Furry heroes to sniff out TB in Mozambique

[Image] The furry heroes have helped to clear vast areas of land in Mozambique and Thailand, which can now be used for development.

[Image] Apopo founder Bart Weetjens used his childhood experiences with pet rats as the foundation for his inspired idea.

[Image] Rats can survey a mine-infested area quicker than humans, and with virtually no risk of setting off a mine.
(Images: Apopo)

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Janine Erasmus

Already a hero in Southern Africa for its ability to sniff out landmines, the African giant pouched rat (Cricetomys gambianus) is once more turning out to be a lifesaver by accurately detecting the presence of tuberculosis bacteria in human sputum samples.

Both initiatives are run by the Belgian NGO Anti-Persoonsmijnen Ontmijnende Product Ontwikkeling (Apopo), whose founder Bart Weetjens came up with the idea of training the rats while he was an engineering student.

Weetjens developed the methodology after conducting a study of the landmine situation in sub-Saharan Africa. He realised that conventional methods of landmine detection and disarming were dangerous, time-consuming and expensive, and was inspired to use the rodents by his own childhood pet experiences, as well as an article on gerbils as explosives hunters which he read while conducting his landmine survey.

Named for their large cheek pouches, the remarkable rodents are renowned for their acute sense of smell and their intelligence and willingness to be trained. At under 2kg on average, the rats are too light to trigger an explosion, making them the ideal weapon in the war against landmines.

Apopo runs mine clearing programmes in Mozambique and Thailand, and in 2012 started preparing for operations in Angola, another heavily mined country, where it hopes to eventually deploy as many as 80 rats.

Its headquarters are in Morogoro, Tanzania, where training takes place in what the organisation calls “near-real conditions” – the only difference is that the landmines in the training fields are already disarmed.

Using the rats’ sensitive noses for humanitarian purposes has paid off handsomely. Apopo says that the Mozambican team, including 47 accredited rats, has made about 4.3-million square metres of land usable again in the southern Gaza province, which it has now cleared. Over 1 860 landmines, 776 dangerous unexploded ordnance, and 12 817 small arms and items of ammunition were dealt with in 2011 alone.

In its 2011 annual report, the organisation revealed that it will start mine-clearing operations in the neighbouring Manica province, on the Zimbabwe border, during 2012.

According to the Halo Trust, an organisation that specialises in clearing away the remains of warfare, the northern half of Mozambique is now clear of mines – in total, 100 843 devices were removed from 552 minefields. In the south, however, there are still an estimated 520 minefields that are yet to be cleared in the Maputo, Manica and Tete provinces. Many mines lie in land that is earmarked for development, but can’t be used because of the buried threat.

But thanks to the rats, the job has become easier in recent years. Two rats, each with a human handler, can survey 300 square metres of land in one hour. Two trained people using metal detectors will take about two days to cover the same area, says Apopo.

Land that is safe to work on has important implications for the Mozambican people, many of whom have been maimed by landmines. Now that they can plough their lands without fear they can at least feed their families and even earn an income.

All rats are trained to the requirements of the International Mine Action Standards organisation, and training takes about nine months, using positive reinforcement and food rewards. The animals have to pass a test once their performance has noticeably reached a plateau, and if they pass – which most do on the first attempt – they are officially licenced as a mine detection animal.

Sniffing out TB, saving lives

The intelligent little creatures have now turned their talents to another life-saving task – sniffing out pulmonary tuberculosis (TB), a disease that is second only to HIV/Aids as a single-organism killer, according to the World Health Organisation (WHO).

Apopo says that the highly trained rats can analyse 40 sputum samples in seven minutes, a task that would take an entire day by a technician using a microscope. This equates to about 1 680 samples in a day’s work.

This technology was developed by Apopo in partnership with the Tanzanian National Tuberculosis and Leprosy Program and the Institute for Tropical Medicine in Belgium, among others. It complies with the WHO TB diagnostic group’s seven top priorities required for a recognised diagnostic method.

The rats work in special automated cages which hold samples below a series of sniffer holes. The cage can register their response and activate a click and food reward, while sending data directly to a database. The method has boosted the detection of new cases by an astonishing 40%, says the organisation.

Rats use their sense of smell to swiftly sniff out the volatile organic compounds released by Mycobacterium tuberculosis in positive samples, scratching at those which are TB-positive. If an unknown sample is targeted by at least two rats, this is quickly confirmed with microscopy.

These samples are reported to the hospitals, who follow up with a positive diagnosis, treatment and counselling of patients.

The rats discover between five and 15 new patients every week, says Apopo. In its 2011 annual report it supplies figures of almost 98 000 sputum samples analysed since 2008, with 45 000 second-line screenings, out of which 7 700 positives were found by Direct Observation of Treatment, Short-course or Dots clinics, and an additional 2 300 cases – which were missed by the Dots method of screening – were found by rats.

In 2011 the organisation received approval for a grant from the Flemish government that would allow it to start working in Mozambique.

Apopo hopes to increase the rate of detection of new cases in this country, as it too is struggling with a high TB burden. Operations are expected to start in Maputo in December.

Killer on the loose

Although TB is both preventable and curable, almost 9-million new patients contracted the disease in 2010 worldwide, says the WHO, on top of the millions who are already chronically ill.

Nearly 1.5-million succumbed – of these deaths, over 95% occurred in low- and middle-income countries, and the burden in East Africa is high compared to other regions.

The disease is named as one of the top three causes of death among women aged 15 to 44, and about 10-million children were orphaned in 2010 as a result of their parents dying of TB.

In Southern Africa, there is the growing incidence of multidrug-resistant TB and its successor, extensively drug-resistant TB (XDR-TB), which arose out of the mismanagement of patients infected with the former strain. The XDR-TB form was first publicised in South Africa, following an outbreak in 2006 which killed all but one of the patients.

The WHO estimates that one in three people on the planet carry the M. tuberculosis organism, although not all are ill and therefore can’t transmit the disease. All age groups are at risk, but those whose immune systems are already weakened, whether by lifestyle choices such as smoking or by another disease such as Aids or diabetes, are at greater risk of falling ill.