Schistosoma/Schistosomiasis

Schistosomiasis is an infection caused by Schistosoma, a trematode. Schistosomiasis occurs in developing countries with poor sanitation. Freshwater snails are the intermediate host and are transmitted to humans through skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Structure and Function of the Skin contact with contaminated fresh water. The clinical presentation occurs as a result of the host’s immune response to antigens from the eggs. Most patients are asymptomatic, but others may develop acute schistosome dermatitis, acute schistosomiasis syndrome, or chronic schistosomiasis. The diagnosis can be made with microscopic evaluation of the urine or feces, serology, or PCR PCR Polymerase chain reaction (PCR) is a technique that amplifies DNA fragments exponentially for analysis. The process is highly specific, allowing for the targeting of specific genomic sequences, even with minuscule sample amounts. The PCR cycles multiple times through 3 phases: denaturation of the template DNA, annealing of a specific primer to the individual DNA strands, and synthesis/elongation of new DNA molecules. Polymerase Chain Reaction (PCR). The treatment for schistosomiasis is praziquantel.

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Editorial responsibility: Stanley Oiseth, Lindsay Jones, Evelin Maza

Table of Contents

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General Characteristics and Epidemiology

General features of Schistosoma

  • Trematode 
  • Parasitic flatworm
  • Eggs:
    • Round or oval shaped
    • Hinged at 1 end
  • Adults:
    • Elongated
    • Tubular
    • 10–20 mm long
    • Males are shorter than females.
    • Oral and ventral suckers
Schistosoma eggs

Photomicrograph depicting a grouping of 3 different species of Schistosoma eggs: S. japonicum, S. mansoni, and S. haematobium.

Image: “21017” by CDC/Dr. Brodsky. License: Public Domain

Clinically relevant species

  • GI disease:
    • S. mansoni
    • S. japonicum
    • S. mekongi
    • S. intercalatum
  • Genitourinary tract disease: S. haematobium

Epidemiology

  • Worldwide annual incidence: 200–300 million
  • Men > women
  • Children and adolescents > adults
  • Mortality rate: 0.3 per 100,000 cases

Geographic distribution

  • S. mansoni:
    • Sub-Saharan Africa
    • South America
    • Caribbean
    • Middle East
  • S. japonicum:
    • China
    • Philippines
    • Thailand
    • Indonesia
  • S. haematobium:
    • Africa
    • Middle East
  • S. mekongi: Southeast Asia
  • S. intercalatum: Central and West Africa

Pathogenesis

Reservoir

  • Humans
  • Mammals:
    • Domesticated and wild animals
    • Livestock
  • Freshwater snails are intermediate hosts.

Transmission

Transmission occurs through skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Structure and Function of the Skin contact with infected fresh water.

Host risk factors

Schistosoma occupies freshwater environments in areas with poor sewerage management.

  • Recreational exposures:  
    • Swimming
    • Playing in water or mud
  • Occupational exposures: 
    • Fishing
    • Laundry

Life cycle

  • Schistosoma larvae (miracidia) penetrate a snail (intermediate host) → asexual reproduction and maturation into cercariae → released from the snail into water
  • Cercariae penetrate human skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Structure and Function of the Skin → become schistosomulae after shedding their forked tails
  • Migration into the bloodstream → infect the liver Liver The liver is the largest gland in the human body. The liver is found in the superior right quadrant of the abdomen and weighs approximately 1.5 kilograms. Its main functions are detoxification, metabolism, nutrient storage (e.g., iron and vitamins), synthesis of coagulation factors, formation of bile, filtration, and storage of blood. Liver → maturation and reproduction
  • Adult worms move through the portal vessels to the mesenteric venules of the intestines.
  • The females lay eggs → penetrate the intestines → excreted in feces
  • Eggs hatch in water → cycle continues
  • Note: S. haematobium occupy the vesical venous plexus → eggs are excreted in the urine
The life cycle of schistosoma

The life cycle of Schistosoma

Image by Lecturio.

