Schistosomiasis

Slide 1 · Schistosomiasis

Pathogenesis • Morphology • Clinicopathologic correlations

Dr Abu Suraih Sakhri

MBBS, MD (Pathology)

www.abusuraihsakhri.com

Slide 2 · Learning objectives

Explain how freshwater transmission and vascular migration establish infection.

Connect egg-induced immune responses to granulomas and tissue fibrosis.

Recognize the dominant hepatic, intestinal, pulmonary, renal and urinary patterns.

Relate characteristic morphology to the major clinical complications.

Slide 3 · Schistosomiasis: A tissue-based helminth disease

Infection by blood flukes of the genus Schistosoma.

Disease expression depends on the schistosome species and organ distribution.

Persistent host reactions to parasite eggs are central to tissue injury.

The supplied textbook estimates more than 200 million people infected; This is a textbook figure, not a verified current prevalence estimate.

Slide 4 · The two principal organ patterns

Hepatointestinal disease

S. Mansoni and S. Japonicum predominate.

Egg deposition affects bowel and liver.

Fibrosis and portal hypertension drive severe disease.

Urinary disease

S. Haematobium predominates.

Egg-induced bladder and ureteral inflammation.

Hematuria, obstruction and bladder neoplasia association.

Slide 5 · Species, setting and predominant injury

Parasite

Geographic setting

Main lesion

S. Mansoni

Latin America; Africa; Middle East

Gut and liver

S. Japonicum

East Asia

Gut and liver

S. Mekongi

East Asia

Severe hepatointestinal involvement

S. Haematobium

Africa

Bladder and urinary tract

Slide 6 · Freshwater exposure is the transmission setting

Freshwater snails are required intermediate hosts.

Slow-moving tropical rivers, lakes and irrigation ditches support the cycle.

Human contact with cercaria-containing freshwater enables skin penetration.

Water and irrigation infrastructure can therefore influence exposure.

Slide 7 · Life cycle: Freshwater to human

Snail releases cercariae

Cercariae penetrate skin

Worms migrate and mature

Eggs exit in stool or urine

Schematic

Eggs entering fresh water can infect snails and renew the cycle.

Only certain developmental stages are infective to humans.

Slide 8 · Cercariae initiate human infection

Free-swimming cercariae leave the freshwater snail.

They contact and penetrate human skin.

Proteolytic enzymes assist passage through the keratinized surface.

Minimal skin reaction at this stage.

Slide 9 · Migration occurs through vascular compartments

Skin and local tissues

Peripheral blood / lymphatics

Lungs and heart

Splanchnic / portal vessels

Schematic

Schistosomes disseminate through the circulation after entering the host.

The hepatic vasculature is the principal site of maturation described for intestinal species.

Slide 10 · Liver maturation precedes adult localization

S. Mansoni and S. Japonicum reach hepatic vessels during maturation.

Mature male and female flukes form pairs.

Pairs subsequently relocate into venous systems where egg production occurs.

Adult localization differs from the final tissue distribution of trapped eggs.

Slide 11 · Adult worm site is not the sole disease site

Adult residence

Mature worm pairs inhabit venous beds.

Commonly portal or pelvic veins.

The vascular location influences where eggs are deposited.

Egg deposition

Eggs migrate across tissue walls or lodge in organs.

Local inflammation follows the eggs.

Injured tissue can be distant from mature worms.

Slide 12 · Egg production maintains the inflammatory stimulus

Adult females release hundreds to thousands of eggs per day (textbook description).

Eggs secrete proteases that contribute to local inflammatory reactions.

Continued deposition maintains repeated episodes of tissue injury.

Both transit and trapping of eggs are pathologically important.

Slide 13 · Egg passage produces two excretion pathways

Eggs enter intestinal tissue

Inflammatory migration across bowel wall

Eggs eliminated in stool

Eggs enter bladder wall in S. Haematobium

Inflammatory migration across urothelium

Eggs eliminated in urine

Stool pathway

Urine pathway

Slide 14 · Inflammation has a paradoxical role

Local host inflammation assists movement of eggs through bowel or bladder walls.

