Giardia/Giardiasis

Giardiasis is caused by Giardia lamblia (G. lamblia), a flagellated protozoan that can infect the intestinal tract. Giardia transmission occurs most commonly through consumption of cysts in contaminated water or through the fecal-oral route. Excystation occurs in the gastrointestinal (GI) tract, and trophozoites attach to the intestinal wall villi and cause malabsorption Malabsorption Malabsorption involves many disorders in which there is an inability of the gut to absorb nutrients from dietary intake, potentially including water and/or electrolytes. A closely related term, maldigestion is the inability to break down large molecules of food into their smaller constituents. Malabsorption and maldigestion can affect macronutrients (fats, proteins, and carbohydrates), micronutrients (vitamins and minerals), or both. Malabsorption and Maldigestion. The hallmark symptom of giardiasis is foul-smelling steatorrhea. Patients who develop chronic infections may experience weight loss, failure to thrive Failure to Thrive Failure to thrive (FTT), or faltering growth, describes suboptimal weight gain and growth in children. The majority of cases are due to inadequate caloric intake; however, genetic, infectious, and oncological etiologies are also common. Failure to Thrive, and vitamin deficiencies as a result of malabsorption Malabsorption Malabsorption involves many disorders in which there is an inability of the gut to absorb nutrients from dietary intake, potentially including water and/or electrolytes. A closely related term, maldigestion is the inability to break down large molecules of food into their smaller constituents. Malabsorption and maldigestion can affect macronutrients (fats, proteins, and carbohydrates), micronutrients (vitamins and minerals), or both. Malabsorption and Maldigestion. The diagnosis is made through detection of Giardia organisms, antigens, or deoxyribonucleic acid ( 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) in the stool. Management includes supportive treatment and antimicrobial therapy with metronidazole, tinidazole, or nitazoxanide. Prevention measures include proper handwashing and water treatment.

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Editorial responsibility: Stanley Oiseth, Lindsay Jones, Evelin Maza

Table of Contents

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General Characteristics of Giardia

Giardiasis is caused by the flagellated protozoan, Giardia lamblia (G. lamblia, also known as G. duodenalis or G. intestinalis).

Characteristics

  • Unicellular
  • Eukaryotic Eukaryotic Eukaryotes can be single-celled or multicellular organisms and include plants, animals, fungi, and protozoa. Eukaryotic cells contain a well-organized nucleus contained by a membrane, along with other membrane-bound organelles. Cell Types: Eukaryotic versus Prokaryotic
  • Oval shaped
  • Anaerobic
  • Reproduces through binary fission
  • Contains a mitosome in place of mitochondria

Forms

  • Trophozoites:
    • Active, feeding, and replicating stage
    • Contain 2 nuclei
    • 4 pairs of flagella
    • Cannot survive outside a host
  • Cysts:
    • Dormant stage
    • Contain 4 nuclei
    • No flagella
    • Resistant to environmental stressors (heat, cold, desiccation)
    • Can survive outside a host and several months in cold water
    • Responsible for transmission
Sem image of giardia lamblia trophozoites

Scanning electron microscopic (SEM) image of G. lamblia trophozoites

Image: “SEM” by CDC/Dr. Stan Erlandsen. License: Public Domain

Epidemiology and Transmission

Epidemiology

  • Giardiasis occurs worldwide.
    • 3rd most common cause of 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 in children < 5 years of age
    • > 300 million cases annually
  • Prevalence: 
    • 2%–5% worldwide
    • 20%–40% in developing countries
  • In the United States:
    • Approximately 5% of adults are asymptomatic carriers.
    • Common regions in the United States:
      • Western mountain regions
      • Northern states
    • Most common July–October

