class kinetoplasta
TRANSCRIPT
Class Kinetoplasta: Class Kinetoplasta: Trypanosomes and Their Trypanosomes and Their
KinKin
CHAPTER 5CHAPTER 5
Class KinetoplastaClass Kinetoplasta
Species that parasitize Species that parasitize everything from humans everything from humans to plantsto plants
Members have a Members have a single single large mitochondrion large mitochondrion containing a kinetoplast containing a kinetoplast at at the base of the flagellumthe base of the flagellum
kinetoplastkinetoplast- - is a is a disc-shaped that contains disc-shaped that contains DNADNA
Another characteristics:
- sizable flagellar pocket (sometimes
elogated)
- paraxial rod, a latticelike crystalline
- undulating membrane (depends on the sp)
- glycocalyx (surface coating)
Two unique features of the Two unique features of the KinetoplastKinetoplast
Glycosomes - which glycolytic reaction occurs
Splicing of a short characteristic RNA piece into every molecule of mRNA
Difference between other genera:Difference between other genera: Host distribution Life cycles Medical and
veterinary importance
Three recognized families:
1. F. Bodonidae
2. F. Trypanosomatidae
3. F. CryptobiaeCryptobiae
Cryptobia branchialis
family Trypanosomatidae
Family Trypanosomatidae Family Trypanosomatidae
General Charateristics:
1. have single nucleus (elongated or round)
2. Most of them are heteroxenous
heteroxenous = means a parasite that lives
within more than one host during the life cycle.
3. hemoflagellates = means protozoans with
flagella that thrive in the blood stream
Different forms of Trypanosomatidae
form of this members would differ in terms of : shape, position of kinetosome and kinetoplast, development of the flagella or shape of the flagellar pockets
a. Amastigote = a spheroid stage in Leishmania
shortest flagellum
= kinetoplast is found in between the kinetosome and nucleus, short flagella
b. choanomastigote = in Crithidia, the flagella arise at the collar structure
c. Epimastigote= kinetoplast and kinetosome found in between the nucleus and the anterior end.
d paramastigote = kinetoplast and kinetosome are located beside the nucleus
e. opisthomastigote = kinetoplast is at the end and no undulating mambrane
Trypanosomatidae Insect parasites
Crithidia Herpetomonas
Plant parasites Phytomonas
Amphibian parasites Trypanosoma
mega Fish parasites
Trypanosoma
Crithidia
Herpetomonas
Phytomonas
Reptiles Leptomonas Animals
Trypanosoma Leishmania
Cryptobiae Fishes
Trypanoplasma
Bodonidae free-living
Trypanoplasma·Fig. 1.
Life cycle of Trypanoplasma sp. in fish (carp) and vector leech (). 1 Transformed metacyclic stages with a long free end of the (F2) and a thick (TH) occur in the blood after inoculation by the leech.
2–4 During stumpy forms finally appear, whose recurrent flagellum (SF) has a short end.
These forms (4) are mainly found in the bloodstream when fish are kept in cold water, and may infect during a blood meal.
5–7 Developmental stages inside the pharynx, esophagus and upper intestine of the vector have a reduced surface coat (SS).
The slender forms (7, 8) are attached to the intestinal wall. The stumpy forms (7.1–7.4) are seen free inside the blood masses and may recolonize the intestine after each sucking phase.
8 Metacyclic stages with a thicker surface coat (TS) are found in the anterior parts of the intestine and are injected into fish during blood meal of the . F1, free flagellum; F2, recurrent flagellum; FR, long free end of ; KI, ; N, nucleus; SJ, short free end of recurrent flagellum; SS, slight surface coat; TS, thick surface coat
Trypanosoma Trypanosoma are of the class kinetoplastida, a monophyletic[1] group of unicellular
parasitic protozoa. The name is derived from the Greek trypaô
(boring) and soma (body) because of their corkscrew-like motion.
Trypanosomes infect a variety of hosts and cause various disease, including the fatal disease sleeping sickness in humans.
Trypanosoma undergo a complex lifecycle which includes several different morphological forms.
Characteristic of this order is the mitochondrial genome, known as the kinetoplast. It is made up of a highly complex series of catenatated circles and minicircles and require a cohort of proteins for organisation during cell division
Species of Trypanosoma include the following: T. avium, which causes trypanosomiasis in birds T. boissoni, in elasmobranch T. brucei, which causes sleeping sickness in
humans and nagana in cattle T. carassii, in freshwater teleosts T. cruzi, which causes Chagas disease in
humans T. congolense, which causes nagana in cattle,
horses, and camels Trypanosoma equinum, in South American
horses, transmitted via Tabanidae,
T. equiperdum, which causes dourine or Covering sickness in horses and other Equidae
T. evansi, which causes one form of the disease surra in certain animals (a single case report of human infection in 2005 in India[2] was successfully treated with suramin[3])
Trypanosoma levisi, in rats Trypanosoma melophagium, in sheep, transmitted via
Melophagus ovinus Trypanosoma percae, in the fish species Perca
fluviatilis Trypanosoma rangeli, believed to be nonpathogenic
to humans T. rotatorium, in amphibians
T. simiae, which causes nagana in animals T. suis, which causes a different form of surra T. theileri, a large trypanosome infecting
ruminants T. triglae, in marine teleosts T. vivax, which causes the disease nagana
Trypanosoma cruziTrypanosoma cruzi Causal Agent:
The protozoan parasite, Trypanosoma cruzi, causes Chagas disease, a zoonotic disease that can be transmitted to humans by blood-sucking triatomine bugs. To see drawings of some common species of triatomine bugs found in the United States
Vector insect Triatoma infestans (Kissing Bug)