Pathophysiology

Clinical disease is caused by:

  • Movement of eggs through the splanchnic venous system to:
    • Liver
    • Lungs Lungs Lungs are the main organs of the respiratory system. Lungs are paired viscera located in the thoracic cavity and are composed of spongy tissue. The primary function of the lungs is to oxygenate blood and eliminate CO2. Lungs
    • Spleen Spleen The spleen is the largest lymphoid organ in the body, located in the LUQ of the abdomen, superior to the left kidney and posterior to the stomach at the level of the 9th-11th ribs just below the diaphragm. The spleen is highly vascular and acts as an important blood filter, cleansing the blood of pathogens and damaged erythrocytes. Spleen
    • Brain
    • Spinal cord Spinal cord The spinal cord is the major conduction pathway connecting the brain to the body; it is part of the CNS. In cross section, the spinal cord is divided into an H-shaped area of gray matter (consisting of synapsing neuronal cell bodies) and a surrounding area of white matter (consisting of ascending and descending tracts of myelinated axons). Spinal Cord
  • Immune response to proteins and carbohydrates Carbohydrates Carbohydrates are one of the 3 macronutrients, along with fats and proteins, serving as a source of energy to the body. These biomolecules store energy in the form of glycogen and starch, and play a role in defining the cellular structure (e.g., cellulose). Basics of Carbohydrates secreted by the eggs leads to:
    • Bowel inflammation Inflammation Inflammation is a complex set of responses to infection and injury involving leukocytes as the principal cellular mediators in the body's defense against pathogenic organisms. Inflammation is also seen as a response to tissue injury in the process of wound healing. The 5 cardinal signs of inflammation are pain, heat, redness, swelling, and loss of function. Inflammation → blood loss and scarring
    • Periportal fibrosis → portal hypertension Portal hypertension Portal hypertension is increased pressure in the portal venous system. This increased pressure can lead to splanchnic vasodilation, collateral blood flow through portosystemic anastomoses, and increased hydrostatic pressure. There are a number of etiologies, including cirrhosis, right-sided congestive heart failure, schistosomiasis, portal vein thrombosis, hepatitis, and Budd-Chiari syndrome. Portal Hypertension and esophageal varices
    • Bladder inflammation Inflammation Inflammation is a complex set of responses to infection and injury involving leukocytes as the principal cellular mediators in the body's defense against pathogenic organisms. Inflammation is also seen as a response to tissue injury in the process of wound healing. The 5 cardinal signs of inflammation are pain, heat, redness, swelling, and loss of function. Inflammation → pseudopolyps and bladder cancer

Clinical Presentation

Most patients are asymptomatic. Symptomatic individuals can present in several ways:

Acute schistosome dermatitis

Also known as “swimmer’s itch”:

  • Pruritic rash at the site of cercariae entry:
    • May be papular or urticarial
    • Due to a hypersensitivity reaction
  • Feet and lower legs are more often affected.
Swimmer's itch

A papular rash due to acute schistosome dermatitis:
The hypersensitivity reaction occurs when skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Structure and Function of the Skin is penetrated by Schistosoma cercariae.

Image: “5249” by CDC. License: Public Domain

Acute schistosomiasis syndrome (Katayama fever Fever Fever is defined as a measured body temperature of at least 38°C (100.4°F). Fever is caused by circulating endogenous and/or exogenous pyrogens that increase levels of prostaglandin E2 in the hypothalamus. Fever is commonly associated with chills, rigors, sweating, and flushing of the skin. Fever)

Occurs due to a systemic hypersensitivity reaction 3–8 weeks after the initial infection:

  • Fever
  • Chills
  • Fatigue
  • Urticaria Urticaria Urticaria is raised, well-circumscribed areas (wheals) of edema (swelling) and erythema (redness) involving the dermis and epidermis with associated pruritus (itch). Urticaria is not a single disease but rather is a reaction pattern representing cutaneous mast cell degranulation. Urticaria (Hives)
  • Angioedema Angioedema Angioedema is a localized, self-limited (but potentially life-threatening), nonpitting, asymmetrical edema occurring in the deep layers of the skin and mucosal tissue. The common underlying pathophysiology involves inflammatory mediators triggering significant vasodilation and increased capillary permeability. Angioedema
  • Nonproductive cough
  • Myalgias
  • Arthralgias
  • Abdominal pain Pain Pain has accompanied humans since they first existed, first lamented as the curse of existence and later understood as an adaptive mechanism that ensures survival. Pain is the most common symptomatic complaint and the main reason why people seek medical care. Physiology of Pain
  • Diarrhea Diarrhea Diarrhea is defined as ≥ 3 watery or loose stools in a 24-hour period. There are a multitude of etiologies, which can be classified based on the underlying mechanism of disease. The duration of symptoms (acute or chronic) and characteristics of the stools (e.g., watery, bloody, steatorrheic, mucoid) can help guide further diagnostic evaluation. Diarrhea

Chronic schistosomiasis

Presentation can vary depending on the number of eggs in the tissues, the infection site, and the immune response of the host.

