Schistosomiasis (mechanism of disease)

This is a flowchart on schistosomiasis, covering the etiology, pathophysiology, life cycle, and manifestations.

ADDITIONAL TAGS:
Risk factors / SDOH
Cell / tissue damage
Structural factors
Medicine / iatrogenic
Infectious / microbial
Pressure physiology
Immunology / inflammation
Signs / symptoms
Tests / imaging / labs
Environmental / exposure
Cancer / neoplasm
Parasite transport
Pathophysiology
Etiology
Manifestations
South America
Caribbean
Africa
Schistosoma mansoni
Middle east
Schistosoma haematobium
China
Southeast Asia
Schistosoma japonicum
Humans come in contact with contaminated water (e.g., while swimming)
Cercaria (larva form) penetrate the skin
Cercaria enter circulation
Maturation into adult schistosomes
Migration to veins of target organs
Females lay eggs
Capillary closure and chronic inflammation in affected organs
Eggs penetrate lumen of intestines or bladder
Infected human excretes schistosome eggs in urine, feces
Eggs hatch in water, release miracidia (flat, ciliated larva)
Humans = definitive host
Miracidia develop into cercaria, are released back into the water
Miracidia infect specific fresh- water snails
Snails = intermediate host
Rural areas with freshwater sources and poor sanitation
Pathogen: schistosomes (parasitic trematodes)
Local reaction (swimmer's itch or cercarial dermatitis): pruritic maculopapular rash at the point of entry of cercaria into human skin
Schistosomiasis
Serum sickness-like reaction with immune complex formation of antigens released from eggs and/or adult worms with host antibodies
Fever
Fatigue
Cough
Myalgias
Angioedema
Acute schistosomiasis syndrome (Katayama fever):
Incubation period: 3-8 weeks
Spontaneous recovery after 2-10 weeks
Genitourinary schistosomiasis
Hepatosplenic schistosomiasis
Intestinal schistosomiasis
Pulmonary schistosomiasis
Neuro- schistosomiasis
Hematuria, dysuria
Rare tumor: squamous cell carcinoma of the bladder, +/- painless hematuria
Granulomatous inflam in ovaries, fallopian tubes, cervix, vagina
Infertility in women
Bladder neck obstruction
Hydronephrosis
Hepatosplenomegaly
Periportal fibrosis
Portal hypertension
Diarrhea, abdominal pain
Bowel strictures
Intestinal bleeding
Iron deficiency anemia
Pulmonary hypertension
Cor pulmonale
Headache; sensory and motor deficits
Transverse myelitis
Epilepsy, seizures
Life cycle:
Definitive diagnosis (gold standard): direct visualization of schistosome eggs via stool or urine microscopy
By Jack · talk · - derived from File:Schistosomiasis Life Cycle.png, Public Domain, https://commons.wikimedia.org/w/index...