Tanzanian rats detecting TB

Before doctors diagnosed Kulwa Malembeka with Tuberculosis (TB), he experienced severe pains in his chest, he would sweat heavily at night and whenever he coughed, he would discharge thick smelly mucus.

The 44-year-old farmer and trader from Tabora was repeatedly tested for TB at a local district hospital, but doctors could hardly confirm the diagnosis due to lack of expertise. "I was feeling weak and nauseous all the time. I could hardly eat or walk to the bathroom," Malembeka told DW.

Malembeka, who has now fully recovered after going through TB treatment at Kitete hospital in Tabora said many people who contract the disease often die without knowing. "Everybody in my village thought I had HIV/AIDS because I looked gaunt and pale, it was hard to convince them otherwise," he said.

The father of four children said when doctors confirmed the diagnosis, he had to take many pills and get injections which brought about side effects including body aches and poor hearing. "I was very lucky, my family was very supporting. I sometimes wanted to abandon the dose but they encouraged me to finish it and get cured."

Rats to the rescue

While scientists are grappling to find a lasting solution for TB diagnosis and treatment, there seems to be some light at the end of the tunnel. APOPO, an international organization known for its landmine sniffing rats is planning to recruit more giant pouched rats to detect TB in Tanzanian and Mozambican prisons.

Charlie Richter, APOPO's US director, said through its TB detection technology the organization is committed to carry out TB mass screening - using rats that smell the presence of the Mycobacterium Tuberculosis found in sputum samples - mucus that is coughed up by the patient.

"We believe our unique TB Detection Rat technology will prove itself as an effective mass-screening tool. We then aim to expand the program to all prisons, shanty towns, factories and other settings in Tanzania, Mozambique and other high TB-burden countries," Richter said. He said they also plan to do the same in high-risk groups such as those living with HIV/AIDS. "This will improve and save lives all over the globe at a low cost," Richter added.

‘100 TB screens in 20 minutes'

The APOPO TB detection rat technology is fast, cheap and has the potential to greatly lower screening costs in poor countries, Richter said. "While a laboratory technician may take four days to detect tuberculosis, a trained rat can screen a hundred samples in 20 minutes," he said.

According to APOPO, the rats undergo a rigorous training process that begins when they are four weeks old. Right after the rat learns to open its eyes, it is introduced to various stimuli and learns how to socialize and interact with people.

Richter said the testing process starts when a rat is presented with a row of 10 TB sputum samples, when TB is detected the rat hovers over the sample for 3 seconds.

APOPO's current programs have screened over 340,000 TB samples, thus halting over 36,000 further infections, and increased detection rates by over 40 percent in several partnered clinics, Tanzanian health officials said.

Khadija Abraham, an expert at Tanzania's National Leprosy and Tuberculosis Programme, said once trained, the rats have a strong ability to detect a wide range of odorant molecules that could help track down undiagnosed TB cases especially in the rural areas. "Training an animal with a strong and reliable sense of smell to help detect disease in a vast country like Tanzania could potentially offer a valuable solution to help detecting the disease," she said.

WHO cautious on TB detective rats

Although WHO is embracing new innovations in TB diagnosis, treatment and prevention, it insists that such innovations must be supported by evidence-based data.

"Out-of-the-box thinking has produced great innovations in the past; however, any new innovations in TB diagnosis require adequate and evidence-based data to document accuracy, repeatability, and scale-ability before public health policy can be considered," Hannah Monica Dias, WHO TB programme Communications and technical officer told DW.

After HIV/AIDS, Tuberculosis is the world's second leading cause of death from an infectious disease. Approximately 9 million new TB infections occur annually, and according to the World Health Organization (WHO), around 2 million people die from this preventable disease globally every year.