Schistosomiasis

This is a parasitic infection where symptoms develop due to the body’s reaction to the larval worms. The parasite lives inside certain types of snails where it matures and multiply then leaving the snail being able to survive for up to 48 hours in water. The parasite is able to penetrate the skin on contact and thus is usually transmitted where people wade, swim, fish, wash clothes in infested waters. Inside the body they live n blood vessels where the female produces eggs which can travel to the intestine and urinary tract, thus symptoms relate to these systems. It can be spread when infected faeces and urine ends in the fresh water. The disease is also known as Bilharzia and is caused by approximately 5 different subtypes.

Incubation Period
14-84 days

Signs and Symptoms
Within a few days of infection a rash may develop or itchy skin. 1 – 2 months later fever, chills and muscle aches may develop. Untreated it may persist for years where abdominal pain, bloody faeces, bloody urine and liver enlargement may occur. Lungs, liver, intestines and bladder can all be effected. Rarely central nervous system symptoms may occur including paralysis. In children it usually leads to malnutrition, anaemia and learning difficulties. It is also a risk factor for liver fibrosis and bladder cancer.

Diagnosis
Usually from faecal or urinary samples but can also be done from blood samples. The ova are seen microscopically in faeces and urine. Serology for the antibody is usually also done. The ova are shed intermittently thus different samples should be taken. A detailed travel history should also be taken.

Treatment 
Cases are treated with Praziquantel. Timing is very important as it works on the adult parasite. Usually 6-8 weeks from exposure. It has been used widely in mass treatment campaigns.

Prevention
When travelling to effected areas avoid swimming, wading in fresh water. Drink safe water as the contact of infested water with lips can lead to infection. If in contact with fresh water vigorous towel drying may prevent parasite penetration.  Use water for bathing that has been in a storage tank for at least 1-2 days.