What Is Schistosomiasis, An Endemic Parasitic Disease? Causes, Symptoms, Complications And Treatments

Schistosomiasis is known by many names: bilharziasis, bilharzia, Schistosoma haematobium or urogenital schistosomiasis. It is a group of chronic disorders caused by a parasitic flatworm commonly known as a blood fluke of the genus Schistosoma.

Schistosomiasis is known to cause a range of urogenital (relating to both the urinary and genital organs) disorders such as bladder cancer, painful urination and spontaneous abortion. Studies say that around 230 million people worldwide are estimated to have been affected by all forms of schistosomiasis, with around 700 million at risk. [1]

According to the CDC, the infection is considered to be history's most serious parasitic infection, but secondary to malaria. Schistosomiasis is endemic in around 74 countries, especially Africa and the Middle East.

In this article, we will discuss schistosomiasis. Take a look.

Causes Of Schistosomiasis

There are around three main species of schistosomes that affect humans: S. haematobium, Schistosoma japonicum and S. mansoni. The intermediate host of these parasites is freshwater snails, with humans the main host.

The freshwater snails release the larvae forms of the parasites in the water bodies. When the human skin comes in contact with these larvae, they penetrate the human skin and enter their body. Again, transmission from humans takes place when they pass excreta or urine into freshwater. [2]

Inside the snail host, the parasite undergoes asexual reproduction (a type of reproduction in which only one parent is involved to reproduce offspring), and then after 4-6 weeks, shed thousands of larvae into the water. In the human host, these larvae take around 10-12 weeks to mature and reproduce again.

The matured worms live near the urogenital organs and release eggs at the same place. Maximum of the eggs pass out of the human body through excreta or urine, while half of them gets trapped inside the urogenital organs, leading to tissue inflammation and thus, various disorders relating to the bladder, urethra, uterus, cervix, vagina and lower ureters. [3]

Symptoms Of Schistosomiasis

Some of the symptoms of schistosomiasis may include:

• Stomach pain
• Blood in the stool.
• Diarrhoea
• Genital lesions.
• Fever and chills.
• Pain during sexual intercourse.
• Cough
• Inflammation of the seminal vesicles in men.
• Inflammation in the prostate gland.
• Reduced mental abilities in children.
• Muscle ache
• Rashes
• Malaise

Note: The symptoms are not developed instantly but mainly within one or two months after the infestation as the larvae take time to mature and reproduce.

Risk Factors Of Schistosomiasis

Some of the risk factors of schistosomiasis may include:

• Living in areas with poor sanitation and unavailability of safe drinking water.
• Involved in works related to agriculture and fishing.
• Washing clothes in infested water bodies.
• Living near freshwater rivers or lakes.
• Having immunodeficiency medical conditions.
• Travelling to areas when the infection is endemic.

Complications Of Schistosomiasis

In the advanced stage of schistosomiasis, some of the complications that could be noted are:

• Enlargement of the liver
• Enlargement of the spleen
• Hypertension
• Accumulation of fluid in the peritoneal cavity (the space within the stomach containing intestines and liver).
• Kidney damage.
• Fibrosis of the ureter.
• Bladder cancer
• Chronic vaginal bleeding
• Infertility
• Anaemia
• Seizures
• Paralysis
• Ectopic pregnancies
• Death

Diagnosis Of Schistosomiasis

Some of the methods to diagnose schistosomiasis may include:

• Urinalysis or stool test: To identify parasitic eggs in the urine and stools. [4]
• Serology test: For patients with symptoms or symptomatic travellers.
• Complete blood count: This test helps identify underlying conditions like anaemia and malnutrition.
• X-ray: This helps identify fibrosis of the lungs, if due to schistosomiasis.
• Ultrasound: To view any damage to the liver, kidneys or internal urogenital organs.

Treatments Of Schistosomiasis

The treatment of schistosomiasis can vary from person to person depending on the severity. Some of the treatment methods for schistosomiasis may include:

• Anthelmintic drugs: It includes medicines like praziquantel. [5] The drug is administered at various doses to different patients and can also help reverse lower reproductive tract abnormalities in women.
• Other drugs: It includes medicines to treat mild to moderate symptoms such as vomiting, abdominal pain or inflammation.

To Conclude

Schistosomiasis could be a life-threatening disease if left untreated for long. Also, there's no vaccine for the condition which makes its early diagnosis and treatment important.