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Emergent Management of Acute Schistosomiasis

  • Author: Grant Wei, MD, FAAEM, FACEP; Chief Editor: Robert E O'Connor, MD, MPH  more...
Updated: May 06, 2016


Owing to increased population flow from areas where schistosomiasis is endemic, emergent management of acute schistosomiasis is likely to become a matter of increased concern. Schistosomiasis (also known as bilharzia, bilharziasis, bilharziosis, or snail fever) is a human disease syndrome caused by infection from one of several species of parasitic trematodes of the genus Schistosoma. Schistosomiasis is a major source of morbidity and mortality for developing countries in Africa, South America, the Caribbean, the Middle East, and Asia.[1]

Tourism to and immigration from endemic areas can result in schistosomiasis cases presenting anywhere in the developed world. Acute schistosomiasis among travelers may be increasing, and rates of emigration from endemic areas are rising. In the complete absence of routine presymptomatic screening of these groups in developed countries, it is increasingly likely that patients with acute or chronic schistosomiasis will present to emergency departments (EDs) with a variety of complaints in nonendemic areas.[2, 3]

Pediatric and adolescent patients who have traveled or lived in endemic areas are at the highest risk for exposure to schistosomes and are at risk for serious long-term complications. These patients usually respond well to drug therapy and should receive aggressive treatment and follow-up care.

Most human schistosomiasis is caused by S haematobium, S mansoni, or S japonicum, with the former causing urinary symptoms and the latter two causing intestinal symptoms. Less prevalent species, such as S mekongi and S intercalatum, may also cause systemic human disease. Less importantly, other schistosomes with avian or mammalian primary hosts can cause severe dermatitis in humans (eg, swimmer's itch secondary to Trichobilharzia ocellata).[4, 5, 6, 7, 8, 9, 10]

Schistosomiasis is transmitted via eggs excreted in feces or urine of infected individuals. The larvae are then maintained in a freshwater snail intermediate host, where they mature and are eventually released. Infection occurs when humans come into contact with infested freshwater, allowing the larvae to penetrate the skin.


Prehospital and Emergency Department Care

Prior to the patient’s arrival at the hospital, support and stabilization are provided for acute complications of infection, if present. These might include volume depletion, heart failure, and gastrointestinal (GI) bleeding.

Emergency department care

In the emergency department (ED), the physician confirms the diagnosis,[11] begins antibiotic therapy, and stabilizes patients with acute complications of schistosomiasis.

The criterion standard in diagnosing schistosomiasis is microscopic egg detection in urine or feces. However, it takes 1-3 months for larvae to fully mature and lay eggs, so early diagnosis is not always possible. There are also tests to detect schistosomal antigens or antischistosomal antibodies in blood, urine, or sputum. Other methods that are currently being studied include polymerase chain reaction (PCR) testing and assays for certain schistosomal cytokines or biomarkers. As these diagnostic tools may not be readily available in the emergency department, it is important to obtain a thorough history (especially travel history) and physical examination.[12]

Acutely, patients with schistosomiasis may present with the following:

  • Pruritic rash due to cercarial penetration into the skin
  • Nonspecific symptoms such as fever, myalgias, and malaise
  • Right upper quadrant abdominal pain
  • Diarrhea
  • Dysuria or hematuria

Important laboratory findings include (1) eosinophilia and (2) hematuria and proteinuria, which is associated with urinary schistosomiasis.

