Type: Prelims Only

Why in the news?

The emergence of new variants KP.2 and KP1.1, known as the FLiRT variants, has raised global concerns.

• Despite vaccination efforts, these variants pose challenges, leading to concerns about a potential rise in COVID-19 cases.

What are the FLiRT Variants of COVID-19?

• KP.2 and KP1.1, dubbed ‘FLiRT’ variants, are descendants of the Omicron JN.1 which spread globally over the winter last year.

Features and Differences from Other Variants

• New Spike Mutations: The FLiRT group includes two specific mutations that are believed to enhance the virus’s ability to infect human cells.
• Transmission and Evasion: Preliminary studies suggest that KP.2, the more prevalent of the two, may possess enhanced capabilities to evade immune responses generated by vaccines and previous infections.

Are FLiRT Variants Riskier than JN.1?

• Increased Immune Evasion: Research indicates that KP.2 shows a significant ability to escape immunity from both the latest vaccines and previous infections.
• Reproduction Number: The reproduction number of KP.2 may be higher than that of JN.1, indicating a potentially greater ability to spread.
• No definitive evidence: While there’s no definitive evidence that FLiRT variants cause more severe illness, their ability to circumvent immune defences can lead to more infections and, by extension, potential increases in hospitalizations.

Why in the news?

Patients with fever in India often undergo testing and treatment for typhoid fever, primarily relying on the Widal test.

• The Widal test, though widely used, has several limitations that affect its accuracy and reliability.

Typhoid diagnosis using Widal Test

• The Widal test is used primarily to diagnose typhoid fever.
• Typhoid fever, caused by Salmonella Typhi and related bacteria, presents with symptoms like high fever, stomach pain, weakness, and gastrointestinal issues.
• It detects antibodies in the patient’s blood against the O (somatic) and H (flagellar) antigens of Salmonella Typhi.
• Procedure:

1. The presence of these antibodies is detected through an agglutination reaction.
2. The test involves serial dilution of the patient’s serum.
3. The highest dilution at which agglutination occurs indicates the antibody titer, with higher titers suggesting an active infection.

Diagnostic Challenges:

• The gold standard for diagnosing typhoid involves isolating the bacteria from blood or bone marrow cultures, which is time-consuming and resource-intensive.
• Widal test is commonly used due to its convenience and accessibility. However, the Widal test’s interpretation is complicated by factors like the need for multiple serum samples, variations in cutoff values, and potential cross-reactivity with antibodies from other infections or vaccines.

Challenges with Widal Test:

• Impractical: A single positive Widal test does not confirm typhoid.
• Complicated result interpretation: High background antibody levels and variability in test cutoff values.
• Cross-reactivity with antibodies from other infections and false negatives due to prior antibiotic therapy undermine test reliability.

Consequences of Widal Test Use:

• Erroneous results obscure the true burden of typhoid in India, leading to inappropriate treatment and financial strain on patients.
• Overuse of antibiotics based on Widal test results contributes to antimicrobial resistance, exacerbating the challenge of treating typhoid.

Why in the news?

• Magnetic Resonance Imaging (MRI) revolutionized medical diagnostics, offering non-invasive insights into soft tissues.
• The pioneering efforts of Paul Lauterbur and Peter Mansfield led to its commercialization, earning them the Nobel Prize in Medicine in 2003.

What is MRI?

• Magnetic resonance imaging (MRI) is a non-invasive diagnostic procedure used to obtain detailed images of soft tissues within the body.
• It is particularly valuable for imaging sophisticated structures like the brain, cardiovascular system, spinal cord, joints, muscles, liver, and arteries.
• MRI is instrumental in diagnosing and monitoring various conditions, including cancer, neurological disorders (such as Alzheimer’s and stroke), and cardiovascular diseases.
• Functional MRI (fMRI) can also assess brain activity by monitoring changes in blood flow.

Working Principle:

• MRI utilizes the magnetic properties of hydrogen atoms (one proton with one electron around it), which are abundant in water and fat molecules found throughout the body.
• The MRI machine generates a powerful magnetic field, aligning hydrogen atoms within the body.
• Radiofrequency pulses are then applied, causing hydrogen atoms to absorb energy and emit signals.
• These emitted signals are detected by sensors and processed by a computer to create detailed images of the body’s internal structures.

Components of an MRI Machine:

The MRI machine consists:

• Superconducting Magnet: Large magnet (superconducting magnet) that produces a powerful and stable magnetic field.
• Gradient Coils: Gradient magnets produce smaller magnetic fields with varying strengths and directions, allowing for precise imaging of specific body areas.
• Radiofrequency Coils: This emit radiofrequency pulses to excite hydrogen atoms in the body. The frequency of pulse the ‘excess’ atoms have to absorb is called the Larmor frequency.
• Detectors: It capture emitted signals from hydrogen atoms and convert them into image data for analysis.

Advantages of MRI:

• High-Resolution Imaging: MRI offers high-resolution imaging with excellent tissue contrast, allowing for accurate diagnosis and treatment planning.
• Versatile Viewing Angles: It can visualize structures from various angles without the need for repositioning, providing comprehensive information.
• Safety and Non-Invasiveness: MRI scans are non-invasive and do not involve ionizing radiation, making them safe for repeated use.
• Enhanced Image Quality: Contrast agents can enhance image quality by highlighting specific tissues or abnormalities.

Limitations of MRI:

• High Costs: MRI machines are expensive to purchase and maintain, resulting in high healthcare costs for patients.
• Requirement for Patient Stillness: Patients undergoing MRI scans must remain still for extended periods to prevent image distortion, which can be challenging for some individuals.
• Discomfort or Anxiety: The strong magnetic fields and loud noises produced during MRI scans may cause discomfort or anxiety for patients.
• Limitations with Metallic Implants: Certain metallic implants or objects can interfere with MRI scans, limiting their use in individuals with such implants.

Why in the news?

• Researchers at the Fred Hutchinson Cancer Center in the US have identified specific subtypes of Fusobacterium nucleatum associated with colorectal cancer (CRC) tumors.
• These subtypes, particularly Fusobacterium nucleatum animalis (Fna), have been found in relatively higher quantities in CRC tumors.

About Fusobacterium nucleatum

• Fusobacterium nucleatum is a species of bacteria commonly found in the human mouth.
• It is a gram-negative anaerobic bacterium, meaning it does not require oxygen for growth.
• While typically residing in the oral cavity, it has been associated with various diseases and conditions, including periodontal diseases and colorectal cancer.

Association with Colorectal Cancer (CRC):

• In cases of colorectal cancer (CRC), Fusobacterium nucleatum has been found within tumors in the gut.
• Studies have shown that this bacterium can aid cancer cells in evading the immune system and promoting metastasis, or the spread of cancer to other parts of the body.
• Its presence in CRC tumors has led to investigations into its potential role in the development and progression of colorectal cancer.

Impact:

• Assisting cancer cells in evading the immune system.
• Promoting inflammation and creating an environment conducive to tumor growth.
• Facilitating metastasis by interacting with cancer cells and promoting their spread to other tissues.