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Schistosomiasis

Disease Details

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Description: Schistosomiasis, also known as bilharzia, is a parasitic disease caused by blood flukes of the genus Schistosoma, leading to various symptoms depending on the affected organs, commonly the intestines or urogenital system.
Type: Schistosomiasis is a parasitic disease, not a genetic condition. It is caused by infection with parasitic worms of the genus Schistosoma. Therefore, it does not involve genetic transmission.
Signs And Symptoms: Many individuals do not experience symptoms. If symptoms do appear, they usually take 4–6 weeks from the time of infection. The first symptom of the disease may be a general feeling of illness. Within 12 hours of infection, an individual may complain of a tingling sensation or light rash, commonly referred to as "swimmer's itch", due to irritation at the point of entrance. The rash that may develop can mimic scabies and other types of rashes. Other symptoms can occur 2–10 weeks later and can include fever, aching, a cough, diarrhea, chills, or gland enlargement. These symptoms can also be related to avian schistosomiasis, which does not cause any further symptoms in humans.The manifestations of schistosomal infection vary over time as the cercariae, and later adult worms and their eggs, migrate through the body. If eggs migrate to the brain or spinal cord, seizures, paralysis, or spinal-cord inflammation are possible.
Prognosis: Schistosomiasis, also known as bilharzia, is a parasitic disease caused by flatworms of the genus Schistosoma. The prognosis for schistosomiasis can vary based on several factors, including the type of Schistosoma species, the intensity of infection, access to treatment, and the presence of complications.

For many individuals, especially in areas where access to medical care is available, the prognosis is generally good with appropriate antiparasitic treatment, such as praziquantel. However, if left untreated, chronic schistosomiasis can lead to serious complications including liver damage, kidney failure, infertility, and bladder cancer. Early diagnosis and treatment are crucial in improving outcomes and reducing long-term health issues.
Onset: The onset of schistosomiasis typically occurs within days to weeks after exposure to contaminated water. Initial symptoms may include a rash or itchy skin, followed by fever, chills, muscle aches, and cough as the parasites migrate in the body. Chronic infection can develop months to years later, leading to more severe health issues such as liver damage, kidney failure, and bowel obstruction.
Prevalence: Schistosomiasis, also known as bilharzia, affects over 240 million people worldwide, primarily in tropical and subtropical regions, especially sub-Saharan Africa. The disease is prevalent in areas with poor sanitation and access to clean water, where the parasitic schistosomes' freshwater snails intermediate hosts are found.
Epidemiology: The disease is found in tropical countries in Africa, the Caribbean, eastern South America, Southeast Asia, and the Middle East. S. mansoni is found in parts of South America and the Caribbean, Africa, and the Middle East; S. haematobium in Africa and the Middle East; and S. japonicum in the Far East. S. mekongi and S. intercalatum are found locally in Southeast Asia and central West Africa, respectively.The disease is endemic in about 75 developing countries and mainly affects people living in rural agricultural and peri-urban areas.
Intractability: Schistosomiasis is not considered to be intractable. It is a treatable disease, most commonly addressed with the antiparasitic medication praziquantel. Effective public health measures, such as improved sanitation and access to clean water, alongside mass drug administration programs, can significantly reduce its prevalence and impact. However, challenges like reinfection and drug resistance can complicate eradication efforts.
Disease Severity: Schistosomiasis, also known as bilharzia, varies in severity depending on the species of the parasite, the level of infection, and the individual's health. It can cause a range of symptoms, from mild irritation and discomfort to severe, life-threatening complications. Chronic infection can lead to significant health problems, including liver damage, kidney failure, infertility, or bladder cancer. Early diagnosis and treatment are crucial to prevent serious outcomes.
Healthcare Professionals: Disease Ontology ID - DOID:1395
Pathophysiology: Schistosomiasis, also known as bilharzia, is caused by parasitic flatworms of the genus Schistosoma. The pathophysiology involves several key stages:

1. **Transmission:** The infection begins when larval forms of the parasite, called cercariae, are released into freshwater by infected snails. These cercariae are free-swimming and penetrate human skin upon contact.

2. **Migration:** Once inside the host, the cercariae transform into schistosomula and migrate through the bloodstream to reach the liver, where they mature into adult worms.

3. **Maturation and Reproduction:** Mature worms pair and migrate to the mesenteric veins of the intestines or the venous plexus of the bladder, depending on the species. Female worms lay eggs, which are the primary cause of pathology.

4. **Egg Excretion and Immune Response:** Eggs can pass out of the body in feces or urine, completing the life cycle if they reach freshwater. However, some eggs become trapped in host tissues, eliciting an immune response.

5. **Granuloma Formation:** The immune response to trapped eggs leads to granuloma formation and chronic inflammation. In the intestines, this can cause diarrhea, abdominal pain, and blood loss. In the liver, it can lead to periportal fibrosis and portal hypertension. In the bladder, it leads to hematuria and can contribute to bladder cancer.

