Normally, when a bacterium invades your body, it’s surrounded and engulfed by a white blood cell. If all goes well, the white blood cell kills the bacterium.
But a few bacteria have some tricks up their sleeves. One of them is the rod-shaped Brucella bacterium, the agent that causes brucellosis, or what is sometimes known as "undulant fever" because it causes people to run debilitating fevers that wax and wane over long periods of time.
Untreated, brucellosis makes people sick for years. Over time, the bacteria settle in the joints where they can do real damage. Both literally and figuratively, brucellosis is a crippling disease.
People get the malady from farm animals like cattle and goats that are infected. Often it’s unpasteurized milk that transmits the disease.
“Raw milk is quite risky in terms of spreading the infection from cattle to people,” Dr. Jean Celli told me recently. Celli is a new researcher at the Paul G. Allen School for Global Animal Health at Washington State University. He studies brucellosis, including how it behaves in the white blood cells of animals and people.
When the brucellosis bacterium is engulfed by a white blood cell, it hides inside a compartment of the cell called the endoplasmic reticulum (ER for short). Normally a white blood cell would kill a bacterium, but once one is inside the ER the white blood cell is hampered in any further response to the invader.
“The brucellosis bacterium multiplies in the ER,” Celli told me. “It can also be transported by the white blood cells and spread elsewhere in the body.”
In this country, people who are diagnosed with the disease take antibiotics for several weeks and are generally able to put the disease behind them. But the situation is different in the developing world. In the first place, making the diagnosis is not simple. The symptoms – fever and fatigue – are the same as for some other diseases, including influenza and malaria. To make a rigorous diagnosis, doctors must culture samples of blood or bone marrow. That requires good laboratory work.