eMedicine Specialties > Infectious Diseases > Parasitic Infections
Schistosomiasis: Differential Diagnoses & Workup
Updated: Nov 26, 2007
- Overview
- Differential Diagnoses & Workup
- Treatment & Medication
- Follow-up
- Multimedia
Differential Diagnoses
| Hepatitis, Viral | Typhoid Fever |
| Leishmaniasis | Urethral Cancer |
| Malaria | |
| Myeloproliferative Disease | |
| Peptic Ulcer Disease |
Other Problems to Be Considered
Acute nephritis
Acute viral syndrome (including HIV)
Cancer of the urogenital tract
Drug reactions
Epilepsy
Helminthic parasitic diseases
Pancreatitis
Renal tuberculosis
Space-occupying lesion
Tropical splenomegaly
Visceral leishmaniasis
Workup
Laboratory Studies
- Stool or urine analysis
- Identify and speciate the eggs in the stool or urine.
- Urinary excretion of eggs is not uniform. The urine is most likely to be positive for S hematobium from 10 am until 2 pm.
- Quantification of the egg excretion is calculated by collecting 24-hour urine or stool, homogenizing the sample, and counting the eggs in a measured sample.
- Urine or stool egg count in a 24-hour collection quantitates the severity of the infection.
- Fewer than 100 eggs per gram indicates a light infection, 100-400 eggs per gram indicates a moderate infection, and more than 400 eggs per gram indicates a heavy infection.
- Egg viability test
- This test is important for assessing the effectiveness of treatment.
- It requires mixing the stools or urine with room-temperature distilled water and observing for hatching miracidia.
- An active infection produces viable eggs, while treated or past infection results in nonviable eggs and an absence of miracidia.
- Acute illness is often associated with eosinophilia in the blood and tissues.
- With chronic illness, peripheral eosinophilia may be minimal or absent while tissue eosinophilia persists.
- Urinary schistosomiasis (occurs with chronic disease)
- Urine syringe filtration techniques provide a quantitative estimate of eggs in the urine.
- Urine analysis and culture for hematuria, proteinuria, leukocyturia, and associated urinary infections
- A Salmonella urinary tract infection should always lead to suspicion of schistosomiasis.
- Blood chemistries, including renal function tests
- Blood cultures for salmonella bacteremia
- CBC count for anemia and eosinophilia
- Intestinal and liver schistosomiasis (chronic disease)
- Direct stool examination is not a sensitive test.
- Concentration techniques such as a Kato-Katz thick smear are needed. This demonstrates the number of eggs excreted per day.
- Blood in the stool should be ruled out.
- CBC for anemia and eosinophilia
- Additional testing for HIV and HPV should be considered in female genital schistosomiasis (FGS).
- Liver function test results usually are within the reference range until the end stage of disease. An exception may include a mild elevation of alkaline phosphatase levels. If liver function test results are abnormal, look for other co-infections or diseases.
- Diagnostic tests for hepatitis B and C should be considered in liver schistosomiasis.
- Serology
- The antibody test is a useful epidemiological tool but cannot be used to differentiate active and past illness.
- It does not allow quantification of egg burden.
- Serology findings can be used to reach a diagnosis in a patient from a nonendemic area because a negative antibody test result would be expected.
- Detecting antibodies specific to S mansoni, S hematobium, and S japonicum adult worm microsomal antigens (ie, Mansoni adult worm microsomal antigen [MAMA], hematobium adult worm microsomal antigen [HAMA], japonicum adult worm microsomal antigen [JAMA]) have been reported to be highly specific for all 3 species when used in the Falcon assay screening test (FAST), enzyme-linked immunoassay (ELISA), and immunoblot assays.3
Imaging Studies
- With acute schistosomiasis, a chest radiograph sometimes demonstrates a generalized increase in vascular and interstitial marking and mild lymphadenopathy.
- Urinary schistosomiasis (occurs with chronic disease)
- Plain abdominal radiographs may demonstrate bladder and ureteral calcifications.
- On a sonogram, hydronephrosis, hydroureters, and bladder wall irregularities may be visible.
- Urography may demonstrate abnormalities in the ureter and bladder wall.
- Liver and intestinal schistosomiasis (chronic disease)
- Ultrasonography of liver and spleen is used to reach an early and accurate diagnosis of periportal fibrosis and a diagnosis of hepatosplenomegaly and ascites.
