Life Cycle
The tsetse fly (genus Glossina) is a large, brown, biting fly that serves as both a host and vector for the trypanosome parasites. While taking blood from a mammalian host, an infected tsetse fly injects metacyclic trypomastigotes into skin tissue. From the bite, parasites first enter the lymphatic system and then pass into the bloodstream. Inside the mammalian host, they transform into bloodstream trypomastigotes, and are carried to other sites throughout the body, reach other body fluids (e.g., lymph, spinal fluid), and continue to replicate by binary fission.
The entire life cycle of African trypanosomes is represented by extracellular stages. A tsetse fly becomes infected with bloodstream trypomastigotes when taking a blood meal on an infected mammalian host. In the fly's midgut, the parasites transform into procyclic trypomastigotes, multiply by binary fission, leave the midgut, and transform into epimastigotes. The epimastigotes reach the fly's salivary glands and continue multiplication by binary fission.
The entire life cycle of the fly takes about three weeks.
In addition to the bite of the tsetse fly, the disease can be transmitted by:
- Mother-to-child infection: the trypanosome can sometimes cross the placenta and infect the fetus.
- Laboratories: accidental infections, for example, through the handling of blood of an infected person and organ transplantation, although this is uncommon.
- Blood transfusion
- Sexual contact (This may be possible)
Read more about this topic: African Trypanosomiasis
Famous quotes containing the words life and/or cycle:
“And he thought to himself...., Soul, you have ample goods laid up for many years; relax, eat, drink, be merry. But God said to him, You fool! This very night your life is being demanded of you. And the things you have prepared, whose will they be?”
—Bible: New Testament, Luke 12:17-20.
“The lifelong process of caregiving, is the ultimate link between caregivers of all ages. You and I are not just in a phase we will outgrow. This is lifebirth, death, and everything in between.... The care continuum is the cycle of life turning full circle in each of our lives. And what we learn when we spoon-feed our babies will echo in our ears as we feed our parents. The point is not to be done. The point is to be ready to do again.”
—Paula C. Lowe (20th century)