Schistosomiasis, urinary is endemic in most of Africa. People are infected while swimming or wading in freshwater. Cercarial dermatitis occurs within 24 hours of skin penetration. Chronic infection can lead to obstructive uropathy, hydronephrosis, pyelonephritis, and bladder cancer.
CASES/YEAR
0 (US); 169,000,000 (Global)
OTHER NAMES
Schistosoma haematobium;
INCUBATION
2-6 weeks for Katayama fever; [CCDM, p. 554] First eggs in stool 1-3 months after exposure; [Merck Manual, p. 1723]
INITIAL SYMPTOMS
Dysuria, urinary frequency, and hematuria for S. haematobium; The hematuria occurs typically at the end of urination. [CCDM] "Swimmer's itch" is a pruritic papular rash that develops within 24 hours at the site of penetration. [PPID, p. 3454]
PRECAUTIONS
"Not communicable from person to person;" [CCDM, p. 546]
COMMENTS
FINDINGS:
Cercarial dermatitis occurs within 24 hours of skin penetration and usually consists of papules at sites of entry on the lower legs. Acute schistosomiasis (Katayama fever) is rare in S. haematobium infections. Egg deposition in the lungs may cause pulmonary nodules and cor pulmonale. Other complications of chronic S. haematobium infection are chronic renal failure and transverse myelitis. [Guerrant, p. 851-2] Diseases related to chronic infection include obstructive uropathy, hydronephrosis, pyelonephritis, and bladder cancer. [ID, p. 2378] Repeated pyelonephritis may lead to renal failure. Marked eosinophilia is present early. Eosinophilia may be present or absent in chronic infections. [Guerrant, p. 851, 943] Katayama's fever (fever, lymphadenopathy, urticaria, and eosinophilia) is unusual in urinary schistosomiasis. [PPID, p. 3454] Symptoms of pulmonary involvement are cough, dyspnea, and hemoptysis. [Cohen, p. 1778] Eggs can lodge in the spinal cord (transverse myelitis) and CNS (seizures). [Merck Manual, p. 1724]
EPIDEMIOLOGY:
Humans are the main reservoirs, and snails are intermediate hosts for these trematode infections. Human infections commonly last more than 10 years. [CCDM, p. 554-5] Most cases in travelers are acquired in sub-Saharan Africa. People are infected while swimming, bathing, or wading in freshwater in endemic areas. Prevalence rates can exceed 50% in some areas, e.g., Burkina Faso, Mali, Lake Malawi, Lake Tanganyika, Lake Victoria, Omo River, Zambezi River, and the Nile River. "The distribution of schistosomiasis is very focal and determined by the presence of competent snail vectors, inadequate sanitation, and infected humans." Control programs are effective, but there are no international guidelines for certification of elimination. [CDC Travel, p. 339]
DIAGNOSTIC
Identify eggs by microscopic exam; Serology: positive tests do not prove current infection; [CCDM] Serological tests useful in travelers with light infections; [CDC Travel]
SCOPE
Urinary schistosomiasis is endemic in most of Africa with low risk in North Africa, the Middle East, India, and Bangladesh; [CDC Travel]
SIGNS & SYMPTOMS
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>fever
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>myalgia
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G hepatomegaly
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H anemia
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H eosinophilia
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H lymphadenopathy
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H splenomegaly
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N headache
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N seizure
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R cough
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R dyspnea
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S papules or plaques
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U hematuria
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U pyuria
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*acute renal failure
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*cancer
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*glomerulonephritis
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*myelitis
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*myocarditis
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*paralysis
ENTRY
Skin or Mucous Membranes (Includes Conjunctiva), Swimming
SOURCE
Waterborne (Ingesting, Inhaling, or Swimming)
RISK FACTORS
- Swim in contaminated water (skin)
- Travel to endemic area
REFERENCES FOR CASES/YEAR
1.
2. (Global) 200-300 million infected by schistosomes; [Harrison ID, p. 1146] In Sub-Saharan Africa, 112 million are infected and 436 million at risk for infection by S. haematobium; In Sub-Saharan Africa, 54 million are infected by S. mansoni [http://www.who.int/schistosomiasis/epidemiology/table/en/] Calculate: Assume same ratio of 54/112 with total = 250 million; Then of 250 million total infections, 169 million are urinary and 81 million are intestinal/hepatic;