GASTROINTESTINAL INFECTIONS





Acronyms



Bacterial diarrhea

Definition

  • Acute diarrhea < 7 days
  • Prolonged diarrhea 7 - 13 days
  • Persistent diarrhea 14 - 29 days
  • Chronic diarrhea ≥ 30 days

Etiology

Causes of diarrhea in the U.S. (annual cases / 100,000 people)
  • Noroviruses - most common cause of diarrhea in adults and children
  • Salmonella - 16.4
  • Campylobacter - 14.3
  • Shigella - 2.3
  • Shiga toxin–producing Escherichia coli - 1.1
  • Enterotoxigenic E. coli
  • Vibrio - 0.4
  • Yersinia - 0.3

Traveler's diarrhea

  • Traveler's diarrhea is a collective term for diarrhea that occurs in people who are traveling to foreign countries, particularly less developed countries where food preparation may be suboptimal
  • Traveler's diarrhea is primarily caused by bacteria (80 - 90% of cases) with E. coli enterotoxigenic species being the most common pathogen followed by Campylobacter jejuni, Shigella, and Salmonella. Viruses and protozoans like Giardia account for the remaining 10 - 20% of cases.
  • Bacterial and viral etiologies present with the sudden onset of urgent diarrhea accompanied by abdominal cramping, fever, and vomiting. Bloody diarrhea may or may not be present. Bacteria that produce toxins (e.g. E. coli) typically cause symptoms within a few hours of ingesting the offending food. Other bacteria and viruses may take 6 - 72 hours to produce symptoms. Giardia and other protozoa usually take 1 - 2 weeks before symptoms occur.
  • Untreated bacterial diarrhea usually lasts 3 - 7 days. Viral diarrhea lasts 2 - 3 days, and protozoal diarrhea can last weeks to months. Antibiotics reduce the length of bacterial diarrhea by about 1 day if the pathogen is susceptible. [35]
  • Bismuth subsalicylate (e.g. Pepto-Bismol and Kaopectate) has been shown to prevent traveler's diarrhea. In one study, the incidence of traveler's diarrhea was reduced by about 50% in subjects who took 2 - 4 grams per day. [PMID 2406858]

Symptoms

  • Noroviruses - sudden onset of vomiting and nonbloody diarrhea; outbreaks may occur in nursing homes, hospitals, and cruise ships; most common cause of foodborne infections; incubation period 10 - 51 hours; duration of illness is 1 - 4 days
  • Salmonella (nontyphoidal) - acute onset of watery diarrhea and fever; bloody diarrhea may occur; 95% of cases are foodborne (e.g. poultry or hen's eggs); nontyphoidal Salmonella is common in the U.S.; Salmonella Typhi causes a severe systemic infection (Typhoid fever) marked by fever and abdominal pain. It is uncommon in the U.S. but may be seen in travelers returning from endemic areas (Asia).
  • Campylobacter jejuni - sudden onset of watery diarrhea; fever and bloody diarrhea are common; foodborne transmission in 80% of cases; many infections occur during international travel (traveler's diarrhea)
  • Shigella - severe bloody diarrhea and fever are common; only a small inoculum is required for infection, so spreads easily; may be foodborne or waterborne
  • Shiga toxin–producing E. coli (enterohemorrhagic E. coli, E. coli O157:H7) - watery diarrhea progressing to bloody diarrhea; most commonly acquired from food (ground beef or produce); may also spread person-to-person and in water; can cause a hemolytic-uremic syndrome that may be worsened by antibiotic treatment
  • Enterotoxigenic E. coli - acute watery diarrhea; causes nearly half of cases of traveler's diarrhea; often foodborne
  • Vibrio vulnificus - associated with raw shellfish and seafood ingestion; watery diarrhea that may become bloody; Vibrio cholerae is associated with cholera outbreaks in areas with unclean water
  • Yersinia enterocolitica - acute watery diarrhea; may cause fever and bloody diarrhea; associated with a pseudo-appendicitis syndrome; seen most often in Canada and Scandinavia
  • Clostridium difficile (C. diff) - diarrhea that may be bloody; typically seen in patients with recent exposure to antibiotics (within 3 months); most common cause of diarrhea in healthcare settings (e.g. hospital); elderly patients are most affected
  • Diarrhea accompanied with significant vomiting - typically caused by a viral gastroenteritis [1,2,3,4,5]

Stool testing

Overview
  • Stool leukocyte testing is not recommended because it does not help establish the etiology of infectious diarrhea
  • Stool cultures have low yield and are not recommended in mild-to-moderate diarrhea
  • In symptomatic patients, stool cultures identify a pathogen in less than 50% of patients in most studies
  • One stool sample is typically sufficient when looking for a bacterial pathogen. Sample should be processed within 4 hours after passage when performing microscopy, and within 12 hours for cultures.
  • Routine stool cultures and bacterial stool pathogen panels typically test for Salmonella, Shigella, Campylobacter, and Enterohemorrhagic E Coli (detects Shiga toxin). Yersinia and Vibrio are not included in standard tests and must be ordered separately.
  • For cases of bloody diarrhea, it is important to test for the presence of Shiga toxin to help identify Shiga toxin–producing E. coli
  • Follow-up testing is not recommended in most people [1,2,3,4,5,30]
Indications for stool cultures in outpatients
  • Acute, severe diarrhea with fever (≥ 38.5°C, 101.3°F) lasting greater than 48 hours
  • Bloody diarrhea
  • Recent antibiotic exposure (check for C. difficile)
  • Persistent diarrhea (≥ 14 days) - also check for parasites
C. difficile testing
  • For patients with recent antibiotic exposure or hospitalization, testing for C. difficile should be performed
  • C. difficile testing is usually done in two steps. The first step involves screening with a GDH antigen EIA test or a toxin gene NAAT. If either test is positive, a toxin EIA test is performed for confirmation. The tests are described below.