Intestinal schistosomiasis:

  • Abdominal pain Pain Pain has accompanied humans since they first existed, first lamented as the curse of existence and later understood as an adaptive mechanism that ensures survival. Pain is the most common symptomatic complaint and the main reason why people seek medical care. Physiology of Pain
  • Decreased appetite
  • Diarrhea Diarrhea Diarrhea is defined as ≥ 3 watery or loose stools in a 24-hour period. There are a multitude of etiologies, which can be classified based on the underlying mechanism of disease. The duration of symptoms (acute or chronic) and characteristics of the stools (e.g., watery, bloody, steatorrheic, mucoid) can help guide further diagnostic evaluation. Diarrhea
  • Intestinal bleeding
  • Complications:
    • Bowel strictures
    • Intestinal polyps and dysplasia

Hepatosplenic schistosomiasis:

  • Hepatosplenomegaly
  • Complications of portal hypertension Portal hypertension Portal hypertension is increased pressure in the portal venous system. This increased pressure can lead to splanchnic vasodilation, collateral blood flow through portosystemic anastomoses, and increased hydrostatic pressure. There are a number of etiologies, including cirrhosis, right-sided congestive heart failure, schistosomiasis, portal vein thrombosis, hepatitis, and Budd-Chiari syndrome. Portal Hypertension:
    • Esophageal varices (bleeding risk)
    • Pulmonary hypertension Pulmonary Hypertension Pulmonary hypertension (PH) or pulmonary arterial hypertension (PAH) is characterized by elevated pulmonary arterial pressure, which can lead to chronic progressive right heart failure. Pulmonary hypertension is grouped into 5 categories based on etiology, which include primary PAH, and PH due to cardiac disease, lung or hypoxic disease, chronic thromboembolic disease, and multifactorial or unclear etiologies. Pulmonary Hypertension (consequence of portosystemic collaterals allowing egg embolization to the lungs)
  • Note: Liver function is not compromised.

Genitourinary schistosomiasis:

  • Dysuria
  • Urinary frequency
  • Terminal hematuria (blood at the end of urine stream)
  • Hemospermia
  • Genital ulcerations
  • Complications:
    • Ureteral strictures
    • Bladder neck obstruction 
    • Hydronephrosis Hydronephrosis Hydronephrosis is dilation of the renal collecting system as a result of the obstruction of urine outflow. Hydronephrosis can be unilateral or bilateral. Nephrolithiasis is the most common cause of hydronephrosis in young adults, while prostatic hyperplasia and neoplasm are seen in older patients. Hydronephrosis
    • Bladder cancer
    • Infertility Infertility Infertility is the inability to conceive in the context of regular intercourse. The most common causes of infertility in women are related to ovulatory dysfunction or tubal obstruction, whereas, in men, abnormal sperm is a common cause. Infertility (due to ovary or fallopian tube Fallopian Tube A pair of highly specialized canals extending from the uterus to its corresponding ovary. They provide the means for ovum transport from the ovaries and they are the site of the ovum's final maturation and fertilization. The fallopian tube consists of an interstitium, an isthmus, an ampulla, an infundibulum, and fimbriae. Its wall consists of three layers: serous, muscular, and an internal mucosal layer lined with both ciliated and secretory cells. Uterus, Cervix, and Fallopian Tubes involvement)

Neuroschistosomiasis:

  • Acute myelopathy
  • Transverse myelitis
  • Intracerebral lesions
  • Multifocal encephalopathy

