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Giardia/Giardiasis

Giardiasis is caused by Giardia Giardia A genus of flagellate intestinal eukaryotes parasitic in various vertebrates, including humans. Characteristics include the presence of four pairs of flagella arising from a complicated system of axonemes and cysts that are ellipsoidal to ovoidal in shape. Nitroimidazoles lamblia (G. lamblia), a flagellated protozoan that can infect the intestinal tract. Giardia Giardia A genus of flagellate intestinal eukaryotes parasitic in various vertebrates, including humans. Characteristics include the presence of four pairs of flagella arising from a complicated system of axonemes and cysts that are ellipsoidal to ovoidal in shape. Nitroimidazoles transmission occurs most commonly through consumption of cysts Cysts Any fluid-filled closed cavity or sac that is lined by an epithelium. Cysts can be of normal, abnormal, non-neoplastic, or neoplastic tissues. Fibrocystic Change in contaminated water or through the fecal-oral route Fecal-oral route Echovirus. Excystation occurs in the gastrointestinal (GI) tract, and trophozoites Trophozoites Cells or feeding stage in the life cycle of sporozoan protozoa. In the malarial parasite, the trophozoite develops from the merozoite and then splits into the schizont. Trophozoites that are left over from cell division can go on to form gametocytes. Amebicides attach to the intestinal wall villi and cause malabsorption Malabsorption General term for a group of malnutrition syndromes caused by failure of normal intestinal absorption of nutrients. Malabsorption and Maldigestion. The hallmark symptom of giardiasis is foul-smelling steatorrhea Steatorrhea A condition that is characterized by chronic fatty diarrhea, a result of abnormal digestion and/or intestinal absorption of fats. Diarrhea. Patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship who develop chronic infections Infections Invasion of the host organism by microorganisms or their toxins or by parasites that can cause pathological conditions or diseases. Chronic Granulomatous Disease may experience weight loss Weight loss Decrease in existing body weight. Bariatric Surgery, 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 General term for a group of malnutrition syndromes caused by failure of normal intestinal absorption of nutrients. Malabsorption and Maldigestion. The diagnosis is made through detection of Giardia Giardia A genus of flagellate intestinal eukaryotes parasitic in various vertebrates, including humans. Characteristics include the presence of four pairs of flagella arising from a complicated system of axonemes and cysts that are ellipsoidal to ovoidal in shape. Nitroimidazoles organisms, antigens, or deoxyribonucleic acid Deoxyribonucleic acid A deoxyribonucleotide polymer that is the primary genetic material of all cells. Eukaryotic and prokaryotic organisms normally contain DNA in a double-stranded state, yet several important biological processes transiently involve single-stranded regions. DNA, which consists of a polysugar-phosphate backbone possessing projections of purines (adenine and guanine) and pyrimidines (thymine and cytosine), forms a double helix that is held together by hydrogen bonds between these purines and pyrimidines (adenine to thymine and guanine to cytosine). DNA Types and Structure ( DNA DNA A deoxyribonucleotide polymer that is the primary genetic material of all cells. Eukaryotic and prokaryotic organisms normally contain DNA in a double-stranded state, yet several important biological processes transiently involve single-stranded regions. DNA, which consists of a polysugar-phosphate backbone possessing projections of purines (adenine and guanine) and pyrimidines (thymine and cytosine), forms a double helix that is held together by hydrogen bonds between these purines and pyrimidines (adenine to thymine and guanine to cytosine). DNA Types and Structure) in the stool. Management includes supportive treatment and antimicrobial therapy with metronidazole Metronidazole A nitroimidazole used to treat amebiasis; vaginitis; trichomonas infections; giardiasis; anaerobic bacteria; and treponemal infections. Pyogenic Liver Abscess, tinidazole Tinidazole A nitroimidazole alkylating agent that is used as an antitrichomonal agent against trichomonas vaginalis; entamoeba histolytica; and giardia lamblia infections. It also acts as an antibacterial agent for the treatment of bacterial vaginosis and anaerobic bacterial infections. Nitroimidazoles, or nitazoxanide. Prevention measures include proper handwashing and water treatment.