Transmission

  • Fecal-oral transmission
  • Waterborne transmission:
    • Poorly filtered water supplies
    • Mountain streams, lakes, rivers
  • Outbreaks have been associated with:
    • Ski resorts
    • Daycare centers
    • Refugee camps
    • Camping
  • High-risk groups:
    • Young children
    • Immunocompromised (immunoglobulin deficiency states)
    • Cystic fibrosis Cystic fibrosis Cystic fibrosis is an autosomal recessive disorder caused by mutations in the gene CFTR. The mutations lead to dysfunction of chloride channels, which results in hyperviscous mucus and the accumulation of secretions. Common presentations include chronic respiratory infections, failure to thrive, and pancreatic insufficiency. Cystic Fibrosis patients
    • Blood group A
    • Hypochlorhydria
    • Travelers

Pathogenesis

Virulence factors

  • Antigenic variation:
    • Able to express different variant surface-specific proteins (VSPs)
    • Allows escape from a host’s adaptive immunity
  • Adhesive disc: 
    • Composed of microtubules
    • Allows attachment to the intestinal wall

Life cycle and pathophysiology

  • Cysts are ingested → 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 acid, bile, and trypsin trigger conversion into the trophozoite form (excystation)
  • Trophozoites attach to the intestinal wall with the adhesive disc.
    • Results in:
      • 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
      • Villous atrophy
      • ↓ Brush border enzymes Enzymes Enzymes are complex protein biocatalysts that accelerate chemical reactions without being consumed by them. Due to the body's constant metabolic needs, the absence of enzymes would make life unsustainable, as reactions would occur too slowly without these molecules. Basics of Enzymes (e.g., disaccharidase, lactase)
    • Leads to malabsorption Malabsorption Malabsorption involves many disorders in which there is an inability of the gut to absorb nutrients from dietary intake, potentially including water and/or electrolytes. A closely related term, maldigestion is the inability to break down large molecules of food into their smaller constituents. Malabsorption and maldigestion can affect macronutrients (fats, proteins, and carbohydrates), micronutrients (vitamins and minerals), or both. Malabsorption and Maldigestion
    • Trophozoites do not invade the intestinal wall.
  • Binary fission occurs → some organisms form into cysts (encystation) → excreted in feces
Cycle of giardia lamblia

This image shows the life cycle of G. lamblia. Cysts can survive for long periods of time in cold water and then be inadvertently consumed. Once consumed, the cysts transform into trophozoite form, replicate, and infect the intestines. The trophozoites attach to the intestinal villi, resulting in symptoms.

Image: “Giardia life cycle” by LadyofHats. License: Public Domain, edited by Lecturio.

Clinical Presentation

While some patients may be asymptomatic, the hallmark clinical feature of giardiasis is malabsorptive 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.

Acute giardiasis

  • Incubation period: 7–14 days
  • Duration: 2–4 weeks
  • Common symptoms:
    • Diarrhea (often steatorrhea):
      • Foul smelling
      • Watery or greasy
      • Non-bloody
    • Malaise
    • Flatulence
    • Nausea
    • Anorexia
    • Abdominal cramping and bloating
    • Weight loss
    • Low-grade 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 (uncommon)

Chronic giardiasis

  • May develop after the acute phase in some patients
  • Symptoms may wax and wane over months.
  • Common signs and symptoms:
    • Loose stools:
      • Often steatorrhea
      • Not 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
    • Malaise and fatigue
    • Abdominal cramping
    • Flatulence and burping
    • Malabsorption:
      • Hypoalbuminemia
      • Vitamin deficiencies (A, B12, folate Folate Folate and vitamin B12 are 2 of the most clinically important water-soluble vitamins. Deficiencies can present with megaloblastic anemia, GI symptoms, neuropsychiatric symptoms, and adverse pregnancy complications, including neural tube defects. Folate and Vitamin B12)
      • Weight loss and failure to thrive Failure to Thrive Failure to thrive (FTT), or faltering growth, describes suboptimal weight gain and growth in children. The majority of cases are due to inadequate caloric intake; however, genetic, infectious, and oncological etiologies are also common. Failure to Thrive