Manifestations of chronic schistosomiasis can also months or years after acute infection. Symptoms are nonspecific, as multiple systems can be affected depending on the primary location of egg production and on the species of schistosome involved. Manifestations may include the following:

  • CNS: Headache, seizure, increased intracranial pressure (ICP), myeloradiculopathy, transverse myelitis
  • Cardiopulmonary: Cough, wheezing, dyspnea on exertion, hemoptysis
  • Gastrointestinal: Diarrhea, hematemesis, portal hypertension
  • Genitourinary: Dysuria, hematuria, irregular menstruation, pelvic pain, genital lesions

Management of hepatosplenic,[13, 14] GI, urinary, cardiopulmonary, and central nervous system (CNS) complications are summarized as follows:

  • Volume depletion secondary to diarrhea - Rarely severe, and is treated with intravenous or oral volume replacement; minor lower GI bleeding and chronic anemia may be present but rarely require transfusion
  • Portal hypertension with hematemesis - Treatment with fluid resuscitation, transfusion, endoscopic therapy, or surgery may be required
  • Urinary obstruction - May require stenting or other drainage procedures
  • Salmonella (or other gut source) sepsis - May require antibiotics and fluids
  • Pulmonary hypertension and cor pulmonale - May require oxygen, diuresis, antiarrhythmics, or other interventions
  • Cerebral infection - May require seizure control or management of intracranial pressure
  • Transverse myelitis - May require steroids and supportive care as well as antihelminthic therapy

Definitive therapy can be initiated and often completed in the ED if the diagnosis is clear. During acute infections, antihelminthic treatment may at first exacerbate symptoms as a result of increased antigen release, usually requiring corticosteroid support. Treatment may produce a Loefflerlike syndrome in cases of heavy infestation, which may require pulmonary support.

In the case of pregnant patients, physicians may prefer to defer treatment of schistosomiasis until after the first trimester.[15]


Clearly communicating with the hospital's diagnostic laboratory personnel is crucial for optimal egg detection in stool and urine specimens.[16, 17] Consult specialists as indicated by the complications present or the need for diagnostic procedures, such as colonoscopy.


Pharmacologic Therapy

Treatment of schistosomiasis is unusual in that only one drug, praziquantel, is in wide use. It is given as a one-time dose of 40 mg/kg and can be given to pregnant women after the first trimester. For children younger than 5 years, dose is determined by height.[18] The drug works by increasing permeability of schistosomal cells to calcium, inducing contraction and thus paralysis of the parasites. Drug resistance has been reported and can be produced in laboratory settings but appears still to be uncommon in human infections. Myrrh derivatives have not demonstrated success in testing, but artemisinins[19] are showing efficacy, and trioxolanes[20] also show promise as future drugs.

Drug regimens result in curing the infection in 60-98% of cases and reduce egg burden in the remainder. Dead eggs may continue to shed for months, but treatment should arrest egg-laying, granuloma formation, and future complications. Although frank fibrosis may not reverse, evidence indicates that portal and pulmonary hypertension from granulomatous changes may improve significantly after treatment, particularly in younger patients.


Inpatient and Outpatient Care

Inpatient care

Initiate inpatient care for unstable patients with complications, such as GI bleeding, decompensated heart failure, and toxicity, according to the usual indications. Inpatient care is indicated for CNS infections, and therapy should include corticosteroids to reduce inflammation around schistosomal eggs. Surgery may be indicated to remove large masses or granulomas.

Outpatient care

Reevaluate patients for symptom resolution and determination of cure. For uncomplicated cases, 4-6 weeks is the optimal follow-up time, corresponding with the maturation of eggs and immature worms that may have survived initial treatment. Retreatment is indicated after reexposure and reinfection. Patients with likely ongoing exposure may benefit from annual treatment in addition to education to reduce exposure risk.

Response may be evaluated by quantitatively decreased egg counts from urine or stool specimens or by antigen testing. Some patients require retreatment. Patients with evidence of portal hypertension, pulmonary hypertension, CNS infection, or urinary obstruction require long-term follow-up care.