Last updated: Sep 19, 2022

Editorial responsibility: Stanley Oiseth, Lindsay Jones, Evelin Maza

General Characteristics of Giardia

Giardiasis is caused by the flagellated protozoan, Giardia Giardia A genus of flagellate intestinal eukaryotes parasitic in various vertebrates, including humans. Characteristics include the presence of four pairs of flagella arising from a complicated system of axonemes and cysts that are ellipsoidal to ovoidal in shape. Nitroimidazoles lamblia (G. lamblia, also known as G. duodenalis or G. intestinalis).

Characteristics

  • Unicellular Unicellular Cell Types: Eukaryotic versus Prokaryotic
  • 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 Binary fission Cell Types: Eukaryotic versus Prokaryotic
  • Contains a mitosome in place of mitochondria Mitochondria Semiautonomous, self-reproducing organelles that occur in the cytoplasm of all cells of most, but not all, eukaryotes. Each mitochondrion is surrounded by a double limiting membrane. The inner membrane is highly invaginated, and its projections are called cristae. Mitochondria are the sites of the reactions of oxidative phosphorylation, which result in the formation of ATP. They contain distinctive ribosomes, transfer RNAs; amino Acyl tRNA synthetases; and elongation and termination factors. Mitochondria depend upon genes within the nucleus of the cells in which they reside for many essential messenger RNAs. Mitochondria are believed to have arisen from aerobic bacteria that established a symbiotic relationship with primitive protoeukaryotes. The Cell: Organelles

Forms

  • Trophozoites Trophozoites Cells or feeding stage in the life cycle of sporozoan protozoa. In the malarial parasite, the trophozoite develops from the merozoite and then splits into the schizont. Trophozoites that are left over from cell division can go on to form gametocytes. Amebicides:
    • Active, feeding, and replicating stage
    • Contain 2 nuclei
    • 4 pairs of flagella Flagella A whiplike motility appendage present on the surface cells. Prokaryote flagella are composed of a protein called flagellin. Bacteria can have a single flagellum, a tuft at one pole, or multiple flagella covering the entire surface. In eukaryotes, flagella are threadlike protoplasmic extensions used to propel flagellates and sperm. Flagella have the same basic structure as cilia but are longer in proportion to the cell bearing them and present in much smaller numbers. Helicobacter
    • Cannot survive outside a host
  • Cysts Cysts Any fluid-filled closed cavity or sac that is lined by an epithelium. Cysts can be of normal, abnormal, non-neoplastic, or neoplastic tissues. Fibrocystic Change:
    • Dormant stage
    • Contain 4 nuclei
    • No flagella Flagella A whiplike motility appendage present on the surface cells. Prokaryote flagella are composed of a protein called flagellin. Bacteria can have a single flagellum, a tuft at one pole, or multiple flagella covering the entire surface. In eukaryotes, flagella are threadlike protoplasmic extensions used to propel flagellates and sperm. Flagella have the same basic structure as cilia but are longer in proportion to the cell bearing them and present in much smaller numbers. Helicobacter
    • Resistant to environmental stressors ( heat Heat Inflammation, 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 Trophozoites Cells or feeding stage in the life cycle of sporozoan protozoa. In the malarial parasite, the trophozoite develops from the merozoite and then splits into the schizont. Trophozoites that are left over from cell division can go on to form gametocytes. Amebicides

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 Prevalence The total number of cases of a given disease in a specified population at a designated time. It is differentiated from incidence, which refers to the number of new cases in the population at a given time. Measures of Disease Frequency
    • 2%–5% worldwide
    • 20%–40% in developing countries
  • In the United States:
    • Approximately 5% of adults are asymptomatic carriers Carriers The Cell: Cell Membrane.
    • 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 Outbreaks Sudden increase in the incidence of a disease. The concept includes epidemics and pandemics. Influenza Viruses/Influenza have been associated with:
    • Ski resorts
    • Daycare centers
    • Refugee camps
    • Camping
  • High-risk groups:

Pathogenesis

Virulence Virulence The degree of pathogenicity within a group or species of microorganisms or viruses as indicated by case fatality rates and/or the ability of the organism to invade the tissues of the host. The pathogenic capacity of an organism is determined by its virulence factors. Proteus factors

