Schistosomiasis



Schistosomiasis







Key Facts


Terminology



  • Synonym



    • Bilharziasis


  • Definition



    • Infection caused by Trematoda (flukes)


Etiology/Pathogenesis



  • 3 most common types that affect humans are



    • Schistosoma haematobium (urinary tract)


    • Schistosoma mansoni (intestinal tract)


    • Schistosoma japonicum (intestinal tract)


  • Pathogenesis



    • Snails are intermediate host


    • Schistosoma eggs travel via the portal-systemic collateral veins to the lung


Clinical Issues



  • Acute phase


  • Chronic phase


  • Laboratory findings



    • Eosinophilia


    • Possible false-positive HIV test


  • Treatment



    • Good if treated early and patient not immunocompromised


    • Can be fatal in some cases


Top Differential Diagnoses



  • Fungal granulomatous infection


  • Pulmonary tuberculosis


  • Pulmonary hypertension


  • Bacterial bronchopneumonia






Lung parenchyma with an easily identifiable granulomatous reaction shows that the center of the granulomas contain necrosis and hemorrhage. These changes can be seen in other infections as well.






High-power view of the central necrosis of the granulomatous reaction shows the outlines of Schistosoma image. This organism can be easily missed in a cursory review.


TERMINOLOGY


Synonyms



  • Bilharziasis


Definitions



  • Infection caused by Trematoda (flukes)


ETIOLOGY/PATHOGENESIS


Infectious Agents



  • 3 most common types affecting humans are



    • Schistosoma haematobium (urinary tract)


    • Schistosoma mansoni (intestinal tract)


    • Schistosoma japonicum (intestinal tract)



      • Snails are intermediate host


Pathogenesis in Pulmonary Schistosomiasis



  • Schistosoma eggs travel via the portal-systemic collateral veins to the lung


CLINICAL ISSUES


Epidemiology



  • Incidence



    • Approximately 10% worldwide


  • Age



    • Any age group can potentially be affected


  • Gender



    • No gender predilection


  • Ethnicity



    • No ethnic predilection


Presentation



  • Acute phase



    • Fever


    • Cough


    • Asthma-like symptoms


    • Urticaria


    • Diarrhea


    • Hepatomegaly


    • Splenomegaly


    • Lymphadenopathy


  • Chronic phase



    • Acute symptoms subside over a period of weeks


    • Patients may be asymptomatic


Laboratory Tests



  • Eosinophilia


  • Possible false-positive HIV test


Treatment



  • Drugs



    • Praziquantel (all types of Schistosoma)


    • Oxamniquine (S. mansoni)


    • Metrifonate (S. haematobium)


Prognosis



  • Good if treated early and patients not immunocompromised


  • Can follow aggressive course in immunocompromised individuals


MICROSCOPIC PATHOLOGY


Histologic Features



  • Granulomatous reaction


  • Granulomatous endarteritis


  • Thickening of pulmonary vasculature


  • Schistosoma eggs deposited in arterioles


  • Acute inflammatory reaction


DIFFERENTIAL DIAGNOSIS

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Jul 9, 2016 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on Schistosomiasis

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