Trypanosoma

Genus of parasitic protozoa

Trypanosoma is a genus of parasitic protozoa belonging to the family Trypanosomatidae. These organisms are responsible for several significant diseases in humans and animals, including African trypanosomiasis (sleeping sickness) and Chagas disease.

Morphology

Trypanosoma species are characterized by their elongated, spindle-shaped bodies. They possess a single flagellum that originates from a basal body located near the posterior end of the organism. The flagellum is attached to the body, forming an undulating membrane. The nucleus is centrally located, and the kinetoplast, a unique organelle containing mitochondrial DNA, is situated near the basal body.

Diagram of trypanosomatid morphologies

Life Cycle

The life cycle of Trypanosoma involves both an insect vector and a vertebrate host. In the case of African trypanosomiasis, the tsetse fly serves as the vector, while in Chagas disease, the triatomine bug is the vector. The parasites undergo several developmental stages in both the insect and vertebrate hosts.

In the Insect Vector

In the tsetse fly, Trypanosoma undergoes a series of transformations, starting as procyclic trypomastigotes in the midgut, then migrating to the salivary glands where they become epimastigotes and finally transform into metacyclic trypomastigotes, which are infective to the vertebrate host.

In the Vertebrate Host

Once transmitted to the vertebrate host through the bite of the insect vector, the metacyclic trypomastigotes enter the bloodstream and transform into bloodstream trypomastigotes. These forms multiply by binary fission and are responsible for the clinical manifestations of the disease.

Pathogenesis

Trypanosoma species cause disease by evading the host's immune system through antigenic variation. They periodically change their surface glycoproteins, making it difficult for the host to mount an effective immune response. This leads to chronic infections and, in the case of African trypanosomiasis, can result in severe neurological symptoms and death if untreated.

Diagnosis and Treatment

Diagnosis of trypanosomiasis involves detecting the parasites in blood, lymph, or cerebrospinal fluid. Serological tests and molecular methods such as PCR are also used. Treatment depends on the stage of the disease and the specific Trypanosoma species involved. Drugs such as pentamidine, suramin, melarsoprol, and eflornithine are used to treat African trypanosomiasis, while benznidazole and nifurtimox are used for Chagas disease.

Prevention

Preventive measures include controlling the insect vectors through insecticide spraying, using insect repellent, and wearing protective clothing. In endemic areas, surveillance and early treatment of infected individuals are crucial to prevent the spread of the disease.

Also see

• African trypanosomiasis
• Chagas disease
• Kinetoplastida
• Protozoa