Prophylaxis with annual praziquantel treatment may be recommended for those living in endemic regions. Several vaccines are also in clinical development, particularly ones that target S haematobium and S mansoni.[21]

Potential complications

There is controversy as to whether schistosomiasis infection increases susceptibility to hepatitis B or C infection. Although this is not proven, studies have shown that previous schistosomiasis infection can lead to increased rate of liver cirrhosis and overall mortality if the individual also contracts hepatitis B or C.[22]

Contributor Information and Disclosures

Grant Wei, MD, FAAEM, FACEP Assistant Professor, Assistant Program Director, Assistant Clerkship Director, Department of Emergency Medicine, Rutgers Robert Wood Johnson Medical School, Robert Wood Johnson University Hospital

Disclosure: Nothing to disclose.


Tanya Shevavesh, MD Resident Physician, Department of Emergency Medicine, Rutgers Robert Wood Johnson Medical School

Tanya Shevavesh, MD is a member of the following medical societies: American College of Emergency Physicians, Emergency Medicine Residents' Association

Disclosure: Nothing to disclose.

Specialty Editor Board

Francisco Talavera, PharmD, PhD Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Received salary from Medscape for employment. for: Medscape.

Jeter (Jay) Pritchard Taylor, III, MD Assistant Professor, Department of Surgery, University of South Carolina School of Medicine; Attending Physician, Clinical Instructor, Compliance Officer, Department of Emergency Medicine, Palmetto Richland Hospital

Jeter (Jay) Pritchard Taylor, III, MD is a member of the following medical societies: American Academy of Emergency Medicine, South Carolina Medical Association, Columbia Medical Society, South Carolina College of Emergency Physicians, American College of Emergency Physicians, American Medical Association, Society for Academic Emergency Medicine

Disclosure: Serve(d) as a director, officer, partner, employee, advisor, consultant or trustee for: Chief Editor for Medscape.

Chief Editor

Robert E O'Connor, MD, MPH Professor and Chair, Department of Emergency Medicine, University of Virginia Health System

Robert E O'Connor, MD, MPH is a member of the following medical societies: American Academy of Emergency Medicine, American College of Emergency Physicians, American Association for Physician Leadership, American Heart Association, Medical Society of Delaware, Society for Academic Emergency Medicine, Wilderness Medical Society, American Medical Association, National Association of EMS Physicians

Disclosure: Nothing to disclose.

Additional Contributors

Amy J Behrman, MD Associate Professor, Department of Emergency Medicine, Director, Division of Occupational Medicine, University of Pennsylvania School of Medicine

Amy J Behrman, MD is a member of the following medical societies: American College of Physicians, American College of Occupational and Environmental Medicine

Disclosure: Nothing to disclose.

Joseph A Salomone III, MD Associate Professor and Attending Staff, Truman Medical Centers, University of Missouri-Kansas City School of Medicine; EMS Medical Director, Kansas City, Missouri

Joseph A Salomone III, MD is a member of the following medical societies: American Academy of Emergency Medicine, National Association of EMS Physicians, Society for Academic Emergency Medicine

Disclosure: Nothing to disclose.

  1. Sousa-Figueiredo JC, Stanton MC, Katokele S, Arinaitwe M, Adriko M, Balfour L, et al. Mapping of Schistosomiasis and Soil-Transmitted Helminths in Namibia: The First Large-Scale Protocol to Formally Include Rapid Diagnostic Tests. PLoS Negl Trop Dis. 2015 Jul. 9 (7):e0003831. [Medline].

  2. Meltzer E, Artom G, Marva E, Assous MV, Rahav G, Schwartzt E. Schistosomiasis among travelers: new aspects of an old disease. Emerg Infect Dis. 2006 Nov. 12(11):1696-700. [Medline].

  3. Moudgil A, Kosut J. Urinary schistosomiasis: an uncommon cause of gross hematuria in the industrialized countries. Pediatr Nephrol. 2007 Aug. 22(8):1225-7. [Medline].

  4. Vennervald BJ, Dunne DW. Morbidity in schistosomiasis: an update. Curr Opin Infect Dis. 2004 Oct. 17(5):439-47. [Medline].

  5. Wilson MS, Mentink-Kane MM, Pesce JT, et al. Immunopathology of schistosomiasis. Immunol Cell Biol. 2007 Feb-Mar. 85(2):148-54. [Medline].