- On CT scan of the liver, calcified capsules and septa are visible.
- Mucosal irregularities are revealed by contrast studies of the intestine.
- Lung schistosomiasis (chronic disease)
- CT scan of the lungs may demonstrate early interstitial fibrosis.
- Findings on echocardiogram reflect pulmonary hypertension due to egg emboli to pulmonary vasculature.
- CNS schistosomiasis also occurs with chronic disease, and a CT scan and MRI scan of the brain and spinal cord may show lesions.
Other Tests
- Detecting circulating antigen
- Because these tests measure parasite antigen as opposed to host antibody response, they reflect active infection. The tests are still investigational.
- With effective treatment, a reduction in antigenemia is expected.
- The 2 proteoglycan gut-associated antigens that appear most promising are circulating anodic antigen (CAA) and circulating cathodic antigen (CCA). These antigens can be found in urine or serum.
- Studies are underway to evaluate the sensitivity and specificity of these investigational antigen tests.
Procedures
- Rectal biopsy or bladder mucosal biopsy
- Mucosal biopsy is effective for visualizing eggs.
- Biopsy is helpful when stool sample findings are negative or in light infection.
- Obtain multiple biopsy samples and crush them between slides (to increase egg-detecting sensitivity).
- Sigmoidoscopy/proctoscopy
- To obtain mucosal biopsies (including rectal)
- For diagnosis and to identify complications such as pedunculated and sessile polyps
- Upper endoscopy
- Assess for esophageal varices.
- Treat upper intestinal bleeding with endoscopic sclerotherapy.
- Cystoscopy
- To obtain mucosal biopsy for diagnosis
- To assess complications such as bladder cancer
- Surgical biopsy findings may be used to diagnose ectopic schistosomiasis.
More on Schistosomiasis |
| Overview: Schistosomiasis |
 Differential Diagnoses & Workup: Schistosomiasis |
| Treatment & Medication: Schistosomiasis |
| Follow-up: Schistosomiasis |
| Multimedia: Schistosomiasis |
| References |
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References
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Al-Sherbiny MM, Osman AM, Hancock K, et al. Application of immunodiagnostic assays: detection of antibodies and circulating antigens in human schistosomiasis and correlation with clinical findings. Am J Trop Med Hyg. Jun 1999;60(6):960-6. [Medline]. [Full Text].
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Lucey DR, Maguire JH. Schistosomiasis. Infect Dis Clin North Am. Sep 1993;7(3):635-53. [Medline].
MMWR. Acute schistosomiasis with transverse myelitis in American students returning from Kenya. MMWR Morb Mortal Wkly Rep. Aug 10 1984;33(31):445-7. [Medline].
Pearce EJ. Progress towards a vaccine for schistosomiasis. Acta Trop. May 2003;86(2-3):309-13. [Medline].
Ross AG, Bartley PB, Sleigh AC, et al. Schistosomiasis. N Engl J Med. Apr 18 2002;346(16):1212-20. [Medline].
Shoff WH, Chen EH, Shepherd SM. Shistosomiasis (part I and II). Infect Dis Pract. 2005;29:419-36.
Vennervald BJ, Dunne DW. Morbidity in schistosomiasis: an update. Curr Opin Infect Dis. Oct 2004;17(5):439-47. [Medline].
WHO Expert Committee. Prevention and control of schistosomiasis and soil-transmitted helminthiasis. World Health Organ Tech Rep Ser. 2002;912:i-vi, 1-57, back cover. [Medline].
Further Reading
Keywords
schistosomiasis, bilharzia, Schistosoma hematobium, Schistosoma mansoni, Schistosoma japonicum, Schistosoma intercalatum, Schistosoma mekongi, S hematobium, S mansoni, S japonicum, S intercalatum, S mekongi, blood flukes, Katayama fever, acute schistosomiasis, chronic schistosomiasis, gastrointestinal schistosomiasis, periportal fibrosis, Symmers clay pipestem fibrosis, urinary tract schistosomiasis, female genital schistosomiasis, FGS, schistosomal cor pulmonale, CNS schistosomiasis, transverse myelitis, hepatic schistosomiasis, cardiopulmonary schistosomiasis, liver schistosomiasis
