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Blood Fluke

Last updated date: 27th Feb 2024
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Blood Fluke in Humans

The word blood fluke is a synonym for schistosome. It is any specific parasitic flatworms that reside in the veins of the host organism. S. haematobium was the first discovery of blood fluke in humans a.k.a urinary blood fluke. A German surgeon named Theodor Bilharz was working in Cairo, identified the blood fluke parasite as a causative agent of urinary infection in 1851. After his discovery, the infection (generally including all schistosome infections) was named bilharzia or bilharziasis.

Blood fluke has a higher and a lower classification, a scientific name, order, Class, and the kingdom it belongs to. On this page, we will understand all these. Besides this, we will also understand blood fluke symptoms, flatworm blood fluke, vesical blood fluke, blood fluke examples, blood fluke infection, and blood fluke treatment.

Blood Fluke of a Man

The blood fluke of man looks like this:

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About Blood Fluke 

The below table classifies the Schistosoma blood fluke:


Corresponding Name

Higher Classification


Lower Classification

(Blood Fluke Examples)

  • Schistosoma Mansoni

  • Schistosoma Japonicum

  • Schistosoma Mekongi

  • Schistosoma Malayensis

Scientific Name










What is Blood Fluke?

Blood fluke or Schistosoma is a variety of trematodes, ordinarily known as blood accidents. 

It is a parasitic flatworm blood fluke responsible for a profoundly huge gathering of contaminations in people named schistosomiasis, which is considered by the World Wellbeing. Association as the second-most financially decimating parasitic sickness, with many millions tainted around the world.

Blood Fluke Infection

  • A mature blood fluke resides in the blood vessel of the human intestines.

  • Blood flukes reproduce sexually in the human host. Fertilize the eggs exit host in feces.

  • Eggs develop in water into ciliated larvae. Larvae infect snails.

  • Asexual reproduction occurs within a snail. As a result, another type of small larva, i.e., motile larva takes birth.

  • Thus, larva penetrates the skin and blood vessels of humans. So, a blood fluke infection occurs in this way.

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Now, let’s understand this whole process in detail:

Blood Fluke Infection Life Cycle 

  • In the human host, eggs containing miracidia are killed with excrement or pee into water. 

  • In water, the eggs incubate and discharge miracidia. 

  • The miracidia swim and enter a snail (transitional host). 

  • Inside the snail, the miracidia progress through 2 ages of sporocysts to become cercariae. 

  • The free-swimming cercariae are delivered from the snail and infiltrate the skin of the human host. 

  • During the entrance, the cercariae lose their forked tail, turning out to be schistosomula. The schistosomula is shipped through the vasculature to the liver. There, they develop into grown-up worms. 

  • The matched (male and female) adult worms move (contingent upon their species) to the intestinal veins in the entrail or rectum or to the venous plexus of the genitourinary parcel, where they dwell and start to lay eggs.

So, blood flukes in skin, what are the blood fluke symptoms, and what is the blood fluke treatment;  let’s understand these:

Blood Fluke Effects

Schistosoma blood fluke or flatworm blood fluke or vesical blood fluke are parasitic flatworms that infect various parts of the body, such as blood vessels, gastrointestinal tract, lungs, liver, depending on the species.

Below are the Blood Fluke Effects:

Blood fluke or Schistosomiasis is a disease with a blood fluke parasite of the class Schistosoma, which is procured transcutaneously by swimming or swimming in polluted freshwater. The life forms taint the vasculature of the gastrointestinal or genitourinary framework. 

Blood fluke symptoms are dermatitis, followed by a week later fever, chills, sickness, abdominal pain, looseness of the bowels, discomfort, and myalgia. 

Ongoing manifestations shift with species however incorporate bleeding loose bowels (eg, with S. Mansoni and S. Japonicum) or hematuria (For instance, S. Haematobium). 

The conclusion is by recognizing eggs in the stool, pee, or biopsy examples. 

Serologic tests might be delicate and explicit yet don't give data about the worm trouble or clinical status. However, blood fluke treatment is recommended.

Blood Fluke Species

Schistosomiasis is by a wide margin the main trematode contamination. Schistosoma is the lone trematode that attacks through the skin; any remaining trematodes contaminate just by means of ingestion. Around 221 million individuals are contaminated around the world. 

Five types of schistosomes contaminate people. All have comparable life cycles including freshwater snails. S. Haematobium causes urinary tract illness; the other Schistosoma species cause intestinal sickness. 

Geographic Dissemination Contrasts by Blood Fluke Species: 

  • S. Haematobium: Generally conveyed over the African landmass with more modest foci in the Center East, Turkey, and India 

  • S. Mansoni: Boundless in Africa, foci in Center East, and the lone species in the Western Side of the equator in pieces of South America and some Caribbean islands 

  • S. Japonicum: Asia, basically in China, the Philippines, Thailand, and Indonesia 

  • S. Mekongi: Southeast Asia 

  • S. Intercalatum: Focal and West Africa 

People are the principal supply of contamination. Canines, felines, rodents, pigs, ponies, and goats are supplies for S. japonicum, and canines are repositories for S. Mekongi. 