  6. Wynn TA, Thompson RW, Cheever AW, Mentink-Kane MM. Immunopathogenesis of schistosomiasis. Immunol Rev. 2004 Oct. 201:156-67. [Medline].

  7. Gryseels B, Polman K, Clerinx J, Kestens L. Human schistosomiasis. Lancet. 2006 Sep 23. 368(9541):1106-18. [Medline].

  8. King CH. Toward the elimination of schistosomiasis. N Engl J Med. 2009 Jan 8. 360(2):106-9. [Medline].

  9. Wang LD, Chen HG, Guo JG, et al. A strategy to control transmission of Schistosoma japonicum in China. N Engl J Med. 2009 Jan 8. 360(2):121-8. [Medline].

  10. Centers for Disease Control and Prevention. Division of Parasitic Diseases. Schistosomiasis. Parasitic Disease Information. Available at Accessed: February 3, 2010.

  11. Gandasegui J, Fernández-Soto P, Carranza-Rodríguez C, Pérez-Arellano JL, Vicente B, López-Abán J, et al. The Rapid-Heat LAMPellet Method: A Potential Diagnostic Method for Human Urogenital Schistosomiasis. PLoS Negl Trop Dis. 2015 Jul. 9 (7):e0003963. [Medline].

  12. Weerakoon KG, Gobert GN, Cai P, McManus DP. Advances in the Diagnosis of Human Schistosomiasis. Clin Microbiol Rev. 2015 Oct. 28 (4):939-67. [Medline].

  13. Bezerra AS, D'Ippolito G, Caldana RP, Cecin AO, Ahmed M, Szejnfeld J. Chronic hepatosplenic schistosomiasis mansoni: magnetic resonance imaging and magnetic resonance angiography findings. Acta Radiol. 2007 Mar. 48(2):125-34. [Medline].

  14. Lapa M, Dias B, Jardim C, et al. Cardiopulmonary manifestations of hepatosplenic schistosomiasis. Circulation. 2009 Mar 24. 119(11):1518-23. [Medline].

  15. Friedman JF, Mital P, Kanzaria HK, Olds GR, Kurtis JD. Schistosomiasis and pregnancy. Trends Parasitol. 2007 Apr. 23(4):159-64. [Medline].

  16. Lier T, Simonsen GS, Haaheim H, et al. Novel real-time PCr for detection of Schistosoma japonicum in stool. Southeast Asian J Trop Med Public Health. 2006 Mar. 37(2):257-64. [Medline].

  17. Sandoval N, Siles-Lucas M, Pérez-Arellano JL, et al. A new PCR-based approach for the specific amplification of DNA from different Schistosoma species applicable to human urine samples. Parasitology. 2006 Nov. 133:581-7. [Medline].

  18. Colley DG, Bustinduy AL, Secor WE, King CH. Human schistosomiasis. Lancet. 2014 Jun 28. 383 (9936):2253-64. [Medline].

  19. Utzinger J, Xiao SH, Tanner M, Keiser J. Artemisinins for schistosomiasis and beyond. Curr Opin Investig Drugs. 2007 Feb. 8(2):105-16. [Medline].

  20. Xiao SH, Keiser J, Chollet J, et al. In vitro and in vivo activities of synthetic trioxolanes against major human schistosome species. Antimicrob Agents Chemother. 2007 Apr. 51(4):1440-5. [Medline]. [Full Text].

  21. Merrifield M, Hotez PJ, Beaumier CM, Gillespie P, Strych U, Hayward T, et al. Advancing a vaccine to prevent human schistosomiasis. Vaccine. 2016 Mar 29. [Medline].

  22. Abruzzi A, Fried B, Alikhan SB. Coinfection of Schistosoma Species with Hepatitis B or Hepatitis C Viruses. Adv Parasitol. 2016. 91:111-231. [Medline].

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