Diagnosis, Management, and Prevention

Diagnosis

  • Microscopic examination of urine and stool for eggs
  • Serologic testing:
    • ELISA
    • Indirect hemagglutination
    • Immunofluorescent antibody test
  • Antigen testing:
    • Schistosome circulating antigen
    • Circulating cathodic antigen
    • PCR PCR Polymerase chain reaction (PCR) is a technique that amplifies DNA fragments exponentially for analysis. The process is highly specific, allowing for the targeting of specific genomic sequences, even with minuscule sample amounts. The PCR cycles multiple times through 3 phases: denaturation of the template DNA, annealing of a specific primer to the individual DNA strands, and synthesis/elongation of new DNA molecules. Polymerase Chain Reaction (PCR)
  • Parasite DNA DNA The molecule DNA is the repository of heritable genetic information. In humans, DNA is contained in 23 chromosome pairs within the nucleus. The molecule provides the basic template for replication of genetic information, RNA transcription, and protein biosynthesis to promote cellular function and survival. DNA Types and Structure testing ( PCR PCR Polymerase chain reaction (PCR) is a technique that amplifies DNA fragments exponentially for analysis. The process is highly specific, allowing for the targeting of specific genomic sequences, even with minuscule sample amounts. The PCR cycles multiple times through 3 phases: denaturation of the template DNA, annealing of a specific primer to the individual DNA strands, and synthesis/elongation of new DNA molecules. Polymerase Chain Reaction (PCR))
  • CT and MRI may show nonspecific changes for neuroschistosomiasis.

Management

  • Anthelmintic therapy (praziquantel):
    • ↑ Calcium ion permeability in adult worms
    • Damage to the worm induces a host immune response.
  • Corticosteroids to reduce inflammation Inflammation Inflammation is a complex set of responses to infection and injury involving leukocytes as the principal cellular mediators in the body's defense against pathogenic organisms. Inflammation is also seen as a response to tissue injury in the process of wound healing. The 5 cardinal signs of inflammation are pain, heat, redness, swelling, and loss of function. Inflammation in:
    • Acute schistosomiasis syndrome
    • Neuroschistosomiasis

Prevention

Personal protection in endemic areas:

  • Avoid swimming or wading in freshwater.
  • Vigorously towel off after brief, accidental water exposure.
  • Wear protective clothing and footwear.
  • Boil bath water.

Control strategies:

  • Sanitation programs (dispose of human urine and feces away from freshwater sources)
  • Snail control
  • Community-based mass-treatment programs

Comparison of Similar Helminths

Table: Comparison of similar helminths and their associated diseases
Organism Enterobius Enterobius Enterobiasis is a helminth infection caused by Enterobius vermicularis, also known as a pinworm. This infection is typically seen in children and is transmitted through the fecal-oral route. The primary clinical feature is anal pruritus, but patients are often asymptomatic. Enterobius/Enterobiasis vermicularis Toxocara Toxocara Toxocariasis is caused by the nematodes Toxocara canis and T. cati. These species frequently infect dogs and cats and are most commonly transmitted to humans via accidental ingestion of eggs through the fecal-oral route. Toxocara are not able to complete their life cycle in humans, but they do migrate to organs (including the liver, lungs, heart, brain, and eyes), where they cause inflammation and tissue damage. Toxocariasis canis Ascaris Ascaris Ascaris is a genus of parasitic nematodes. The infection, ascariasis, is most often caused by A. lumbricoides. Transmission occurs primarily via ingestion of water or food contaminated with Ascaris eggs. Most patients with ascariasis are asymptomatic. Ascaris/Ascariasis lumbricoides Strongyloides stercoralis Schistosoma mansoni
Characteristics Nematode Nematode Nematode Nematode Trematode
Reservoir Humans Dogs Humans
  • Humans
  • Dogs
  • Cats
Humans
Transmission Fecal–oral Fecal–oral Fecal–oral Skin contact with contaminated soil Skin contact with contaminated water
Clinical
  • Pruritus ani
  • Abdominal pain Pain Pain has accompanied humans since they first existed, first lamented as the curse of existence and later understood as an adaptive mechanism that ensures survival. Pain is the most common symptomatic complaint and the main reason why people seek medical care. Physiology of Pain and vomiting are less common.
  • Visceral larva migrans
  • Ocular larva migrans
  • Cough
  • Wheezing Wheezing Wheezing is an abnormal breath sound characterized by a whistling noise that can be relatively high-pitched and shrill (more common) or coarse. Wheezing is produced by the movement of air through narrowed or compressed small (intrathoracic) airways. Wheezing
  • Hemoptysis Hemoptysis Hemoptysis is defined as the expectoration of blood originating in the lower respiratory tract. Hemoptysis is a consequence of another disease process and can be classified as either life threatening or non-life threatening. Hemoptysis can result in significant morbidity and mortality due to both drowning (reduced gas exchange as the lungs fill with blood) and hemorrhagic shock. Hemoptysis
  • Abdominal cramping
  • Nausea
  • Malnutrition Malnutrition Malnutrition is a clinical state caused by an imbalance or deficiency of calories and/or micronutrients and macronutrients. The 2 main manifestations of acute severe malnutrition are marasmus (total caloric insufficiency) and kwashiorkor (protein malnutrition with characteristic edema). Malnutrition in children in resource-limited countries
  • Cough
  • Wheezing Wheezing Wheezing is an abnormal breath sound characterized by a whistling noise that can be relatively high-pitched and shrill (more common) or coarse. Wheezing is produced by the movement of air through narrowed or compressed small (intrathoracic) airways. Wheezing
  • Abdominal pain Pain Pain has accompanied humans since they first existed, first lamented as the curse of existence and later understood as an adaptive mechanism that ensures survival. Pain is the most common symptomatic complaint and the main reason why people seek medical care. Physiology of Pain
  • Diarrhea Diarrhea Diarrhea is defined as ≥ 3 watery or loose stools in a 24-hour period. There are a multitude of etiologies, which can be classified based on the underlying mechanism of disease. The duration of symptoms (acute or chronic) and characteristics of the stools (e.g., watery, bloody, steatorrheic, mucoid) can help guide further diagnostic evaluation. Diarrhea
  • Rash
  • Swimmer’s itch
  • Katayama fever Fever Fever is defined as a measured body temperature of at least 38°C (100.4°F). Fever is caused by circulating endogenous and/or exogenous pyrogens that increase levels of prostaglandin E2 in the hypothalamus. Fever is commonly associated with chills, rigors, sweating, and flushing of the skin. Fever
  • Chronic infections lead to granuloma formation, causing brain, lung, intestinal, and liver Liver The liver is the largest gland in the human body. The liver is found in the superior right quadrant of the abdomen and weighs approximately 1.5 kilograms. Its main functions are detoxification, metabolism, nutrient storage (e.g., iron and vitamins), synthesis of coagulation factors, formation of bile, filtration, and storage of blood. Liver disease.
Diagnosis
  • Clinical
  • Cellophane tape test
  • Serology
  • Biopsy
Stool analysis
  • Stool analysis
  • Serology
  • Stool analysis
  • Serology
Management
  • Albendazole
  • Mebendazole
  • Pyrantel pamoate
  • Albendazole
  • Mebendazole
  • Albendazole
  • Mebendazole
  • Ivermectin
  • Albendazole
Praziquantel
Prevention Good hygiene
  • Good hygiene
  • Deworm dogs.
  • Proper disposal of dog feces
  • Good hygiene
  • Clean raw fruits and vegetables before consuming.
  • Wear shoes and protective clothing.
  • Improve sanitation.
  • Avoid swimming or bathing in contaminated water.
  • Drink boiled or bottled water.
  • Improve sanitation.

