Schistosomiasis

Infection with parasitic blood flukes. Two types of schistosomes are found in Malawi: urinary schistosomiasis (S. haematobium) and intestinal schistosomiasis (S. mansoni). S haematobium is endemic in many areas, particularly around the lake shore. S. mansoni mainly occurs in the central and Southern Highlands, Likoma Island and in the Lower Shire Valley

Clinical presentation

Cercarial dermatitis

Within hours after infection
Worms enter and migrate under the skin. “Swimmers itch” and maculopapular rash.

Acute schistosomiasis syndrome (Katayama fever)

Ca. six weeks after infection
Systemic hypersensitivity syndrome
Symptoms can include: fever (not an essential component), urticaria, angioedema, cough, abdominal pain, hepatosplenomegaly.
Usually self-limiting. More frequent in individuals who do not live in endemic setting, hence not common in Malawians.

Organ manifestations

Months or years after infection (most frequent presentation in endemic areas with ongoing exposure)
Adult worms live in the veins of the bowel or bladder and shed eggs. Eggs get trapped in tissue and cause damage through granulomatous inflammation, tissue scarring and calcification.
Disease severity depends on anatomic distribution of the trapped eggs, worm burden & duration of infection, severity of the host immune response, egg laying sites of the adult worms, and co-infections (e.g. HIV or malaria).

Unspecific symptoms: microcytic anaemia, malnutrition, fatigue, growth retardation, cognitive delay and disability

Urogenital Schistosomiasis

Acute:

Chronic:

Intestinal Schistosomiasis

Acute:

Chronic:

Complications of both types

Investigations

Treatment

Prevention

Reference:

CDC - See http://www.cdc.gov/parasites/schistosomiasis/health_professionals/index.html
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Lectures of tropical medicine and hygiene at LSTM