  • Glutamate dehydrogenase (GDH) antigen EIA - GDH is an enzyme secreted by Clostridium species. GDH EIA testing has a high sensitivity (89 - 97%) for the presence of Clostridium species, but it cannot differentiate between toxin-producing and non-toxin-producing strains, giving it a specificity of 88 - 92%. GDH is typically used as a screening test, with positive results confirmed with a toxin EIA test.
  • Toxin gene NAAT - toxin gene NAATs detect genes that encode for C. difficile toxins. The tests have a high sensitivity (93 - 98%) for the presence of toxin-producing Clostridium species, but they cannot confirm active toxin secretion, making their specificity 93 - 95%. Toxin NAATs are often used as screening tests, with positive results confirmed with a toxin EIA test.
  • Toxin EIA tests - toxin EIA tests detect the presence of C. difficile toxins A and B. The tests have low sensitivities (76 - 88%) and are therefore not recommended for screening. A positive GDH or NAAT is typically confirmed with a toxin EIA test, which has a specificity of 99%. If a toxin EIA test is negative in the setting of a positive NAAT or GDH, one of the following may be true, and clinical judgment should prevail: (1) C. difficile colonization without active infection, (2) false-negative toxin EIA test, (3) toxin levels are below the threshold for detection. [30,32,37,39]

Treatment overview

Watery diarrhea
  • Empiric antimicrobial therapy is not recommended in most people with acute watery diarrhea and no recent international travel. Empiric treatment should also be avoided in people with persistent watery diarrhea lasting 14 days or more.
Bloody diarrhea
  • See stool testing above
  • In immunocompetent children and adults with bloody diarrhea, empiric antimicrobial therapy while waiting for test results is not recommended. If empiric treatment is given, adults should receive a fluoroquinolone or azithromycin, and children should receive a third-generation cephalosporin (infants < 3 months of age) or azithromycin. Therapy choice should be based on etiologic risk factors.
Antimotility agents (e.g. loperamide)
  • May be used in adults
  • Do not give to children < 18 years old [28]

Treatment regimens

Campylobacter species
  • Pediatric
    • Azithromycin 10 mg/kg/day (max 500 mg/day) given once daily for 3 - 5 days [CTE] ($)
    • Erythromycin base 30 mg/kg/day (max 2000 mg/day) given in 2 - 4 divided doses for 3 - 5 days [CTE] ($$$-$$$$)
  • Adults
Clostridium difficile (C. difficile) (See also C. difficile testing)

  • Pediatric (IDSA 2017)
    • Initial episode, nonsevere
      • Metronidazole 7.5 mg/kg/dose (max 500 mg/dose) 3 - 4 times a day for 10 days [IDSA] ($)
      • Vancomycin 10 mg/kg/dose (max 125 mg/dose) by mouth 4 times a day for 10 days [IDSA] ($$$$)
    • First recurrence, nonsevere
      • Metronidazole 7.5 mg/kg/dose (max 500 mg/dose) 3 - 4 times a day for 10 days [IDSA] ($)
      • Vancomycin 10 mg/kg/dose (max 125 mg/dose) by mouth 4 times a day for 10 days [IDSA] ($$$$)

  • Adults (IDSA 2021)
    • Initial episode
      • Preferred: Fidaxomicin (Dificid®) 200 mg two times a day for 10 days [IDSA,PI] ($$$$)
      • Alternative: Vancomycin 125 mg by mouth 4 times a day for 10 days [IDSA] ($$$$)
      • Alternative (nonsevere✝): Metronidazole 500 mg 3 times a day for 10 - 14 days [IDSA] ($)
      • ✝Nonsevere is defined as WBC < 15,000 cells/μL and creatinine < 1.5 mg/dl
    • First recurrence
      • Preferred: Fidaxomicin (Dificid®) 200 mg two times a day for 10 days OR twice daily for 5 days followed by once every other day for 20 days [IDSA] ($$$$)
      • Alternative: Vancomycin tapered: 125 mg 4 times daily for 10 – 14 days, 2 times daily for 7 days, once daily for 7 days, and then every 2 to 3 days for 2 to 8 weeks [IDSA] ($$$$)
      • Alternative: Vancomycin 125 mg by mouth 4 times a day for 10 days [IDSA] ($$$$)
      • Adjunctive treatment: Bezlotoxumab (Zinplava®) 10 mg/kg given intravenously once during administration of antibiotics. See [Zinplava PI] [IDSA] ($$$$)
    • Second or subsequent recurrence
      • Fidaxomicin (Dificid®) 200 mg two times a day for 10 days OR twice daily for 5 days followed by once every other day for 20 days [IDSA] ($$$$)
      • Vancomycin tapered: 125 mg 4 times daily for 10 – 14 days, 2 times daily for 7 days, once daily for 7 days, and then every 2 to 3 days for 2 to 8 weeks [IDSA] ($$$$)
      • Vancomycin 125 mg by mouth 4 times a day for 10 days followed by rifaximin 400 mg 3 times daily for 20 days [IDSA] ($$$$)
      • Fecal microbiota transplantation
      • Adjunctive treatment: Bezlotoxumab (Zinplava®) 10 mg/kg given intravenously once during administration of antibiotics. See [Zinplava PI] [IDSA] ($$$$) [38]

  • Prevention
    • In 2023, VOWST®, a capsule containing fecal microbiota spores, was approved to prevent C. difficile recurrence in adults. It is given as 4 capsules once daily for 3 consecutive days, starting two to four days after completion of C. difficile treatment. In a trial where adults with ≥ 3 C. difficile infections were randomized to VOWST or placebo, C. difficile recurrence was 12% and 40%, respectively, at 8 weeks [PMID 35045228], and 21% and 47% at 24 weeks [PMID 36260754]

