7-9. Human African Trypanosomiasis

Question 1

Where is T.b. rhodesiense and T.b. gambiense found?

Answer 1

E Africa (T. b. rhodesiense)
W/C Africa (T. b. gambiense)

Question 2

What disease does T. brucei cause?

Answer 2

Human sleeping sickness

Question 3

Which species is the main cause of sleeping sickness?

Answer 3

T. b. gambiense

Question 4

What is the tseste vector of each species and where are they found?

Answer 4

gambiense - riverine vector - Palpalis and Fusca

rhodesiense - savannah vector - Mortisans

Question 5

What is the life cycle of T. brucei?

Answer 5

injected into human as metacyclic trypomastigote form
transform into bloodstream trypomastigotes
multiply
are ingested by fly
transform into pro cyclic trypomastigotes in midgut
leave midgut and transform into epimastigotes
multiply in salivary gland and become metacyclic trypomastigotes
….are injected into human…

Question 6

How does T. brucei evade the immune response?

Answer 6

VSG
Triggers immune response of IgM antibodies
Can change its expression so immune system can no longer recognise it

Question 7

What are 4 symptoms of early stage disease?

Answer 7

enlarged lymph glands or spleen
headaches
undulating fever
general malaise

Question 8

What occurs in late stage disease?

Answer 8

The parasite invades internal organs including the CNS

Question 9

What are symptoms of late stage disease?

Answer 9

severe headaches
sleeping pattern affected
personality changes
impaired mental function
weight loss
coma and death

Question 10

What occurs in late stage in terms of neuropathology?

Answer 10

AHL - necrosis in small blood vessels in the brain

Question 11

What are the differences in pathology between T. b. gambiense and T. b. rhodesiense disease?

Answer 11

gambiense - chronic disease, long asymptomatic period

rhodesiense - acute virulent infection, quickly detectable

Question 12

What are the 4 licensed drugs for HAT in order of price, and which species do they target?

Answer 12

Suramin - early stage rhodesiense
Petamidine - early stage gambiense
Melarsoprol - late both
Elflornithine - late gambiense

Question 13

How is trypanosomiasis diagnosed?

Answer 13

lumbar puncture

Question 14

What are the three animal trypanosomes?

Answer 14

t. b. brucei
t. b. congolense
t. b. vivid

Question 15

Control of t.b. gambiense

Answer 15

case detection and treatment
reduce person to person transmission
little vector control

Question 16

Control of t.b. rhodesiense

Answer 16

Vector control

Cattle treatment

Question 17

What is a disadvantage of using traps for tsetse control?

Answer 17

not sustainable

Question 18

What are the disadvantages of using cattle dips for tsetse control

Answer 18

expensive

no effect on tsetse population

Question 19

Discuss mass spraying for tsetse control

Answer 19

Good as knocks down flying adults

Bad as very expensive

Question 20

Example of the sterile insect technique of tsetse flies

Answer 20

Tanzibar
Sterile:Normal ratio was >100:1
>70% barren females

Question 21

Which drugs used in SOS initiative?

Answer 21

Early stage 1st line drugs : Suramin and Pentimidine

Late stage 1st line drugs: Melarsoprol and Eflornithine

Question 22

Which species of cattle are resistant to Babesia but susceptible to trypanosomes?

Answer 22

Bos indicus

Question 23

Which species of cattle are resistant to trypanosomes but susceptible to babesia?

Answer 23

Bos taurus

Question 24

How can herds be treated with both TBD and trypanosomes in mind?

Answer 24

Treat the older, larger individuals with insecticide to kill tsetse flies
Younger individuals bitten by ticks get immunity
Only treat half of the herd

Question 25

Which method may be good for gambiense HAT control?

Answer 25

Tiny insecticide impregnanted targets