In a small, hot room in a compound located in Tanzania’s lush southern highlands are three white-clad technicians, a glass-and-metal chamber, and a large brown rat named Charles.
After being gently dropped into the chamber, Charles aims his long snout towards the first of a series of 10 sliding metal plates in the chamber’s base. A technician swiftly opens it, revealing a small hole. Charles sniffs at it … and moves on. The hole is re-closed, and there’s a clink of metal as the next plate is yanked back. This time, Charles is gripped. He sniffs hard, scratching at the metal, the five claws on each paw splayed with the pressure. The technician calls out, “Two!”
Over by the window, her colleague is holding a chart, which he keeps raised so the others cannot see it. He inserts a tick. I glance over. The chart is a grid of small boxes, 10 across by 10 down, each marked with an alphanumeric code. Two of the boxes in each line are shaded gray. The tick has been placed in one that is white. It’s highly possible that Charles has just saved someone’s life.
Charles is an African giant pouched rat, a species endemic to sub-Saharan Africa. He’s also a pioneer, one of 30 of his species that live and work here in Morogoro, a few hundred kilometers west of Tanzania’s largest city, Dar es Salaam, on a program to sniff out tuberculosis (TB).
TB is a disease that can destroy the lungs. About 9 million new cases are diagnosed worldwide every year, one-quarter of them in Africa. Africa also has the highest TB death rate per head of population. Antibiotics can cure TB, but it’s fatal if untreated, and many patients are never diagnosed. This is partly because the 125-year-old microscope-based test used across Tanzania (and in many other cash-strapped countries) picks up only about 60 percent of cases, a figure that drops as low as 20 percent for people also infected with HIV.