Protista-Trypanosoma+cruzi

= ** Trypanosoma cruzi ** = ==

** Scientific Classification **

 * **Scientific Name** || //Trypanosoma cruzi// ||
 * **Kingdom** || Protista ||
 * **Phylum** || Sarcomastigophora ||
 * **Class** || Zoomastigophora ||
 * **Order** || Kinetoplastida ||
 * **Family** || Trypanosomatidae ||
 * Common names: ** Chagas Disease, American Trypanosomiasis

Introduction
//Trypanosoma cruzi// is a zooflagellate(any flagellate protozoan) that causes Chagas disease.Chagas disease is named after Carlos Chagas, a physician who discovered the disease in 1909. This disease mainly affects the lungs and heart, impairing the cardiac and respiratory systems. It can also affect the liver and the nervous system. Although //Trypanosoma cruzi// is transmitted by various insect vectors, the primary vector is the reduviidae bug(see picture below) as it accounts for most previous Chagas disease cases. These insects are only found in the Americas, particularily areas where poverty exists. Children is the main victim of this disease.

Phylum Sarcomastigophora
This phylum consist of single celled organisms which have only one type of nucleus. The two subphyla are Mastigophora(Flagellates) and Sarcodina (Amebas). Protozoa of this phylum are all unicellular or colonial protozoa. They are all homokaryotic (one type of nucleus) and they can be either autotrophic or heterotrophic. Some protists in this phylum can actually be multinucleated. As well, they move by means of the flagella and/or pseudopods during some point of their lives. In this phylum, sexual reproduction is not widespread.

Genus Trypanosoma
Trypanosoma is a zooflagellate protozoan parasite that is found in the blood of vertebrates. They are sometimes known as endoparasites, blood parasites, or extra cellular parasites. They have a nucleus, a flagellum, undulating membrane, blepharoplast (basal granule) and Kinotoplst. Organisms of the genus Trypanosoma can take on four forms; Leis mania, Leptomonad, Crithidial and Trypanosomal stages. These organisms reproduce asexually.

**What does it look ****like? **
The reduviid bug are dark-coloured bugs with a red or orange stripes around the edges of the abdomen. They have narrow heads that are attached to oval-shaped bodies that measure about 10-25mm in length. As well, they have a short, curved beak and long antennas.
 * Reduviid bug:**

__Nucleus:__ The nucleus is elongate and located in the central area of the cell. It has a rounded shaped in epimastigotes and spheromastigotes. There is a continuity between the outer nuclear membrane and the endoplasmic reticulum.
 * Cellular Structure of //Trypanosoma cruzi://**

__Nucleolus__ The nucleolus is found in the center of the nucleus. It is separated during cell division and reappears when cell division is almost complete. It has been discovered that a nucleolus is not found in trypomastigote forms. As well, there appears to be a decrease in trascription rates(process by which RNA is synthesized) of the RNA polymerases when epimastigotes transform into trypomastigotes.

__Cell Surface__ The cell surface of trypanosomatids are composed by two parts: plasma membrane and a layer made up of the subpellicular microtubules. Cellular components such as mucins, transialidase, and some types of glycoproteins are associated with the cell surface. They form the glycocalyx whcih is also known as the cell coat. The surface of trypomastigotes is extreamly wrinkly due to the exposed proteins.

__ Flagellum __ An important distinct feature of the //Trypanosomatidae// family is that they all have a flagellum. Sometimes, the flagellum may emerge from the anterior tip or from somewhere along the side. The length of the flagellum varies according to the developmental stage.



__ Cytostome __ Just like many other protists, the //Trypanosoma cruzi has a// cytostome. The cytostome is a mouth-like opening through which food passes. The opening of the cytostome usually has a diameter of up to 0.3 µm. However, it can be shorter in the deeper portion. Macromolecules are concentrated in reservosome.

__ Subpellicular microtubules __ Another important feature of the //Trypanosoma cruzi// is the presence of a layer of microtubules located just below the plasma membrane. Scientists have observed that the microtubules are connected to each other as well as the plasma membrane by means of short filaments. This is probably what is responsible for the rigidity of the cell. It is very difficult to destroy the cell; even by mechanical means.

__Mitochondrion and Kinetoplast__ //Trypanosoma cruzi// possess only one mitochondrion that extends throughout the cell. A portion of the mitochondrion consist of a complex arrangement of BNA fibrils which form the important strucutre called kinetoplast (an independent replicating structure). Between 20 and 25% of the //Trypanosoma cruzi// 's DNA is kinetoplast DNA. The Kinetoplast DNA is in fact the most structurally complex mitochondrial DNA in nature. It is unique to unicellular flagellates of the order Kinetoplastida. The Kinetoplast DNA is basically a network of circular DNAs.



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 * Reduviid bug:** These bugs are found in southern United States, South America and Central America. Females like to lay their eggs in cracks and small openings. That is why reduviid bugs are most commonly found in poor housing where they dwell in thatched roofs and broken walls. They also live under furniture and in animal pens. They are attracted to warmth and carbon dioxide.======

//Trypanosoma cruzi:// Since the T. cruzi is a protist, the ecology of their vector (Reduviid bug) and host is their habitat.

Daily Activities
Reduviid bugs hide during the day and come out at night to feed on their victims, who are usually asleep.

1. reduviid bug sucks in trypomastigotes when taking blood from an infected human. 2. Trypomastigotes develop into epimastigotes 3. epimastigotes divide and develop into infectious metacyclic trypomastigotes 4. Reduviid bug takes a blood meal from another human 5. Sucking in blood causes the bug to defecate on the host's skin. 6. Infectious metacyclic trypomastigotes is left near the bite 7. Human scratches the bite site, inoculating him/her self with the trypanosome.
 * Basic transmission cycle:**

**Facinating Fact:** The bite of the reduviid bug is not infectious. It is when the human rubs the feces into the bite that causes the infection.



Epidemiology
Chagas disease can be found in Central and South America as well as a portion of the southern United States. It is estimated that about 15 million people are infected with //Trypanosoma cruzi,// 50, 000 of these people will die each year, and another 100 million people still remain at risk.





Microvideograph of Trypanosoma cruzi in hemoculture: media type="youtube" key="7q9PTljtRhE?fs=1" height="385" width="640"

References:
The Protozoans. (2010). The New Book of Popular Science. Retrieved November 15, 2010, from Grolier Online []

Vorhaus, L. J. (2010). Chagas' Disease. Encyclopedia Americana. Retrieved November 15, 2010, from Grolier Online []

Petrakis, P. L. (2010). Trypanosomiasis. Grolier Multimedia Encyclopedia. Retrieved November 15, 2010, from Grolier Online []

Protozoan. ( 2010). In Encyclopædia Britannica. Retrieved November 15, 2010, from Encyclopædia Britannica Online School Edition: [|http://][|school][|.eb.com/eb/][|article][|-32604]

Protist. ( 2010). In Encyclopædia Britannica. Retrieved November 15, 2010, from Encyclopædia Britannica Online School Online School Edition: []

Image Resources:
"CDC - Chagas Disease." //Centers for Disease Control and Prevention//. N.p., n.d. Web. 15 Nov. 2010. <[]>

"Home-Institute for OneWorld Health." //Home-Institute for OneWorld Health//. N.p., n.d. Web. 15 Nov. 2010. .