This permits parasite eggs to reach the external environment.

The same reaction produces mucosal injury and chronic granulomas.

Transmission biology is therefore linked directly to tissue pathology.

Slide 15 · A trapped egg initiates the tissue lesion

Egg lodged in tissue

Local immune recognition

Granulomatous inflammation

Healing / scarring

Schematic

The principal target of host injury is often an egg rather than an adult worm.

Duration and location of egg retention help explain chronic organ damage.

Slide 16 · Acute clinical disease follows early infection

Acute schistosomiasis may present as a severe febrile illness.

It peaks approximately two months after infection.

Fever is linked in the source to early inflammatory cytokine responses.

The chronic dominant lesions develop through retained eggs and fibrosis.

Slide 17 · Early immune response: Th1 and fever

Early helper T-cell response

Th1 cells produce IFN-γ

Macrophage activation

TNF, IL-1, IL-6 → fever

Schematic

Robbins explicitly links the early Th1-skewed response with febrile disease.

This is an immune-mediated systemic manifestation.

Slide 18 · Inflammatory cytokines explain the acute syndrome

IFN-γ activates macrophages in the early response.

Activated macrophages secrete TNF, IL-1 and IL-6.

These cytokines contribute to systemic fever.

This systemic pathway differs from the later fibrosing tissue response.

Slide 19 · Chronic immune response: Profibrotic axis

Persistent egg deposition

Th2-dominant response

Profibrotic macrophages

Granulomas and fibrosis

Schematic

The source describes Th2 dominance in chronic infection, not total absence of Th1 activity.

Activated macrophages and Th2 responses are central to severe hepatic fibrosis.

Slide 20 · Th1 and Th2: Complementary pathogenic roles

Early Th1-skewed response

IFN-γ production.

Macrophage inflammatory cytokines.

Strong connection to acute fever.

Chronic Th2-dominant response

Activated profibrotic macrophages.

Persistent egg-associated granulomas.

Strong connection to collagenous scarring.

Slide 21 · Granulomas involve more than one helper T-cell subset

Both Th1 and Th2 cells contribute to granulomas around retained eggs.

Th2-biased activity becomes prominent in chronic infection.

Granulomas localize a persistent antigenic focus but can injure organs.

The fibrosis is a host-response consequence of prolonged parasitism.

Slide 22 · The schistosome egg is the granuloma focus

Schistosome egg

Macrophages

Lymphocytes

Eosinophils

Neutrophils

Schematic: Cell types are labeled, not drawn to histologic scale

The egg may contain a miracidium.

The cellular infiltrate is explicitly mixed, with eosinophils characteristic of helminth lesions.

Slide 23 · The egg changes during lesion evolution

In early lesions, an egg containing a miracidium lies centrally.

The miracidium degenerates with time.

Egg remnants may become calcified.

Old calcified eggs can coexist with chronic inflammation or scarring.

Slide 24 · The liver is injured by portal egg retention

Intestinal venous egg deposition

Eggs reach portal circulation

Eggs lodge in hepatic parenchyma

Persistent granulomas / fibrosis

Schematic

S. Mansoni and S. Japonicum cause the dominant hepatointestinal pattern.

Portal delivery of eggs explains lesions within hepatic tissue.

Slide 25 · Early liver and bowel morphology

White, pinhead-sized granulomas scatter through gut and liver.

Each granuloma is centered on a schistosome egg.

The granulomas may contain a prominent eosinophilic component.

Early inflammatory foci precede widespread fibrous remodeling.

Slide 26 · Granuloma composition is diagnostically meaningful

Egg with miracidium

Macrophages

Lymphocytes

Neutrophils

Eosinophils

Schematic: Cell types are labeled, not drawn to histologic scale

Helminth-associated granulomas are characteristically eosinophil rich.

The label is a simplified cellular map, not a genuine histology image.