E. Coli enterotoxigenic species
  • Pediatric
    • Azithromycin 10 mg/kg/day (max 500 mg/day) given once daily for 3 days [CTE] ($)
    • Ceftriaxone 50 mg/kg/day IM/IV given once daily for 3 days [CTE] ($)
    • Rifaximin 200 mg three times a day for 3 days. Approved for ≥ 12 years old. [PI] ($$$$)
  • Adults
E. Coli hemorrhagic species (Shiga toxin-producing, E. coli O157:H7)
  • Antibiotics are contraindicated
Salmonella species (nontyphoidal)
  • Pediatric
    • Mild-Moderate disease - treatment is not routinely recommended
    • Severe disease or high-risk patients (see below)
      • Azithromycin 20 mg/kg/day given once daily for 7 days [CTE] ($)
      • Ceftriaxone 100 mg/kg/day IV given in 2 divided doses for 7 - 10 days [CTE] ($)
      • Sulfamethoxazole-trimethoprim 10 mg/kg/day (trimethoprim component) given in 2 divided doses for 5 - 7 days [IDSA] ($)

  • Adults
    • Mild-to-moderate disease - treatment is not routinely recommended
    • Severe disease or high-risk patients (see below)
    • High-risk defined as having one of the following:
      • Age < 6 months or > 50 years
      • Heart valve disease including prosthetic heart valve
      • Severe coronary artery disease
      • Cancer
      • Kidney failure
      • Immunosuppression
      • Significant joint disease
Shigella species
Vibrio vulnificus
  • Pediatric
    • Azithromycin 10 mg/kg/day (max 500 mg/day) given once daily for 3 days [CTE] ($)
    • Ceftriaxone 50 mg/kg/day IM/IV given once daily for 3 days [CTE] ($)
  • Adults
Yersinia enterocolitica

Diverticulitis

Pathology

  • Diverticulosis is a condition where outpockets form along the colon's inner surface, and the sigmoid colon is most commonly affected. The outpocketings have a narrow neck that can become obstructed by fecal matter. When obstruction occurs, the pocket becomes inflamed, and diverticulosis becomes diverticulitis.
  • Seventy-five percent of diverticulitis cases are uncomplicated, meaning only colon wall inflammation is present. Diverticulitis is considered complicated if abscess, stricture, perforation, obstruction, or fistula are present. [22,23,24,31,36]

Epidemiology

  • The prevalence of diverticulosis increases with age, affecting 10% of people less than 40 and 50 - 70% of people 80 and older
  • Approximately 20% of people with diverticulosis will develop diverticulitis over the course of their lifetime
  • 80% of diverticulitis cases occur in patients who are ≥ 50 years old [22,23,24,31,36]

Risk factors

  • Increasing age
  • Low dietary fiber
  • Family history
  • Lack of exercise
  • Obesity
  • NSAIDs
  • Smoking
  • Constipation
  • Red meat consumption [22,23,24,31]

Symptoms

  • Left lower quadrant pain
  • Constipation
  • Fever
  • Nausea without vomiting
  • Elevated white count (leukocytosis) - present in 55% of cases
  • Elevated C-reactive protein [22,23,24,31,36]

Diagnosis

CT imaging
  • Diverticulitis is diagnosed with a CT scan with sensitivity of 93 - 97% and a specificity close to 100%. CT findings consistent with diverticulitis include thickening of the colonic wall, pericolonic fat stranding (indicating edema or inflammation), abscesses, localized air bubbles, and free air or fluid.
  • For patients with recurrent disease, a clinical diagnosis is sometimes made [22,23,24,31,36]
AGA 2021 recommendations
  • CT should be considered to confirm the diagnosis of diverticulitis in patients without a prior imaging confirmed diagnosis and to evaluate for potential complications in patients with severe presentations. Imaging should also be considered in those who fail to improve with therapy, are immunocompromised, or who have multiple recurrences and are contemplating prophylactic surgery in order to confirm the diagnosis and location(s) of disease. [36]

Recurrence

Overview
  • Recurrence rates for diverticulitis are as follows:
    • First episode: 8% within a year and 20% over ten years
    • Second episode: 18% within a year and 55% over ten years
    • Third episode: 40% within three years
  • Patients with complicated diverticulitis have a higher risk of recurrence; however, the risk of complicated disease decreases with each recurrence.
  • Recurrent attacks of uncomplicated diverticulitis are no longer an indication for elective colectomy, as diverticulitis does not appear to be a progressive disease [22,23,24,31,36]

Colonoscopy recommendations

Overview
  • Colon cancer can present with some of the same symptoms as diverticulitis, so a follow-up colonoscopy is recommended in most patients, particularly after the first episode. In a meta-analysis that included 50,445 patients with acute diverticulitis, the overall prevalence of colon cancer was 1.9%. Patients with complicated diverticulitis had a higher prevalence (7.9%) than those with uncomplicated diverticulitis (1.3%). [36]
AGA 2021 recommendations
  • Whether patients should have a colonoscopy after an episode of diverticulitis depends on the patient’s history, most recent colonoscopy, and disease severity and course. Colonoscopy is advised after an episode of complicated diverticulitis and after a first episode of uncomplicated diverticulitis, but can be deferred if a recent (within 1 year) high quality colonoscopy was performed.
  • After an acute episode of diverticulitis, colonoscopy should be delayed by 6 – 8 weeks or until complete resolution of the acute symptoms, whichever is longer. Colonoscopy should be considered sooner if alarm symptoms are present. Alarm symptoms include the following: change in stool caliber, iron deficiency anemia, blood in stool, weight loss, and abdominal pain. [36]

Prevention of recurrence

Overview
  • No preventive measure has been proven effective in a large randomized controlled trial
  • Possible beneficial strategies include the following:
    • High-fiber diet
    • Smoking cessation
    • Weight loss
    • Exercise
    • Avoidance of nuts, corn, and popcorn (found to have no benefit in a large prospective study) [22,23,24,25,26,31,34]
AGA 2021 recommendations
  • Medical therapy
    • To reduce the risk of recurrence, patients with a history of diverticulitis should consume a high-quality diet, achieve or maintain a normal body mass index, be routinely physically active, and not smoke. Additionally, patients with a history of diverticulitis should avoid regular use (2 or more times per week) of nonsteroidal anti-inflammatory drugs except aspirin prescribed for secondary prevention of cardiovascular disease.
    • Patients should understand that approximately 50% of the risk for diverticulitis is attributable to genetic factors
  • Surgery
    • An elective segmental resection should not be advised based on the number of diverticulitis episodes
    • A discussion of elective segmental resection for patients with a history of diverticulitis should be personalized to consider severity of disease, patient preferences and values, as well as risks and benefits, including quality of life. Patients should understand that surgery reduces, but does not eliminate, diverticulitis risk, and that chronic gastrointestinal symptoms do not always improve with surgery. [36]