  • Antigenic variation:
    • Able to express different variant surface-specific proteins Proteins Linear polypeptides that are synthesized on ribosomes and may be further modified, crosslinked, cleaved, or assembled into complex proteins with several subunits. The specific sequence of amino acids determines the shape the polypeptide will take, during protein folding, and the function of the protein. Energy Homeostasis (VSPs)
    • Allows escape Escape With constant immune mechanisms holding unstable tumor cells in equilibrium, tumor-cell variants may emerge. These cancer cells may express fewer antigens on their surfaces or lose their MHC class I expression.Variants may also protect themselves from T-cell attack via expression of IC molecules on their surfaces, like normal cells.Creation of an immunosuppressive state in the microenvironment is another way to grow without immunologic interference. Cancer Immunotherapy from a host’s adaptive immunity
  • Adhesive disc: 
    • Composed of microtubules Microtubules Slender, cylindrical filaments found in the cytoskeleton of plant and animal cells. They are composed of the protein tubulin and are influenced by tubulin modulators. The Cell: Cytosol and Cytoskeleton
    • Allows attachment to the intestinal wall

Life cycle Cycle The type of signal that ends the inspiratory phase delivered by the ventilator Invasive Mechanical Ventilation and pathophysiology

  • Cysts Cysts Any fluid-filled closed cavity or sac that is lined by an epithelium. Cysts can be of normal, abnormal, non-neoplastic, or neoplastic tissues. Fibrocystic Change 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: Anatomy acid, bile Bile An emulsifying agent produced in the liver and secreted into the duodenum. Its composition includes bile acids and salts; cholesterol; and electrolytes. It aids digestion of fats in the duodenum. Gallbladder and Biliary Tract: Anatomy, and trypsin Trypsin A serine endopeptidase that is formed from trypsinogen in the pancreas. It is converted into its active form by enteropeptidase in the small intestine. It catalyzes hydrolysis of the carboxyl group of either arginine or lysine. Proteins and Peptides trigger Trigger The type of signal that initiates the inspiratory phase by the ventilator Invasive Mechanical Ventilation conversion into the trophozoite form (excystation)
  • Trophozoites Trophozoites Cells or feeding stage in the life cycle of sporozoan protozoa. In the malarial parasite, the trophozoite develops from the merozoite and then splits into the schizont. Trophozoites that are left over from cell division can go on to form gametocytes. Amebicides 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 Atrophy Decrease in the size of a cell, tissue, organ, or multiple organs, associated with a variety of pathological conditions such as abnormal cellular changes, ischemia, malnutrition, or hormonal changes. Cellular Adaptation
      • Brush border Brush border Tubular System 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 Disaccharidase Enzymes belonging to the class of glycoside hydrolases which break down disaccharides into simpler sugars, monosaccharides. Rotavirus, lactase Lactase An enzyme which catalyzes the hydrolysis of lactose to d-galactose and d-glucose. Defects in the enzyme cause lactose intolerance. Digestion and Absorption of Carbohydrates)
    • Leads to malabsorption Malabsorption General term for a group of malnutrition syndromes caused by failure of normal intestinal absorption of nutrients. Malabsorption and Maldigestion
    • Trophozoites Trophozoites Cells or feeding stage in the life cycle of sporozoan protozoa. In the malarial parasite, the trophozoite develops from the merozoite and then splits into the schizont. Trophozoites that are left over from cell division can go on to form gametocytes. Amebicides do not invade the intestinal wall.
  • Binary fission Binary fission Cell Types: Eukaryotic versus Prokaryotic occurs → some organisms form into cysts Cysts Any fluid-filled closed cavity or sac that is lined by an epithelium. Cysts can be of normal, abnormal, non-neoplastic, or neoplastic tissues. Fibrocystic Change (encystation) → excreted in feces
Cycle of giardia lamblia

This image shows the life cycle Cycle The type of signal that ends the inspiratory phase delivered by the ventilator Invasive Mechanical Ventilation of G. lamblia. Cysts Cysts Any fluid-filled closed cavity or sac that is lined by an epithelium. Cysts can be of normal, abnormal, non-neoplastic, or neoplastic tissues. Fibrocystic Change can survive for long periods of time in cold water and then be inadvertently consumed. Once consumed, the cysts Cysts Any fluid-filled closed cavity or sac that is lined by an epithelium. Cysts can be of normal, abnormal, non-neoplastic, or neoplastic tissues. Fibrocystic Change transform into trophozoite form, replicate, and infect the intestines. The trophozoites Trophozoites Cells or feeding stage in the life cycle of sporozoan protozoa. In the malarial parasite, the trophozoite develops from the merozoite and then splits into the schizont. Trophozoites that are left over from cell division can go on to form gametocytes. Amebicides attach to the intestinal villi, resulting in symptoms.

