Trypanosomiasis, Leishmaniasis Flashcards
The main source of oral Chagas
Acai fruit
Also cane sugar juice
Congenital chagas when rx?
Dont treat during pregnancy as teratohgenic risk
Aim to detect congenital early.
Then treat mother and child (Benznidazole or nifurtimox)
chagas in breast milk?
Only in acute infection
NOT chronic form
Contraindications to chagas rx
Pregnancy
CKD
End stage cardiac disease
Old and historic exposure only
What does rx for chagas not prevent
Poor cardiac outcomes in those with established Chagas cardiac disease
What causes sleeping sickness?
All found in Africa but which type confined to domestic and wild animals?
Which is west / central Africa?
Which in East and southern?
Which is worse with more rapid progression?
- Trypanosomiasis
- T brucie bruicie in animals only
- T brucie gambiense in West/central
- T brucie rhodesiense in East/South - worse with more rapid progression of sx
African Trypanosomiasis Vector? ? Lifecycle
- Tetse fly (genus Glossina)
- Trypomastigotes taken up by tetse and multiply by fission in stomach then penetrate gut wall and move to salivary glands . Fly takes about 20 days to become infective and remains infective for rest of life
African Trypanosomiasis local sx?
- Chancre appears around 3 days after bite and increases in size for 3 weeks
- May get lymphadenopathy
Acute African Trypanosomiasis systemic effects? After how long?
Parasitaemia after 5-12 days. Gets fever in waves due to antigenic variation (Variable Surface Glycoproteins,)
-> incomplete immune response.
Later, they enter CNS to cause a lymphocytic meningoencephalitis
Why do you get waves of parasataemia in African Trypanosomiasis?
Main response is IgM production which partially controls parasataemia but parasites have antigenic variability which means immune control is incomplete
What is kerandels sign?
- Delayed hyperaethesia in Trypanosomiasis
- Apply firm pressure over a bone -> delay before patient shows signs of pain
Compare Trypanosoma brucei gambiense and Trypanosoma brucei rhodesiense
Trypanosoma brucei gambiense
- Fever, headache, joint pains, lymph glands enlarged in Posterior neck. Generalised pruritus
- Characteristic thickening of facial tissue -> sad or expressionless face. Mild splenomegaly
Late stage -> Behavioural / psych disturbance. Sleep wake pattern reversed qand slowly starts to sleep all of the time. Progress to general CNS / Cerebellar signs
Death usually in months of CNS involvement
Trypanosoma brucei rhodesiense
- Prominent fever and systemic sx
- Pleural/Pericardial effusions common with myocarditis
- May cause jaundice and anaemia
- Lymph enlargement in groin / axillary
- Death usually within a few weeks and before prominent CNS signs due to myocarditis
African Trypanosomiasis dx?
- Thick blood films (can use romanowsky stain like in malaria)
- [Note may be difficult to find especially in late stage t b gambiense]
- Posterior cervical lymph gland aspirate in T.b. gambinese
- Bone marrow aspirate- often used if negative in early stages
- Aspirate the chancre
All patients with African Trypanosomiasis should have LP. What needs to happen before this? What stain for LP? Seen?
- 2 doses of either suramin or pentamidine to reduce risk of introducing parasites into CSF
- Romanowsky stain
- Very high CSF IgM
- Increased protein or sometimes trypomastigotes
Screening test for African Trypanosomiasis? What do you do before starting Rx?
- Card indirect agglutination test for trypanosomes (CAITT)
- Can use just CATT for t.b. gambinese
- Lateral flow other option
Need to confirm parasitology before starting rx
-Blood smear (thick thin drop)
-Lymph node aspiration
-Blood concentration methods
[Card African Typano - CAT test]
Rx of African Trypanosomiasis
West african?
East / south African?
