The document discusses various parasitic diseases including schistosomiasis and echinococcosis. It describes the causative agents, transmission, pathogenesis and complications of schistosomiasis including urinary schistosomiasis and intestinal schistosomiasis. Long-term infection with urinary schistosomiasis can lead to squamous cell carcinoma of the bladder due to chronic irritation and squamous metaplasia. Hydatid cysts caused by echinococcus granulosus are also discussed, including their gross and microscopic appearance. Images show examples of lesions caused by these parasitic infections.

1. Bilharziasis

2. Learning Objectives
1. Aetiology , mode of transmission and pathogenesis of urinary and
intestinal Schistosomiasis
2. Description of the morphology of colonic and urinary Schistosomiasis
(sandy patches, polyps, ulcer, cystitis, cystic cystitis, glandularis, Brunn’s
nests)
3. The relationship of squamous metaplasia in urinary Schistosomiasis to
development of carcinoma.
4. Complications of Schistosomiasis like hepatic fibrosis and others
5. The gross and histological appearance of the hydatid disease and the
hydatid cyst.

3. Schistosomiasis
• Also known as bilharzia or bilharziosis
• Parasitic disease caused by several species of trematodes
• This disease is most commonly found in Asia, Africa and South
America, especially in areas where the water contains
numerous freshwater snails, which may carry the parasite

4. Schistosoma
Species of Schistosoma that can infect humans:
• Schistosoma mansoni cause intestinal
schistosomiasis
• Schistosoma haematobium causes urinary
schistosomiasis
• Schistosoma japonicum causes Asian intestinal
schistosomiasis

5. Schistosoma
Route of Entry
• Human can acquire
the disease by
swimming or playing in
infected water
• Parasitic larvae easily
enter through skin and
further mature within
organ tissues
life cycle

6. Pathological Lesions
Continuing infection and irritation may cause granulomatous
reactions and fibrosis in the affected organs, which may result
in manifestations that include:
• Colonic polyposis with bloody diarrhea (Schistosoma
mansoni )
• Portal hypertension with hematemesis and splenomegaly
(S. mansoni, S. japonicum)
• Cystitis, ureteritis and hematuria (S. haematobium)
continuous irritation causes squamous metaplasia,
dysplasia and squamous cell carcinoma of the bladder
• Glomerulonephritis
• Central nervous system granulomatous lesions

8. Schistosoma haematobium
Infection of the bladder with numerous calcified
eggs and extensive scarring

9. Schistosoma mansoni
Granuloma with a miracidium-containing egg (center) and
numerous, adjacent, scattered eosinophils.

10. Schistosoma mansoni
Pipe stem Fibrosis; Pipe-shaped fibrosis formed around hepatic portal veins
in some cases of long-continued heavy infection with Schistosoma mansoni

11. Clinical Manifestations
Acute schistosomiasis: may occur weeks after the initial
infection with following clinical manifestations :
• Mild itching and a papular dermatitis of the feet after swimming in polluted
streams containing cercariae
• Abdominal pain and diarrhea
• Fever, cough and fatigue
• Hepatosplenomagly and esophageal varices
Chronic Schistosomiasis: clinical features includes:
• Hematuria and mild anemia
• Malnutrition

12. Diagnosis
• Detection of parasitic antigens by ELISA in a patient blood
sample. This screening method is highly effective
• Microscopic identification of eggs in stool or, less commonly in
the urine is another way of arriving at a positive diagnosis

13. Echinococcosis (HYDATID CYST)

14. Echinococcosis
Causative agent: A parasitic disease caused by
Echinococcus granulosis
Transmission: Fecal-oral contamination
Distribution: Worldwide where sheep are common
Life cycle:
The ingestion of infective eggs by man is followed
by hatching of oncospheres in the intestine which
penetrate the intestinal wall and migrate to various
tissues , often liver or lungs, where hydatid cyst
development occurs over many years

15. Life Cycle of Echinoccocus

16. Pathological Lesion
Grossly:
• Intact cyst from an infected viscera shows gray-white to
off-white membranous unilocular cyst filled with clear fluid
which is separated from the visceral tissue by fibrous
tissue
• Cutting open cyst shows large number of daughter larvae
with characteristic hooklets of the scolex which settle out
and form the so-called hydatid sand
Microscopically:
• Basophilic laminated cyst wall lined by a germinal
epithelium and scattered hooklets and multiple scolex
• Surrounding visceral tissue shows chronic inflammation
and fibrosis

17. Gross Morphology Hydatid Cyst

18. Microscopy: Hydatid Cyst wall and Scolices
Laminated cyst wall with hydatid sand
Scattered hooklets and multiple scolex

19. Echinococcosis
Clinical manifestations
• The hydatids produce cystic mass lesions
• Rupture of hydatid cysts may produce anaphylaxis
• Scolices released from ruptured cyst can produce
additional cysts
Diagnosis:
• Ultrasound or CT scan to locate hydatid cysts
• Serologic methods by ELISA may aid in diagnosis
• Microscopic examination of hydatid sand, hook lets
and scloex

20. Protozoal Infections
Name of protozoa Disease
Entameba histolytica: Dysentery, Amebic live abscess
Giardia lamblia: Noisy watery diarrhea with abdominal
cramps
Leishmania donovani: Non healing cutaneous ulcer and bone
marrow involvement
Plasmodium; vivax, falciparum: Malaria fever with chills
Trichomonas vaginalis: Foul smelling vaginal discharge

21. Amebic Typhilitis

22. Amebic Typhilitis
• Flask shaped ulcer in
cecum due to Entameba
histolytica
• Under high power, some
of the organisms
Trophozoite form shows
ingested red blood cells

24. Home Assignment
Q. Which type of malignancy is associated with
schistosomiasis?
2/19/2018

25. Learning Outcomes
1. Know the different types of causative agents and mode
of transmission of Schistosomiasis
2. Understand the pathogenesis of both urinary and
intestinal Schistosomiasis.
3. List the complications of both urinary and intestinal
Schistosomiasis.
4. Know the relation between malignancy and urinary
Schistosomiasis
5. Diagnosis of Schistosomiasis
6. Identify gross and histological appearance of the
hydatid cyst.
7. Identify trophozoites of ameba in amebic ulcer

26. References
• Robbins Basic Pathology, 9th Edition (2013)
By: Kumar, Abbas, Aster
Web Path
• www.fleshandbone.com
• www.studentconsult.com