Image: “ Giardia Giardia A genus of flagellate intestinal eukaryotes parasitic in various vertebrates, including humans. Characteristics include the presence of four pairs of flagella arising from a complicated system of axonemes and cysts that are ellipsoidal to ovoidal in shape. Nitroimidazoles life cycle Cycle The type of signal that ends the inspiratory phase delivered by the ventilator Invasive Mechanical Ventilation” by LadyofHats. License: Public Domain, edited by Lecturio.

Clinical Presentation

While some patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship 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 Incubation The amount time between exposure to an infectious agent and becoming symptomatic. Rabies Virus period: 7–14 days
  • Duration: 2–4 weeks
  • Common symptoms:
    • 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 (often steatorrhea Steatorrhea A condition that is characterized by chronic fatty diarrhea, a result of abnormal digestion and/or intestinal absorption of fats. Diarrhea):
      • Foul smelling
      • Watery or greasy
      • Non-bloody
    • Malaise Malaise Tick-borne Encephalitis Virus
    • Flatulence
    • Nausea Nausea An unpleasant sensation in the stomach usually accompanied by the urge to vomit. Common causes are early pregnancy, sea and motion sickness, emotional stress, intense pain, food poisoning, and various enteroviruses. Antiemetics
    • Anorexia Anorexia The lack or loss of appetite accompanied by an aversion to food and the inability to eat. It is the defining characteristic of the disorder anorexia nervosa. Anorexia Nervosa
    • Abdominal cramping Abdominal cramping Norovirus and bloating Bloating Constipation
    • Weight loss Weight loss Decrease in existing body weight. Bariatric Surgery
    • 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 Acute phase Short Bowel Syndrome in some patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship
  • Symptoms may wax and wane over months.
  • Common signs and symptoms:
    • Loose stools:
      • Often steatorrhea Steatorrhea A condition that is characterized by chronic fatty diarrhea, a result of abnormal digestion and/or intestinal absorption of fats. Diarrhea
      • 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 Malaise Tick-borne Encephalitis Virus and fatigue Fatigue The state of weariness following a period of exertion, mental or physical, characterized by a decreased capacity for work and reduced efficiency to respond to stimuli. Fibromyalgia
    • Abdominal cramping Abdominal cramping Norovirus
    • Flatulence and burping
    • Malabsorption Malabsorption General term for a group of malnutrition syndromes caused by failure of normal intestinal absorption of nutrients. Malabsorption and Maldigestion:
      • Hypoalbuminemia Hypoalbuminemia A condition in which albumin level in blood (serum albumin) is below the normal range. Hypoalbuminemia may be due to decreased hepatic albumin synthesis, increased albumin catabolism, altered albumin distribution, or albumin loss through the urine (albuminuria). Nephrotic Syndrome in Children
      • 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 Weight loss Decrease in existing body weight. Bariatric Surgery 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 ELISA An immunoassay utilizing an antibody labeled with an enzyme marker such as horseradish peroxidase. While either the enzyme or the antibody is bound to an immunosorbent substrate, they both retain their biologic activity; the change in enzyme activity as a result of the enzyme-antibody-antigen reaction is proportional to the concentration of the antigen and can be measured spectrophotometrically or with the naked eye. Many variations of the method have been developed. St. Louis Encephalitis Virus): detects antigen Antigen Substances that are recognized by the immune system and induce an immune reaction. Vaccination in the stool
  • Direct immunofluorescence assay (DFA): Utilizes fluorescein-tagged monoclonal antibodies Monoclonal antibodies Antibodies produced by a single clone of cells. Ebolavirus and Marburgvirus to detect a specific antigen Antigen Substances that are recognized by the immune system and induce an immune reaction. Vaccination.
  • Nucleic acid amplification Nucleic acid amplification Laboratory techniques that involve the in-vitro synthesis of many copies of DNA or RNA from one original template. Septic Arthritis assay (NAAT): detects and copies (amplifies) specific Giardia Giardia A genus of flagellate intestinal eukaryotes parasitic in various vertebrates, including humans. Characteristics include the presence of four pairs of flagella arising from a complicated system of axonemes and cysts that are ellipsoidal to ovoidal in shape. Nitroimidazoles deoxyribonucleic acid Deoxyribonucleic acid A deoxyribonucleotide polymer that is the primary genetic material of all cells. Eukaryotic and prokaryotic organisms normally contain DNA in a double-stranded state, yet several important biological processes transiently involve single-stranded regions. DNA, which consists of a polysugar-phosphate backbone possessing projections of purines (adenine and guanine) and pyrimidines (thymine and cytosine), forms a double helix that is held together by hydrogen bonds between these purines and pyrimidines (adenine to thymine and guanine to cytosine). DNA Types and Structure ( DNA DNA A deoxyribonucleotide polymer that is the primary genetic material of all cells. Eukaryotic and prokaryotic organisms normally contain DNA in a double-stranded state, yet several important biological processes transiently involve single-stranded regions. DNA, which consists of a polysugar-phosphate backbone possessing projections of purines (adenine and guanine) and pyrimidines (thymine and cytosine), forms a double helix that is held together by hydrogen bonds between these purines and pyrimidines (adenine to thymine and guanine to cytosine). DNA Types and Structure) sequences
  • Stool microscopy:
    • Microscopic evaluation of stool for trophozoites Trophozoites Cells or feeding stage in the life cycle of sporozoan protozoa. In the malarial parasite, the trophozoite develops from the merozoite and then splits into the schizont. Trophozoites that are left over from cell division can go on to form gametocytes. Amebicides or cysts Cysts Any fluid-filled closed cavity or sac that is lined by an epithelium. Cysts can be of normal, abnormal, non-neoplastic, or neoplastic tissues. Fibrocystic Change
    • May require repeated stool examinations
    • Can detect other potential parasites
    • Less sensitive than ELISA ELISA An immunoassay utilizing an antibody labeled with an enzyme marker such as horseradish peroxidase. While either the enzyme or the antibody is bound to an immunosorbent substrate, they both retain their biologic activity; the change in enzyme activity as a result of the enzyme-antibody-antigen reaction is proportional to the concentration of the antigen and can be measured spectrophotometrically or with the naked eye. Many variations of the method have been developed. St. Louis Encephalitis Virus, DFA, or NAAT
Fecal sample showing giardia lamblia cysts

