Schistosomiasis Life Cycle


Depending on where the adult flukes are found, the parasitic disease schistosomiasis can either be intestinal or urogenital in nature. Millions of people in numerous nations in Africa and the Middle East are afflicted by schistosomiasis (Schistosoma haematobium), more specifically known as urogenital schistosomiasis. Numerous urogenital problems, including dysuria, hematuria, urinary blockage, spontaneous abortion, and bladder cancer, are caused by it. This activity discusses schistosomiasis (Schistosoma haematobium) evaluation and management as well as the role of the healthcare team in diagnosing and treating individuals with this ailment.

Children who contract the infection repeatedly may experience anemia, malnutrition, and academic issues. The parasite can harm the liver, gut, lungs, and bladder after years of infection. Rarely, eggs can induce convulsions, paralysis, or inflammation of the spinal cord when they are detected in the brain or spinal cord.

Following an infection, symptoms like fever, chills, coughing, and muscle aches may appear within 1-2 months. Schistosomiasis can last for years if left untreated. Abdominal pain, an enlarged liver, blood in the stool or urine, and difficulty in urinating are all indications of chronic schistosomiasis.

What is Schistosomiasis?

Image 1: Liver schistosomiasis under microscope showing presence of Schistosoma ova, calcified eggs of the flat worm, in hepatic tissue

One of the most common diseases in the world is still schistosomiasis. The condition simply won't go away despite more than a century of control efforts and the emergence of highly efficient antischistosomal medication therapy in the 1980s.

Schistosoma japonicum, Schistosoma mansoni, Schistosoma haematobium, Schistosoma intercalatum, or Schistosoma mekongi are the five trematode species that can infect humans and cause schistosomiasis, often known as bilharziasis. Because the parasite must go through multiple developmental stages in freshwater, including a period of growth within specific species of intermediate host snails, there is a strong correlation between parasite transmission and the ensuing risk of human infection.

Disease endures even after an infection has ended. A significant risk of death from variceal gastrointestinal bleeding results from the late fibrotic consequences of the inflammation caused by schistosomiasis in some patients, particularly those with intestinal schistosomiasis. Late complications of urinary schistosomiasis include an irreversible obstruction of the urinary tract with a risk of renal failure and bladder cancer brought on by inflammation. The risk of infection-related inflammation and associated problems is perhaps highest in the Asian type of intestinal schistosomiasis caused by the species S. japonicum.

The pharaohs were aware of schistosomiasis, one of the most complex human diseases, more than 5000 years ago. The existence of snail species in Africa during the Paleolithic period may point to a far older origin for this parasitic disease. Ancient Egyptians understood that schistosomiasis was a worm-caused illness that resulted in bloody stools and urine.

Each year, 230 to 250 million people worldwide contract schistosomiasis. There are a million people who could get sick. This illness results worldwide, there are 2,80,000 fatalities each year and 3.3 million lives with a disability. Schistosomiasis in humans is one of the most common parasite illnesses.

The illness, which is present in 75–76 nations, is listed as the second-most common parasitic disease, behind malaria. Numerous developing nations in Asia, Africa, Caribbean islands, and South America all have schistosomes. Non-endemic regions are equally susceptible to schistosomiasis. Immigration and water-based development projects are two ways it can spread.

Life Cycle of Schistosomiasis

The Egg Stage

Depending on the type of worm, female flukes up to 25 mm long discharge 3,500 eggs into the bloodstream each day. These eggs move to the colon or bladder before being discharged through the feces or urine into the surrounding environment.

The Larval Stage

  • Miracidium: The eggs hatch and release miracidium larvae when they are in water and in a favorable environment. The ciliated larva of the miracidium species swims to the intermediate host, which in this case are snails.

  • Cercariae: The larvae eventually mature into fork-tailed larvae known as cercaria. From the snails, the cercariae larvae erupt into the water. These larvae lose their tails when they come in touch with a mammal, allowing them to enter the skin tissues and feed on blood there. The cercaria larva turns to schistosomula once it loses its tail.

  • Schistosomula: The schistosomula enters the liver where it develops after passing via the lungs, heart, and liver. The portal vein system is used to let the schistosomula leave the liver once they have reached maturity.

The Adult Stage

The sexual maturity of the female and male worms takes place at this stage. After reaching maturity, the worms mate. The placement of adult worms in the intestine varies depending on the species. They move to many locations inside people rather than staying in one spot. The feces and urine are used to release the eggs that the fertilized female worms produce into the colon, the bladder, and the ureters.


Small flatworm parasites of the Schistosomatidae family, often known as blood flukes, are the cause of a series of chronic disorders known as schistosomiasis, sometimes known as bilharzia or bilharziasis. Schistosomiasis is characterized by inflammation of the intestines, bladder, liver, and other organs. In the urethra or the intestine, people can get the blood-worm disease schistosomiasis. The main species that can infect humans are S. haematobium and S. japonicum. In the schistosomiasis life cycle, hosts include both snails and animals. Snails can reproduce asexually, while mammals can only reproduce sexually. Linalool, SpAE, Rubb7-tn1, and Rubb12-tri are a few of the pharmacological possibilities that have been researched. There are currently no vaccinations available for this illness.

Schistosomiasis symptoms include cough, fever, skin rashes, and liver inflammation. Blood is discovered in urine and feces in more serious situations. There are various forms of schistosomiasis that can be found in various places. For instance, S. japonicum is found in Japan, whereas S.haematobium is found in Africa and some areas of the Middle East.


Q1. How can I avoid getting schistosomiasis?

Ans: Maintaining a good hygiene system with functional defecation facilities is the answer. Additionally, stay away from swimming in freshwater areas like lakes and rivers where schistosomiasis is known to be common. Make careful to only consume clean, safe water.

Q2. How does schistosomiasis spread?

Ans: Schistosomiasis is an infectious disease that people contract when their skin comes into contact with water polluted with Schistosoma eggs. Basically, people live in certain areas with poor defecation facilities are more prone to getting this disease.

Q3. How does one get treatment for schistosomiasis?

Ans: A drug called praziquantel is used for treating the disease schistosomiasis. After the worms have grown slightly, praziquantel is most effective, thus therapy may need to be repeated a few weeks after the initial dose.

Q4. How long can it live in the body?

Ans: The average lifespan as a human host is 3–10 years, although in certain situations this lifespan can reach 40 years. Medication can be used to treat this condition quickly.

Q5. How can schistosomiasis be cured?

Ans: Praziquantel, a drug that kills the worms, can usually be used to successfully cure schistosomiasis after a brief course of treatment. After the worms have grown a little, praziquantel is most effective, thus therapy may need to be repeated a few weeks after the initial dose.