Using rats to fight tuberculosis

The Belgian organization Apopo is breeding rats to help medical professionals detect tuberculosis (TB), one of Africa's most deadly diseases. Gilbert, an African Giant Pouched rat, is smelling at human sputum samples hidden in a rectangular cage in a research centre in Morogoro, Tanzania. He's one of the forty so-called 'hero rats' that Apopo has on its books.

Every time Gilbert scratches both of his front paws at a sample that has already been tested positive for tuberculosis at the hospital, he gets a reward of a mix of bananas and peanuts, motivating him to continue working.

Apopo has been using rats already for many years to locate landmines in countries like Mozambique, Angola and Cambodia. In Mozambique alone the project has found and destroyed 2,587 landmines, over 1000 explosive devices and some 13,000 small arms and ammunitions.

The African Giant Pouched rat has a very sensitive sense of smell and is relatively calm. Training each rat takes up to nine months and costs some 6000 euros but the animals live up to eight years, are easy to keep and don’t bond to one trainer like dogs do.

Apopo breeds most of the rats themselves on site. This allows the organization to start training the rats just after they have opened their eyes. Once in a while the organization accepts wild rats to help with the breeding program.

A patient gives a sputum sample at the Mbagala Kuu Hospital in Dar es Salaam, Tanzania's biggest city. Tuberculosis, an infectious disease affecting the lungs, killed more than 1.3 million people worldwide in 2012 according to the World Health Organization.

The samples from sick patients that test negative for TB, also get sent to the Apopo facilities. Because many public clinics have outdated technology, more than half of the tuberculosis sufferers in Africa go undetected. This has dramatic results, as one untreated person with active TB can infect 10 to 15 other people per year.

Patient Savera Komba (left) was coughing, lost a lot of weight and complained of tiredness. She was tested negative for TB at the hospital. Her sputum sample, however, was sent to the Apopo research centre in Morogoro, where the rats flagged it as positive.

Apopo lab technicians retest samples that were tested negative at the hospital but got flagged as positive by the rats. After confirmation, the patient is informed and needs to return to the hospital to start treatment.

Savera Komba still weighs only 39 kilograms, but since she started to take the medication, she has begun to feel better and is happy again, she says. "Without the rats, maybe I would be dead now," she told DW.

Using rats to detect tuberculosis isn’t yet approved by the World Health Organization. Still, 1700 undetected patients were identified by Gilbert and the other trained rats last year in Tanzania. These encouraging results have prompted Apopo to open another TB lab in Mozambique and there are plans to expand to South Africa soon too.

The main advantage of Apopo's tuberculosis rats? They're fast. A rat can process as many samples in seven minutes as a lab technician can in one day. Because of this, this method could also be suitable in the future for quickly screening large samples from communities at risk of contracting tuberculosis, for instance in refugee camps or in prisons.