Tuberculosis (TB) remains one of the world’s most deadly diseases, causing more than 10 million new infections worldwide each year. It is estimated that about 28% of new tuberculosis cases in the world occur in India. It is estimated that the country has killed 500,000 people every year, about 500,000 people per minute. Despite great advances in health care, testing for tuberculosis remains a major challenge, especially among remote and underserved populations.
The government’s National Tuberculosis Phase-Out Plan (NTEP) aims to eradicate tuberculosis in India by 2025, five years from the 2030 global target, but the opportunity looks bleak. Although the 2024 report of the Indian Tuberculosis Report shows that the incidence of tuberculosis has decreased by 16% since 2015 (new cases occur every year) and 18% of tuberculosis-related deaths, elimination remains a challenge.
Traditional diagnostic techniques often fail to detect tuberculosis at an early stage, especially in children and people with hypobacterial burden (Mycobacterium tuberculosis concentrations exist in sputum samples). This means that many cases may not be detected, leading to the spread of the disease. If the first test is negative and is usually diagnosed only at the late stage, many people are reluctant to seek a second diagnosis. Slow and insufficient diagnostic facilities are another problem: Residents in rural and remote areas have to travel long distances to get tested. Although the government has free TB treatment, travel is often a huge cost for patients. Here, innovative approaches can make a significant difference.
African giant pouch rat in tuberculosis diagnosis
Such an initiative is Apopo, a nonprofit based in Tanzania, working in 11 countries and training African giant bag rats (nicknamed Herorats) to detect TB in sputum samples. “These rats have excellent olfactory ability to sniff diseases due to their sensitive olfactory receptors,” said Tefera Agizew, head of tuberculosis at Apopo. He said rats showed very accurate accuracy, especially when detection traditional methods were often missed, as secondary diagnostic tools. Their ability to identify tuberculosis quickly and accurately helps improve early diagnosis and reduce transmission, especially in areas where health care resources are limited. Dr. Agizew said rats have successfully changed the diagnosis of tuberculosis in three countries: Tanzania, Mozambique and Ethiopia.
Rats are raised and raised in facilities, through a rigorous training process, from two to three months old, and lasting to nine months | Image source: Apopo Herorats via Instagram
Rats were raised and raised in facilities, undergoing a rigorous training process, starting at two to three months of age and lasting until nine months. They were exposed to sputum samples, and when they successfully identified TB positive samples, the researchers declared their success by clicking, and then rewarded smoothies made from avocados, ground food pellets and bananas. This positive reinforcement helps hone their skills. It is worth noting that 100 samples can be tested in just 20 minutes, and technicians are usually performed for three to four days using conventional sputum microscopes.
Otherwise, the rat’s food habits will be controlled. They are fed during and after testing. Each morning, Apopo staff collect test samples from directly observed treatment (DOT) facilities for reevaluation. Samples were placed under ten sniffing holes in a rectangular chamber (205 cm x 55 cm) and were evaluated on average five rats per day. Through operational adjustment training, the rat signaled by holding his nose in the scent hole for three seconds or more. The processor monitored and recorded these responses and further analyzed mouse positive samples using Ziehl-Neelsen (Zn) microscope and fluorescence microscope.
Through manipulation adjustment training, the rats responded positively by holding their nose in the scent hole for three seconds or more. Image source: Apopo Herorats via Instagram
Posted in BMC infectious diseases Last April, the rats were shown to be able to detect an increase in TB cases in children and adults in Tanzania. The study said that it is often difficult for children to detect tuberculosis compared to routine tests, but rats are determined at twice the rate. The study studied 35,766 patients, of which 5.3% (1900/35,766) were smear-positive and 94.7% (33,866/35,766) were smear-negative or Xpert-negative. Among the negative results, 2,029 cases of tuberculosis were detected using rats, otherwise missed, the paper said. “When the bacterial load is small or 1+, they can detect six times as many as 2+ or 3+ in children and adults,” said Dr. Agizew, lead investigator of the study. Other studies on the detection of drug-resistant tuberculosis rats are underway.
Animal disease testing
The giant pouch in Africa is not the only animal that can detect diseases, and tuberculosis is not the only animal to use. Some animals do well where skills are insufficient. Dogs, for example, are widely used: They have 125 to 300 million olfactory receptors and a special sensory organ called Jacobson, located in its nasal cavity and are specially designed to detect pheromones and other chemical signals. Some studies have shown that trained dogs may be able to recognize Parkinson’s disease.
Unlike dogs that require extensive training, ants are learning quickly and cheaply, making them a promising alternative to cancer testing. “Insects can help us develop diagnostic tools faster,” published by Debajit Saha, assistant professor at Michigan State University in the United States of America’s French Studies in Science directants were found to detect cancer cells within three days using chemical clues and sugar rewards. Their ability to distinguish cancer types highlights their medical potential. “Our findings show that ants can serve as a fast, feasible and easy-to-work living tool for detecting cancer biomarkers,” said Baptiste Piqueret, principal investigator at Laboratoire D’Ethologie d’Ethologie expérimentaleet comparatee in France.
Bees have a highly sensitive olfactory antennal lobe (a kind of highly developed olfactory sense). Debajit Saha’s research shows that they can detect lung cancer using synthetic biomarkers (artificial artificial respiration, containing cancer). The response changes of neural activity in bee antennae to cancer and non-cancerous samples, distinguishing small cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC) with 88% accuracy, respectively.
Dr. Saha and his team aim to develop diagnostic tools that can detect early stage lung cancer, a disease that can only be detected in the late stages. “The field is growing. Researchers are returning to Mother Nature and applying what we have learned from these animals,” said Dr. Saha.
Indian scene
Can “Herorats” be the solution as India is still struggling to cope with undiagnosed tuberculosis, especially in underserved areas?
TB experts believe this may work. “The work of ‘Herrorats’ sounds fascinating and can be seen as a secondary means of diagnosis, but whether it can be implemented in India,” said Dewraj Sarkar, TB official in Darjeeling, West Bengal.
Rajendra Kumar, National TB Officer of Chandigarh, believes that integrating rat-based TB tests into NTEP can significantly enhance case testing, especially in children and smear-negative patients. “The cost-effectiveness, speed and accuracy of trained African giant rats make them viable secondary screening tools in the high-TB Dutch region,” he said. He added that starting with certain high-TB burden areas and states and subsequent expansion of controls ensures feasibility and effectiveness.
“If the central tuberculosis department proactively cooperates with Apopo and implements the program, it will help high-load states like Maharashtra to detect cases faster,” said Sandeep Sangale of Sto, Maharashtra.
Dr Agizew said he hopes to resume discussions interrupted by the Covid-19 pandemic, bringing these trained mice into India as a secondary diagnostic tool, noting that such collaboration could significantly accelerate diagnosis, save lives and may support the country’s efforts to eliminate TB.
(Neelanjana Rai is an independent journalist covering global health, indigenous communities, innovation and environmental issues. Neelanjana189@gmail.com)
publishing – February 28, 2025 at 05:00 am IST
