Chikungunya is a viral fever. This disease is caused when a mosquito named Aedes aegypti, also known as the yellow fever mosquito, bites and the virus enters our body. Chikungunya disease is not spread directly from human to human but when Aedes mosquito bites a sick person and then bites a healthy person, this disease spreads. When Chikungunya virus enters the human body, that person suffers from fever, cough, cold, body pain and joint pain.
Various Blood Tests for Chikungunya Diagnosis
Three types of blood tests can be used to diagnose Chikungunya and which test should be done depends primarily on timing of the test:
- Genomic testing, using PCR or RT-PCR method
- Testing for antibodies (IgM and IgG antibodies)
- Virus isolation test
Genomic testing, using PCR (Polymerase Chain Reaction) or RT-PCR method
If a test is carried out within one week of the onset of Chikungunya, then genomic testing using PCR method is appropriate. This test can offer accurate diagnosis of chikungunya but may not be available in all the labs and often costs more than other tests. This test is generally not advisable after 7-8 days of onset of the disease because after one week it becomes difficult to detect and identify the virus behind chikungunya.
Testing for antibodies (IgM antibodies and IgG antibodies)
When we suffer from Chikungunya fever, our body starts generating antibodies to fight the virus. About 7-8 days after the onset of Chikungunya disease, body generates IgM antibodies and about 4-5 days after this, generation of IgG antibodies starts. These tests are also called Chikungunya IgM and Chikungunya IgG tests. This is why it is important to understand how many days after the onset of Chikungunya fever, test is being conducted and accordingly the results of these tests should be interpreted. IgM antibodies remain in the body for a long time, often for many months. These antibodies for Chikungunya can be tested in two ways: Immunology and ELISA method.
- Immunology or Immuno-Assay is an easy, fast & cheaper method to diagnose chikungunya fever, but it requires good machines and experienced personnel to interpret the test results correctly because this test may not diagnose presence of Chikungunya with complete accuracy.
- ELISA method is relatively better to diagnose both types of antibodies- IgG and IgM. However, this method requires a larger quantity of blood sample and takes longer time it may take 1-2 days to complete sometimes.
Virus Isolation Test
According to the quality of test results, this method is considered the best method for investigation of the disease. After onset of Chikungunya fever, this test can be done within a week when the virus stays in the body. But this method is not so popular in India because it is a difficult and time consuming method. Test result of this method is affected by many things, such as sample collection time, transportation of the sample, temperature during transportation and correct storage of samples etc.
Complete Blood Count
When Chikungunya occurs, white blood cells and platelet count in the blood declines. Chikungunya virus in the blood of our body seems to change the usual mix of blood so this test is used for preliminary investigation of Chikungunya.