1. Common Clinical Presentations of Parasitic Infections
Parasites causing this clinical presentation
How did the parasite produce this presentation (Pathogenesis)
Mode of infection
Hepatosplenomegaly
Enlarged lymph nodes
Anaemia
Dysentery

2. A child presenting with hepatosplenomegaly
Helminths causing hepatosplenomegaly:
Schistosoma
Skin penetration by Furcocercous cercaria
HOW?
Schistosoma eggs that pass in the circulation as emboli to the liver cause hepatosplenomegaly

3. A child presenting with hepatosplenomegaly
Protozoa causing hepatosplenomegaly:
Leishmania infantum, Leishmania donovani, Leishmania chagasi
Visceral leishmaniasis
Promastigote
Trypanosoma b.gambiense, Trypanosoma b.rhodesiense
Sleeping sickness
Stumpy metacyclic trypanosomes
Trypanosoma cruzi
Chagas’ disease

4. How can Leishmania cause hepatosplenomegaly?
Amastigotes multiply in skin macrophage
Via blood stream to
Taken by
Promastigotes
Amastigotes
Reticulo-endothelial cells present in human viscera
Through the bite of female Phlebotomus injecting Promastigote stage with saliva
When amastigotes enter reticulo-endothelial cells present in liver & spleen
Hepatosplenomegaly occurs

5. How can African Trypanosomes cause Hepatosplenomegaly?
How can American Trypanosomes cause Hepatosplenomegaly?
Short stumpy metacyclic trypanosomes enter the site of bite with saliva of Glossina
Short stumpy metacyclic trypanosomes contaminate skin abrasion by winged bug faeces
To blood stream
C-shaped Trypanosoma cruzi
Polymorphic trypanosomes
amastigote
To liver & spleen
Hepatosplenomegaly occurs

6. Parasites causing Enlarged lymph nodes
Helminths affecting lymph nodes:
W.bancrofti
Usually affects lymph nodes draining genitalia & lower limbs
Brugia malayi
Usually affects lymph nodes draining legs below knees & arms below elbows
O.volvulus
Hanging groin containing enlarged lymph nodes

7. Enlarged lymph nodes Protozoa affecting lymph nodes:
Leishmania infantum, Leishmania donovani, Leishmania chagasi
Visceral leishmaniasis
Trypanosoma b.gambiense, Trypanosoma b.rhodesiense
Sleeping sickness
Winterbottom sign
Trypanosoma cruzi
Chagas’ disease
Toxoplasma gondii
Toxoplasmosis

8. Decrease in number of RBCs below 4 millions / ml
Anaemia
Decrease in number of RBCs below 4 millions / ml
Helminthic infections causing anaemia:
a- Schistosomiasis
b- Trichuriasis
Iron deficiency:
Due to blood loss
c- Ancylostomiasis
d- Diphyllobothriasis
Megaloblastic:
Due vit B12 deficiency
Schistosomiasis
Due to hypersplenism
Trichuriasis
Blood in urine
Blood in stool
Due to toxic products of the worm

9. Protozoal infections associated with anaemia
Malaria:
haemolytic anaemia
due to rupture of infected red cells.
merozoites
Babesiosis:
haemolytic anaemia
due to rupture of infected red cells.
Sleeping sickness:
Polymorphic trypanosomes
hypoplastic anaemia
Leishmania amastigotes
due to bone marrow affection.
Visceral leishmaniasis:

10. Mode of Infection with Schistosoma
Skin penetration by furcocercous cercaria from contaminated canal water.
Aided by:
- Surface tension of drying droplets of water.
- Proteolytic enzymes secreted by penetration glands.
Proteolytic enzymes
- Strong lashing movement of the tail pressing the body of the cercaria into the skin.

11. Skin penetration by filariform larvae
Mode of infection with
D.latum
T.trichiura
A.duodenale
ingestion of plerocercoid larva in improperly cooked infected salmon, Perch or Trout fish
Skin penetration by filariform larvae
Ingestion of embryonated eggs in contaminated raw vegetables and contaminated water.
Negative geotropism
Positive hygrotropism
Thermotropism

12. Through the bite of Hard Tick injecting sporozoite stage with saliva
Mode of infection with
Malaria
Babesiosis
Through the bite of female Anopheles injecting sporozoite stage with saliva
Through the bite of Hard Tick injecting sporozoite stage with saliva

13. Visceral leishmaniasis
Mode of infection with
Visceral leishmaniasis
Sleeping sickness
Through the bite of female Phlebotomus injecting Promastigote stage with saliva
Through the bite of Glossina injecting short stumpy metacyclic trypanosomes

14. A patient presenting with Dysentery
Painful frequent evacuation of small quantities of stool containing mucus tinged with blood.
This indicates that the large intestine is affected
Parasites causing dysentery:
1- Schistosoma mansoni.
2-Trichuris trichiura.
3- Strongyloides stercoralis (heavy infection).
4- Entamoeba histolytica.
5- Balantidium coli.
6- Leishmania (visceral)
7- P.falciparum

15. How can helminths cause Dysentery
1- Schistosoma mansoni
2- Trichuris trichiura
3- heavy infection with Strongyloides stercoralis
Anterior part of worms embedded in intestinal mucosa cause oedematous, hyperaemic, fragile mucosa.
Number of worms increase and fill the small and large intestine
Egg pass in stool with mucus and blood
stool with mucus & blood
stool with mucus & blood

16. How Entamoeba and Balantidium cause Dysentery
Balantidium trophozoite
Entamoeba trophozoite
Boring action of cilia
Histolytic enzyme
Flask-shaped ulcer
Flask-shaped ulcer

17. How can Leishmania cause Dysentery?
Amastigotes multiply in skin macrophage
Via blood stream to
Taken by
Promastigotes
Amastigotes
Reticulo-endothelial cells present in human viscera
When amastigotes enter payer’s patches of Intestinal mucosa:
Diarrhoea & dysentery occur

18. How can P.falciparum cause Dysentery?
Knobs develop on surface of infected RBCs
Knobs are parasite antigens expressed on the surface of infected red cells containing trophozoites and schizont stages.
Infected RBCs adhere to receptors found on endothelium of blood capillaries of intestine
Diminished blood supply to intestine
necrosis of intestinal wall cause dysentery.
Normal RBC
Infected RBC

19. Strongyloides stercoralis
Mode of infection with
Trichuris trichiura
Strongyloides stercoralis
Skin penetration by filariform larvae
Ingestion of embryonated eggs in contaminated raw vegetables and contaminated water.
Negative geotropism
Positive hygrotropism
Thermotropism

20. Entamoeba histolytica Balantidium coli
Mode of infection with
Entamoeba histolytica
Balantidium coli
Ingestion of quadrinucleate cyst
Ingestion of cyst
- In contaminated raw green vegetables and contaminated water.
- Through flies and food handlers.
- By faeco-oral route (hand to mouth). This is called autoinfection.

21. Mode of infection of Visceral Leishmania Falciparum malaria
Through the bite of female Phlebotomus injecting Promastigote stage with saliva
Through the bite of female Anopheles gambia injecting sporozoite stage with saliva