Schistosomiasis

Symptoms of schistosomiasis are caused not by the worms themselves but by the body's reaction to the eggs. Praziquantel is the treatment of choice because Katayama fever may progress to include neurologic complications

About

• From worms that cause schistosomiasis live in fresh water
• Also called Bilharzia

Source

• Ponds, lakes, rivers, reservoirs, canals
• Showers that take unfiltered water directly from lakes or rivers
• Not from sea, chlorinated swimming pools

Geographical

• Africa, South America, the Caribbean, the Middle East and Asia

Microbiology

• Schistosoma mansoni: Intestinal and liver disease
• Schistosoma haematobium: Bladder disease/cancer
• Schistosoma japonicum: Intestinal and liver disease

Lifecycle

• The parasites live in certain types of freshwater snails.
• They release an invasive form called cercariae
• Infection simply with contact with contaminated water
• Worms burrow into your skin.
• Then move to liver and bowel and bladder.
• Produce eggs lost in faeces and urine

Clinical: Acute Infection

• Often asymptomatic.
• Transient itch on skin with red bumps "swimmer's itch"
• After weeks pyrexias and itchy, red, blotchy and raised rash
• Develop cough and diarrhoea
• Muscle and joint pain, abdominal pain, malaise

Katayama fever

• Katayama fever is caused by infection with Schistosoma mansoni.
• Approximately 4-8 weeks after exposure the parasite migrates through the portal and pulmonary circulations.
• This may be asymptomatic but in some cases evokes a hypersensitivity response and a serum sickness type illness.
• Eosinophilia is usual. Since there is not a large enteric burden of parasites during this phase of the illness, stool studies may not be positive and serology may be helpful, particularly in patients from nonendemic areas.

Clinical: Chronic Infection

• Anaemia, abdominal pain and swelling
• Diarrhoea and blood in faeces
• Cystitis, dysuria, frequency, haematuria
• Seizures (fits), headaches, dizziness
• Weakness and numbness in your legs
• Risks of Fibrosis and Bladder cancer
• Colonic polyps and strictures

Investigations

• Hb: low from haematuria
• U&E: Immune complex glomerulonephritis
• WCC: raised eosinophils
• CXR: pneumonitis, infiltrates, granulomas
• LFTS: Hepatitis

Management

• Short course of a medication called praziquantel, that kills the worms. It is most effective once the worms have grown a bit, so treatment may be delayed until a few weeks after you were infected, or repeated again a few weeks after your first dose.
• Praziquantel has a particularly dramatic effect on patients with schistosomiasis. Studies of those treated have shown that within six months of receiving a dose of praziquantel, up to 90% of the damage done to internal organs due to schistosomiasis infection can be reversed
• Steroid medication can also be used to help relieve the symptoms of acute schistosomiasis or symptoms caused by damage to the brain or nervous system.