AGA 2021 treatment recommendations

Diet
  • A clear liquid diet is advised during the acute phase of uncomplicated diverticulitis. Diet should advance as symptoms improve.
Antibiotics
  • Antibiotic treatment can be used selectively, rather than routinely, in immunocompetent patients with mild uncomplicated diverticulitis. Uncomplicated diverticulitis is defined as no evidence of systemic inflammation, abscess, perforation, peritonitis, stricture, fistula, or obstruction.
  • Antibiotic treatment is advised in patients with uncomplicated diverticulitis who have comorbidities or are frail, who present with refractory symptoms or vomiting, or who have a C-reactive protein > 140 mg/L or baseline white blood cell count > 15 X 109 cells/L. Antibiotic treatment is advised in patients with complicated diverticulitis or uncomplicated diverticulitis with a fluid collection or longer segment of inflammation on CT scan (86 mm vs 65 mm). [36]

Treatment regimens

Observation
Antibiotic regimens (duration 7 - 14 days)

Helicobacter pylori (H. pylori)

Overview

  • H. pylori is a gram-negative bacteria that resides in the stomach lining. It is usually acquired during the first few years of life and persists thereafter unless treated. H. pylori infects 50% or more of the world's population, while in the U.S., the prevalence is around 30%. It is more common in Asians and people from Central and South America. H. pylori causes no symptoms in the majority of infected individuals but is associated with a higher risk of certain GI conditions

Associated conditions

  • Duodenal and gastric ulcers - peptic ulcers occur in 1 - 10% of patients infected with H. pylori. Eradication of H. pylori reduces the risk of recurrent duodenal and gastric ulcers by 33% and 25%, respectively.
  • Gastric cancer - gastric cancer occurs in 0.1 - 3% of patients infected with H. pylori. A number of studies have now found that treating H. pylori lowers the risk of gastric cancer in high-risk patients (see screening below)
  • Gastric MALT lymphoma - MALT lymphoma occurs in < 0.01% of patients infected with H. pylori. In patients with localized disease, H. pylori treatment causes tumor regression in 60 - 90% of patients.
  • GERD and dyspepsia - there is no conclusive evidence that treating H. pylori improves GERD or dyspepsia symptoms
  • Iron deficiency anemia - some studies have suggested an association between iron deficiency anemia and H. pylori infection, while others have not. The ACG recommends testing adults with unexplained iron deficiency anemia for H. pylori.

Whom to test and treat (ACG 2024 recommendations)

  • Peptic ulcer disease: prior history or active disease
  • Marginal zone B-cell lymphoma, MALT type
  • Uninvestigated dyspepsia in patients who are under the age of 60 years
    • In high-risk populations for gastric cancer, test and treat at age 45-50 years
  • Functional dyspepsia
  • Adult household members of individuals who have a positive non-serological test for H. pylori
  • Patients taking long-term NSAIDs or starting long-term treatment with lowdose aspirin
  • Patients with unexplained iron deficiency anemia
  • Patients with idiopathic (autoimmune) thrombocytopenic purpura
  • Primary and secondary prevention of gastric adenocarcinoma
    • Current or history of gastric premalignant conditions (GPMC)
    • Current or history of early gastric cancer resection
    • Current or prior history of gastric adenocarcinoma
    • Patients with gastric adenomas or hyperplastic polyps
    • Persons with first degree relative with gastric cancer
    • Individuals at increased risk for gastric cancer including certain non-White racial/ethnic groups, immigrants from high gastric cancer incidence regions/countries, hereditary cancer syndromes associated with an increased risk for gastric cancer
    • Patients with autoimmune gastritis [40]

Screening

Overview
  • H. pylori eradication has been found to reduce the risk of gastric cancer in certain high-risk populations, while population-wide screening in Asian populations has had inconclusive results. ACG recommendations on whom to test and treat are provided above, while screening studies are summarized below.

Studies
  • Population screening
    • A long-term study in China, where the incidence of gastric cancer is among the highest in the world, found that treating people who were seropositive for H. pylori antibodies reduced the risk of gastric cancer [PMID 31511230]
    • A population-wide study (N=240,000) in Taiwan found that an invitation for H. Pylori screening did not reduce gastric cancer incidence or mortality. [PMID 39348147]
  • Family history
    • A study performed in South Korea found that treating people with H. pylori who had first-degree relatives with gastric cancer lowered the risk of gastric cancer. [PMID 31995688]
  • Gastric cancer recurrence
    • A study among patients with gastric cancer infected with H. pylori found that H. pylori treatment decreased the risk of recurrence [PMID 29562147].

Diagnostic tests

Overview
  • The three main noninvasive tests for H. pylori are the serologic H. pylori antibody (IgG) test, the urea breath test, and the fecal antigen test. H. pylori testing can also be performed on biopsies retrieved during endoscopic procedures (e.g. EGD).
  • For noninvasive testing, the ACG recommends the urea breath test or the fecal antigen test over the serologic antibody test because the antibody test will remain positive for years after exposure and is therefore not specific for active infection
  • When testing for cure after treatment, only the urea breath test and the fecal antigen test should be performed
Test preparation
  • For the urea breath test and the fecal antigen test, patients should stop PPIs and bismuth preparations 2 weeks before the test (some guidelines recommend 30 days) because they can cause false-negative results
  • H2 antagonists (e.g. Pepcid) may be taken during this period but should be stopped 24 hours before the test
Test for cure
  • Test for cure is recommended in all patients and should be performed ≥ 30 days after the completion of treatment. Patients should follow the same test preparation as the initial test (see above).
Tests
  • H. pylori antibody (IgG) - tests for IgG antibodies to H. pylori; sensitivity is 85% and specificity is 79%; cannot be used to confirm treatment success
  • Urea breath test - test involves drinking C-labeled urea which is converted to CO2 by H. pylori urease. Labeled CO2 is then measured in a breath sample. Sensitivity and specificity are as high as 95%
  • Fecal antigen test - detects H. pylori antigen in the stool; sensitivity and specificity are as high as 95% for monoclonal antibody tests
  • Endoscopic testing - tests are performed on biopsies taken during endoscopy; tests include urease-based testing, histological assessment, and culture

