ELISA Performance in Testing for Hepatitis B Infections

ELISA Performance in Testing for Hepatitis B Infections : Hepatitis B is a major public health threat. It is caused by the hepatitis B virus (HBV) and causes severe liver infection. Roughly 1.5 million people are newly infected each year, and an estimated 820,000 people die each year from a Hepatitis B infection. The virus is spread through contact; semen, blood, and other body fluids transmit the virus from an infected person.

Though many people will only experience a short-term illness from an HBV infection, some experience long-term symptoms resulting from chronic infection. Short-term infections cause symptoms such as stomach pain, fatigue, nausea, and jaundice. However, chronic infections can result in liver cancer, cirrhosis, or other life-threatening conditions. Early diagnosis of an infection is a strong way to prevent further spread and allow for fast treatment. Both ELISA tests and rapid tests are used in diagnostics.

ELISA Testing for HBV

Enzyme-Linked Immunosorbent Assay (ELISA) test kits search your blood for antibodies. Each ELISA test is intended to detect a single type of biological molecule through specialized enzymes that attach to the target antibody in your blood. For hepatitis B, microwells are coated with anti-HBsAg antibodies and then treated with the samples. If the HBsAg antibodies are present in the sample, the fluid in each well will change color. The color intensity is directly proportional to HBsAg concentration in the sample.

A study in the International Journal of Scientific Research found that an ELISA test correctly diagnosed 655 positive HBV cases from the total sample volume of 13,964. The second study, in the National Journal of Laboratory Medicine, found ELISA tests to accurately diagnose all patients in the 200-sample size; six positives and 194 negatives. For both studies, the sensitivity, specificity, PPV (positive predictive value), and NPV (negative predictive value) are all 100%.

Rapid Testing for HBV

The rapid test for the hepatitis B virus is a single-step immunoassay based on the antigen capture principle. The sample is applied to the test strip, and lateral flow from capillary action draws it past the anti-HBsAg conjugate dried onto the test strip. If the sample is HBV positive, the HBV antibodies will attach to the strip and result in a colored line.

In the International Journal of Scientific Research study, 525 samples were found to be positive from a total sample size of 13,964. This means the rapid test incorrectly diagnosed 130 samples. The resulting data is as follows:

Sensitivity: 83.4%
Specificity: 100%
PPV: 100%
NPV: 99.4%

The rapid test in the National Journal of Laboratory Science diagnosed five samples as positive from a total of 200 samples. The rapid test incorrectly diagnosed one sample. The resulting data from this study are as follows:

Sensitivity: 80.15%
Specificity: 100%
PPV: 100%
NPV: 99.03%.

Diagnosing Hepatitis B

ELISA testing was 100% effective in detecting and diagnosing an HBV infection. These tests require a skilled laboratory technician to complete them correctly, and laboratory-based testing services may not be available everywhere. HBV rapid tests are much easier to use and do not require complex testing methods, but they are less reliable in detecting an HBV infection. While rapid testing is useful, it should always be followed up with ELISA testing to ensure any false negatives are caught and quarantined to prevent virus spread.