Trypanosomiasis, Flashcards
Trypanosomes
They are _______________
pass through different morphologic stages ( ————,————, and ________)
haemoflagellates
epimastigote,amastigote, and trypomastigote
There are two distinct types of human trypanosomes:
(1) African, which causes ______ and is transmitted by _________ (eg, _______)
(2) American, which causes _________ and is transmitted by ______ (eg, _______)
sleeping sickness
tsetseflies; Glossina
Chagas’ disease; kissing bugs; Triatoma
Types
There are two distinct types of human trypanosomes:
(1) _______, which causes sleeping sickness
– (2)_______, which causes Chagas disease
African
American
Types
There are two distinct types of human trypanosomes:
(1) African: Trypanosoma __________ and Trypanosoma _____________;
– (2) American, Trypanosoma _________
brucei rhodiense
brucei gambiense
cruzi
African Trypanosomiasis
______________(HAT), also known as ________
Human African trypanosomiasis
sleeping sickness,
African Trypanosomiasis (Sleeping Sickness)
is caused by two protozoan parasite subspecies:
-Trypanosoma ___________
– Trypanosoma __________
brucei gambiense
Brucei rhodesiense
African Trypanosomiasis is caused by two protozoan parasite subspecies:
Trypanosoma brucei gambiense (______ African trypanosomiasis) and
– Trypanosoma brucei rhodesiense (_______ African trypanosomiasis).
West
East
Epidemiology
HAT occurs only in _______, where endemic foci are found in about ____ countries – recognized tsetse fly belts
About _______ new cases are reported annually to the World Health Organization
sub-Saharan Africa
20
10,000
T b gambiense
transmitted by the _______ tsetse _________ and several other humid forest tsetse vectors, extends from ____ to Central Africa and produces a relatively (Acute or chronic?) infection with progressive ______ involvement.
Streamside; Glossina palpalis
West
Chronic
CNS
Trypanosoma brueci rhodesiense, transmitted by the _______ Glossina _______, Glossina ______, and Glossina _______, occurs in the _______ and _________ savannas of Africa, with foci west of Lake Victoria.
woodland-savanna
morsitans; pallidipes; fuscipes
eastern and southeastern
Vector: tsetse flies that belong to the genus ________
Glossina
Trypanosoma brueci rhodesiense
It causes a (smaller or larger?) number of cases but is (more or less?) virulent.
Smaller; more
________ and _________ may serve as reservoirs of T b rhodesiense, whereas _______ are the principal reservoir of T b gambiense.
Bushbuck and other antelopes
humans
Aetiological agents
Three trypanosome subspecies,
Trypanosoma brucei _____
T. brucei ————
T. brucei ______
as a group they are often referred to as the ___________
brucei
rhodesiense
gambiense
T. brucei complex.
Aetiological agents
Three trypanosome subspecies, Trypanosoma brucei brucei, T. brucei rhodesiense, and T. brucei gambiense are distinguishable morphologically
T/F
F
Indistinguishable
Aetiological agents
T. b. gambiense primarily infects _______, and may also infect __________
T. b. rhodesiense, which is primarily a parasite of ______, can infect _____,
humans
wild and domestic animals
wild game
humans
Aetiological agents of Trypanosomiasis
this __________ forms the primary basis of the distinction between the two subspecies (gambiense and rhodiense)
difference in host specificity
Aetiological agents
T. b. brucei is a parasite of ___________
wild and domestic animals
Aetiological agents
T. b. brucei is infectious to humans.
T/F
F
T. b. brucei is not infectious to humans
Trypanosoma appears in the blood as ______mastigotes with _____ bodies supporting a (longitudinal or transverse?) (medial or lateral?) undulating membrane and a flagellum that borders the free edge of the membrane and emerges at the (anterior or posterior ?) end as a whiplike extension
trypo; elongated
longitudinal; lateral
Anterior
Trypanosoma
The kinetoplast is a ______ staining body lying immediately adjacent to the ______ from which the _______ arises
•
darkly
basal body
flagellum
The kinetoplast is a ____________________________
circular DNA inside the single mitochondrion
Life cycle of trypanosomes bbn
Trypanosomes are parasites with a 2-host life cycle:
_________ and ________.
The life cycle starts when the trypanosomes are ingested during a
______ by the tsetse fly from a __________ in West African trypanosomiasis or _______ in the East African form.
The trypanosomes multiply over a period of _______ in the fly’s ________ ; then, the trypanosomes migrate to the _________, where they develop into _________.
The ———————- infect humans.
mammalian and arthropod
blood meal; human reservoir ; an animal reservoir
2-3 weeks; midgut; salivary gland; epimastigotes
metacyclic trypomastigotes
Pathophysiology of Trypanosomiasis
The parasites escape the initial host defense mechanisms by extensive __________________ known as major ________________________.
