How SUA's Rat Technology Enhances TB Detection

To many people in Tanzania, rats are enemies to kill on sight. But to scientists at Sokoine University of Agriculture (SUA), rats --- more so those known as panya buku in Kiswahili, are a treasure.

And for a big reason; they have enliven tuberculosis (TB) detection in Tanzania. You talk of rats before Nelson Magara, a young graduate who own a new silver-coated saloon, he fumes: "Rats? They are destructive."

And he quips, "A good rat is a dead rat." Magara is uncompromising. "Rats are destructive small creatures. They hide in your car and they cut the wires.

The car suddenly loses power and it will take you days to detect the problem. Rats are bad!" But to scientists at SUA-APOPO, rats are heroes in the field of landmine detection and now the detection of pulmonary tuberculosis (TB) in sputum (spit saliva).

They are called Apopo Hero Rats or simply HeroRATs. Innovative scientists, at the Apopo's Headquarter of Training and Research Center in Tanzania focus on scent detection theory and technology, animal welfare and use of veterinary skills in using rats to detect TB and land-mines.

At the just-ended Dar es Salaam International Trade Fair (DITF) SUA pavilion, the HeroRATs (or, as they were called "the SUA rats") were one of the major centres of attraction.

The innovation is pioneered by APOPO, a global NGO, with roots in Belgium and operational headquarters at SUA, Morogoro. Dr Georgies Mgode of SUA's Pest Management Centre and a collaborative scientist with Apopo Tanzania TB Detection Program says rats have put up phenomenal performance. "They are effective and fast they have shown similar performance in Maputo, Mozambique.

They have been effective in detecting land mines in Mozambique, Angola and Cambodia." Mr Alberto Zacarias, International Mine Detection Rats Supervisor, recalls: "I first met the amazing HeroRATs in 2008 when I was an APOPO deminer, detecting land-mines in Mozambique. I was about to embark on my new career as a Mine Detection Rat Handler.

Although I had worked with trained dogs (sniffer dogs) before, I was amazed at the rat's abilities, their speed and accuracy." In Tanzania, the rats are helping to detect, or are evaluating, suspected TB patients. Some 152,000 presumptive TB patients have been evaluated by HeroRATs in Tanzania so far.

Why is this innovation significant? Health experts agree that public clinics in Sub-Saharan Africa use conventional microscope to detect Tuberculosis. This method is known to be slow and inaccurate and, it is said, "detects only 50 percent of the patients who actually have Tuberculosis." A publication by the Apopo organisation contends: "Apopo HeroRATs can check 100 patients for tuberculosis intervention in 20 minutes.

This takes a laboratory technician in a public clinic up to 4 days." According to the publication, the HeroRATs "has diagnosed 9,127 TB patients who were initially missed by local clinics using smear microscopy."

Last year in Maputo, a total of 9,166 presumptive TB patients were screened by the HeroRATs while 666 patients who were earlier missed by conventional methods were diagnosed by the rats.

The rats' performance has amused patients too. Ms Nuru Hasani testifies: "When I fell ill I went to hospital for examination. However, the test showed TB negative. About the same time, two of my grandchildren fell sick. The rats checked our samples and we tested positive! I was lined up for treatment. At first I couldn't believe it; but now I know rats can really find the disease.

They helped all of us." APOPO works with "partner clinics" and it maintains that it has raised detection rates in those clinics "by over 40 per cent since 2007." It has 24 clinics in Dar es Salaam; one in Coast Region, three in Morogoro while "almost all hospitals in Maputo use this technology."

Dr Mgode says the speed at which the HeroRATs check large numbers of samples means they could be deployed as a fast and effective tool to screen whole communities for tuberculosis.

"By detecting tuberculosis early, lives will be saved and additional infections will be prevented and billions of money the government spends on TB treatment ," he explains.

Last December, the United Nations World Health Organisation (WHO) said tuberculosis was killing more people than HIV, making it the world's biggest infectious disease killer.

"We asked ourselves: why we can't have a simple and affordable technology that covers many TB suspects within a short time" Dr Mgode recalls. The speed and accuracy shown by the rats against microscopes prompted them into pushing for this innovation. But why rats? According to Dr Mgode, rats are among mammalians with so many olfactory receptor genes in their brains that enable them to be highly sensitive to different smells.

The scientists decided to use that advantage. APOPO working on this advantage quickly realised that the rats from SUA were trainable and developed the APOPO Mine Detection Rats project.

The project targets large cities with high rates of tuberculosis because in these cities, the influx of people looking for work creates crowded living and working conditions that act as incubators for the disease.

Dr Mgode says research on TB detection rats is ongoing. A diagnostic accuracy study that compares the accuracy of TB detection rats with other diagnostic methods such as solid and liquid culture, GeneXpert and microscopy will be completed this year.

"With the support of the USAID Development Innovation Ventures (USAID-DIV), APOPO is also conducting an 'active case finding' research project that screens prisoners in Tanzanian jails for Tuberculosis," he says.

He explains that TB detection rats may offer a cost effective way to break the TB cycle by screening large numbers of people in high-risk settings such as jails, boarding schools, miners communities, refugees camps and factories which are considered incubators for TB.

Prof Apia Massawe, Director of SUA-Pest Management Centre, says collaboration between APOPO and the varsity's centre addresses positively new and emerging challenges in the scientific world.

The collaboration is now embedded in the newly established African Centre of Excellence in Innovative Rodent Pest Management and Biosensor Technology Development hosted at SUA-Pest Management Centre.

Source : DailyNews By Emmanuel Rubagumya