West African - T b gambiense
Fexinidazole for both stages
[OR
-Early disease - pentamidine
-CNS - NECT nifurtimox, eflornithine combo tx ]
East African - T b rhodesiense
-Early - Sumarin
-CNS - Melarsoprol + surmarin + prednisolone
[West Games Play Evenly
East Rather Sneaky Managing]
What combination of drugs often used in Late stage t.b. gambiense infection (with CNS features)
Eflornithine and Nifurtimox
Which African Trypanosomiasis makes up 90% of infections
- T b gambiense
T b gambiense vs rhodesiense usual hosts
- Gambiense hosts usually human and may see linear patterns of infections along river
- Rhodesiense often hosts in cattle / antelope
Sleeping sickness control
- Detection and treatment of cases. Using CATT or CIATT or blood / gland screening where cases present.
- Need to establish effective treatment centres when an outbreak
Vector control - May need to treat cattle in epidemic
- Insecticide-treated traps
South American Trypanosomiasis also called? Caused by? Key difference in appearance to t brucei?
- Chagas disease
- Trypanosoma cruzi - has large kinetoplast
South American Trypanosomiasis Vector? key ways you get infected?
- Triatomine bugs (all stages feed on blood but only adults can fly)
-triatoma infestans
-or Rhodnius prolixus
-Panstrongylus,
Trypanosomes are excreted in bug faeces - may rub into wound or conjunctiva
-Bite from triatoma infestans
-or consume if on food
-Blood (especially platelet transfusion)
Acute vs chronic chagas sx? How many people get chronic
Acute - Oedema at site of entry either bite or orbital oedema (romanas sign)
- Then lymphadenopathy, hepato/splenomegaly
15-40% get chronic
- Biventricular cardiomyopathy, megaoesophagus/megacolon
[Big oedema at site of infection followed by big liver and spleen followed by big oesophagus and colon]
What causes megaoesophagus and megacolon in chagas
Damage to parasympathetic nerve plexus
Chagas dx
Ideally PCR / ELISA
Blood microscopy in resource limited
[Xenodiagnosis (take an uninfected bug and allow to feed on pt. Then after 3 weeks dissect bug and look for the parasite in gut)]
Name a drug rx of acute chagas
Benznidazole for 2 months
[Or Nifurtimox]
Chagas reservoir? Name 2 control methods of chagas ?
- ONLY mamals infected - Rodents or small marsupials are most common reservoir
[Think about mice in labs] - Blood transfusion screening
- Spraying of Insecticide - Piretroids
- Elimination of cracks in walls/replacement of rooves with metal sheets reduces habitat of bugs
Presents with fever, Posterior cervical lympadenitis with an expressionless face?
T gambiense
Trypomastigote: blood form
Found in the blood of infected mammals
What disease might I give you?
Chagas - Triatoma infestans
Trypomastigote
Nucleus in centre, kinetoplast at head
EPIMASTIGOTE
Amastigote in chagas
Amastigotes chagas
Chagas life cycle
T cruzi vs T brucie
What stage for replication in humans?
Where in vector is it found?
Testse fly for west Africa? east African?
West - Gambinese - Glossina palpalis
East - Rhodesiense - Glossina morsitans
[The MORtality is higher with Rhodesiense]
African Trypanosomiasis life cycle
Infective vs diagnostic stage?
Infective - Trypomastigotes
Diagnostic - Trypomastigotes
Which leish vector in new world? Old world?
Lutzomyia sp. in the New World
Phlebotomus sp. in the Old World.
[Plebs in life of brian = old]
Leish life cycle
The infected person bitten by sandfly
Takes up macrophages infected with amastigotes
Amastigotes tun into promastigotes in gut which divide
Sanfly takes blood meal and inject promastigote
Taken up by macrophages and turn into amastigotes
amastigotes break out of cell
Main cause of cutaneous leish in old world
L. L. Major
Which specific leish in Ethiopia
L L aethiopia
Can you distinguish amistagotes of leish on microscope?
no morphologically the same
Leissh new world which causes visceral disease?
Leishmania infantum (syn. L. chagasi).