African Sleeping Sickness

A recent Discover magazine article entitled “Much Too Tired” (October 2000) tells the story of Christopher Post, who after returning from a month long trip to Tanzania and Rwanda, discovered a red spot on his left arm. He also noticed that he was often tired, achy, and hot. But after a few days, Mr. Post was even worse and his fever was higher. He then went to the emergency room.

After the doctor’s initial screening, he discovered that Mr. Post had contracted African sleeping sickness, which is caused by members of the genus Trypanosoma. The protozoan is carried by the tsetse fly, which picks the parasite up from infected animals or humans. The fly cuts into the flesh of animals to get to the blood. If the fly feeds from an infected animal, then the parasites grow in the fly’s stomach. When they reach maturity, they then migrate to the fly’s salivary glands from which they can then infect the fly’s next victim.

Once the parasite is inside the host, it begins to take over the blood stream. Trypanosoma has a canny was of dealing with the body’s immune defenses. As early as 1910, researchers noticed wave after wave of parasites in the blood of sleeping sickness victims. This is caused by the organism’s lifecycle of producing offspring with altered surface proteins. Each new surface triggers a release of a new set of antibodies, which work in the beginning, but ultimately fail as the organism quickly adapts. Eventually, the host’s own immune system begins to work against him. Antibodies begin to attack the host’s tissues and cause damage to the kidneys and heart. Eventually, the parasites will infiltrate the nervous system and be detectable in the spinal fluid. When this happens the host will most likely suffer convulsions, coma, and eventually death.

The treatment for African sleeping sickness is melarsoprol, an arsenic-based parasite poison that also kills about six percent of the victims. This story does have a happy ending. Mr. Post survived his treatment and the parasites have been cleaned from his body. But, the only reason for his survival is the good fortune of living in a country with advanced medical technology and highly trained physicians. In countries like those in Africa, thousands of people die every year from a tiny protozoan.