WEEK 1 Human African Trypanosomiasis Flashcards
What is human african trypanosomiasis also known as?
African sleeping sickness
How many countries does it infect and the amount of people?
36 countries in sub saharan africa, with a high risk in a belt running through central africa.
60 million people at risk
What are the different transmission cycles?
Zoonotic (animal to human) and antrhopomorphic (human to human)
Where is it common and what prevalence?
Rural populations up to 50%
How many major epidemics have there been in the last century, and what is an evident trend?
3
when screening stops due to political instability and civil unrest the amount of cases increase
What is the causative agent of HAT?
Trypanosoma brucei a protozoan parasite
WHat is the insect vector of HAT
Tsetse fly (Glossina spp)
How many species / sub species can transmit the infection and which sex?
BOth sexes
4 species & sub species
How many different groups is the Tsetse fly split into and what are they?
3
riverine, savannah, forest
Why could prevention control work on these species? the biological reasons
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
What is special about the distribution of HAT and Tsetse fly?
wherever the fly is HAT is.
what is the major form of Trypanosoma brucei?
Trypomastigote - flagellum pocket found posterior of nucleus, flagellum attached to cell body by undulating membrane
kinetoplast located between nucleus and posterior end
what are the 4 trypomastigote forms of T.brucei?
and are they associated with insect or mammal
Procyclic trypomastigote - insect
Long slender blood stream trypomastigote - mammal
Metacyclic trypomastigote - insect to humans
Short stumpy trypomastigote - humans to insects
What is the other morphology found in the insect salivary gland?
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
What is the life cycle of t.brucei?
see slide 14 of lecture 2 week 1
What are the 2 sub species of t.brucei that cause HAT and which disease do they cause?
t. b.gambiense - West African
t. b.rhodesiense - East Africa
how are the 2 infections distinct?
fly, ecology, and range
east african - savannah, dry bush or woodland, east / southern africa
west african - riverine, rainforest or lakes, west/central africa
how are the 2 infections distinct with the transmission cycle and non human reservoirs?
east african - zoonotic ungulate to human, wild and domestic animals
west african - anthropomorphic human to human , rare to have non human reservoirs
What is the difference between the epidemiology, disease progression, parasitaemia, and asymptomatic carriers of the 2 infectoins?
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
What are the three direct diagnosis methods?
Blood smear
enrichment
cerebrospinal fluid
what is the indirect method of diagnosis?
Card Agglutination test for trypanosomiasis or CATT
what are the 5 licensed drugs?
Suramin, Pentamidine Melarsoprol Eflornithine NECT
What are the 6 prevention controls?
Pre-20th century Land clearing Slaughter of wild animals pesticide campaigns trapping irradiated males
Explain the pathology of the infection when it has first entered human blood stream?
intermittent fever and headache
Explain the pathology of the infection when it has entered the lymphatic systme?
Continued febrile episodes
DEteriorating health
Odemas and swellings of lymphatic fluid around the lymph nodes
Explain the pathology when it first crosses the blood brain barrier?
Anorexia
mild neurological symmptoms
apathy
Wxplain the pathology when it has been in the CNS for a long time?
Severe sleep disturbance severe neurological symptoms change in personality convulsions coma eventually leading to death if not treated
