Trypanosomiasis, Flashcards by Iseoluwa Ojo

Trypanosomes

They are _______________

pass through different morphologic stages ( ————,————, and ________)

haemoflagellates

epimastigote,amastigote, and trypomastigote

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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

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Types
There are two distinct types of human trypanosomes:
(1) _______, which causes sleeping sickness

– (2)_______, which causes Chagas disease

African

American

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Types
There are two distinct types of human trypanosomes:
(1) African: Trypanosoma __________ and Trypanosoma _____________;
– (2) American, Trypanosoma _________

brucei rhodiense

brucei gambiense

cruzi

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African Trypanosomiasis

______________(HAT), also known as ________

Human African trypanosomiasis

sleeping sickness,

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African Trypanosomiasis (Sleeping Sickness)

is caused by two protozoan parasite subspecies:

-Trypanosoma ___________

– Trypanosoma __________

brucei gambiense

Brucei rhodesiense

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African Trypanosomiasis is caused by two protozoan parasite subspecies:

Trypanosoma brucei gambiense (______ African trypanosomiasis) and
– Trypanosoma brucei rhodesiense (_______ African trypanosomiasis).

West

East

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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

10,000

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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

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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

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Vector: tsetse flies that belong to the genus ________

Glossina

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Trypanosoma brueci rhodesiense

It causes a (smaller or larger?) number of cases but is (more or less?) virulent.

Smaller; more

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________ and _________ may serve as reservoirs of T b rhodesiense, whereas _______ are the principal reservoir of T b gambiense.

Bushbuck and other antelopes

humans

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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.

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Aetiological agents
Three trypanosome subspecies, Trypanosoma brucei brucei, T. brucei rhodesiense, and T. brucei gambiense are distinguishable morphologically

T/F

Indistinguishable

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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

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Aetiological agents of Trypanosomiasis

this __________ forms the primary basis of the distinction between the two subspecies (gambiense and rhodiense)

difference in host specificity

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Aetiological agents

T. b. brucei is a parasite of ___________

wild and domestic animals

Aetiological agents

T. b. brucei is infectious to humans.

T/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

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

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