6. **Chronic Disease:** Chronic schistosomiasis can result in significant morbidity, including hepatosplenomegaly, ascites, and organ damage due to persistent inflammation and fibrosis.

Early detection and treatment are crucial to prevent these long-term complications. Treatment typically involves antiparasitic medications such as praziquantel.
Carrier Status: Schistosomiasis, also known as bilharzia, is not characterized by a traditional carrier status as seen in some other diseases. The infection occurs when individuals come into contact with freshwater contaminated with larval forms of the parasite released by infected snails. Humans are definitive hosts where the adult parasites live and reproduce, but they do not carry the disease asymptomatically over long periods in a way that would typically be described as a "carrier" in the context of infectious diseases.
Mechanism: Schistosomiasis, also known as bilharzia, is caused by parasitic flatworms called schistosomes. These parasites primarily affect the urinary tract or intestines.

**Mechanism:**
1. **Life Cycle**: Schistosomiasis begins when larval forms of the parasite, known as cercariae, are released into freshwater by infected snails (the intermediate host). Human infection occurs when these cercariae penetrate the skin.
2. **Migration and Development**: Inside the human host, the larvae migrate through the bloodstream to the liver, where they mature into adult worms.
3. **Egg Production**: Adult worms then migrate to the blood vessels of the bladder or intestines, where they lay eggs. Some of these eggs are excreted in urine or feces, continuing the cycle when they reach water.
4. **Pathology**: The main pathology arises from the immune response to the eggs trapped in tissues, causing inflammation and tissue damage.

**Molecular Mechanisms:**
1. **Parasite Penetration**: Schistosomes secrete proteolytic enzymes like elastase and serine proteases to degrade skin and extracellular matrix proteins, facilitating skin penetration.
2. **Immune Evasion**: Schistosomes can evade the host's immune system by coating themselves with host proteins, such as albumin and immunoglobulins, making them appear as "self" to the host immune system.
3. **Granuloma Formation**: The immune response to schistosome eggs involves the formation of granulomas, which are clusters of immune cells that form around the eggs. Key molecules involved include cytokines like IL-4, IL-13, and TNF-α, which drive the granulomatous and fibrotic responses.
4. **Fibrosis and Tissue Damage**: The chronic inflammation and granuloma formation can lead to fibrosis and damage in organs such as the liver, leading to conditions like portal hypertension or in the urinary tract, leading to obstructive uropathy.

Understanding these mechanisms is crucial for developing targeted treatments and interventions for schistosomiasis.
Treatment: Two drugs, praziquantel and oxamniquine, are available for the treatment of schistosomiasis. They are considered equivalent in relation to efficacy against S. mansoni and safety. Because of praziquantel's lower cost per treatment, and oxaminiquine's lack of efficacy against the urogenital form of the disease caused by S. haematobium, in general praziquantel is considered the first option for treatment. Praziquantel can be safely used in pregnant women and young children. The treatment objective is to cure the disease and to prevent the evolution of the acute to the chronic form of the disease. All cases of suspected schistosomiasis should be treated regardless of presentation because the adult parasite can live in the host for years.Schistosomiasis is treatable by taking by mouth a single dose of the drug praziquantel annually.Praziquantel only eliminates the adult schistosomes, but it is not effective in killing the eggs and immature worms. Live eggs can be excreted by the infected individuals for weeks after treatment with praziquantel. The immature worms can survive and grow up to be adult schistosomes after praziquantel therapy. Thus, it is important to have repeated schistosomiasis testing of the stool and/or urine around 4–6 weeks after praziquantel therapy. Treatment of praziquantel may be repeated to ensure complete elimination of the parasite.The WHO has developed guidelines for community treatment based on the impact the disease has on children in villages in which it is common:
When a village reports more than 50 per cent of children have blood in their urine, everyone in the village receives treatment.
When 20 to 50 percent of children have bloody urine, only school-age children are treated.
When fewer than 20 percent of children have symptoms, mass treatment is not implemented.Other possible treatments include a combination of praziquantel with metrifonate, artesunate, or mefloquine. A Cochrane review found tentative evidence that when used alone, metrifonate was as effective as praziquantel. Mefloquine, which has previously been used to treat and prevent malaria, was recognised in 2008–2009 to be effective against schistosomes.Historically, antimony potassium tartrate remained the treatment of choice for schistosomiasis until the development of praziquantel in the 1980s.Post-treatment monitoring
Osteopontin (OPN) is a promising tool for monitoring praziquantel efficacy and post-treatment fibrosis regression as (OPN) expression is modulated by S. mansoni egg antigens and its levels correlate with severity of schistosomiasis fibrosis and portal hypertension in mice and humans. Praziquantel pharmacotherapy reduces systemic OPN levels and liver collagen content in mice.
Compassionate Use Treatment: For schistosomiasis, the primary treatment is Praziquantel, which is both effective and widely used. However, in certain cases where standard treatments are not effective or suitable, compassionate use or off-label options might be considered:

1. **Oxamniquine**: This drug is mainly used as a second-line treatment for Schistosoma mansoni infections, especially in areas where Praziquantel resistance or intolerance is a concern.