Treatment success rates


Treatment Cure rate
Optimized bismuth quadruple
(initial therapy)		 87%
Rifabutin triple (Talicia)
(initial therapy)		 84%
Voquezna TriplePak
(initial therapy)		 81%
Voquezna DualPak
(initial therapy)		 79%
High-dose dual therapy
(salvage therapy)		 75.6%
Levofloxacin triple
(salvage therapy)		 74.5%

Recurrence

  • Annual recurrence rates for H. pylori after successful treatment are 4.3% worldwide and 1% in the U.S. Recurrence is more common in developing countries and areas with a higher prevalence of infection. Retreatment is recommended in high-risk populations. [19,20,21,27,29,33,40]

Treatment regimens

Pediatric
  • PPI + Amoxicillin 50 mg/kg/day (max 2000 mg/day) given in 2 divided doses + Clarithromycin 20 mg/kg/day (max 1000 mg/day) given in 2 divided doses. Treat for 10 - 14 days. [CTE] ($$-$$$)
  • PPI + Amoxicillin 50 mg/kg/day (max 2000 mg/day) given in 2 divided doses + Metronidazole 20 mg/kg/day (max 1000 mg/day) given in 2 divided doses. Treat for 10 - 14 days [CTE] ($$-$$$)
  • Sequential therapy
    • Days 1 - 5: PPI + Amoxicillin 50 mg/kg/day (max 2000 mg/day) given in 2 divided doses
    • Days 6 - 10: PPI + Clarithromycin 20 mg/kg/day (max 1000 mg/day) given in 2 divided doses + Metronidazole 20 mg/kg/day (max 1000 mg/day) given in 2 divided doses. [CTE] ($$-$$$)
Adults (ACG 2024)

  • All therapies given for 14 days
  • Reference [40]
2024 ACG recommended H. pylopri regimens for treatment-naive adults
(Duration of therapy is 14 days)
Optimized bismuth quadruple
Rifabutin triple (Talicia)
  • Each Talicia capsule contains omeprazole 10 mg, amoxicillin 250 mg, and rifabutin 12.5 mg. Dosing is 4 capsules three times daily.
Voquezna DualPak
Voquezna TriplePak

  • All therapies given for 14 days
  • Reference [40]
2024 ACG recommended H. pylopri salvage regimens for treatment-experienced adults
(Duration of therapy is 14 days)
Optimized bismuth quadruple
Rifabutin triple
  • PPI standard to double dose twice daily
  • Amoxicillin 1000 mg twice or three times daily
  • Rifabutin 150 mg twice daily, 300 mg once daily, or Talicia, which contains 50 mg three times daily
Levofloxacin triple
Voquezna TriplePak
High-dose dual therapy

Other regimens
PPI dosing for H. pylori treatment
  • Omeprazole (Prilosec®)
    • Children ≥ 1 year: 1 - 1.2 mg/kg/d given in 2 divided doses [PMID 9200377, 16285942]
    • Adults: 20 mg twice daily
    • How supplied: 2.5, 10 mg powder for suspension | 10, 20, 40 mg capsule
  • Lansoprazole (Prevacid®)
    • 13 - 22 kg: 15 mg once daily
    • 23 - 45 kg: 15 mg twice daily [PMID 19166421]
    • Adults: 30 mg twice daily
    • How supplied: 15, 30 mg capsule | 15, 30 mg disintegrating tablet
    • Capsules and tablets can be mixed or dissolved in food. See Prevacid® PI sec 2.3 for instructions.
  • Esomeprazole (Nexium®)
    • Children (> 15 kg): 1.5 mg/kg/day (max 40 mg/day) given once daily [PMID 21407111]
    • Adults: 40 mg once daily
    • How supplied: 20, 40 mg capsule | 2.5, 5, 10, 20, 40 mg powder for suspension
  • Pantoprazole (Protonix®)
    • Adults: 40 mg twice daily
    • How supplied: 20, 40 mg tablet | 40 mg granules for suspension
  • Rabeprazole (Aciphex®)
    • Adults: 20 mg twice daily
    • How supplied: 20 mg tablet | 5, 10 mg sprinkle capsule
Prepackaged treatments
  • Omeclamox-Pak® - omeprazole 20 mg twice a day + amoxicillin 1000 mg twice a day + clarithromycin 500 mg twice a day for 10 days ($$$$)
  • Prevpac® - lansoprazole 30 mg twice a day + amoxicillin 1000 mg twice a day + clarithromycin 500 mg twice a day for 14 days ($$$$)
  • Pylera® - omeprazole 20 mg twice a day + Pylera® capsule (bismuth 140 mg / metronidazole 125 mg / tetracycline 125 mg) 3 capsules 4 times a day for 10 days ($$$$)
  • Talicia® - each Talicia capsule contains omeprazole 10 mg, amoxicillin 250 mg, and rifabutin 12.5 mg. Dosing is 4 capsules every 8 hours for 14 days. ($$$$)
  • Voquezna® Dual Pak - vonoprazan 20 mg twice daily plus amoxicillin 1000 mg three times daily for 14 days. ($$$$)
  • Voquezna® Triple Pak - vonoprazan 20 mg plus amoxicillin 1000 mg plus clarithromycin 500 mg, each given twice daily for 14 days. ($$$$)

