21 Sleeping Sickness
One of the neglected tropical diseases, one of the diseases that led to the formation of tropical medicine as a speciality
1896 -> 1900’s - An ugandan outbreak of Rinderprest (Cow measles) killing over 800,000 people. Lot’s of arable land returned to bushland = increased tsetse flies = increased sleeping sickness
Congo railway to cote d’ivoire, made by the french. Conscripted 1/3 of male population of french equatorial africa to make this railway. Huge mortality. One of the things people were dying of was sleeping sickness.
Colonial authorities wanted to put in public health campaigns, to protect their investment!
They’d inject 5000 people a day, with two needles, HIV was kicking off around this time. They did this for half of the population. V v likely to give HIV that initial kick in spread.
Burden of disease: 0.05 million/year
Occurs in concentrated epidemics in very unstable parts of the world
21.1 Parasite
Typanosoma brucei brucei - Nagana - cattle disease
West African Sleeping Sickness - T b gambiense
East African Sleeping Sickness - T b rhodesiense
21.1.1 Life Cycle
Tsetse Fly (Glossina spp) takes blood meal and injects a trypomastigote
This is an extracellular infection. Divide in blood.
Tsets fly takes another blood meal, they replicate in the gut
21.2 Vector
Rhodesiense - East and Southern Africa - Savannah Gambiense - West - Riverine vegetation
Has a characteristic “hatchet” cell in the wing
21.3 Epidemiology
Only place they really overlap is in Uganda
21.3.1 West African
50-70,000 cases - highly focal
Human to human (via tsetse)
Still tends to be a disease exacerbated by conflict (Angola, Congo, and Sudan all had high cases during war)
Eastern congo, southern sudan, central african republic all currently have outbreaks, worsened by conflict
21.3.2 East African
~ 1000 cases
Zoonotic infection - primarily game animals
21.4 Clinical Features
You get bitten, you get parasites
You get an inflammatory reaction at the site of bite - primary chancre
Followed by haemolyphatic stage - fever, lymphadenopathy (posterior cervical chain, winterbottom’s sign), hepatosplenomegaly
winterbottom’s sign was used by slavers to work out who would die on the transatlantic sail. (winterbottom was not a slaver, he was a doctor opposed to it). Mothers maybe used to try and induce it in kids
then meningoencephalitic stage as parasites cross bbb
this is faster in the east african form, and the disease is much more severe. this is as parasite is adapted for animals not humans in east african.
21.4.1 Chancre
3-15 days after the bite
only really see it in the east african form
21.4.2 Haemolymphatic (Stage 1)
“Waves of parasitaemia”
- fever
- headache
- joint pains,
- rash
- itch
in gambien can occur from many months to years
in rhodesian this can be much faster
This wave happens as the parasite adapts to immune system, changing their glycoprotein coat, avoiding antibody response.
21.4.3 Meningoencephalitic (Stage 2)
Later in west african than in east african
- Neuropychiatric, parkinsonian
- Wasting
- coma
- death
21.5 Diagnosis
Direct with thick and thin films. You see the trypanosomes. Remember they come in waves, with the fever!
Lymph node aspirates. Stick a green needle into a lymph node and massage the node. Spray the contents on to a slide
Indirect with CATT (card agglutination test for trypanosomiasis). It is fairly sensitive, more specific. But it is only for gambiense.
Getting replaced with novel rapid diagnostic tests. Dipstick. Again only for the gambiense form.
It often occurs in an outbreak remember!
So often there’ll be mass screening with rapid tests, lymph node biopsies, lumbar puncture.
In CSF you do it based on WCC (>5), which is quite a low cut off! So other studies sometimes use >20. You will rarely rarely see parasites. And in HIV +ve patients, they’ll often have raised WCC in the CSF anyway, so you should prob use >20 instead.
In CSF you might see a “Morula cell of Mott” - a B Cell lymphocyte - is pathognmomic
21.6 Treatment
GET IT FROM MOODLES SLIDES
21.7 Prevention and Control
Case finding and treatment
Fly control - dark blue and black stripy traps with insecticide. Very attractive to tsetse flies and do work. Tsetse flies do not reproduce often, if you release sterile males you can stop reproduction and reduce fly numbers