Differential Diagnosis

  • Gastroenteritis Gastroenteritis Gastroenteritis is inflammation of the stomach and intestines, commonly caused by infections from bacteria, viruses, or parasites. Transmission may be foodborne, fecal-oral, or through animal contact. Common clinical features include abdominal pain, diarrhea, vomiting, fever, and dehydration. Gastroenteritis: inflammation Inflammation Inflammation is a complex set of responses to infection and injury involving leukocytes as the principal cellular mediators in the body's defense against pathogenic organisms. Inflammation is also seen as a response to tissue injury in the process of wound healing. The 5 cardinal signs of inflammation are pain, heat, redness, swelling, and loss of function. Inflammation of the stomach Stomach The stomach is a muscular sac in the upper left portion of the abdomen that plays a critical role in digestion. The stomach develops from the foregut and connects the esophagus with the duodenum. Structurally, the stomach is C-shaped and forms a greater and lesser curvature and is divided grossly into regions: the cardia, fundus, body, and pylorus. Stomach and intestines, which is commonly caused by infections from bacteria Bacteria Bacteria are prokaryotic single-celled microorganisms that are metabolically active and divide by binary fission. Some of these organisms play a significant role in the pathogenesis of diseases. Bacteriology: Overview, viruses, or parasites. Clinical features include abdominal pain Pain Pain has accompanied humans since they first existed, first lamented as the curse of existence and later understood as an adaptive mechanism that ensures survival. Pain is the most common symptomatic complaint and the main reason why people seek medical care. Physiology of Pain, diarrhea, vomiting, fever Fever Fever is defined as a measured body temperature of at least 38°C (100.4°F). Fever is caused by circulating endogenous and/or exogenous pyrogens that increase levels of prostaglandin E2 in the hypothalamus. Fever is commonly associated with chills, rigors, sweating, and flushing of the skin. Fever, and dehydration Dehydration Volume status is a balance between water and solutes, the majority of which is Na. Volume depletion refers to a loss of both water and Na, whereas dehydration refers only to a loss of water. Dehydration is primarily caused by decreased water intake and presents with increased thirst and can progress to altered mental status and low blood pressure if severe. Volume Depletion and Dehydration. Diagnostic testing with stool analysis or culture is not always required, but can help determine the etiology. Most cases are self-limited; therefore, the only required treatment is supportive therapy (fluids). 
  • Inflammatory bowel disease (IBD): chronic inflammation Inflammation Inflammation is a complex set of responses to infection and injury involving leukocytes as the principal cellular mediators in the body's defense against pathogenic organisms. Inflammation is also seen as a response to tissue injury in the process of wound healing. The 5 cardinal signs of inflammation are pain, heat, redness, swelling, and loss of function. Inflammation of the GI tract due to a cell-mediated immune response to the GI mucosa. Crohn’s disease and ulcerative colitis Ulcerative colitis Ulcerative colitis (UC) is an idiopathic inflammatory condition that involves the mucosal surface of the colon. It is a type of inflammatory bowel disease (IBD), along with Crohn's disease (CD). The rectum is always involved, and inflammation may extend proximally through the colon. Ulcerative Colitis are types of IBD. Symptoms include diarrhea, abdominal pain Pain Pain has accompanied humans since they first existed, first lamented as the curse of existence and later understood as an adaptive mechanism that ensures survival. Pain is the most common symptomatic complaint and the main reason why people seek medical care. Physiology of Pain, weight loss, and extraintestinal manifestations. Diagnosis includes imaging, endoscopy, and biopsy. Management involves steroids, aminosalicylates, immunomodulators, and biologic agents.
  • Viral hepatitis: liver Liver The liver is the largest gland in the human body. The liver is found in the superior right quadrant of the abdomen and weighs approximately 1.5 kilograms. Its main functions are detoxification, metabolism, nutrient storage (e.g., iron and vitamins), synthesis of coagulation factors, formation of bile, filtration, and storage of blood. Liver inflammation Inflammation Inflammation is a complex set of responses to infection and injury involving leukocytes as the principal cellular mediators in the body's defense against pathogenic organisms. Inflammation is also seen as a response to tissue injury in the process of wound healing. The 5 cardinal signs of inflammation are pain, heat, redness, swelling, and loss of