Stool microscopy revealing the presence of 2 G. lamblia cysts Cysts Any fluid-filled closed cavity or sac that is lined by an epithelium. Cysts can be of normal, abnormal, non-neoplastic, or neoplastic tissues. Fibrocystic Change

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

Management

  • Supportive care:
  • Antimicrobial therapy:
    • Options: 
      • Metronidazole Metronidazole A nitroimidazole used to treat amebiasis; vaginitis; trichomonas infections; giardiasis; anaerobic bacteria; and treponemal infections. Pyogenic Liver Abscess
      • Tinidazole Tinidazole A nitroimidazole alkylating agent that is used as an antitrichomonal agent against trichomonas vaginalis; entamoeba histolytica; and giardia lamblia infections. It also acts as an antibacterial agent for the treatment of bacterial vaginosis and anaerobic bacterial infections. Nitroimidazoles
      • Nitazoxanide
    • Consider treating individuals (even asymptomatic) who are:
      • At risk for transmission to others (food handlers, daycare setting)
      • In contact with immunocompromised immunocompromised A human or animal whose immunologic mechanism is deficient because of an immunodeficiency disorder or other disease or as the result of the administration of immunosuppressive drugs or radiation. Gastroenteritis individuals
      • In contact with pregnant women
  • Recurrent or persistent symptoms:

