid test kits where the blood sample can be tested in the doctor’s office or the blood sample is sent to the laboratory. Results from these tests are usually enough to confirm a dengue diagnosis. However, these tests are unable to detect dengue serotypes and do not give information on dengue serotypes. Information of dengue serotype plays an important role in surveillance purposes and in certain cases of severe dengue. To obtain this specific information, molecular tests such as the nucleic acid amplification test (NAAT) may be used on top of the 3 tests.
In essence, dengue tests are used to confirm a dengue diagnosis. Dengue symptoms are not enough to suggest a person is experiencing dengue infection. Thus, dengue tests in either laboratory or rapid test kits help doctors to understand if the patient is indeed affected by dengue. There is no cure for dengue but treatment available helps to support patients and alleviate symptoms. Treatment ranges from ensuring patients drink plenty of fluid, fluid replacement therapy and analgesic medication such as paracetamol. In severe cases, blood transfusion might be needed. To be hospitalised for a day or two or allowed to stay at home with home remedies depends on the stage of the dengue case. Prevention is indeed the best way to protect one from dengue infection.