WEEK 1 Human African Trypanosomiasis

Question 1

What is human african trypanosomiasis also known as?

Answer 1

African sleeping sickness

Question 2

How many countries does it infect and the amount of people?

Answer 2

36 countries in sub saharan africa, with a high risk in a belt running through central africa.
60 million people at risk

Question 3

What are the different transmission cycles?

Answer 3

Zoonotic (animal to human) and antrhopomorphic (human to human)

Question 4

Where is it common and what prevalence?

Answer 4

Rural populations up to 50%

Question 5

How many major epidemics have there been in the last century, and what is an evident trend?

Answer 5

3

when screening stops due to political instability and civil unrest the amount of cases increase

Question 6

What is the causative agent of HAT?

Answer 6

Trypanosoma brucei a protozoan parasite

Question 7

WHat is the insect vector of HAT

Answer 7

Tsetse fly (Glossina spp)

Question 8

How many species / sub species can transmit the infection and which sex?

Answer 8

BOth sexes

4 species & sub species

Question 9

How many different groups is the Tsetse fly split into and what are they?

Answer 9

3

riverine, savannah, forest

Question 10

Why could prevention control work on these species? the biological reasons

Answer 10

Female flies are viviparous. the female deposits a fully developed single larva that burrows intot he soil and emerges as an adult fly. the key thing is that this emerged adult fly is free from t.brucei.
Flies prodcuce up to 4 generations per year

Question 11

What is special about the distribution of HAT and Tsetse fly?

Answer 11

wherever the fly is HAT is.

Question 12

what is the major form of Trypanosoma brucei?

Answer 12

Trypomastigote - flagellum pocket found posterior of nucleus, flagellum attached to cell body by undulating membrane
kinetoplast located between nucleus and posterior end

Question 13

what are the 4 trypomastigote forms of T.brucei?

and are they associated with insect or mammal

Answer 13

Procyclic trypomastigote - insect
Long slender blood stream trypomastigote - mammal
Metacyclic trypomastigote - insect to humans
Short stumpy trypomastigote - humans to insects

Question 14

What is the other morphology found in the insect salivary gland?

Answer 14

Epimastigote - flagellum pocket located between nucleus and anterior end. the flagellum is attached to the cell body for part of its length via the undulating membrane
kinetoplast is located vetween nucleus and anterior end

Question 15

What is the life cycle of t.brucei?

Answer 15

see slide 14 of lecture 2 week 1

Question 16

What are the 2 sub species of t.brucei that cause HAT and which disease do they cause?

Answer 16

t. b.gambiense - West African

t. b.rhodesiense - East Africa

Question 17

how are the 2 infections distinct?

fly, ecology, and range

Answer 17

east african - savannah, dry bush or woodland, east / southern africa
west african - riverine, rainforest or lakes, west/central africa

Question 18

how are the 2 infections distinct with the transmission cycle and non human reservoirs?

Answer 18

east african - zoonotic ungulate to human, wild and domestic animals
west african - anthropomorphic human to human , rare to have non human reservoirs

Question 19

What is the difference between the epidemiology, disease progression, parasitaemia, and asymptomatic carriers of the 2 infectoins?

Answer 19

East african - sporadic, rapid progression to death, high parasite load, rare to have asymptomatic carriers
West african - endemic, slow progression to death, low parasite load, common asymptomatic carriers

Question 20

What are the three direct diagnosis methods?

Answer 20

Blood smear
enrichment
cerebrospinal fluid

Question 21

what is the indirect method of diagnosis?

Answer 21

Card Agglutination test for trypanosomiasis or CATT

Question 22

what are the 5 licensed drugs?

Answer 22

Suramin,
Pentamidine
Melarsoprol
Eflornithine
NECT

Question 23

What are the 6 prevention controls?

Answer 23

Pre-20th century
Land clearing
Slaughter of wild animals
pesticide campaigns
trapping
irradiated males

Question 24

Explain the pathology of the infection when it has first entered human blood stream?

Answer 24

intermittent fever and headache

Question 25

Explain the pathology of the infection when it has entered the lymphatic systme?

Answer 25

Continued febrile episodes
DEteriorating health
Odemas and swellings of lymphatic fluid around the lymph nodes

Question 26

Explain the pathology when it first crosses the blood brain barrier?

Answer 26

Anorexia
mild neurological symmptoms
apathy

Question 27

Wxplain the pathology when it has been in the CNS for a long time?

Answer 27

Severe sleep disturbance
severe neurological symptoms
change in personality
convulsions coma
eventually leading to death if not treated