Prevention

  • Handwashing:
    • Soap and water preferred
    • Alcohol-based disinfection is not effective against cysts Cysts Any fluid-filled closed cavity or sac that is lined by an epithelium. Cysts can be of normal, abnormal, non-neoplastic, or neoplastic tissues. Fibrocystic Change.
  • 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 Protozoa Nitroimidazoles
Giardia Giardia A genus of flagellate intestinal eukaryotes parasitic in various vertebrates, including humans. Characteristics include the presence of four pairs of flagella arising from a complicated system of axonemes and cysts that are ellipsoidal to ovoidal in shape. Nitroimidazoles 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 Trichomonas A genus of parasitic flagellate eukaryotes distinguished by the presence of four anterior flagella, an undulating membrane, and a trailing flagellum. Nitroimidazoles
Characteristics
  • 4 pairs of flagella Flagella A whiplike motility appendage present on the surface cells. Prokaryote flagella are composed of a protein called flagellin. Bacteria can have a single flagellum, a tuft at one pole, or multiple flagella covering the entire surface. In eukaryotes, flagella are threadlike protoplasmic extensions used to propel flagellates and sperm. Flagella have the same basic structure as cilia but are longer in proportion to the cell bearing them and present in much smaller numbers. Helicobacter
  • 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 Flagella A whiplike motility appendage present on the surface cells. Prokaryote flagella are composed of a protein called flagellin. Bacteria can have a single flagellum, a tuft at one pole, or multiple flagella covering the entire surface. In eukaryotes, flagella are threadlike protoplasmic extensions used to propel flagellates and sperm. Flagella have the same basic structure as cilia but are longer in proportion to the cell bearing them and present in much smaller numbers. Helicobacter
  • Undulating membrane
  • Ovoid shape
  • Facultative anaerobe
Forms
  • Cyst
  • Trophozoite
Transmission
  • Waterborne
  • Fecal-oral
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 African sleeping sickness African trypanosomiasis, or african sleeping sickness, is a parasitic infection caused by the protozoa trypanosoma brucei. There are 2 notable subtypes, t. Brucei gambiense and t. Brucei rhodesiense. Transmission is primarily vector borne through the tsetse fly. Trypanosoma brucei/African trypanosomiasis
  • Chagas disease Chagas disease Infection with the protozoan parasite trypanosoma cruzi, a form of trypanosomiasis endemic in central and south america. It is named after the brazilian physician carlos chagas, who discovered the parasite. Infection by the parasite (positive serologic result only) is distinguished from the clinical manifestations that develop years later, such as destruction of parasympathetic ganglia; chagas cardiomyopathy; and dysfunction of the esophagus or colon. Trypanosoma cruzi/Chagas disease
Trichomoniasis
Diagnosis
  • ELISA ELISA An immunoassay utilizing an antibody labeled with an enzyme marker such as horseradish peroxidase. While either the enzyme or the antibody is bound to an immunosorbent substrate, they both retain their biologic activity; the change in enzyme activity as a result of the enzyme-antibody-antigen reaction is proportional to the concentration of the antigen and can be measured spectrophotometrically or with the naked eye. Many variations of the method have been developed. St. Louis Encephalitis Virus
  • DFA
  • NAAT
  • Stool microscopy
  • Blood smear Blood smear Myeloperoxidase Deficiency
  • Biopsy Biopsy Removal and pathologic examination of specimens from the living body. Ewing Sarcoma
  • 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)
  • 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. Skin: Structure and Functions test
  • Antibody titers
  • Microscopy of vaginal secretions
  • NAAT
  • Urine or urethral swab culture
Treatment
  • Metronidazole Metronidazole A nitroimidazole used to treat amebiasis; vaginitis; trichomonas infections; giardiasis; anaerobic bacteria; and treponemal infections. Pyogenic Liver Abscess
  • Tinidazole Tinidazole A nitroimidazole alkylating agent that is used as an antitrichomonal agent against trichomonas vaginalis; entamoeba histolytica; and giardia lamblia infections. It also acts as an antibacterial agent for the treatment of bacterial vaginosis and anaerobic bacterial infections. Nitroimidazoles
  • Nitazoxanide
Depends on the clinical syndrome: Depends on the clinical disease:
  • Metronidazole Metronidazole A nitroimidazole used to treat amebiasis; vaginitis; trichomonas infections; giardiasis; anaerobic bacteria; and treponemal infections. Pyogenic Liver Abscess
  • Tinidazole Tinidazole A nitroimidazole alkylating agent that is used as an antitrichomonal agent against trichomonas vaginalis; entamoeba histolytica; and giardia lamblia infections. It also acts as an antibacterial agent for the treatment of bacterial vaginosis and anaerobic bacterial infections. Nitroimidazoles
Prevention
  • Handwashing
  • Water treatment
  • Insecticides Insecticides Pesticides designed to control insects that are harmful to man. The insects may be directly harmful, as those acting as disease vectors, or indirectly harmful, as destroyers of crops, food products, or textile fabrics. Trypanosoma cruzi/Chagas disease
  • Insect repellent Insect repellent Substances causing insects to turn away from them or reject them as food. St. Louis Encephalitis Virus
  • Bed nets
  • Protective clothing
  • Treatment of sex Sex The totality of characteristics of reproductive structure, functions, phenotype, and genotype, differentiating the male from the female organism. Gender Dysphoria partners
  • Condoms Condoms A sheath that is worn over the penis during sexual behavior in order to prevent pregnancy or spread of sexually transmitted disease. Nonhormonal Contraception

