Parasitology points:
1. Ascariasis --> spread by egg ingestion
2. Trypanosoma cruzi --> spread by triatomine fly
3. Trypanosoma brucei --> spread by tsetse fly
4. P.falciparum --> affects all stages of RBC
5. Casoni test --> for hydatidiasis.
6. Malaria --> diagnosed by the Giemsa stained blood smears
7. Leishmania donovanii --> primarily affects macrophages
8. Mosquito to human transmission --> sporozoites
9. Schistosoma haematobium --> causes squamous
metaplasia of urinary bladder.
10. Wucheria bancrofti
11. Entamoeba --> invades liver
12. Diphylobothrium latum --> causes non megaloblastic
anemia.
Trypanosoma:
General points of hemoflagellates:
Amastigotes , do not have flagella --> Promastigote, has
flagella at ant. end and an undulating membrane -->
Epimastigote, flagella at side of body to run along short
undulating membrane --> Trypomastigote, kinetoplast distal
and posterior to nucleus, with flagella and UM near it.
3 major pathogens:
1. T. Cruzi --> Chagas dx
2. T. gambiense and 3. T. rhodesiense --> Sleeping sickness
T. Cruzi:
V: ruedevid bug, triatoma fly
In man:
Bug bites --> the feces of the bug are infected with metacyclic
trypomastigotes --> rubbed at bite site --> enter blood -->
penetrate cardiac muscle and change into amastigote and
finally become trypomastigote.
In bug:
Trypo. --> epimastigote --> amasti.
Affects glial, reticuloendo. and myocardial cells.
Bites around mouth or eyes
Focal Lymphangitis and oedema at bite site --> Chagoma
Congestive heart failure
Cardiac arythmias and megacolon due to neuronal cells
affected
Chagoma + eye swelling + temporal region swelling +
conjunctivitis --> ROMANA’S Sign
Fever + lymphadenopathy and hepatosplenomegaly
CARDIOMYOPATHY --> CARDIAC FAILURE
MEGA ESOPHAGUS AND MEGACOLON
Direct examination, blood and muscle biopsy shows
amastigotes.
Culture is done on N.N.N medium Novy McNeal Nicolle
Xenodiagnoses --> vector fed on suspect and later on
examined for parasite
U. T.Gambiense and T. Rhodesience:
V: Tsetse fly
Spread to lymph node and brain
Fly: bites reservoir animal, takes in trypomastigotes -->
epimastigotes and into metacyclic trypomastigotes that are
injected at site of bite.
In man: MT enter blood and form trypomastigotes.
RARELY AS AMASTIGOTES IN TISSUES
DEMYELINATING ENCEPHALITIS
SKIN ULCER --> Try. Chancre
Intermittent weekly fever and lymphadenopathy
Enlargement
of
posterior
cervical
LNs
-->
WINTERBOTTOM SIGN
Encephalitis may progress to somnolence and coma and
death.
Blood or aspirate of chancre or LN CSF shows
trypanosomes
LEISHMANIA:
4 major pathogens:
1. L. Donovani --> visceral L.
2. L. tropica &
3. L. mexicana --> both causes cutaneous L.
4. L. braziliences --> mucocutaneous L.
V: sandfly
Exist in host as amastigotes and promastigotes in vector
Both have replicative ability
Dx based on amastigote in aspirate or biopsy
L. Donovanii:
Causes kala azar , V.L
Sandfly bites infected host and ingests macrophage
containing amastigote, dissolution of macrophage and
amastigotes released become promastigotes and multiply,
migrate to neck and bites.
In humn, bite occurs --> promastigotes engulfed and survive
in macrophage --> change into amastigotes --> inf.
Macrophages die and progeny released infecting other
macros and reticendo cells.
Liver spleen BM severely affected
Pancytopenia occurs
Splenomegaly is STRIKING