Schistosomiasis (Bilharzia) Treatment & Management

Updated: Jul 24, 2017
  • Author: Shadab Hussain Ahmed, MD, AAHIVS, FACP, FIDSA; Chief Editor: Michael Stuart Bronze, MD  more...
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Treatment

Approach Considerations

Prehospital care should include treating acute complications, such as acute intestinal bleeding. Stabilize patients who have acute complications. If appropriate, include schistosomiasis as one of the differential diagnoses.

Send urine or stool samples to the parasitology laboratory with a special request to look for eggs indicative of schistosomiasis.

Patients with severe complications, such as GI bleeding, GI obstruction, renal failure, cardiac failure, bacteremia due to Salmonella, and CNS complications, need inpatient care.

Acute schistosomiasis and Katayama fever

Patients should receive antischistosomal drugs and corticosteroids, especially if acutely ill. Steroids reduce inflammation and help suppress changes that result from killing of the parasites. As maturing schistosomes are less susceptible to therapy than adult worms, a second course of treatment is necessary. This is given several weeks after the first course of therapy.

The drug of choice for treating all species of schistosomes is praziquantel. Cure rates of 65-90% have been described after a single treatment with praziquantel. In individuals not cured, the drug causes egg excretion to be reduced by 90%. [55] Praziquantel affects the membrane permeability of the parasite, which causes vacuolation of the tegument. It paralyses the worm and exposes it to attack by the host immune system. However, as praziquantel is ineffective on developing schistosomula, it may not abort early infection. Praziquantel can be used in pregnant and lactating women. [56] Resistance to praziquantel occurs in the field and is well defined. [57, 58] Adverse effects include dizziness, headache, nausea, vomiting, diarrhea, abdominal discomfort, bloody stool, urticaria, and fever following initiation of treatment. These are usually mild and last about 24 hours. These are reactions from dying worms.

Neurologic disease

Treatment of schistosomiasis affecting the CNS consists of praziquantel with glucocorticoids. In CNS disease, corticosteroids are used to reduce inflammation and edema around eggs. If patients present with seizures, anticonvulsant therapy may also be needed. Observe patients with suspected or known cysticercosis as they may develop seizures or neurologic effects from dying cysticerci.

Surgical care

Surgical care includes removal of tumor masses, ligation of esophageal varices, and porta-caval shunt surgeries. Large granulomas in urinary bladder or lungs may warrant surgical extirpation.

Consultations

Appropriate consultations depend on the suspected complications but may include an infectious disease physician, urologist, gynecologist, or gastroenterologist.

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Corticosteroids

The symptoms of Katayama syndrome often require administration of corticosteroids to suppress the inflammatory process, but no consensus exists regarding proper antihelminthic treatment. Prednisolone 40mg daily for 5 days can be used for the hypersensitivity reaction. Treatment is essentially supportive.

Persons with CNS involvement should be given corticosteroids to prevent inflammation and edema around eggs. Repeated courses of corticosteroid therapy may be warranted to suppress recrudescent neurologic symptoms.

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Outpatient Care

Response to treatment is evaluated by counting the amount of decrease in egg excretion. In the initial 2 weeks after treatment, the egg count may not decrease, because eggs laid before the treatment require 2 weeks to be shed. Viable eggs can be excreted for 6-8 weeks after treatment.

When measured 5-10 days after treatment, newer tests that measure antigens may help to assess therapeutic response. Persistent circulating antigen and the excretion of eggs indicate residual infection. These patients should be retreated with praziquantel.

Follow-up

Antischistosomal drugs inhibit egg-laying by adult worms. Therefore, patients’ stool and urine should be tested for 6 months after treatment. Treatment is repeated for those excreting eggs. If symptoms recur, hematuria occurs, or eosinophilia is noted, repeat parasite investigation should be performed. However, serology can remain positive for years.

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Pregnancy

Schistosomiasis affects the uterine environment during pregnancy. These pregnant women develop severe anemia, have low ̶ birth-weight infants, and are at increased risk for infant and maternal mortality. Schistosomiasis has been found in placenta, and newborns have been diagnosed with this condition, thus confirming congenital infection. [4] Infected pregnant women have a higher rate of spontaneous abortions and a higher risk for ectopic pregnancies. In addition, increased pelvic blood flow during pregnancy is thought to increase the infection load. WHO recommends giving praziquantel to pregnant and lactating women to decrease the disease burden and improve the pregnancy and fetal outcomes. [30]

A retrospective study of 88 women with schistosomiasis who received praziquantel during pregnancy, in a mass treatment campaign, did not show an increase in the rate of abortion, preterm deliveries, or congenital abnormalities compared with untreated women. [59]

Starting treatment after the first trimester may be advisable. [60] Praziquantel is excreted in human breast milk. No adverse effects of praziquantel administration during lactation have been reported. [60, 61]

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Deterrence and Prevention

No vaccine or prophylactic chemotherapy for schistosomiasis is currently available. However, clinical trials involving human volunteers are underway to develop an effective vaccine against schistosomiasis. Moreover, clinical studies show that artemether may be used as a prophylactic agent if given once every 2-4 weeks. [62]

Travelers to endemic areas should avoid contact with fresh water. Suspect acute schistosomiasis in a setting of recent contact with fresh water and treat early if diagnostic test results are positive or clinical suspicion is high. Early treatment after high-risk exposures should minimize morbidity.

People returning from endemic areas with history of exposure to fresh water should be screened by serologic testing for schistosomiasis. Many infections are silent and may remain asymptomatic. Urine and stool screening should be obtained in patients with positive serologies for species identification. [60] Rates of schistosomiasis seropositivity have been recorded as 44% and 23% in African refugees. [63]

Topical lipid formulations of N,N-diethyl-m-toluamide (DEET), such as LipoDEET, are effective in killing schistosome cercariae. Minimal absorption, low cost, and a range of activity against insects and schistosomes make this compound an excellent prophylactic agent against human and animal schistosomiasis, especially for travelers. [64]

Endemic regions

Controlling schistosomiasis in an endemic area should include the following:

  • Population-based preventive chemotherapy - WHO has recommended preventive chemotherapy for at-risk populations in endemic areas [65]

  • Provision of a safe water supply

  • Health education that includes improvement of water sanitation and avoidance of schistosome-contaminated urine or stool

  • Snail control

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