“The main concern is the number of individuals that the rats would flag as positive where no other evidence would support that diagnosis – a re-evaluation by a human might be confirmation bias,” said Mike Barer, Professor of Clinical Microbiology at the University of Leicester.
“A standard TB treatment course is six months and there is an adverse reaction rate within that.
“Possible side effects include liver and eye damage, and so it’s never a good idea to treat someone who isn’t unwell,” Prof Barer added.
“That being said, smear microscopy can miss a lot of cases, particularly because in Africa there are often difficulties including other bugs contaminating the samples. You also need a reasonable level of technical expertise to have confidence in the results, so there are definitely problems,” he explained.
Experts have also noted that the rats cannot differentiate between TB and drug-resistant strains.
Agizew and his team at APOPO, however, think their four-legged friends are an important contribution to the fight against tuberculosis, and hope to expand their work in future.
“In Tanzania and Ethiopia, TB is declining at an annual rate of 5 per cent – which is not enough. Our rats are contributing to a faster decline, which is what is needed if we are to eliminate the disease,” he said.
“In an ideal world, we would want to expand – 2.5 million cases are coming each year from India, if we could start a programme there, I think it would make a huge difference,” Agizew added.
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