function. Inflammation caused by infection from a hepatitis virus Virus Viruses are infectious, obligate intracellular parasites composed of a nucleic acid core surrounded by a protein capsid. Viruses can be either naked (non-enveloped) or enveloped. The classification of viruses is complex and based on many factors, including type and structure of the nucleoid and capsid, the presence of an envelope, the replication cycle, and the host range. Virology: Overview. Patients may present with a viral prodrome of fever Fever Fever is defined as a measured body temperature of at least 38°C (100.4°F). Fever is caused by circulating endogenous and/or exogenous pyrogens that increase levels of prostaglandin E2 in the hypothalamus. Fever is commonly associated with chills, rigors, sweating, and flushing of the skin. Fever, anorexia, and nausea. Right upper quadrant abdominal pain Pain Pain has accompanied humans since they first existed, first lamented as the curse of existence and later understood as an adaptive mechanism that ensures survival. Pain is the most common symptomatic complaint and the main reason why people seek medical care. Physiology of Pain, jaundice Jaundice Jaundice is the abnormal yellowing of the skin and/or sclera caused by the accumulation of bilirubin. Hyperbilirubinemia is caused by either an increase in bilirubin production or a decrease in the hepatic uptake, conjugation, or excretion of bilirubin. Jaundice, and transaminitis also occur. Diagnosis is made with viral serologic testing to differentiate viral hepatitis from schistosomiasis. Management of acute hepatitis is supportive.
  • Acute pancreatitis Acute pancreatitis Acute pancreatitis is an inflammatory disease of the pancreas due to autodigestion. Common etiologies include gallstones and excessive alcohol use. Patients typically present with epigastric pain radiating to the back. Acute Pancreatitis: inflammation Inflammation Inflammation is a complex set of responses to infection and injury involving leukocytes as the principal cellular mediators in the body's defense against pathogenic organisms. Inflammation is also seen as a response to tissue injury in the process of wound healing. The 5 cardinal signs of inflammation are pain, heat, redness, swelling, and loss of function. Inflammation of the pancreas Pancreas The pancreas lies mostly posterior to the stomach and extends across the posterior abdominal wall from the duodenum on the right to the spleen on the left. This organ has both exocrine and endocrine tissue. Pancreas. Patients present with a sudden onset of severe epigastric pain Pain Pain has accompanied humans since they first existed, first lamented as the curse of existence and later understood as an adaptive mechanism that ensures survival. Pain is the most common symptomatic complaint and the main reason why people seek medical care. Physiology of Pain, which is typically sharp and radiates to the back. Acute pancreatitis Acute pancreatitis Acute pancreatitis is an inflammatory disease of the pancreas due to autodigestion. Common etiologies include gallstones and excessive alcohol use. Patients typically present with epigastric pain radiating to the back. Acute Pancreatitis is associated with alcohol abuse and gallstones. Diagnosis is based on abdominal pain Pain Pain has accompanied humans since they first existed, first lamented as the curse of existence and later understood as an adaptive mechanism that ensures survival. Pain is the most common symptomatic complaint and the main reason why people seek medical care. Physiology of Pain, lipase elevation, and/or imaging (reveals pancreatic edema Edema Edema is a condition in which excess serous fluid accumulates in the body cavity or interstitial space of connective tissues. Edema is a symptom observed in several medical conditions. It can be categorized into 2 types, namely, peripheral (in the extremities) and internal (in an organ or body cavity). Edema). Management includes bowel rest, pain Pain Pain has accompanied humans since they first existed, first lamented as the curse of existence and later understood as an adaptive mechanism that ensures survival. Pain is the most common symptomatic complaint and the main reason why people seek medical care. Physiology of Pain control, and IV fluid hydration.
  • Contact dermatitis: an erythematous, papular dermatitis often with areas of vesiculation (due to direct skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Structure and Function of the Skin exposure to an offending irritant with a direct cytotoxic effect). Diagnosis is based on history and physical exam findings. Management includes avoidance of offending irritants, adoption of protective measures, and the use of emollients and moisturizers. Topical steroids are the 1st-line intervention.