Slide 27 · Pigment deposition is a separate morphologic clue

Schistosome intestinal pigment is heme-derived and regurgitated by worms.

The dark pigment accumulates in Kupffer cells and splenic macrophages.

This pigment as iron-free.

The hepatic surface or parenchyma may appear darkened.

Slide 28 · Colonic disease can form inflammatory patches

Chronic bowel exposure to eggs produces focal inflammatory lesions.

Colonic patches can accompany S. Mansoni or S. Japonicum infection.

Egg-centered granulomas are the local pathologic substrate.

The intestinal phenotype may coexist with hepatosplenic damage.

Slide 29 · Colonic pseudopolyps are chronic inflammatory change

Pseudopolyp formation in later infection.

They reflect patchy mucosal inflammatory remodeling.

The term describes a protruding lesion, not an epithelial neoplasm.

Colonic changes should be interpreted within the broader egg-related process.

Slide 30 · Advanced hepatic morphology is distinctive

Liver surface becomes irregular and bumpy.

Cut surfaces show widened portal zones, fibrosis and granulomas.

Fibrous expansion may be extensive around portal tracts.

The source specifically notes absence of intervening regenerative nodules.

Slide 31 · Pipestem fibrosis is a portal-centered scar

Recurrent periportal granulomas

Portal fibrous expansion

Broad fibrous portal tracts

“Pipestem” appearance

Schematic

The name comes from thick fibrous tracks resembling clay pipe stems.

This morphologic pattern links parasite injury to portal vascular obstruction.

Slide 32 · Pipestem fibrosis is not defined by regenerative nodules

Schistosomal pattern

Broad fibrous portal tracts.

Portal expansion and obliteration.

No intervening regenerative nodules described.

Interpretive caution

Do not equate every fibrotic liver with nodular cirrhosis.

Specify the observed periportal pattern.

Portal hypertension can arise without classic cirrhotic nodularity.

Slide 33 · Portal vein injury produces portal hypertension

Portal egg granulomas

Periportal fibrosis

Portal vein obliteration

Portal hypertension

Schematic

Vascular narrowing is the mechanistic link.

Clinical sequelae arise from elevated portal venous pressure.

Slide 34 · Congestive splenomegaly reflects portal hypertension

Portal resistance impairs normal splanchnic venous drainage.

Chronic congestion enlarges the spleen.

Severe congestive splenomegaly as a consequence.

The splenic finding reflects hemodynamic disease rather than primary splenic parasitism alone.

Slide 35 · Esophageal varices are a major portal consequence

Portal hypertension promotes collateral venous pathways.

Esophageal varices arise from the abnormal collateral circulation.

They mark clinically important portal disease.

Varices must be connected to portal venous obstruction in mechanistic teaching.

Slide 36 · Ascites completes the portal-hypertension phenotype

Advanced portal fibrosis may be accompanied by ascites.

Ascites coexists with splenomegaly and varices in severe disease.

It signifies an important clinical consequence of portal pathology.

The initiating lesion remains the egg-driven inflammatory response.

Slide 37 · Hepatosplenic disease: A causal synthesis

Retained hepatic eggs

Granulomas + fibrosis

Portal venous obstruction

Splenomegaly / varices / ascites

Schematic

The pathway accounts for the most serious chronic intestinal-species complications.

Each step connects morphology to clinical physiology.

Slide 38 · Pulmonary lesions arise via diverted eggs

Portal collateral pathways can redirect schistosome eggs to the lungs.

Eggs lodge in pulmonary vascular beds.

Granulomatous pulmonary arteritis may follow.

Pulmonary disease can therefore complicate hepatosplenic schistosomiasis.

Slide 39 · Pulmonary vascular remodeling has several stages

Egg-induced arteritis

Intimal hyperplasia

Progressive luminal obstruction

Pulmonary pressure burden

Schematic

Robbins also describes scars and organizing thrombi in affected arteries.

The lesions share some morphologic features with pulmonary hypertension.

