American Trypanosomes

Question 1

Geographical distribution:

Answer 1

Central and south africa

Question 2

Habitat of A.Trypanosomes:

Answer 2

Blood and RES
S.M of heart and intestine
Brain cells

Question 3

Reservior hosts:

Answer 3

Domestic animals, cats, dogs and pigs.

Wild animals, Armadillos and rodents

Question 4

Revesrvoir hosts are a lot of animlas so:

Answer 4

It is a zoonotic disease

Question 5

Insect vector :

Answer 5

Reduviid bug “Triatoma megista” (winged bug) , kissing bug because it attacks face

Question 6

Morphological types

Answer 6

In man T.cruzi occurs in 2 forms:
Trypomastigote
Amastigote

Question 7

Trypomastigote form:

Answer 7

Present in blood only (extracellular)
C or S shaped about 20u length
Non dividing form
Large post. Kinoplast with undulating membrane and free flagellum

Question 8

Amastigote form:

Answer 8

From leishmanoid form (intracellular)

Actively dividing by simple fission

Question 9

Which t.cruzi form that actively dividing:

Answer 9

Amastigote

Question 10

Which form present in blood only(extracellular)?

Answer 10

Trypomastigote

Question 11

Infective stage:

Answer 11

Metacyclic form

Question 12

Mode of infection:

Answer 12

Contamonation of bite wound by metacyclic forms in stool of triatoma magista (post. Station)
Blood transfusion and organ transplant
Congenital (intrauterine)
Accidental in the laboratory

Question 13

How triatoma magista transmits the infection

Answer 13

the infective stage is present in the post half of the insect (rectum) that contaminates bite wound.
As T.megista usually defecates during biting

Question 14

Trypanosoma cruzi is opportunistic parasite:

Answer 14

It can produce severe fetal disease in immunosuppressed patients

Question 15

Life cycle in triatoma:

Answer 15

Forgut》midgut》rectum
Triatoma bites an infected person
It sucks trypanomastigotes
They develop into the midgut into epimastigote forms (crithidia)
Which muliply and develop into metacyclic forms (in the rectum) these are the infective stages that pass in stool and contaminate bite wound.
It is infective for whole its life (1-2years)

Question 16

Life cycle in man:

Answer 16

Metacyclic forms reach blood and develop to trypomastigotes which invade RES and S.Ms of heart and intestine and brain cells where they change to amastigotes which reach blood and insect takes it and so on

Question 17

A.trypanosomes are asymptomatic except in :

Answer 17

Immunocompromized patients.

Question 18

Chagas disease occurs in :

Answer 18

Congenital