Cryptosporidium parvum

Overview

  • Epidemiology - Cryptosporidium is a protozoan parasite that is passed through person-to-person contact, waterborne outbreaks (drinking water and swimming pools), and infected animals (newborn calves and lambs); an estimated 748,000 cases occur annually in the United States
  • Symptoms - average incubation period is about 7 days; watery diarrhea is the most prominent symptom; mild fever, abdominal cramps, nausea and vomiting may occur; duration of symptoms is typically 7 - 14 days; infection is usually self-limited in immunocompetent patients; recurrent episodes of diarrhea can occur for up to 30 days
  • Diagnosis
    • Stool studies for ova and parasites (O&P) - organism is viewed under a microscope; identifying Cryptosporidium requires special preparation techniques that may not be performed on a standard stool study and may not be available; sensitivity is improved with 3 serial stool samples
    • Cryptosporidium enzyme immunoassay (EIA) - test performed on stool; higher sensitivity and specificity than stool studies [6,9,12]

Treatment

Pediatric
  • Mild-to-moderate disease - treatment is not routinely recommended
  • Severe disease
    • Nitazoxanide
      • 1 - 3 years: 5 ml (100 mg) twice a day with food for 3 days [CDC/PI] ($$$$)
      • 4 - 11 years: 10 ml (200 mg) twice a day with food for 3 days [CDC/PI] ($$$$)
Adults
  • Mild-to-moderate disease - treatment is not routinely recommended
  • Severe disease
    • Nitazoxanide 500 mg twice a day for 3 days [CDC/PI] ($$$$)

Cyclospora cayetanensis

Overview

  • Epidemiology - Cyclospora is a coccidian parasite that is passed through food and water contaminated with feces; in the U.S., the most common source of infection is imported fresh produce (raspberries, basil, snow peas, and mesclun lettuce)
  • Symptoms - incubation period is 2 - 11 days (average 7 days); symptoms include watery diarrhea, loss of appetite, abdominal cramping and bloating, nausea and vomiting; symptoms may last for weeks; infection is self-limited in most patients
  • Diagnosis
    • Stool studies for ova and parasites (O&P) - organism is viewed under a microscope; identifying Cyclospora requires special preparation techniques that may not be performed on a standard stool study and may not be available; sensitivity is improved with 3 serial stool samples
    • Cyclospora PCR - test performed on stool; detects parasite DNA in stool; not widely available; higher sensitivity and specificity than stool studies [6,9]

Treatment

Pediatric
Adults

Entamoeba histolytica (Amebiasis)

Overview

  • Epidemiology - Entamoeba histolytica is a protozoan parasite that is passed through food and water contaminated with feces; Entamoeba dispar is a similar parasite that does not cause disease and is far more common than E. histolytica; an estimated 500 million people worldwide are infected with Entamoeba, and most of these cases are E. dispar; under microscopic exam, both organisms look the same
  • Symptoms 80 - 90% of infections are asymptomatic and self-limited; incubation period is typically 2 - 4 weeks; symptoms include diarrhea, abdominal pain, and cramping; in more severe cases, colitis with bloody diarrhea and fever may develop; liver abscess may occur in disseminated disease, but this is rare (1% of cases)
  • Diagnosis
    • Stool studies for ova and parasites (O&P) - organism is viewed under a microscope; sensitivity is improved with 3 serial stool samples; E. histolytica and E. dispar are indistinguishable under a microscope
    • E. histolytica enzyme immunoassay (EIA) - test performed on stool; test can distinguish between E. histolytica and E. dispar; higher sensitivity and specificity than stool studies
    • E. histolytica (Amebiasis) antibody titer - test performed on serum; typically ordered to identify etiology of liver abscess; has low sensitivity for intestinal amebiasis [6,7,8]

Treatment

Pediatric
  • Treatment includes systemic agent followed by luminal agent
    • Systemic agents
    • Luminal agents
      • Paromomycin 25 - 35 mg/kg/day (max 1500 mg/day) given in 3 divided doses for 5 - 10 days [PI] ($-$$)
Adults
  • Treatment includes systemic agent followed by luminal agent. Asymptomatic intestinal colonization may be treated with a luminal agent only.
    • Systemic agents
      • Metronidazole 750 mg 3 times a day for 5 - 10 days [IDSA/CTE] ($)
      • Tinidazole 2000 mg once daily for 3 days [PI] ($-$$)
    • Luminal agents
      • Paromomycin 500 mg 3 times a day for 7 days [IDSA] ($-$$)

Giardia intestinalis, G. duodenalis, G. lamblia

Overview

  • Epidemiology - Giardia is a flagellated protozoan primarily passed through water contaminated with fecal material from animals or humans; an estimated 2.5 million cases of giardiasis occur annually in the U.S.
  • Symptoms - symptoms typically appear between 6 - 15 days after infection and include fatty, yellowish diarrhea, weight loss, and abdominal pain; in most cases, the infection is self-limited with a duration of 2 - 4 weeks; a significant portion of people (30 - 50%) will develop chronic infection with intermittent diarrhea
  • Diagnosis
    • Stool studies for ova and parasites (O&P) - organism is viewed under a microscope; organism sheds intermittently therefore sensitivity is improved with 3 serial stool samples (85 - 90%)
    • Giardia lamblia enzyme immunoassay (EIA) - test is performed on stool and has high sensitivity (> 90%) and specificity (95 - 100%) [6,9,10,11]

Treatment

Pediatric
  • Metronidazole 5 mg/kg/dose (max 250 mg/dose) 3 times a day for 7 - 10 days [CTE] ($)
  • Nitazoxanide
    • 1 - 3 years: 5 ml (100 mg) twice a day with food for 3 days [PI] ($$$$)
    • 4 - 11 years: 10 ml (200 mg) twice a day with food for 3 days [PI] ($$$$)
  • Tinidazole (3 years and older) 50 mg/kg (max 2000 mg) given as a one time dose [PI] ($)
Adults
  • Metronidazole
    • 250 mg - 750 mg 3 times a day for 7 - 10 days [IDSA] ($)
    • 500 mg twice a day for 5 - 7 days [CTE] ($)
  • Nitazoxanide 500 mg twice a day for 3 days [CTE/PI] ($$$$)
  • Tinidazole 2000 mg given as a one time dose [CTE/PI] ($)

