Colon non tumor
Infectious colitis (specific microorganisms)
Schistosomiasis of colon

Author: Nalini Bansal, M.D., D.N.B., PDCC, MNAMS (see Authors page)

Revised: 8 June 2017, last major update April 2017

Copyright: (c) 2003-2017, PathologyOutlines.com, Inc.

PubMed Search: schistosomiasis [title] colon
Cite this page: Schistosomiasis of colon. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/colonschistosomiasis.html. Accessed December 18th, 2017.
Definition / general
  • Schistosomiasis is a parasitic infection caused by a trematode blood fluke (WHO - Schistosomiasis)
  • First identified by Theodor Bilharz in 1852, also known as "bilharziasis"
  • 5 different species: 3 major and 2 minor
    • 3 major species include:
      • Schistosoma mansoni
      • S. japonicum
      • S. haematobium
    • 2 minor species include:
      • S. mekongi
      • S. intercalatum
  • Only S. haematobium causes genitourinary tract disease; all other species affect intestine and liver
Essential features
  • Prevalence of disease highest in sub Saharan Africa
Terminology
  • Bilharziasis
  • Snail fever
ICD-10 coding
  • Intestinal B65.1 
Epidemiology
  • Most patients are ages 15 to 20 years (J Med Case Rep 2014;8:331)
  • Prevalence of schistosomiasis is highest in sub Saharan Africa (Lancet 2012;380:2163
  • There are three major species (J Adv Res 2013;4:445)
    • Schistosoma mansoni: Africa, South America, Middle East
    • S. japonicum: Southeast Asia
    • S. haematobium: Africa, Middle Eastern
Sites
  • Liver, intestine, bladder, lungs, spleen, brain or spinal cord; less common sites of embolization include the skin and peritoneal surfaces
Pathophysiology
  • Freshwater gets contaminated through feces (S. mansoni and S. japonicum) or urine (S. haematobium) from an infected person (Acta Trop 2000;77:41)
  • In water, eggs release miracidia, which enter freshwater snails, the intermediate hosts
  • Within snails, cercariae are formed and are released into the water after about four to six weeks
  • Cercariae can survive in water up to two days
  • Individuals become infected when skin contacts contaminated water and is penetrated by cercariae, which drop their tail and form schistosomulae
  • Schistosomulae enter the circulation and reach the liver, where they mature into adults over two to four weeks
  • Adult worms migrate against portal blood flow to the mesenteric venules of the small and large intestine (S. japonicum and S. mekongi), the mesenteric venules of the colon (S. mansoni, S. intercalatum) or the vesical venous plexus (S. haematobium)
  • Migrating eggs elicit a host immune response
  • Egg derived antigens induce a host Th2 immune response, leading to recruitment of eosinophils, granulomatous reaction and later fibrosis (Immunol Rev 2004;201:156, Immunol Cell Biol 2007;85:148, Front Immunol 2013;4:89)
Etiology
  • Blood fluke, schistosomiasis
Clinical features
  • Can be acute or chronic
  • Acute occurs in travelers of nonendemic region
  • Chronic disease occurs in individuals living in endemic regions
  • Acute manifestations include swimmer’s itch and Katayama fever
  • Swimmer’s itch causes itchy rash after swimming in water due to localized dermatitis
  • Katayama Fever
    • Acute systemic hypersensitivity reaction to parasitic antigens and circulating immune complexes
    • Inflammation of bowel causes ulceration, blood loss and scarring
    • Within liver causes periportal fibrosis (or Symmers pipestem fibrosis) which can cause portal hypertension
  • Chronic disease occurs in endemic areas usually three to eight weeks after infection; can present as diarrhea, chronic or intermittent abdominal pain, poor appetite (World J Surg Oncol 2010;8:68)
  • Chronic colonic ulceration may lead to intestinal bleeding and iron deficiency anemia, intestinal polyps, dysplasia, bowel obstruction or acute appendicitis (Case Rep Infect Dis 2012;2012:896820)
Diagnosis
  • Based on two types of tests: direct assay and indirect assay
    1. Direct assay is either the demonstration of eggs in the stool or urine or demonstration of antigen or DNA of parasite in the blood, urine or stool
      • Circulating anodic antigen (CAA) and circulating cathodic antigen (CCA) excreted in urine are identified in antigen test (Lancet 2006;368:1106)
    2. Indirect assay is the demonstration of antibody to parasite in blood via serology
  • Intensity of intestinal infection is classified as light (up to 100 eggs per gram), moderate (100 to 400 eggs per gram) or severe ( > 400 eggs per gram) (World Health Organization, 2002: 912)
  • Most useful tests for returned travelers is serology
  • Most useful test for individuals living in endemic areas is determining the parasite burden by microscopy for egg detection and antigen detection
Laboratory
  • Egg identification in stool or urine by microscopy
  • Eosinophilia, anemia, thrombocytopenia
Radiology description
  • Colonoscopy can show congested mucosa / greyish yellow nodules / ulceration / polyps
  • USG shows periportal fibrosis in hepatic schistosomiasis
  • Grading of thickness of periportal fibrosis on ultrasonography (Am J Trop Med Hyg 1992;46:403)
    • Grade I: 3 - 5 mm
    • Grade II: 5 - 7 mm
    • Grade III: more than 7 mm
Radiology images