Complications

  • Stunted growth in children
  • Hypersensitivity:
    • 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)
    • Aphthous ulcers
  • Reactive arthritis Reactive arthritis Reactive arthritis is a seronegative autoimmune spondyloarthropathy that occurs in response to a previous gastrointestinal (GI) or genitourinary (GU) infection. The disease manifests as asymmetric oligoarthritis (particularly of large joints in the lower extremities), enthesopathy, dactylitis, and/or sacroiliitis. Reactive Arthritis
  • Acquired lactose intolerance Lactose intolerance Lactose intolerance (LI) describes a constellation of symptoms due to lactase deficiency (LD), the enzyme located in the brush border of the absorptive cells in the small intestine. Lactose is the disaccharide present in milk and requires hydrolysis by lactase to break it down into its 2 absorbable constituents, glucose and galactose. Lactose intolerance typically presents with bloating, abdominal cramping, diarrhea, and flatulence. Lactose Intolerance
  • Biliary invasion can lead to:
    • Cholecystitis Cholecystitis Cholecystitis is the inflammation of the gallbladder (GB) usually caused by the obstruction of the cystic duct (acute cholecystitis). Mechanical irritation by gallstones can also produce chronic GB inflammation. Cholecystitis is one of the most common complications of cholelithiasis but inflammation without gallstones can occur in a minority of patients. Cholecystitis
    • Cholangitis
    • Granulomatous hepatitis

Diagnosis and Management

Diagnosis

  • Enzyme-linked immunosorbent assay (ELISA): detects antigen in the stool
  • Direct immunofluorescence assay (DFA): Utilizes fluorescein-tagged monoclonal antibodies Antibodies Immunoglobulins (Igs), also known as antibodies, are glycoprotein molecules produced by plasma cells that act in immune responses by recognizing and binding particular antigens. The various Ig classes are IgG (the most abundant), IgM, IgE, IgD, and IgA, which differ in their biologic features, structure, target specificity, and distribution. Immunoglobulins to detect a specific antigen.
  • Nucleic acid amplification assay (NAAT): detects and copies (amplifies) specific Giardia deoxyribonucleic acid ( 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) sequences
  • Stool microscopy:
    • Microscopic evaluation of stool for trophozoites or cysts
    • May require repeated stool examinations
    • Can detect other potential parasites
    • Less sensitive than ELISA, DFA, or NAAT
Fecal sample showing giardia lamblia cysts

Stool microscopy revealing the presence of 2 G. lamblia cysts

Image: “ 21085” by CDC. License: Public Domain

Management

  • Supportive care:
    • Rehydration
    • Electrolyte replacement
  • Antimicrobial therapy:
    • Options: 
      • Metronidazole
      • Tinidazole
      • Nitazoxanide
    • Consider treating individuals (even asymptomatic) who are:
      • At risk for transmission to others (food handlers, daycare setting)
      • In contact with immunocompromised individuals
      • In contact with pregnant women
  • Recurrent or persistent symptoms:
    • Repeat stool examination.
    • Evaluate for sources of reinfection.
    • Evaluate for immunodeficiency.
    • Repeat antimicrobial therapy.

Prevention

  • Handwashing:
    • Soap and water preferred
    • Alcohol-based disinfection is not effective against cysts.
  • Proper diaper disposal
  • Boiling potentially contaminated water
  • Public water treatment
  • Infected individuals should avoid swimming in recreational water (pools, lakes, rivers).