2. **Artemisinin derivatives**: Though primarily antimalarial medications, artemisinin derivatives have shown some efficacy against Schistosoma species in experimental studies. These are still considered investigational for this purpose.

3. **Metrifonate**: This is another alternative treatment that has been used for Schistosoma haematobium infections, but its use is limited and less common now due to the greater reliance on Praziquantel.

4. **Anti-fibrotic agents**: Because schistosomiasis can lead to significant organ damage, particularly in the liver, some anti-fibrotic agents are being investigated to treat or reverse this damage. These are still experimental and not part of standard treatment protocols.

5. **Vaccine research**: There are ongoing clinical trials focused on developing vaccines against schistosomiasis, which could provide a long-term solution but are not yet available for routine use.

Patients often need to be part of a clinical trial or have specific medical need for compassionate use access. Always consult healthcare providers or specialists for the most appropriate treatment options.
Lifestyle Recommendations: For individuals affected by schistosomiasis, it is crucial to adopt certain lifestyle recommendations to manage the disease and prevent re-infection:

1. **Avoid Contact with Contaminated Water**: Stay away from freshwater bodies in endemic areas where the parasitic worms are known to thrive, such as lakes, rivers, and ponds.

2. **Safe Water Practices**: Boil or filter water before use for drinking, bathing, or washing, to ensure it is free of parasites.

3. **Proper Sanitation**: Use sanitary facilities to avoid contaminating freshwater with human waste, which can perpetuate the life cycle of the parasites.

4. **Health Monitoring**: Regular medical check-ups and prompt treatment if symptoms arise, to manage the infection and avoid complications.

5. **Protective Clothing**: Wear protective clothing such as boots and gloves if contact with potentially contaminated water is unavoidable.

6. **Public Awareness**: Engage in community efforts to improve public awareness about schistosomiasis transmission and prevention.

Implementing these measures can significantly reduce the risk of schistosomiasis and help manage its impact on health.
Medication: The primary medications used to treat schistosomiasis are praziquantel and oxamniquine. Praziquantel is the most commonly used and is effective against all major species of schistosomes. Oxamniquine is an alternative, mainly used in regions where Schistosoma mansoni is prevalent.
Repurposable Drugs: Several existing drugs have shown potential for repurposing in the treatment of schistosomiasis, though their efficacy may vary and require further research. Some of these repurposable drugs include:

1. **Praziquantel**: Already the primary treatment for schistosomiasis, there's ongoing research to improve its efficacy and reduce resistance.
2. **Oxamniquine**: Previously used as an alternative to praziquantel, particularly for Schistosoma mansoni.
3. **Artemisinin derivatives**: Originally developed for malaria, these drugs have shown some anti-schistosomal activity.
4. **Mefloquine**: Another antimalarial that has demonstrated effectiveness against Schistosoma species in some studies.
5. **Miltefosine**: Primarily used for leishmaniasis, showing some promise in treating schistosomiasis.

Further clinical trials and studies are necessary to confirm their effectiveness and safety in treating schistosomiasis.
Metabolites: Schistosomiasis, also known as bilharzia, involves the following metabolites in the host:

1. **Amino Acids:** Altered levels of amino acids such as tryptophan and kynurenine have been observed.
2. **Lipids:** Lipid metabolism can be disturbed, with notable changes in phospholipid and sphingolipid profiles.
3. **Carbohydrates:** Glycolysis intermediates can be altered, reflecting the impact of the parasite on the host's energy metabolism.
4. **Proteins:** Changes in protein metabolites, including those involved in the immune response, are common.

Studies often leverage metabolomics to understand these alterations, aiding in the diagnosis, monitoring of disease progression, and development of treatments.
Nutraceuticals: Nutraceuticals have been explored as a complementary approach for schistosomiasis, potentially aiding in immune modulation and reducing the severity of the disease. Examples include antioxidants like vitamins C and E, which may help mitigate oxidative stress caused by the parasite.

Nanotechnology in schistosomiasis research involves developing nanoscale drug delivery systems to enhance the efficacy and reduce the toxicity of antiparasitic drugs. These nanocarriers can target the parasite more specifically, improving treatment outcomes and potentially reducing side effects.
Peptides: For schistosomiasis, various peptides have been studied for their potential therapeutic and diagnostic value. These peptides can target specific proteins associated with the schistosome parasite, potentially inhibiting its life cycle or enhancing the immune response against the infection. The "nan" likely refers to nanotechnology, which has been explored for the development of novel diagnostic tools and treatments for schistosomiasis, such as nanoparticle-based drug delivery systems to improve the efficacy and specificity of antiparasitic drugs.