Transmission of these species doesn't happen inside the US (counting Puerto Rico) and Canada, however, the sickness might be found in voyagers and migrants from endemic territories.

Blood Fluke Physiology

Adult Schistosoma worms live and copulate inside venules of the mesentery (normally S. japonicum and S. Mansoni) or bladder (commonly S. haematobium). 

Further, a few eggs enter the intestinal or bladder mucosa and are passed in stool or pee; different eggs stay inside the host organ or are shipped through the gateway framework to the liver and at times to different destinations (eg, lungs, focal sensory system, spinal cord). 

Thereafter, the discharged eggs enter the freshwater, deliver miracidia (first larval stage), which enter snails. After duplication, a huge number of free-swimming, forked-followed cercariae are delivered. 

Cercariae infiltrate human skin inside a couple of moments after openness. At the point when they infiltrate the skin, they lose their forked tail and change into schistosomula, which makes a trip through the circulatory system to the liver, where they develop into adults. The adults then relocate to their definitive home in the intestinal veins of the venous plexus of the genitourinary parcel. 

Eggs show up in stool or pee 1 to 3 months after cercarial infiltration. 

Evaluations of the adult worm life length range from 3 to 7 years. The females range in size from 7 to 20 mm; males are somewhat more modest.

Blood Fluke Symptoms 

The blood fluke symptoms showcase their presence in the following ways:

1. Intense Schistosome Dermatitis 

Most diseases are asymptomatic. A pruritic papular rash (cercarial dermatitis) can foster where cercariae infiltrate the skin. 

2. Intense Katayama Fever 

Katayama fever may happen at the beginning of egg-laying, commonly 2 to about a month after substantial openness. Side effects incorporate fever, chills, hack, queasiness, stomach torment, discomfort, myalgia, urticarial rashes, and checked eosinophilia, looking like serum infection. Indications are more normal and generally more serious in guests than in occupants of endemic regions and ordinarily, keep going for a little while. 

3. Persistent Schistosomiasis 

Persistent schistosomiasis results principally from having reactions to eggs held in tissues. Almost immediately, intestinal mucosal ulcerations brought about by S. Mansoni or S. Japonicum may drain and bring about bleeding loose bowels. As sores progress, central fibrosis, injuries, fistulas, and papillomatous developments may create in the digestive system. 

Granulomatous responses to eggs of S. Mansoni and S. Japonicum in the liver normally don't bargain liver capacity, yet they may cause fibrosis and cirrhosis, which can prompt gateway hypertension, bringing about splenomegaly, and oesophagal varices. Therefore, oesophagal varices may drain, causing hematemesis. 

Eggs in the lungs may create granulomas and central obliterative arteritis, which may, at last, bring about pneumonic hypertension and cor pulmonale. 

With S. haematobium, ulcerations in the bladder divider may cause dysuria, hematuria, and urinary recurrence. After some time, constant cystitis creates. Injuries may prompt hydroureter and hydronephrosis. 

Persistent Schistosomiasis Effects

Papillomatous masses in the bladder are normal, and squamous cell carcinoma of the bladder may create. Blood misfortune from both gastrointestinal and genitourinary parcels much of the time brings about paleness. 

An auxiliary bacterial disease of the genitourinary lot is normal, and industrious or repetitive Salmonella septicemia may happen. 

A few animal categories, prominently S. Haematobium, can cause genital infection in the two people, bringing about various side effects including barrenness. Neurologic inconveniences can happen even in light of Schistosoma diseases. 

Eggs or adult worms held up in the spinal rope can cause transverse myelitis, and those in the cerebrum can create central injuries and seizures.

Key Points on Blood Fluke

Below are the key points on blood fluke:

  • Schistosoma is the lone trematode that attacks the skin; millions of individuals are tainted around the world. 

  • When cercariae infiltrate the skin, they lose their forked tail and become schistosomula, which make a trip through the circulatory system to the liver, where they develop; as grown-ups, they move to their definitive home in the intestinal veins of the venous plexus of the genitourinary lot. 

  • Ova in the liver trigger a granulomatous response that can prompt fibrosis and enter hypertension, bringing about splenomegaly, oesophagal varices, and hematemesis. 

  • Living beings in the digestive tract can cause ridiculous looseness of the bowels, and life forms in the bladder can cause hematuria and ongoing cystitis. 

  • Treat with praziquantel to forestall disease, stay away from contact with new water in endemic territories.

Blood Fluke Diagnosis

Microscopic assessment of stool or pee (S. haematobium) for eggs can be seen in the following manner:

Serologic Tests 

Stool or pee (S. haematobium, infrequently S. Japonicum) is analyzed for eggs. Rehashed assessments utilizing focus procedures might be essential. 