Comparison of Flagellated Protozoa

Table: Comparison of clinically relevant flagellated protozoa
Giardia Leishmania Leishmania Leishmania species are obligate intracellular parasites that are transmitted by an infected sandfly. The disease is endemic to Asia, the Middle East, Africa, the Mediterranean, and South and Central America. Clinical presentation varies, dependent on the pathogenicity of the species and the host's immune response. Leishmania/Leishmaniasis Trypanosoma Trichomonas
Characteristics
  • 4 pairs of flagella
  • Ovoid shape
  • Adhesive disc
  • Anaerobe
  • Antigenic variation
  • Single, polar flagellum
  • Slender, elongated body
  • Single, polar flagellum
  • Undulating membrane
  • Thin, irregularly shaped
  • Antigenic variation
  • 5 flagella
  • Undulating membrane
  • Ovoid shape
  • Facultative anaerobe
Forms
  • Cyst
  • Trophozoite
  • Promastigote
  • Amastigote
  • Trypomastigote
  • Amastigote
  • Epimastigote
  • Trophozoite
  • No cyst form
Transmission
  • Waterborne
  • Fecal-oral
  • Vector (sandfly)
  • Human to human
  • Zoonotic (rodents, dogs, foxes)
  • Vector (tsetse fly, kissing bug)
  • Blood transfusion
Sexually transmitted
Clinical Giardiasis Leishmaniasis Leishmaniasis Leishmania species are obligate intracellular parasites that are transmitted by an infected sandfly. The mildest form is cutaneous leishmaniasis (CL), characterized by painless skin ulcers. The mucocutaneous type involves more tissue destruction, causing deformities. Visceral leishmaniasis (VL), the most severe form, presents with hepatosplenomegaly, anemia, thrombocytopenia, and fever. Leishmania/Leishmaniasis
  • African sleeping sickness
  • Chagas disease Chagas disease Chagas disease is an infection caused by the American trypanosome Trypanosoma cruzi. This parasitic protozoan is transmitted in the feces of reduviid bugs in South and Central America. Acute infection may present with inflammation at the inoculation site (chagoma), fever, and lymphadenopathy. Untreated, chronic infection can progress to severe complications. Trypanosoma cruzi/Chagas disease
Trichomoniasis
Diagnosis
  • ELISA
  • DFA
  • NAAT
  • Stool microscopy
  • Blood smear
  • Biopsy
  • PCR
  • Leishmanin 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 test
  • Antibody titers
  • Blood smear
  • Antibody titers
  • Xenodiagnosis
  • Microscopy of vaginal secretions
  • NAAT
  • Urine or urethral swab culture
Treatment
  • Metronidazole
  • Tinidazole
  • Nitazoxanide
Depends on the clinical syndrome:
  • Amphotericin B
  • Pentavalent antimonials
  • Miltefosine
Depends on the clinical disease:
  • Suramin
  • Pentamidine
  • Melarsoprol
  • Eflornithine
  • Nifurtimox
  • Benznidazole
  • Metronidazole
  • Tinidazole
Prevention
  • Handwashing
  • Water treatment
  • Insecticide
  • Insect repellent
  • Protective clothing
  • Insecticides
  • Insect repellent
  • Bed nets
  • Protective clothing
  • Treatment of sex partners
  • Condoms