Zoonotic hookworms
Ancylostoma braziliense, Ancylostoma caninum, Uncinaria stenocephala

Overview

  • Epidemiology and pathology - Zoonotic hookworms are spread from dogs and cats to humans through feces. Under proper conditions (moisture, warmth, shade), eggs can form larvae in the soil. When humans come in contact with the larvae, the larvae penetrate the skin. In most cases, zoonotic hookworms cannot mature further in humans, and they migrate aimlessly in the epidermis. This migration causes a red, raised eruption to develop called cutaneous larva migrans (image). The eruption may move in the skin as the larvae migratee. The larvae will die after 5 - 6 weeks. In the U.S., zoonotic hookworm infections are most commonly seen in people returning from tropical climates.
  • Symptoms
    • Skin invasion - intense itching at the site of infection. Cutaneous larva migrans (image) - skin eruption with snake-like form that may migrate over days.
    • Other - in rare cases, larvae may migrate to the intestine and lungs and cause eosinophilic enteritis and pneumonitis, respectively
  • Diagnosis - zoonotic hookworm infection is a clinical diagnosis based on history (travel to tropical region), symptoms (intense itching), and characteristic rash (cutaneous larva migrans). There are no serological tests to aid in the diagnosis.
  • Treatment - larvae in the skin typically die in 5 - 6 weeks, making the infection self-limited in most cases. Treatment with ivermectin and albendazole may be indicated to control symptoms. [6]

Treatment

Pediatric
Adult
  • Albendazole 400 mg once daily for 3 - 7 days [CDC] ($$$$)
  • Ivermectin 200 mcg/kg as a single dose [CDC] ($)

Hookworms
Ancylostoma duodenale, Necator americanus

Overview

  • Epidemiology and pathology - hookworms are helminths spread through contaminated soil. Hookworm infections affect an estimated 740 million people worldwide. Humans infected with hookworm shed eggs in their feces. Soil contaminated with feces serves as a medium for eggs to mature into larvae. Larvae then attach to and invade the skin of bare-footed humans (or other skin surfaces) who walk on the soil. The larvae migrate to the lungs through the bloodstream, where they penetrate the alveoli and ascend the bronchial tree to the pharynx. The larvae are swallowed and end up in the small intestine, where they mature into adults and attach to the intestinal lining.
  • Symptoms
    • Skin invasion - may cause itching of feet or hands
    • Lung symptoms - occur within 10 days after skin invasion; cough and sore throat; eosinophilia of lungs
    • Intestinal symptoms - typically asymptomatic; microcytic, hypochromic anemia develops over time because worms suck blood from the intestinal wall; hypoproteinemia may develop; eosinophilia may be present on blood tests; heavy worm burden may produce gastrointestinal symptoms (e.g. abdominal tenderness, nausea)
  • Diagnosis
    • Stool studies for ova and parasites - eggs may be visualized under a microscope; examination of the eggs cannot distinguish between N. americanus and A. duodenale [6,15]

Treatment

Pediatric
  • Albendazole (≥ 6 years old) 400 mg given as a one time dose [CDC] ($$$$)
  • Mebendazole 100 mg twice daily for 3 days or 500 mg given as a one time dose [CDC] ($$$$)
  • Pyrantel pamoate (available over-the-counter) 11 mg/kg/day (max 1000 mg/day) given once daily for 3 days [CDC] ($)
Adults
  • Albendazole 400 mg given as a one time dose [CDC] ($$$$)
  • Mebendazole 100 mg twice daily for 3 days or 500 mg given as a one time dose [CDC] ($$$$)
  • Pyrantel pamoate (available over-the-counter) 11 mg/kg/day (max 1000 mg/day) given once daily for 3 days [CDC] ($)

Ascaris lumbricoides (Roundworm)

Overview

  • Epidemiology and pathology - Ascaris lumbricoides is a roundworm spread through contaminated soil that affects an estimated 30 - 100 million people worldwide. Humans infected with Ascaris shed eggs in their feces, and other humans become infected when they consume feces-contaminated foods. The eggs turn into larvae in the intestine, where they invade the wall of the intestinal lining, enter the circulation, and are carried to the lungs. In the lungs, larvae penetrate the alveoli, ascend the bronchial tree, and are swallowed in the pharynx. In the small intestine, they mature into adult worms and produce eggs. The process takes 2 - 3 months from egg ingestion to mature worm. Adult worms may live for 1 - 2 years and reach lengths of up to 35 cm.
  • Symptoms - typically asymptomatic; lung migration may cause cough, shortness of breath, and other nonspecific respiratory complaints; intestinal symptoms are usually mild abdominal discomfort; heavy infections may lead to malabsorption syndromes and intestinal blockage
  • Diagnosis
    • Stool studies for ova and parasites - eggs may be visualized under a microscope; stool concentration techniques may improve sensitivity
    • Worms in stool - adult worms are occasionally passed in the stool and are easily visualized [6, 17]

Treatment

Pediatric
Adults
  • Albendazole 400 mg given as a one time dose [CDC] ($$$$)
  • Ivermectin 150 - 200 mcg/kg given as a one time dose [CDC] ($)
  • Mebendazole 100 mg twice daily for 3 days or 500 mg given as a one time dose [CDC] ($$$$)

Enterobius vermicularis (Pinworms)