Slide 40 · Pulmonary arterial histology: Key features

Granulomas and scars may disrupt arterial elastic layers.

Organizing thrombi can occupy narrowed lumina.

Intimal hyperplasia contributes to obstruction.

Angiomatoid lesions resembling idiopathic pulmonary hypertension are described.

Slide 41 · Cor pulmonale follows severe pulmonary vascular injury

Progressive arterial obstruction increases pulmonary vascular resistance.

Right-sided cardiac pressure burden may develop.

Cor pulmonale as the ultimate complication.

This complication traces back to displaced eggs and vascular granulomas.

Slide 42 · Renal disease can accompany hepatosplenic infection

Mesangioproliferative glomerulopathy has increased frequency.

Membranous glomerulopathy is also described.

These are renal associations in hepatosplenic schistosomiasis.

The source does not establish a universal renal lesion for all infected patients.

Slide 43 · Renal immune deposits: What is actually described

Observed glomerular findings

Immunoglobulin deposits.

Complement deposits.

Membranous or mesangioproliferative morphology.

Important qualification

Schistosome antigen is rarely found in deposits.

Do not assume every deposit directly contains parasite antigen.

Interpret as an associated glomerular process.

Slide 44 · S. Haematobium targets the urinary tract

Adult parasites favor pelvic venous systems in the source narrative.

Eggs become deposited in bladder and urinary tract tissues.

The dominant local injury is granulomatous cystitis.

The clinical phenotype differs substantially from hepatointestinal disease.

Slide 45 · Early urinary disease: Egg deposition to hematuria

Massive bladder-wall egg deposition

Granulomatous cystitis

Mucosal erosions

Hematuria

Schematic

Mucosal damage directly connects a microscopic inflammatory lesion with visible bleeding.

Urinary infection can be recognized before late calcification develops.

Slide 46 · Urinary granulomas undergo calcification

As urinary lesions age, eggs and granulomas calcify.

Numerous calcified foci can create a sandy mucosal appearance.

Extensive disease can involve large regions of the bladder wall.

The morphologic sequence reflects chronicity, not merely recent infection.

Slide 47 · Calcified bladder: A radiologic correlate

Recurrent bladder egg lesions

Granuloma calcification

Diffuse wall calcification

Dense concentric radiographic rim

Schematic

A dense concentric rim when bladder-wall calcification is severe.

The schematic describes the cause of the appearance; It is not a patient radiograph.

Slide 48 · Ureteral fibrosis is a frequent urinary complication

Inflammation extends to or occurs within ureteral walls.

Healing produces ureteral fibrosis.

Progressive narrowing can obstruct urine drainage.

This as the most frequent complication of S. Haematobium infection.

Slide 49 · Obstructive urinary injury: Full causal pathway

Ureteral inflammation / fibrosis

Urinary outflow obstruction

Hydronephrosis

Chronic pyelonephritis

Schematic

Obstruction explains the linkage between local ureteral injury and renal damage.

The upstream tissue injury originates in granulomatous schistosomiasis.

Slide 50 · Hydronephrosis is a downstream consequence

Fibrotic ureteral narrowing impedes urinary drainage.

The collecting system becomes dilated (hydronephrosis).

Persistent obstruction predisposes to chronic renal complications.

In this infection, renal damage may therefore be obstructive rather than glomerular.

Slide 51 · Two different renal pathways should not be conflated

Hepatosplenic infection

Mesangioproliferative or membranous glomerulopathy.

Immunoglobulin and complement deposits.

Association with severe intestinal-species disease.

Urinary schistosomiasis

Ureteral inflammation and fibrosis.

Obstruction and hydronephrosis.

Chronic pyelonephritis.

Slide 52 · Urinary schistosomiasis and bladder carcinoma

S. Haematobium infection is associated with bladder squamous cell carcinoma.

The source describes squamous metaplasia as a typical precursor change.

Chronic inflammation provides the tissue context for the association.

This is an association; No incidence figure is supplied.

