How the Widal test clouds India’s sense of its typhoid problem

Subject: Science and tech

Sec: Health

Tag: Widal Test, Typhoid

Typhoid Fever:

Typhoid fever is an infectious disease caused by Salmonella typhi bacteria, transmitted through contaminated food and water.
It manifests symptoms like high fever, stomach pain, weakness, nausea, and potentially severe complications if untreated.
Approximately 9 million cases are diagnosed annually worldwide, with significant morbidity and mortality rates.

Typhoid test:

The gold standard for diagnosing typhoid — in addition to a detailed medical history and a thorough examination — is to isolate the bacteria from a patient’s blood or bone marrow and grow them in the lab.
Stool and urine samples can also yield the same but with lower sensitivity.
Cultures are time-consuming and skill- and resource-intensive.

Widal Test and associated challenges:

In India, the Widal test (rapid blood test) is prevalently used for diagnosing typhoid due to its simplicity and cost-effectiveness.
- Our immune system produces antibodies in the blood against the bacteria, causing enteric fever. The Widal test rapidly detects and quantifies these antibodies.
However, this test, developed in the late 1800s, is plagued with inaccuracies such as false positive and negative outcomes.
It requires two serum samples taken 7-14 days apart to confirm a diagnosis, which is often impractical.
Additionally, the test’s results can be skewed by prior antibiotic use, existing immunity levels, or cross-reactions with other infections.

Impact of Misdiagnosis:

Misdiagnosis leads to inappropriate treatment, contributing to the misuse of antibiotics and increasing antimicrobial resistance (AMR).
This not only escalates the disease burden by making it harder to treat but also imposes financial strains on affected individuals, often forcing them to sell assets for treatment costs.

Alternatives and Improvements Needed:

Given the flaws of the Widal test, there is a pressing need for better diagnostic methods. Recommendations include:
- Developing and adopting more accurate and reliable point-of-care tests.
- Implementing a “hub and spoke” model for sample collection and processing, leveraging existing healthcare infrastructure for better diagnosis and surveillance.
- Improving sanitation, access to clean water, and food safety to address the root causes of typhoid.
- Enhancing surveillance systems to monitor and respond to typhoid resistance patterns effectively, with reports such as those from the Indian Council for Medical Research guiding antibiotic usage and policy adjustments.

Way forward:

The mismanagement of typhoid fever diagnosis and treatment underscores the need for systemic improvements in public health strategies, diagnostic technologies, and antibiotic use policies to effectively control this preventable disease in India.

Source: TH