ELISA ELISA An immunoassay utilizing an antibody labeled with an enzyme marker such as horseradish peroxidase. While either the enzyme or the antibody is bound to an immunosorbent substrate, they both retain their biologic activity; the change in enzyme activity as a result of the enzyme-antibody-antigen reaction is proportional to the concentration of the antigen and can be measured spectrophotometrically or with the naked eye. Many variations of the method have been developed. St. Louis Encephalitis Virus: enzyme-linked immunosorbent assay

DFA: direct immunofluorescence assay

NAAT: nucleic acid amplification Nucleic acid amplification Laboratory techniques that involve the in-vitro synthesis of many copies of DNA or RNA from one original template. Septic Arthritis assay

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): polymerase chain reaction Polymerase chain reaction 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)

Differential Diagnosis

  • Amebic dysentery Amebic dysentery Dysentery caused by intestinal amebic infection, chiefly with entamoeba histolytica. This condition may be associated with amebic infection of the liver and other distant sites. Entamoeba spp./Amebiasis: 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. Entamoeba spp./Amebiasis, is an infection caused by Entamoeba histolytica Entamoeba Histolytica A species of parasitic protozoa causing entamoebiasis and amebic dysentery (dysentery, amebic). Characteristics include a single nucleus containing a small central karyosome and peripheral chromatin that is finely and regularly beaded. Amebicides (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 Dysentery Acute inflammation of the intestine associated with infectious diarrhea of various etiologies, generally acquired by eating contaminated food containing toxins, biological derived from bacteria or other microorganisms. Dysentery is characterized initially by watery feces then by bloody mucoid stools. It is often associated with abdominal pain; fever; and dehydration. Gastroenteritis, 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: Anatomy abscess Abscess Accumulation of purulent material in tissues, organs, or circumscribed spaces, usually associated with signs of infection. Chronic Granulomatous Disease. Identification Identification Defense Mechanisms of E. histolytica in the stool or through serologic testing will give the diagnosis. Management includes metronidazole Metronidazole A nitroimidazole used to treat amebiasis; vaginitis; trichomonas infections; giardiasis; anaerobic bacteria; and treponemal infections. Pyogenic Liver Abscess or paromomycin Paromomycin An aminoglycoside antibacterial and antiprotozoal agent produced by species of streptomyces. Amebicides.
  • 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 or viruses Viruses Minute infectious agents whose genomes are composed of DNA or RNA, but not both. They are characterized by a lack of independent metabolism and the inability to replicate outside living host cells. Virology 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 Malaise Tick-borne Encephalitis Virus, and abdominal cramping Abdominal cramping Norovirus. The diagnosis is clinical and the illness is self-limited. 
  • Cryptosporidiosis: an infection with Cryptosporidium Cryptosporidium A genus of coccidian parasites of the family cryptosporidiidae, found in the intestinal epithelium of many vertebrates including humans. Hyper-IgM Syndrome. Patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship 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 Abdominal cramping Norovirus, nausea Nausea An unpleasant sensation in the stomach usually accompanied by the urge to vomit. Common causes are early pregnancy, sea and motion sickness, emotional stress, intense pain, food poisoning, and various enteroviruses. Antiemetics, 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 immunocompromised A human or animal whose immunologic mechanism is deficient because of an immunodeficiency disorder or other disease or as the result of the administration of immunosuppressive drugs or radiation. Gastroenteritis patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship. Diagnosis is with identification Identification Defense Mechanisms 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 Bacterial overgrowth Lactose Intolerance: 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 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: Anatomy, and can result due to alteration in the intestinal anatomy or motility Motility The motor activity of the gastrointestinal tract. Gastrointestinal 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 Weight loss Decrease in existing body weight. Bariatric Surgery, and malabsorption Malabsorption General term for a group of malnutrition syndromes caused by failure of normal intestinal absorption of nutrients. 