Slide 53 · Chronic cystitis creates a metaplastic context

Persistent egg-induced cystitis

Repeated epithelial injury

Squamous metaplasia

Association with squamous carcinoma

Schematic

Do not present the diagram as a deterministic fate for every patient.

The pathologic association matters for urinary tract evaluation.

Slide 54 · Dominant pathology by organ

Organ

Characteristic morphology

Major consequence

Liver

Periportal granulomas; Pipestem fibrosis

Portal hypertension

Colon

Granulomas; Inflammatory patches; Pseudopolyps

Chronic intestinal injury

Pulmonary arteries

Granulomatous arteritis; Intimal thickening

Cor pulmonale

Bladder / ureter

Cystitis; Calcification; Ureteral scarring

Hematuria; Obstruction

Slide 55 · Mechanism-to-manifestation matrix

Mechanism

Morphologic lesion

Clinical correlate

Th1-related cytokines

Systemic inflammatory activity

Acute fever

Egg-centered granulomas

Hepatic / bowel inflammatory foci

Chronic tissue injury

Portal vein obliteration

Pipestem fibrosis

Portal hypertension

Urothelial erosion

Granulomatous cystitis

Hematuria

Slide 56 · Diagnostic sampling follows egg exit routes

Intestinal species release eggs through bowel walls into stool.

S. Haematobium releases eggs through bladder tissue into urine.

The correct specimen depends on the suspected species and organ pattern.

The lecture source supports egg-shedding routes but does not provide test sensitivity or formal diagnostic algorithms.

Slide 57 · Case: Hepatosplenic disease

Clinicopathologic vignette

A patient from a freshwater-exposure setting has severe splenomegaly, ascites and esophageal varices. Liver tissue is described as portal-expanded, fibrotic and granulomatous without regenerative nodules.

Which parasite-associated mechanism best unifies the liver morphology and portal findings?

Slide 58 · Case reasoning: Portal egg injury

Intestinal schistosome infection

Hepatic egg granulomas

Pipestem fibrosis

Portal hypertension

Schematic

Venous obstruction, rather than nodular regeneration, explains the clinical syndrome.

The most relevant parasites are S. Mansoni or S. Japonicum with scope.

Slide 59 · Case: Chronic urinary disease

Clinicopathologic vignette

A patient with freshwater exposure has hematuria and a dense calcified bladder-wall rim. Later evaluation demonstrates ureteral narrowing and hydronephrosis.

What tissue lesion links these findings, and which Schistosoma species is implicated?

Slide 60 · Case reasoning: Chronic urinary egg lesions

S. Haematobium infection

Egg-induced granulomatous cystitis

Calcification + ureteral scarring

Hematuria and obstruction

Schematic

Long-standing egg deposition explains both the bladder wall and ureteral pathology.

Bladder squamous carcinoma is an important associated long-term neoplastic lesion.

Slide 61 · Do not confuse the dominant pathologic outcomes

Hepatic / portal

Eggs reach liver through portal blood.

Periportal scarring obstructs portal veins.

Varices, splenomegaly and ascites are downstream.

Urinary / ureteral

Eggs traverse and lodge in bladder tissue.

Cystitis, calcification and ureteral scars develop.

Hematuria and obstructive renal injury are downstream.

Slide 62 · Schistosomiasis: Integrating the mechanisms

The disease begins with freshwater cercarial penetration and vascular migration.

Adult worm location shapes where eggs accumulate.

Egg-driven granulomatous inflammation explains organ injury.

Chronic fibrosis governs portal and urinary obstruction.

Pulmonary, renal and neoplastic associations should be recognized separately.

Slide 63 · Reading schistosomiasis tissue: key questions

Is an egg visible in the center of a granulomatous lesion?

Are eosinophils present in the mixed inflammatory infiltrate?

Is there evidence of egg degeneration, calcification or chronic fibrosis?

Does the tissue distribution indicate portal, bowel or urinary disease?

Which vascular, obstructive or epithelial complication follows the observed lesion?