Rats are being used to detect landmines and sniff out the deadly disease Tuberculosis (TB), and University of Waikato animal behaviour experts have been working with the animals in Africa with an organisation called APOPO.
Dr Tim Edwards completed his PhD research in Tanzania, working with APOPO and studying the effects of early exposure to target scents on the performance of landmine-detection rats and whether early exposure to TNT facilitated later learning in the animals.
These aren’t any old rats, they are handpicked, and hand reared. Dr Edwards says their living conditions closely mirror those of rats found in the wild, but because the animals are hand raised they are much less vicious than wild rats. “They have clay pots to simulate burrows, things to gnaw on and we built running wheels for each and every one, and they’d spend all night on them.”
The rats have poor vision. They’re nocturnal foragers and have an enhanced sense of smell. And it’s that sense of smell that makes them good at detection work.
After completing his PhD, Dr Edwards was appointed head of research and training at APOPO. He worked on improving rat selection, to ensure they got the best rats for the job. “For landmine detection, the first thing they learn is the scent for TNT, then they transition to deactivated mines before being sent to operational demining sites where there are live mines.”
Dr Edwards also became involved in TB detection and the impact of a variety of factors on the TB-detection rats’ performance, including the influences of temperature on detection accuracy. In 2015, the rats evaluated 21,600 samples from labs in Tanzania and 9048 from Mozambique, and the rats found 1412 new patients with active TB in Tanzania and 645 more in Mozambique, increases of 39% and 53% respectively compared to detections by microscopy alone. That work continues and APOPO is opening a new centre in Ethiopia for TB detection.
Sniffing out TB
One of Dr Edwards’ PhD students Haylee Ellis has been extending the TB research. She spent two-and-a-half years in Tanzania at APOPO’s research and training centre based at Morogoro.
“I first developed a training protocol using the existing apparatus that could be applied to any set of stimuli, and then investigated variables expected to affect accuracy,” she says. “In TB operations, the rats are trained using clinic-positive samples, which tend to be high concentration of bacilli. They are never rewarded for clinic-negative, TB-positive samples, the low concentration of bacilli, the samples we want the rats to find.
“We were interested to know whether this training protocol was actually reinforcing responding to high concentrations at the expense of low concentrations. My analysis is still ongoing, but it does seem that training rats on a high concentration makes it difficult for them to accurately respond to low concentrations."
The APOPO rats have their own training centre and the animals take about nine months to train. “They’re so much bigger than lab rats and their mannerisms are quite different, almost feline,” Haylee says. “They’re much more habituated than lab rats as well; they will lick the salt from your skin, which looks adorable.”
She says living and studying in Tanzania had its challenges. “There were a lot of issues with supply and logistics; during the rainy season the roads really deteriorate, so being late to work was unavoidable some parts of the year. The internet was often patchy, and supplies were expensive and time consuming to obtain. That being said many of the trainers were very dedicated, most people were incredibly kind, and I had a troop of monkeys living in my backyard.”
Haylee hopes to finish her doctorate in July this year and then she’ll be looking for work. “I’m hoping to work for another NGO or industry, there are a lot of problems in the world that detection animals could really help with such as disease detection and conservation and I’d like to be a part of that,” she says.