T. cruzi trypomastigote in cerebrospinal fluid (CSF) stained with Giemsa.
An infected triatomine insect vector (or “kissing” bug) takes a blood meal and releases trypomastigotes in its feces near the site of the bite wound.
Trypomastigotes enter the host through the wound or through intact mucosal membranes, such as the conjunctiva .
Common triatomine vector species for trypanosomiasis belong to the genera a)Triatoma, b)Rhodinius, and c)Panstrongylus.
a) b) c)
Inside the host, the trypomastigotes invade cells near the site of inoculation, where they differentiate into intracellular amastigotes .
The amastigotes multiply by binary fission
and differentiate into trypomastigotes, and then are released into the circulation as bloodstream trypomastigotes .
Trypomastigotes infect cells from a variety of tissues and transform into intracellular amastigotes in new infection sites.
Clinical manifestations can result from this infective cycle.
The bloodstream trypomastigotes do not replicate (different from the African trypanosomes).
Replication resumes only when the parasites enter another cell or are ingested by another vector.
The “kissing” bug becomes infected by feeding on human or animal blood that contains circulating parasites
The ingested trypomastigotes transform into epimastigotes in the vector’s midgut .
The parasites multiply and differentiate in the midgut and differentiate into infective metacyclic trypomastigotes in the hindgut .
Trypanosoma cruzi can also be transmitted through blood transfusions, organ transplantation, transplacentally, and in laboratory accidents.
Clinical Features:
The acute phase is usually asymptomatic,
can present with manifestations that include fever, anorexia, lymphadenopathy, mild hepatosplenomegaly, and myocarditis.
Romaña's sign (unilateral palpebral and periocular swelling) may appear as a result of conjunctival contamination with the vector's feces.
A nodular lesion or furuncle, usually called chagoma, can appear at the site of inoculation. Most acute cases resolve over a period of a few weeks or months into an asymptomatic chronic form of the disease.
This child from Panama is suffering from Chagas disease manifested as an acute infection with swelling of the right eye (Romaña's sign). Source: CDC.
The symptomatic chronic form may not occur for years or even decades after initial infection. Its manifestations include cardiomyopathy (the most serious manifestation); pathologies of the digestive tract such as megaesophagus and megacolon; and weight loss. Chronic Chagas disease and its complications can be fatal. .
Geographic Distribution:Geographic Distribution: The Americas from the The Americas from the
southern United States to southern United States to southern Argentina. southern Argentina. Mostly in poor, rural Mostly in poor, rural areas of Mexico, Central areas of Mexico, Central America, and South America, and South America. Chronic America. Chronic Chagas disease is a Chagas disease is a major health problem in major health problem in many Latin American many Latin American countries. countries.
Causal Agents:Protozoan hemoflagellates belonging to the complex Trypanosoma brucei. Two subspecies that are morphologically indistinguishable cause distinct disease patterns in humans: T. b. gambiense causes West African sleeping sickness and T. b. rhodesiense causes East African sleeping sickness. (A third member of the complex, T. b. brucei, under normal conditions does not infect humans.)
Trypanosoma brucei gambienseTrypanosoma brucei gambienseTrypanosoma brucei rhodesienseTrypanosoma brucei rhodesiense
Clinical Features:Clinical Features: Infection occurs in 3 stages. A trypanosomal
chancre can develop on the site of inoculation.
1. Hemolymphatic stage with symptoms that include fever, lymphadenopathy, and pruritus.
2. In the meningoencephalitic stage, invasion of the central nervous system can cause headaches, somnolence, abnormal behavior, and lead to loss of consciousness and coma.
3. The course of infection is much more acute with T. b. rhodesiense than T. b. gambiense.
Trypansoma brucei sp. in thick blood smears stained with Giemsa.
Trypanosoma brucei sp. in a thin blood smear stained with Giemsa. The trypomastigote is beginning to divide; dividing forms are seen in African trypanosomes, but not in American trypanosomes.
Geographic Distribution:Geographic Distribution:
T. b.T. b. gambiensegambiense is found is found in foci in large areas of in foci in large areas of West and Central West and Central Africa. The distribution Africa. The distribution of of T. b. rhodesienseT. b. rhodesiense is is much more limited, with much more limited, with the species found in the species found in East and Southeast East and Southeast Africa. Africa.