Images hosted on other servers:

USG showing pipestem fibrosis

   

Polyp in the sigmoid colon
found during colonoscopy
showing overlying red mucosa

Large pedunculated polyp

Prognostic factors
  • The adult worms live for 5 - 7 years but can remain in tissue for up to 30 years
  • Embolization of adult worms into the spinal cord or cerebral blood vessels can cause neuroschistosomiasis
Case reports
Treatment
Clinical images

Images hosted on other servers:

schistosomiasis distended stomach

Gross description
  • Acute schistosomiasis: colonic mucosa is edematous and congested with petechial hemorrhage
  • Chronic schistosomiasis: colonic mucosa has flat or elevated yellow nodules with vessels on surface, polyps and intestinal stricture
  • The most characteristic finding is the grayish yellow or yellowish white schistosomal nodules which mimics antibiotic associated / pseudomembranous enterocolitis (World J Gastroenterol 2010;16:723)
Microscopic (histologic) description
  • Ova are mainly seen in the loose submucosa of large intestine, usually with formation of granulomas and infiltration by eosinophils and inflammatory cells
  • Later the muscularis mucosa becomes involved and the overlying mucosa shows small superficial ulcers
  • Fibrosis develops in chronic stage, when only calcified eggs are seen
Microscopic (histologic) images

Images hosted on PathOut server:

Calcified eggs of schistosomiasis, contributed by Dr Nalini Bansal Gupta

Missing Image Missing Image Missing Image Missing Image Missing Image

Within colonic mucosa - Contributed by Dr. Lisa Cerilli




Images hosted on other servers:

Several eggs noted in stroma of polyp

Missing Image

Fluke - anterior part

Missing Image

Fluke - adult (female and male)

Missing Image Missing Image

Eggs



S. japonicum
Missing Image

Fluke - anterior part

Missing Image Missing Image

Fluke - adult (female and male)

Missing Image Missing Image

Eggs

Missing Image

Eggs in rectum



S. mansoni
Missing Image

Fluke - male

Missing Image Missing Image

Eggs

Missing Image

Colon - eggs speciated from stool exam



Within tissue-species not specified
Missing Image

intramucosal calcified bodies

Missing Image

Calcified bodies often clustered

Missing Image

Granuloma surrounding egg

Missing Image

Occasional forms
suggestive of spines
or hooks

Ziehl–Neelsen staining

Positive stains
Negative stains
  • PAS stain
  • Ziehl-Neelsen: Schistosoma haematobium shell is ZN negative
Molecular / cytogenetics description
Differential diagnosis
Board review question #1
  1. How does the Schistosomiasis parasite involve the intestines and bladder?
  2. How do humans acquire Schistosomiasis infections?
  3. What type of parasite is Schistosomiasis?
  4. What is the other name for Schistosomiasis?
  5. Which species of Schistosomiasis affects the urinary bladder?
Board review answer #1
  1. By retrograde movement from portal vein to mesenteric vessels
  2. By swimming / contact with contaminated water
  3. Blood fluke
  4. Bilharziasis
  5. S. haematobium