  • Urinary tract Urinary tract The urinary tract is located in the abdomen and pelvis and consists of the kidneys, ureters, urinary bladder, and urethra. The structures permit the excretion of urine from the body. Urine flows from the kidneys through the ureters to the urinary bladder and out through the urethra. Urinary Tract infection: a wide spectrum disease ranging from simple cystitis to severe pyelonephritis Pyelonephritis Pyelonephritis is infection affecting the renal pelvis and the renal parenchyma. This condition arises mostly as a complication of bladder infection that ascends to the upper urinary tract. Pyelonephritis can be acute or chronic (which results from persistent or chronic infections). Typical acute symptoms are flank pain, fever, and nausea with vomiting. T Pyelonephritis and Perinephric Abscess. Depending on the location of the infection, patients can present with dysuria, urinary urgency/frequency, suprapubic pain Pain Pain has accompanied humans since they first existed, first lamented as the curse of existence and later understood as an adaptive mechanism that ensures survival. Pain is the most common symptomatic complaint and the main reason why people seek medical care. Physiology of Pain, and/or fever Fever Fever is defined as a measured body temperature of at least 38°C (100.4°F). Fever is caused by circulating endogenous and/or exogenous pyrogens that increase levels of prostaglandin E2 in the hypothalamus. Fever is commonly associated with chills, rigors, sweating, and flushing of the skin. Fever. Urinalysis and culture establish the diagnosis. Management options include oral or IV antibiotics. 
  • Diphyllobothriasis Diphyllobothriasis Diphyllobothriasis represents an intestinal parasitic infection caused by the cestode Diphyllobothrium. Diphyllobothriasis is acquired by ingestion of late larvae in undercooked or raw fish. The clinical presentation of diphyllobothriasis varies from asymptomatic, nonspecific symptoms to intestinal obstruction, and/or vitamin B12 deficiency. Diphyllobothrium/Diphyllobothriasis: an intestinal parasitic infection caused by Diphyllobothrium Diphyllobothrium Diphyllobothriasis represents an intestinal parasitic infection caused by the cestode Diphyllobothrium. Diphyllobothriasis is acquired by ingestion of late larvae in undercooked or raw fish. The clinical presentation of diphyllobothriasis varies from asymptomatic, nonspecific symptoms to intestinal obstruction, and/or vitamin B12 deficiency. Diphyllobothrium/Diphyllobothriasis, a cestode, and acquired by ingestion of larvae in undercooked or raw fish from cold-water lake regions. Patients present with abdominal discomfort, diarrhea, glossitis, and anemia Anemia Anemia is a condition in which individuals have low Hb levels, which can arise from various causes. Anemia is accompanied by a reduced number of RBCs and may manifest with fatigue, shortness of breath, pallor, and weakness. Subtypes are classified by the size of RBCs, chronicity, and etiology. Anemia: Overview Diphyllobothriasis Diphyllobothriasis Diphyllobothriasis represents an intestinal parasitic infection caused by the cestode Diphyllobothrium. Diphyllobothriasis is acquired by ingestion of late larvae in undercooked or raw fish. The clinical presentation of diphyllobothriasis varies from asymptomatic, nonspecific symptoms to intestinal obstruction, and/or vitamin B12 deficiency. Diphyllobothrium/Diphyllobothriasis is diagnosed with microscopic examination of the stool for ova and parasites. Management includes anthelmintic therapy such as praziqunatel.
  • Taeniasis Taeniasis Taenia belong to the Cestoda class of helminths. Humans are infected with these tapeworms by eating undercooked beef (T. saginata) or pork (T. solium and T. asiatica). Taeniasis is often asymptomatic, but the ingestion of larvae can cause abdominal discomfort, nausea, and constipation or diarrhea. Taenia/Taeniasis: a tapeworm infection occurring after consumption of raw or undercooked beef or pork. Patients are generally asymptomatic, but may present with the passage of proglottids. Taenia Taenia Taenia belong to the Cestoda class of helminths. Humans are infected with these tapeworms by eating undercooked beef (T. saginata) or pork (T. solium and T. asiatica). Taeniasis is often asymptomatic, but the ingestion of larvae can cause abdominal discomfort, nausea, and constipation or diarrhea. Taenia/Taeniasis solium presentation may rarely include seizures Seizures A seizure is abnormal electrical activity of the neurons in the cerebral cortex that can manifest in numerous ways depending on the region of the brain affected. Seizures consist of a sudden imbalance that occurs between the excitatory and inhibitory signals in cortical neurons, creating a net excitation. The 2 major classes of seizures are focal and generalized. Seizures from neurocysticercosis. Diagnosis requires a high index of suspicion, a stool analysis (for ova and parasites), or imaging. Management includes anthelmintic therapy.

