Rats have a bit of a nasty reputation. Commonly considered disease-ridden and generally disgusting, the mere sight of them can send people screaming into the streets. But news out of Tanzania may improve their reputation. Msnbc.com reports that area medical professionals are using rats to sniff out tuberculosis in human spit.

Rats earned a bad reputation in the Middle Ages, when they acted as the unwitting transport system for fleas that carried the Black Death. But their heightened sense of smell has made them a key player in the study of tuberculosis. Msnbc.com reports that 1,000 samples a week are collected by APOPO, a nonprofit organization that has trained 30 giant-pouched rats to sniff out TB. These samples had been checked by doctors, but rats inevitably find what the doctors missed. As a result, disease detection has improved by 44 percent.

The rats work at a much faster rate than humans. In a mere seven minutes, the rats can process what takes humans a full day to do. Dogs also have been recruited by scientists to detect disease, but some scientists think rats are superior animals for the job. Bart Weetjens is the founder of APOPO. As he told Msnbc.com, "Whatever dogs can detect, rats can detect equally well. They're more calm than most small animals, very intelligent and social, and they love humans." He also points out that rats are much cheaper to work with than dogs.

This is exciting news, because TB can be particularly hard to see under a microscope, and as a result can often go undiagnosed. It is a disease that affects over 2 billion people in the world. TB is a bacterial infection that distresses the lungs, with symptoms such as prolonged coughing, fever, chills and fatigue. It is easily spread by coughing, spitting, sneezing, and even speaking. Left untreated, TB kills about 50 percent of its victims, making early detection crucial. 

If Weetjens and his team of rats have their way, rats may be able to rewrite their roles in the medical history books.

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