About Typhoid fever
- Caused by Salmonella typhi and related bacteria
- Spreads through contaminated food and water
- Symptoms: high fever, stomach pain, weakness, nausea, vomiting, diarrhea or constipation, rash
- Global burden: 90 lakh cases and 1.1 lakh deaths annually (WHO)
Diagnosis of typhoid fever
- Gold standard: isolating bacteria from blood or bone marrow and growing them in a lab
- Limitations in smaller clinical settings: time-consuming, skill- and resource-intensive, affected by prior antibiotic treatment
- PCR-based molecular methods: better but costly and require specialized infrastructure and personnel
Widal test:
- Widely used in India for diagnosing typhoid
- Rapid blood test that detects antibodies against the bacteria
- Flaws: false positives and false negatives
- Requires at least two serum samples taken 7-14 days apart for accurate diagnosis
- Baseline cut-off varies in areas with high typhoid burden
- Cross-reactivity with antibodies produced against other infections or in vaccinated individuals
Consequences of Widal test usage:
- Obscures the actual typhoid burden in India
- Lack of awareness and standardization of kits, poor quality control
- Financial burden on patients: high costs for tests and antibiotic injections
- Contributes to antimicrobial resistance (AMR) due to irrational use of antibiotics
- AMR can be transmitted between bacterial strains and species, posing a global threat
- Difficulty in controlling the preventable disease and additional financial strain on patients