Related Experiment Video
Updated: Jun 19, 2026
15:57
Application of Long-term cultured Interferon-γ Enzyme-linked Immunospot Assay for Assessing Effector and Memory T Cell Responses in Cattle
Published on: July 11, 2015
Interferon-gamma-release assays detect recent tuberculosis re-infection in elderly contacts
1Section of Respiratory Disease, Department of Oncology, Hematology and Respiratory Disease, University of Modena, and Policlinico Hospital of Modena, Modena, Italy. giovanni.ferrara@unipg.it
International Journal of Immunopathology and Pharmacology
|October 14, 2009
Summary
Interferon-gamma blood tests may distinguish recent latent tuberculosis infection (LTBI) from past exposure, unlike the tuberculin skin test (TST). This finding is crucial for accurate tuberculosis diagnosis in elderly populations.
Area of Science:
- Infectious Diseases
- Immunology
- Public Health
Background:
- The tuberculin skin test (TST) has limitations in differentiating recent latent tuberculosis infection (LTBI) from remote infection.
- Accurate diagnosis of recent LTBI is critical for effective contact tracing and treatment, especially in vulnerable populations like the elderly.
Purpose of the Study:
- To evaluate the performance of two interferon-gamma release assays (IGRAs), QuantiFERON-TB Gold (QFT-G) and T-SPOT.TB (TS.TB), in distinguishing recent LTBI from remote infection among elderly nursing home residents exposed to tuberculosis.
- To compare the diagnostic utility of TST, QFT-G, and TS.TB in a high-prevalence setting for remote LTBI.
Main Methods:
- A contact tracing investigation was conducted in a nursing home following a pulmonary tuberculosis case.
- Tuberculin skin test (TST), QuantiFERON-TB Gold (QFT-G), and T-SPOT.TB (TS.TB) were administered to exposed and unexposed elderly individuals 8 weeks post-exposure.
- Interferon-gamma (IFN-γ) measurements were analyzed, with adjustments for T-cell counts, to assess specific immune responses.
Main Results:
- TST, TS.TB, and QFT-G showed positivity rates of 37.5%, 44.4%, and 22.2%, respectively.
- Agreement between TS.TB and QFT-G was substantial in exposed individuals (K=0.915) but poor in unexposed individuals (K=0.218).
- Adjusted IFN-γ production was significantly higher in exposed versus unexposed individuals (16.75±5.40 vs. 2.33±0.71 IFN-γ IU/1000 SFC, p=0.0001), suggesting a distinction between recent and remote infection.
Conclusions:
- QFT-G and TS.TB yielded discordant results in elderly contacts, highlighting potential differences in their detection capabilities.
- Adjusted IFN-γ response, measured by IGRAs, shows promise in differentiating recent tuberculosis infection from long-standing exposure, offering an advantage over TST.
- These findings suggest that IGRAs, particularly when analyzing specific IFN-γ production, may improve the accuracy of diagnosing recent LTBI in epidemiological investigations.
Related Concept Videos
01:26Pulmonary Tuberculosis IV
Tuberculosis, more commonly referred to as TB, is an infectious disease stemming from Mycobacterium tuberculosis. While it primarily impacts the lungs, TB can also affect other body areas. Given its severity and global impact, timely and accurate diagnosis is crucial for controlling its spread and improving patient outcomes.
Several diagnostic approaches are used to detect TB. The conventional method is the Tuberculin Skin Test (TST), also known as the Mantoux test. However, this method has...
Several diagnostic approaches are used to detect TB. The conventional method is the Tuberculin Skin Test (TST), also known as the Mantoux test. However, this method has...
01:23Tuberculosis
Tuberculosis (TB) remains a significant global health concern, primarily targeting the lungs and spreading through airborne transmission. Infection begins when aerosolized droplet nuclei, expelled by an individual with active TB, are inhaled by another person. These microscopic particles carry Mycobacterium tuberculosis, the causative agent of TB. Upon reaching the alveoli, the bacilli are engulfed by alveolar macrophages. However, due to their specialized lipid-rich cell wall, these pathogens...
01:28Pulmonary Tuberculosis II
Tuberculosis, or TB, is a bacterial infectious disease caused by Mycobacterium tuberculosis. While its primary impact is on the lungs, leading to pulmonary tuberculosis, it can also affect various other organs, a condition referred to as extrapulmonary tuberculosis.
Here is a detailed explanation of its pathophysiology:
Transmission: The process begins when a person inhales droplet nuclei containing M. tuberculosis. These are typically released into the air when an individual with pulmonary or...
Here is a detailed explanation of its pathophysiology:
Transmission: The process begins when a person inhales droplet nuclei containing M. tuberculosis. These are typically released into the air when an individual with pulmonary or...
01:29Pulmonary Tuberculosis I
Tuberculosis, often called TB, is a contagious illness primarily caused by Mycobacterium tuberculosis. It mainly affects the lung parenchyma but can also impact other body parts.
Causative Organism
The primary infectious agent causing tuberculosis is Mycobacterium tuberculosis, a slow-growing, acid-fast, aerobic rod that exhibits sensitivity to heat and ultraviolet light. Instances of Mycobacterium bovis and Mycobacterium avium contributing to the development of TB infection are rare.
Mode of...
Causative Organism
The primary infectious agent causing tuberculosis is Mycobacterium tuberculosis, a slow-growing, acid-fast, aerobic rod that exhibits sensitivity to heat and ultraviolet light. Instances of Mycobacterium bovis and Mycobacterium avium contributing to the development of TB infection are rare.
Mode of...
01:31Pulmonary Tuberculosis III
Tuberculosis (TB) is a contagious infection primarily affecting the lung parenchyma but which can also affect other body parts. TB can be classified based on disease development, presentation, and the affected anatomical site.
The first classification is based on the development of the disease, and it includes the following categories:
The first classification is based on the development of the disease, and it includes the following categories:
01:28Pulmonary Tuberculosis V
Medical management of tuberculosis (TB) patients involves a comprehensive approach that includes diagnosis, treatment, and monitoring. The specific strategies can vary depending on the type of tuberculosis (latent or active), the patient's overall health status, and other considerations.
Latent tuberculosis infection occurs when TB bacteria are present in a person's body, but are not causing illness or symptoms. It is not contagious, and preventive treatment is crucial to avoid the progression...
Latent tuberculosis infection occurs when TB bacteria are present in a person's body, but are not causing illness or symptoms. It is not contagious, and preventive treatment is crucial to avoid the progression...