Bilharzia (Schistosomiasis)

What is bilharzia?

Bilharzia is an acute and chronic parasitic disease caused by a kind of parasitic worms known as “cercariae”. Usually, no symptoms appear when a person is first infected. However, this parasite can live in a person’s body for years and causes damage to their internal organs. There is intestinal and urinary schistosomiasis.

The parasites enter the body when there is direct contact with fresh water where certain snails carry the parasite. The infective form of the fluke, cercariae emerge from the snails, pass through a person’s skin and develop into worms that live in the affected person’s blood. Sub-Saharan Africa accounts for about 90% of people living with schistosomiasis.

What are some misconceptions about bilharzia?

Passing bloody urine as a young male who lives around river banks is not a normal everyday occurrence. When symptoms disappear without treatment it does not mean cure is achieved. It may manifest later as bladder cancer or other serious diseases.

What are symptoms of bilharzia?

Symptoms appear as the body reacts to the parasite’s presence, but complications can persist long-term. The disease can affect different parts of the body, including the lungs, the nervous system, and the brain. The area of damage will depend on the species of parasite. Bilharzia is not usually fatal immediately, but it is a chronic illness that can seriously damage the internal organs.

In children, it can lead to reduced growth and problems with cognitive development. Bilharzia can affect people of any age in an affected area, but those who are most at risk include: Children and people who swim, work, or have other contacts with freshwater rivers, canals, lakes, and streams. Approximately 3 to 8 weeks after infection, the person may experience: a rash, fever, headache, body aches, or myalgia breathing difficulties.

Chronic stage

Many people do not show symptoms at the early stage, but they may develop symptoms as the disease progresses. These later symptoms again depend on the type of parasite. If the parasites affect the liver or intestines, symptoms may include:

• Diarrhea and constipation
• Blood in the feces
• Intestinal ulcers
• Liver fibrosis
• High blood pressure around the digestive system

If the parasites affect the urinary system, there may also be:

• Blood in the urine
• Painful urination
• Higher risk of bladder cancer

Over time, anemia can develop. In rare cases, the parasite may affect the brain.

What causes bilharzia?

The infection occurs when infected individuals contaminate fresh water sources with excreta (feces or urine) that carry the eggs of this parasite. The eggs hatch in the water, releasing tiny larvae. When another person comes in contact with this contaminated water, the larvae penetrate his skin. This could happen while a person is diving, swimming, washing, or paddling in contaminated water.

In the body, the larvae develop into adult schistosomes. Adult worms live in the blood vessels where the females release eggs. Some of the eggs are passed out of the body in the feces or urine to continue the parasite’s lifecycle. Others become trapped in body tissues, causing immune progressive damage to organs.

How is bilharzia diagnosed and treated?

Diagnosis is suspected when a person who lives or has traveled to affected areas presents with the symptoms above. A stool or urine sample will indicate whether any eggs are present. The doctor may request a blood test.

There is no vaccine against schistosomiasis. People who live in a high-risk area can take a prescription drug such as praziquantel.

The ways that authorities can use to reduce the chance of people becoming infected in high-risk areas include:

• Reducing the levels of infection: Providing drug treatment to the population can help achieve this.
• Snail control: This may involve the use of chemicals and redesigning or clearing irrigation schemes to make it harder for snails to proliferate. Another option is to introduce predators, such as crayfish.