Here, the topography is an essential determinant of animal groups, so a past filled with openness ought to be imparted to the research facility. On the off chance that the clinical picture recommends schistosomiasis yet, no eggs are found after rehashed assessment of pee or defecation, intestinal or bladder mucosa can be biopsied to check for eggs. 

Contingent upon the antigens utilized, serologic tests might be sensitive and explicit for contamination, however, they don't give data about worm trouble, clinical status, or forecast and don't recognize dynamics from settled disease. 

If patients are not occupants of endemic regions, serologic tests ought to be done ≥ 6 to about two months after the last exposure to freshwater to permit time for the development of the schistosomes into adults and for the advancement of antibodies to them.

Blood Fluke Treatment

The blood fluke diagnosis doesn’t provide a piece of exact information; however, the treatment for the same is available. Now, we will understand the blood fluke treatment ways:


  • One-day oral treatment with praziquantel (20 mg/kg two times every day for S. Haematobium, S. Mansoni, and S. Intercalatum; 20 mg/kg 3 times each day for S. Japonicum and S. Mekongi) is suggested. Praziquantel is viable against grown-up schistosomes, yet not creating schistosomula, which are available right off the bat in disease. 

  • Subsequently, for asymptomatic explorers who have had exposure to possibly defiled new water, treatment is postponed for 6 to about two months after the last exposure. 

  • Unfriendly impacts of praziquantel are by and large gentle and incorporate stomach torment, runs, migraine, and dazedness. Remedial disappointments have been accounted for, however, it is hard to decide if they are because of reinfection, the overall opposition of youthful schistosomes, or praziquantel-safe grown-up schistosomes. 

  • If eggs are available at the hour of finding, follow-up assessment 1 to 2 months after treatment is proposed to help affirm the fix. Treatment is rehashed if eggs are as yet present. 

  • Treatment of intense schistosomiasis (Katayama fever) depends on restricted information. Corticosteroids can improve serious manifestations; treatment with prednisone 20 to 40 mg day by day for 5 days in grown-ups is generally powerful. 

  • Whenever side effects have died down, treatment with praziquantel is given as definite above and rehashed 4 to about a month and a half later after parasites have arrived at adulthood. 

  • Patients with reasonable ova in stool or pee at the time-intense or persistent schistosomiasis are ought to be inspected for living eggs 1 to 2 months after therapy. Retreatment is shown if feasible eggs are available.

Now, let’s have a look at some FAQs on Blood Fluke.

FAQs on Blood Fluke

Q1: What are the Preventive Measures for Blood Fluke Disease?

Ans: Below is the list of the preventive measures for blood fluke disease. 

  • Conscientiously keeping away from contact with sullied new water forestalls schistosomiasis. 

  • Freshwater utilized for washing ought to be bubbled for at any rate 1 moment and afterwards cooled prior to washing. Nonetheless, water that has been held in a capacity tank for at any rate 1-to-2 days ought to be protected without bubbling. 

  • Individuals who are unintentionally presented to potentially tainted water (by falling into a stream) ought to immediately get dry with a towel to eliminate any parasites before they enter the skin. 

  • The clean removal of pee and dung diminishes the probability of disease. 

  • Grown-up occupants of endemic zones are more impervious to reinfection than youngsters, proposing the chance of gained insusceptibility. 

  • Mass people group-based or school-based treatment with praziquantel, training projects, and molluscicides to diminish snail populations are utilized to control schistosomiasis in endemic territories. 

  • However, the vaccination process is underway.

Q2: What Causes Fluke Infection? What is the Treatment for Blood Flukes?


Fluke Infection:

Certain types of accidents cause contaminations of the liver. Individuals are tainted when they swallow growths containing accident hatchlings in crude, half-cooked, dried, salted, or cured freshwater fish or on defiled watercress. 

Treatment for Blood Flukes:

Normally, the treatment of blood accidents is done with the assistance of such medications as Biltricide (Praziquantel), a solitary oral portion is determined by body weight. At 20 mg/kg multiple times for one day or a solitary portion of 40 mg for each kilogram of weight. 

Metronate is taken inside three weeks - when seven days for 10 mg for every kilogram of body weight.

Q3: How Does Blood Fluke Affect People

Ans: Schistosomiasis generally influences poor and rustic networks, especially horticultural and fishing populaces. Ladies doing homegrown tasks in pervaded water, like washing garments, are likewise in danger and can foster female genital schistosomiasis. Insufficient cleanliness and contact with contaminated water make youngsters particularly helpless against disease. 

Relocation to metropolitan zones and populace developments are acquainting the illness with new zones. Expanding populace size and the comparing needs for force and water regularly bring about advancement plans, and ecological alterations work with the transmission. 

With the ascent in the eco-travel industry and travel "off in an unexpected direction", expanding quantities of sightseers are contracting schistosomiasis. Now and again, vacationers present serious intense disease and surprising issues including loss of motion. 

Urogenital schistosomiasis is additionally viewed as a danger factor for HIV contamination, particularly in ladies.