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 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 and villous atrophy Atrophy Decrease in the size of a cell, tissue, organ, or multiple organs, associated with a variety of pathological conditions such as abnormal cellular changes, ischemia, malnutrition, or hormonal changes. Cellular Adaptation in the small bowel Small bowel 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: Anatomy due to gluten Gluten Prolamins in the endosperm of seeds from the triticeae tribe which includes species of wheat; barley; and rye. Celiac Disease. Symptoms include abdominal bloating Bloating Constipation 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 Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship may also have nutritional deficiencies and weight loss Weight loss Decrease in existing body weight. Bariatric Surgery due to malabsorption Malabsorption General term for a group of malnutrition syndromes caused by failure of normal intestinal absorption of nutrients. Malabsorption and Maldigestion. The diagnosis is established with serologic markers and small bowel Small bowel 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: Anatomy biopsy Biopsy Removal and pathologic examination of specimens from the living body. Ewing Sarcoma. 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 Chronic Inflammation 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 An unpleasant sensation induced by noxious stimuli which are detected by nerve endings of nociceptive neurons. Pain: Types and Pathways, weight loss Weight loss Decrease in existing body weight. Bariatric Surgery, and extraintestinal manifestations. Diagnosis includes imaging, endoscopy Endoscopy Procedures of applying endoscopes for disease diagnosis and treatment. Endoscopy involves passing an optical instrument through a small incision in the skin i.e., percutaneous; or through a natural orifice and along natural body pathways such as the digestive tract; and/or through an incision in the wall of a tubular structure or organ, i.e. Transluminal, to examine or perform surgery on the interior parts of the body. Gastroesophageal Reflux Disease (GERD), and biopsy Biopsy Removal and pathologic examination of specimens from the living body. Ewing Sarcoma. Management involves steroids Steroids A group of polycyclic compounds closely related biochemically to terpenes. They include cholesterol, numerous hormones, precursors of certain vitamins, bile acids, alcohols (sterols), and certain natural drugs and poisons. Steroids have a common nucleus, a fused, reduced 17-carbon atom ring system, cyclopentanoperhydrophenanthrene. Most steroids also have two methyl groups and an aliphatic side-chain attached to the nucleus. Benign Liver Tumors, aminosalicylates, immunomodulators, and biologic agents Biologic Agents Immunosuppressants.
  • 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: an intolerance to lactose-containing foods due to lactase Lactase An enzyme which catalyzes the hydrolysis of lactose to d-galactose and d-glucose. Defects in the enzyme cause lactose intolerance. Digestion and Absorption of Carbohydrates deficiency. Symptoms include crampy, abdominal pain Pain An unpleasant sensation induced by noxious stimuli which are detected by nerve endings of nociceptive neurons. Pain: Types and Pathways, bloating Bloating Constipation, nausea Nausea An unpleasant sensation in the stomach usually accompanied by the urge to vomit. Common causes are early pregnancy, sea and motion sickness, emotional stress, intense pain, food poisoning, and various enteroviruses. Antiemetics, 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 Hydrogen breath test Lactose Intolerance. Management includes restriction of dietary lactose and enzyme replacement Enzyme replacement Therapeutic replacement or supplementation of defective or missing enzymes to alleviate the effects of enzyme deficiency (e.g., glucosylceramidase replacement for gaucher disease). Severe Combined Immunodeficiency (SCID).

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
  5. Nazer, H. (2018). Giardiasis. In Cagir, B. (Ed.), Medscape. Retrieved December 11, 2020, from https://emedicine.medscape.com/article/176718-overview
  6. Gladwin, M., & Trattler, B. (2008). Clinical microbiology made ridiculously simple (4th edition). Miami: MedMaster.

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