References

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  2. Gryseels B, De Vlas SJ. Worm burdens in schistosome infections. Parasitol Today 1996; 12:115.
  3. Chistulo L, Loverde P, Engels D. Disease Watch: Schistosomiasis. TDR Nature Reviews Microbiology. 2004. 2:12:
  4. Nicolls DJ, Weld LH, Schwartz E, et al. Characteristics of schistosomiasis in travelers reported to the GeoSentinel Surveillance Network 1997-2008. Am J Trop Med Hyg 2008; 79:729.
  5. Clerinx, J., and Soentjens, P. (2019). Schistosomiasis: Epidemiology and clinical manifestations. In Baron, E.L. (Ed.), UpToDate. Retrieved April 15, 2021, from https://www.uptodate.com/contents/schistosomiasis-epidemiology-and-clinical-manifestations
  6. Soentjens, P., and Clerinx, J. (2021). Schistosomiasis: Diagnosis. In Baron, E.L. (Ed.), UpToDate. Retrieved April 15, 2021, from https://www.uptodate.com/contents/schistosomiasis-diagnosis
  7. Soentjens, P., and Clerinx, J. (2021). Schistosomiasis: Treatment and prevention. In Baron, E.L. (Ed.), UpToDate. Retrieved April 15, 2021, from https://www.uptodate.com/contents/schistosomiasis-treatment-and-prevention
  8. Ahmed, S.B. (2020). Schistosomiasis (Bilharzia). In Bronze, M.S. (Ed.), Medscape. Retrieved April 15, 2021, from https://emedicine.medscape.com/article/228392-overview
  9. Lackey, E.K., and Horrall, S. (2021). Schistosomiasis. [online] StatPearls. Retrieved April 15, 2021, from https://www.ncbi.nlm.nih.gov/books/NBK554434/
  10. Pearson, R.D. (2020). Schistosomiasis. [online] MSD Manual Professional Version. Retrieved April 15, 2021, from https://www.msdmanuals.com/professional/infectious-diseases/trematodes-flukes/schistosomiasis
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