During the parasitemia, most pathologic changes occur in the ______,_________,________, and ________ systems.
This may be the result of immune- mediated reactions against antigens on red blood cells, cardiac tissue, and brain tissue, resulting in hemolysis, anemia, pancarditis, and meningoencephalitis
antigenic variation of parasite surface glycoproteins
variant surface glycoprotein (VSG)
hematologic, lymphatic, cardiac, and central nervous
Pathogenesis of Trypanosomiasis
Infective trypanosomes of T b gambiense and T b rhodesiense are introduced through the bite of the tsetse fly and ____________ to cause variable _____ and_________ (the primary lesion), which may progress to form a ________.
multiply at the site of inoculation
induration and swelling
trypanosomal chancre
Pathogenesis of Trypanosomiasis
They multiply extracellularly as ________ in the blood as well as in lymphoid tissues. They spread to lymph nodes, to the bloodstream, and, in terminal stages, to the _________, where they produce the typical _________ syndrome
trypomastigotes
central nervous system (CNS)
sleeping sickness
typical sleeping sickness syndrome
________ , inability to _____, tissue _______, unconsciousness, and death.
_______ involvement is most characteristic of African trypanosomiasis.
lassitude; eat; wasting
CNS
Diagnosis
A definitive diagnosis of African
trypanosomiasis requires ____________
demonstration of the parasite.
Diagnosis of African trypanosomiasis
Examination of ________ and ____________ for parasites is the cornerstone of HAT diagnosis.
molecular methods like PCR are also being used.
blood smears and cerebrospinal fluid
Treatment of African Trypanosomiasis
complicated because it varies according to the ________ of the disease and the ___________ causing the infection.
clinical stage; trypanosome subspecies
Treatment of African Trypanosomiasis
Toxicity of the drugs used to treat HAT is a (minor or major?) problem.
Suramin, pentamidine, and organic arsenicals have been used for more than 50yrs
Eflornithine was introduced in 1990
Major
Prevention of HAT
By avoiding ______ known to harbor infected insect
wearing clothing that reduces the biting of the flies, and using insect repellent.
instituting fly control principally with aerial insecticides and by altering habitats
searching for and then isolating and treating patients with the disease
____________ is not recommended m
areas
Chemoprophylaxis
Chemoprophylaxis is not recommended for HAT because of the _____________
high toxicity of the drugs that are active against African trypanosomes
no vaccine is available for HAT
T/F
T
AmericanTrypanosomiasis (Chagas’ Disease)
vector;:——————, or “________”
Triatominae
kissing bug
Epidemiology of Chagas’ disease
Chagas’ disease is endemic in all ________ and _____ countries and also in _________.
The infection is not endemic in any of the Caribbean islands.
About 8 million persons are chronically infected with T. cruzi, roughly 56,000 new infections occur each year, and about 12,000 persons die of the illness annually.
South and Central American ; Mexico
Life cycle of cruzi
The T cruzi life cycle consists of 3 main developmental forms.
Epimastigotes are (intra or extra?) cellular and (infective or noninfective?) form of the parasite found in the ____ of insect vectors, where they multiply by _________
As epimastigotes move to the ______, they differentiate into ____________ which are (dividing or non dividing?) forms resistant to _________ that have the capacity to __________
They enter local cells through breaks in the skin, mucous membranes, or the conjunctivas and transform into the third morphologic form, __________.
This final form multiply (intra or extra?) cellularly until the host cell is overwhelmed, at which point they transform into _____________
an extra; noninfective; midgut
binary fission.; hindgut; metacyclic trypomastigotes
non dividing; mammalian complement ; infect mammalian cells.
amastigotes; intra; bloodstream trypomastigotes
Pathogenesis of Cruzi
Infective forms of T cruzi pass to humans by triatomine bug bites
T/F
F
do not
Pathogenesis of Cruzi
Infective forms of T cruzi do not pass to humans by triatomine bug bites ; rather, they are introduced when ___________________________.
At the site of T cruzi entry, there may be a ________________ or _____________
Unilateral swellingof the _____ (______ sign) is characteristic at onset, especially in children.
The primary lesion is accompanied by fever, acute regional lymphadenitis, and dissemination to blood and tissues.
• • •
infected bug feces are rubbed into the conjunctiva, the bite site, or a break in the skin
subcutaneous inflammatory nodule or chagoma.
eyelids; Romaña’s
Interstitial _______ is the most common serious condition in Chagas disease.
myocarditis
Other organs affected are the _______,_____, and _________ , especially with chronic T cruzi infection.
liver, spleen, and bone marrow
Pathogenesis of T cruzi
Invasion or toxic destruction of nerve plexuses in the alimentary tract walls leads to _______ and _____, especially in _______ Chagas disease and megacolon are absent in ___________.
megaesophagus and megacolon
Brazilian
Colombian
Treatment of chagas
________ and _______
Nifurtimox and benznidazole
