The Dengue Virus And The Igg Blood Test

Dengue is a virus carried by mosquitoes and is common in tropical and subtropical regions. It can inflict dengue fever on people. Blood tests can find antibodies produced in response to a dengue infection or the dengue virus itself.

Dengue Virus

The Flavivirus genus is what causes dengue. It also contains viruses like yellow fever, West Nile, and tick-borne encephalitis. Dengue viruses have four different varieties – DENV 1; DENV 2; DENV 3; DENV 4. There is no cross-immunity among these four virus types. Thus, dengue infections can recur in a person’s lifetime.

Dengue Fever

Dengue is contracted when bitten by a mosquito carrying one of the four forms of the dengue virus (DENV). Tropical and subtropical locations include Central and South America, Africa, some parts of Asia, and the Pacific Islands. Dengue is not infectious except when transmission occurs from a pregnant woman to her unborn child. The initial infection usually has subtle symptoms. If you develop a second infection with a different strain of DENV, your chance of severe problems increases.

Who is impacted by dengue fever?

Africa, Central- South America, some regions of Asia, and the Pacific Islands are the hotbeds of dengue fever. The chance of developing a significant illness is higher in children and the elderly.

What symptoms are present in dengue fever?

The majority of dengue infections are symptomless. High temperature (104°F/40°C) is usual if you do experience symptoms accompanied with:

• rashes, 
• extreme discomfort behind your eyes,
• nausea, or/and
• pain in your joints.

The first signs of dengue fever begin four to ten days after a mosquito bite. It remains for three to seven days. After their first symptoms wane, around 1 in 20 dengue patients will develop severe dengue.

Severe dengue (dengue hemorrhagic fever)

A life-threatening progression of dengue symptoms is considered severe dengue. Symptoms of severe dengue occur typically, 24 to 48 hours after your fever goes down. Severe dengue can be lethal. Consult your doctor without delay if you have these symptoms –

• Discomfort in the abdomen or stomach
• Excessive vomiting
• Having blood in your vomit or your feces (stool)
• A runny nose
• Bleeding gums

Diagnosis of dengue fever

Blood tests can identify the dengue virus. To check for it, your blood sample is taken and sent to a lab for analysis. Additionally, this might tell you which of the four versions you have.

There are primarily two kinds of testing available:

• Molecular testing (polymerase chain reaction, PCR). – Is performed to identify which of the four serotypes of the dengue virus is infecting a person. It is done by detecting the virus’s genetic material in the blood. The test is performed during the first week after symptoms (fever) manifest.
• Antibodies tests – used to identify recent or active infections. They look for IgG and IgM, two different kinds of antibodies the body produces against dengue fever infection. The body’s immune system creates different amounts of antibodies during a disease. Hence, a combination of these tests may be necessary for a diagnosis.

Meaning of the test results

Molecular testing is the most precise form of diagnosis because it identifies the virus’s presence. A positive PCR result is thought to be conclusive.  A negative PCR test result could indicate that there is no infection currently present or at all. It can happen if the test is carried out after the 7-day window. During this period the virus is detectable in the sample used. After a negative PCR result, antibody testing is done for confirmation.

Dengue IgG Test: These can either produce a positive or negative result. They can also have an antibody titer explaining the type(s) of antibodies (IgG or IgM) present. Initial blood testing for dengue antibodies may reveal positive results for both IgM and IgG. It indicates that the patient most likely contracted the virus during the past several weeks.

A cross-reaction occurs if someone has had an infection with a comparable virus, such as chikungunya.

The following table lists the possible outcomes of an antibody test:

IgM Result	IgG Result	Possible Interpretation
Positive	Negative	Current infection
Positive	Positive	Current infection
Low or negative or not tested	Four-fold increase in samples taken 2-4 weeks apart	Recent infection
Low or negative	Positive	Past infection
Negative	Negative	Too soon after initial exposure for antibodies to develop or symptoms due to another cause

Conclusion

No vaccine can shield someone from dengue fever. Preventing mosquito bites is essential for reducing virus exposure. Always wear DEET-containing bug repellant, long sleeves, and long pants when traveling in tropical areas. It is advisable to stay indoors at dawn and dusk when mosquitoes are most active.