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Tuberculosis (TB) remains one of the deadliest infectious diseases globally, with over 10 million new cases annually. India carries the highest TB burden, accounting for about 28% of global cases and recording nearly five lakh TB-related deaths each year—roughly one death every minute. Despite progress under the National Tuberculosis Elimination Programme (NTEP), which aims to eliminate TB by 2025 (ahead of the global 2030 target), early and accurate diagnosis remains a major hurdle, especially in children, low bacillary load cases, and underserved regions.

A Novel Solution: HeroRATS in TB Diagnosis

In a groundbreaking initiative, APOPO, a Tanzanian non-profit, has trained African giant pouched rats (HeroRATS) to detect TB by sniffing sputum samples. These rats have highly sensitive olfactory receptors, enabling them to detect TB cases that conventional diagnostics often miss.

Key Features of HeroRATS:

• Can screen 100 samples in 20 minutes, compared to 3–4 days by sputum-smear microscopy.
• Trained through operant conditioning, rewarded with food after accurate detection.
• Detect twice as many TB cases in children and six times more in low-bacillary-load patients than traditional methods.
• Confirmatory tests: Ziehl-Neelsen and fluorescent microscopy.

A 2023 study involving over 35,000 patients in Tanzania showed that HeroRATS detected over 2,000 additional TB cases, particularly among smear- or Xpert-negative patients. The method offers a fast, cost-effective, and scalable secondary diagnostic tool.

Relevance to India

With India facing challenges like poor health infrastructure in rural areas and reluctance to seek re-testing after a negative result, integrating HeroRATS into the NTEP could boost case detection. Experts suggest a phased rollout in high-burden states like Maharashtra and West Bengal. The Central TB Division’s collaboration with APOPO could help accelerate TB diagnosis and reduce transmission.

About Tuberculosis

• Cause: Mycobacterium tuberculosis, mainly affects the lungs, spread via airborne droplets.
• Prevalence: One-fourth of the global population is infected; only 5–10% show symptoms.
• Risk Factors: Weakened immunity, malnutrition, diabetes, tobacco and alcohol use.
• Diagnosis: WHO recommends rapid molecular tests like Xpert MTB/RIF Ultra.
• Prevention: BCG vaccine at birth.
• Treatment: Standard 4–6 month antibiotic course.
• Drug-Resistant TB:
  • MDR-TB: Resistant to isoniazid and rifampicin.
  • XDR-TB: Resistant to multiple drug classes, harder to treat.
• TB-HIV Link: HIV patients are 16 times more likely to develop TB.

Bio-detection Beyond Rats: Macrosmatic Species in Medicine

Several animals with heightened olfactory senses are being used in disease detection:

• Dogs: Detect Parkinson’s, cancers, and diabetes using their 125–300 million olfactory receptors and Jacobson’s organ.
• Ants: Trained to detect cancer cells within three days using chemical signals.
• Honeybees: Can differentiate between types of lung cancer with 88% accuracy using synthetic biomarkers.