Zoom in on microorganisms

Germs that infect humans



© Dennis Kunkel Microscopy, Inc.

Microorganism: the protozoan Trypanosoma

Disease: trypanosomiasis (sleeping sickness)

Occurrence of the disease

Current situation: because these protozoa can cause very serious diseases in humans as well as in animals, the World Health Organization has mobilized many resources in the search for a vaccine against Trypanosoma. In Canada, no cases of trypanosomiasis were reported in 1998.

Mechanism of action of the microorganism: as soon as the parasite enters the bloodstream, it multiplies. The protozoan then invades the central nervous system and causes lesions.

Symptoms of the disease: a deep lethargy, saliva traces around the mouth, and insensitivity to pain.

There is an American equivalent to this disease known as American tripanosomiasis or Chagas’ disease. The symptoms differ (generalized discomfort, fever, and liver problems), but it is caused by the same type of protozoan, namely Trypanosoma.

Incubation period: the incubation period lasts between three days and many years, depending on the strain of protozoan that has infected the person.

Contagious period: an infected fly can propagate the disease as long as it lives. Animals can transmit the parasite to flies as long as they transport the protozoa in their blood.

Hosts: tsetse flies, humans, and certain domesticated and wild animals.

Transmission: transmission occurs when tsetse flies, infected by the protozoa, bite animals (including humans).

Treatment: many drugs, such as suramin, melarsoprol and eflornithine

Geographical distribution of the microorganism: the protozoan is confined to tropical Africa and it follows the distribution of the tsetse fly.

Prevention: protection against bites from tsetse flies.

Vaccine: not available