Tanzania's TB detection rats aid efforts in epidemic fight

The 10 TB-detection rats are working alongside 12 staff made up of rat handlers and laboratory technicians. [iStockphoto]

At least 19 African giant pouched rats are at the frontline of scaling up efforts aimed at ending tuberculosis (TB) in Tanzania by accelerating early detection.

In Dar es Salaam, Tanzania's biggest city, 10 trained rats are housed in a forested state-of-the-art laboratory in the compounds of the Tanzania Veterinary Laboratory Agency with only one mission: to detect TB with the highest accuracy.

Nine other rats trained to detect the smell of mycobacterium TB in human sputum are stationed at the training centre at the Sokoine University of Agriculture in the Morogoro region.

At the lab in Dar es Salaam, the 10 TB-detection rats are working alongside 12 staff made up of rat handlers and laboratory technicians, said Joseph Soka, Apopo TB Detection Manager in Tanzania.

Apopo is a Belgian non-profit organization based in Tanzania that has been investigating the use of African giant pouched rats for the screening of TB since 2007.

By March this year, Apopo TB detection rats had screened 880,224 sputum samples collected from 523,594 presumptive TB patients and found 26,378 additional TB patients that were missed with routine TB program activities in Tanzania, he said.

According to Soka, the rats are trained from a minimum of nine months to a year for them to be fully qualified to be used in routine TB detection operations.

In an interview with Xinhua ahead of World Tuberculosis Day on Friday, Soka said that the lifespan of a rat in captivity is nine to 10 years but they are retired at the age of eight because with age, their performance declines. "But we have started training new rats for TB detection."

Soka said the rats are sourced in the bushes and they are resistant to most tropical diseases and don't get diseases easily.

They also have high receptors, allowing them to evaluate a lot of samples within a short period of time. He said Tanzania's government clinics largely rely on smear microscopy which has a low sensitivity of about 20-60 percent.

"So many TB-positive patients are missed. This is exacerbated by challenging factors such as inadequate funding for training and equipment, power and water cuts, and lack of staff."

Soka explained that as a result, only about half of the visiting patients with active TB are correctly diagnosed, leading to further fatalities and the disease being passed on to the families and colleagues of the missed patient.

However, the APOPO project launched in mid-2007 has helped increase detection rates by 40 percent by supporting national clinics, he said, adding that collaborating clinics have also grown from four initially to 80 now. Soka said the scaling-up of TB diagnostics and active TB case finding on a larger and sustainable scale is essential to ending the epidemic.

"Aligning with the global efforts and End TB strategies, at APOPO we strive to contribute to the End TB epidemic using our unique technology of rat-based TB diagnosis," said Soka.

"APOPO collects sputum samples that have already been tested by microscopy in the partner clinic labs and retest them using TB-detection rats and WHO-endorsed confirmation tests resulting in a detection rate increase of about 40 percent," he told Xinhua.

According to the World Health Organisation statistics, 1.6 million people died of TB and 10.6 million people fell ill with TB in 2021.