ELISA: enzyme-linked immunosorbent assay

DFA: direct immunofluorescence assay

NAAT: nucleic acid amplification assay

PCR: polymerase chain reaction

Differential Diagnosis

  • Amebic dysentery: also known as amebiasis Amebiasis Amebiasis, or amoebic dysentery, is an infection caused by the parasite Entamoeba histolytica. Transmission is through the fecal-oral route or by consumption of contaminated food and water. Most patients infected with E. histolytica are asymptomatic, but about 10% may develop dysentery. Amebiasis, is an infection caused by Entamoeba histolytica (E. histolytica). Symptoms can range from mild 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 to severe dysentery, and complications include 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 abscess. Identification of E. histolytica in the stool or through serologic testing will give the diagnosis. Management includes metronidazole or paromomycin.
  • Traveler’s 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: a 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 that is usually caused by 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 or viruses in the local water, such as enterotoxigenic E. coli (ETEC) or norovirus Norovirus Norovirus is a nonenveloped, single-stranded, positive-sense RNA virus belonging to the Caliciviridae family. Norovirus infections are transmitted via the fecal-oral route or by aerosols from vomiting. The virus is one of the most common causes of nonbacterial gastroenteritis epidemic worldwide. Symptoms include watery and nonbloody diarrhea, nausea, vomiting, and low-grade fever. Norovirus. Symptoms occur after consumption of contaminated water or food, and include watery 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, malaise, and abdominal cramping. The diagnosis is clinical and the illness is self-limited. 
  • Cryptosporidiosis: an infection with Cryptosporidium. Patients will have watery 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, abdominal cramping, nausea, and 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 that lasts 2–3 weeks, but can be more persistent and severe in immunocompromised patients. Diagnosis is with identification of the organism in a stool specimen. Cryptosporidiosis is generally self-limited, but may require nitazoxanide in persistent or severe cases.  
  • Small intestinal bacterial overgrowth: defined as excessive 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 growing in the small intestine Small intestine The small intestine is the longest part of the GI tract, extending from the pyloric orifice of the stomach to the ileocecal junction. The small intestine is the major organ responsible for chemical digestion and absorption of nutrients. It is divided into 3 segments: the duodenum, the jejunum, and the ileum. Small Intestine, and can result due to alteration in the intestinal anatomy or motility. Symptoms can range from mildly symptomatic to chronic 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, weight loss, and malabsorption Malabsorption Malabsorption involves many disorders in which there is an inability of the gut to absorb nutrients from dietary intake, potentially including water and/or electrolytes. A closely related term, maldigestion is the inability to break down large molecules of food into their smaller constituents. Malabsorption and maldigestion can affect macronutrients (fats, proteins, and carbohydrates), micronutrients (vitamins and minerals), or both. Malabsorption and Maldigestion. Bacterial cultures and breath tests can establish the diagnosis. Management includes antibiotics and correction of nutritional deficiencies.
  • Celiac disease Celiac disease Celiac disease (also known as celiac sprue or gluten enteropathy) is an autoimmune reaction to gliadin, which is a component of gluten. Celiac disease is closely associated with HLA-DQ2 and HLA-DQ8. The immune response is localized to the proximal small intestine and causes the characteristic histologic findings of villous atrophy, crypt hyperplasia, and intraepithelial lymphocytosis. Celiac Disease: an immunologically mediated disease resulting in mucosal inflammation and villous atrophy in the small bowel due to gluten. Symptoms include abdominal bloating and foul-smelling 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. Patients may also have nutritional deficiencies and weight loss due to malabsorption Malabsorption Malabsorption involves many disorders in which there is an inability of the gut to absorb nutrients from dietary intake, potentially including water and/or electrolytes. A closely related term, maldigestion is the inability to break down large molecules of food into their smaller constituents. Malabsorption and maldigestion can affect macronutrients (fats, proteins, and carbohydrates), micronutrients (vitamins and minerals), or both. Malabsorption and Maldigestion. The diagnosis is established with serologic markers and small bowel biopsy. Management requires a strict, gluten-free diet.
  • Inflammatory bowel disease (IBD): includes 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. Inflammatory bowel disease is characterized by chronic inflammation of the gastrointestinal (GI) tract due to a cell-mediated immune response to the GI mucosa. Symptoms include 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, 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.
  • Lactose intolerance: an intolerance to lactose-containing foods due to lactase deficiency. Symptoms include crampy, 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, bloating, nausea, and 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. Diagnosis is based on the association with lactose-containing foods and a lactose hydrogen breath test. Management includes restriction of dietary lactose and enzyme replacement.

References

  1. Riedel, S., Jawetz, E., Melnick, J. L., & Adelberg, E. A. (2019). Jawetz, Melnick & Adelberg’s Medical microbiology (pp. 723-727). New York: McGraw-Hill Education.
  2. Leder, K. (2019). Giardiasis: Epidemiology, clinical manifestations, and diagnosis. UpToDate, Retrieved December 09, 2020, from https://www.uptodate.com/contents/giardiasis-epidemiology-clinical-manifestations-and-diagnosis
  3. Bartelt, L. (2020). Giardiasis: Treatment and prevention. UpToDate, Retrieved December 09, 2020, from https://www.uptodate.com/contents/giardiasis-treatment-and-prevention
  4. Pearson, R.D. (2020). Giardiasis. [online] MSD Manual Professional Version. Retrieved December 11, 2020, from https://www.msdmanuals.com/professional/infectious-diseases/intestinal-protozoa-and-microsporidia/giardiasis
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  6. Gladwin, M., & Trattler, B. (2008). Clinical microbiology made ridiculously simple (4th edition). Miami: MedMaster.

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