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Using African Giant Pouched Rats for Tuberculosis Detection
Context:
African Giant Pouched Rats (Cricetomys gambianus), also known as HeroRATS, are being explored as an innovative solution for TB detection.
Role of African Giant Pouched Rats in TB Detection
- Initiative developed by APOPO, a Belgian-Tanzanian non-profit.
- Rats possess an exceptional sense of smell due to highly sensitive olfactory receptors.
- Used as a secondary diagnostic tool, detecting TB in sputum samples.
- Proven effective in Tanzania, Mozambique, and Ethiopia.
Training Process of HeroRATS
- Training duration: Nine months.
- Method: Positive reinforcement using food rewards.
- Process:
- Rats sniff sputum samples placed in a rectangular chamber with 10 sniffing holes.
- A trained rat holds its nose for 3+ seconds at a hole if TB is detected.
- Samples flagged by rats undergo microscopy confirmation.
Detection Efficiency of HeroRATS
- Speed: A rat can analyse 100 samples in 20 minutes, while a human takes 3-4 days.
- Accuracy: Rats detect cases missed by traditional methods, especially in children and smear-negative patients.
- Studies and Scientific Validation:
- 2024 study in BMC Infectious Diseases: Rats detected twice as many TB cases in children compared to conventional methods.
- Study on 35,766 patients: HeroRATS identified an additional 2,029 TB cases.
- Rats detected six times more TB cases in patients with low bacillary loads.
- Ongoing research on drug-resistant TB detection by rats.
Advantages of Using HeroRATS for TB Detection
- Speed and Efficiency: A rat can examine more samples in 10 minutes than a human can in a day.
- Cost-Effectiveness:
- Training cost: $6,700–$8,000 per rat, with a lifespan of 6–8 years.
- GeneXpert machine: Costs $17,000 per unit, with $10–$17 per test.
- High Sensitivity:
- Rats detect cases missed by microscopy.
- Serve as an additional verification tool for diagnostic labs.
Challenges and Limitations
- Lack of WHO Recognition:
- Rats are not officially approved for TB diagnosis.
- Further clinical trials and validation required.
- Inability to Detect Drug-Resistant TB:
- Rats cannot differentiate between drug-sensitive and drug-resistant strains.
- Scalability and Logistics:
- Requires regional rat-training centers for large-scale adoption.
- Cultural barriers as some communities consume rats as food.
- False Positive Concerns:
- Only 25% of suspect samples identified by rats are later confirmed as TB-positive.
- Further confirmatory lab tests required.
Feasibility of Implementing HeroRATS in India
- High TB burden in rural areas necessitates alternative diagnostic tools.
- Potential as a secondary screening tool under NTEP.
- Advantages for India:
- Cost-effective and faster than existing techniques.
Role of Animals in Disease Detection
- Dogs detect Parkinson’s disease due to high olfactory receptor count.
- Ants identify cancer cells within three days.
- Honeybees detect lung cancer with 88% accuracy using synthetic biomarkers.
- Rats in TB detection are part of a broader effort to use animals in medical diagnostics.
- Improved detection in children and smear-negative patients.
- Experts suggest a phased implementation starting with high-TB burden states.
Future Prospects and Research Directions
- Expanding Coverage: Deploying rats in rural areas with limited medical facilities.
- Exploring Other Animals: Research on dogs, honeybees, and electronic noses for TB detection.
- Refining Training Techniques:
- Studying if male and female rats perform differently.
- Investigating if rats can detect latent TB.
- Gaining Institutional Support: Collaboration with health ministries, WHO, and research institutions.