Overview

  • Epidemiology - Enterobius vermicularis, also called pinworms, is the most common helminth infection in the U.S., affecting 20 - 42 million people. Children, institutionalized populations, and homosexuals are at the greatest risk.
  • Pathology - pinworms are spread through the fecal-oral route when eggs from contaminated surfaces are transferred to other people and ingested. Eggs hatch in the stomach and upper intestine. The female worm then matures and migrates to the colon, where at night, she journeys to the anus and deposits her eggs on the perianal skin. The time from egg ingestion to perianal egg deposition is about 1 month. Perianal eggs are easily passed through direct contact to other surfaces (e.g. hands, toys, bedding), where they can survive in an indoor environment for 2 - 3 weeks.
  • Symptoms - the most common symptom is itching around the anus; many infections are asymptomatic; severe cases may cause abdominal pain
  • Diagnosis
    • Direct observation - worms may be seen in anal region 2 - 3 hours after the infected person goes to sleep
    • Cellophane tape test - in the morning, prior to the patient going to the bathroom or washing, the skin around the anus is patted with the sticky side of a piece of transparent (no frost) tape. The tape is then affixed to a glass slide so that it can be observed under a microscope to look for eggs and/or parts of female worms. The test should be performed on three consecutive mornings to increase sensitivity.
    • Fingernail samples - if the patient has scratched their bare anus, samples from under the fingernails may be evaluated under a microscope to look for eggs and/or parts of female worms
    • Stool studies - eggs and worms are not typically found in stool. Stool exams are not recommended. [6,11,12,13]

Treatment

Pediatric
  • Albendazole 10 - 14 mg/kg (max 400 mg) given as a one time dose. May repeat in 2 weeks. [CTE] ($$$)
  • Ivermectin 200 mcg/kg given as a one time dose and repeated in 10 days [PMID 15344847, 18452885, 2929853] ($)
  • Mebendazole 100 mg one time dose. May repeat in 2 weeks. [PI] ($$$$)
  • Pyrantel pamoate (Pin-X®, Reese's Pinworm medicine®, etc.) - available over-the-counter in numerous products. Treat according to product labeling. ($)
Adult
  • Albendazole 400 mg given as a one time dose. May repeat in 2 weeks. [CTE] ($$$$)
  • Ivermectin 200 mcg/kg given as a one time dose and repeated in 10 days [PMID 15344847, 18452885, 2929853] ($)
  • Mebendazole 100 mg one time dose. May repeat in 2 weeks. [PI] ($$$$)
  • Pyrantel pamoate (Pin-X®, Reese's Pinworm medicine®, etc.) - available over-the-counter in numerous products. Treat according to product labeling. ($)

Flatworms
Schistosoma species, S. mansoni, Schistosomiasis, Bilharzia

Overview

  • Epidemiology and pathology - Schistosomiasis is caused by a flatworm that infects an estimated 230 million people worldwide. Infected individuals shed eggs in their feces and urine that reach freshwater and hatch, releasing ciliated miracidia that infect snails. In the snail, the parasite replicates and sheds cercariae (infective larvae) into the water. Cercariae that come in contact with humans penetrate the skin and migrate to the portal vein, where they mature into worms. Worms migrate to the mesenteric veins and produce eggs. Schistosoma mansoni and japonicum typically reside in the mesenteric veins of the intestines, while S. haematobium most often resides in the venous plexus of the bladder. The incubation period for an infection can range from 14 - 84 days, and worms live an average of 3 - 10 years.
  • Symptoms
    • Acute infection - may be asymptomatic; fever, malaise, myalgia, headache, eosinophilia, fatigue, and abdominal pain lasting 2 – 10 weeks can occur (Katayama syndrome)
    • Chronic infection - symptoms are caused by immune reactions to the eggs. Eggs lodged in the blood vessels of the liver or intestine can cause diarrhea, constipation, and blood in the stool. Chronic inflammation can lead to bowel wall ulceration, liver fibrosis, and portal hypertension. S. haematobium eggs tend to lodge in the urinary tract causing dysuria, hematuria, obstructive uropathy, and bladder cancer.
  • Diagnosis
    • Stool studies for ova and parasites - S. mansoni and S. japonicum eggs may be visualized under a microscope; three samples should be collected to increase sensitivity
    • Urine studies for ova and parasites - S. haematobium eggs may be visualized under a microscope; three samples should be collected to increase sensitivity; peak egg excretion occurs between noon and 3PM
    • Schistosoma antibody, IgG - performed on blood; should not be drawn until 6 - 8 weeks after likely infection; cannot distinguish between active infection and past infection [6,12,18]

Treatment

General
  • Treatment should be initiated at least 6 - 8 weeks after exposure
  • Repeat treatment may be needed in 2 - 4 weeks
  • Follow-up urine or stool exam should be performed 1 - 2 months post-treatment
Pediatric (≥ 4 years old)
  • S. mansoni, S. haematobium, S. intercalatum
    • Praziquantel 40 mg/kg/day given in 2 divided doses for 1 day [CDC] ($$$)
  • S. japonicum, S. mekongi
    • Praziquantel 60 mg/kg/day given in 3 divided doses for 1 day [CDC] ($$$)
Adults
  • S. mansoni, S. haematobium, S. intercalatum
    • Praziquantel 40 mg/kg/day given in 2 divided doses for 1 day [CDC] ($$$$)
  • S. japonicum, S. mekongi
    • Praziquantel 60 mg/kg/day given in 3 divided doses for 1 day [CDC] ($$$$)

Strongyloides stercoralis (Roundworm)

Overview

  • Epidemiology and pathology - Strongyloides stercoralis is a roundworm that affects an estimated 30 - 100 million people worldwide. In the U.S., 0 - 6.1% of persons are infected, with immigrants having infection rates of up to 46%. People infected with Strongyloides shed larvae in their feces. When feces-contaminated soil comes in contact with humans, the larvae attach and invade the skin. The larvae then enter the bloodstream and migrate to the lungs, where they penetrate alveoli and ascend the bronchial tree to the pharynx. Swallowed pharyngeal larvae mature into adults in the small intestine, where they become threaded in the intestinal lining and lay more larvae-producing eggs. New intestinal larvae may "autoinfect" the host through the intestinal mucosa or perianal skin. The cycle of autoinfection may persist for many years.
  • Symptoms
    • Skin invasion - may cause itching at site of skin invasion; autoinfection may produce a rash called larva currens - a recurrent, snake-like, red, raised eruption that occurs along the buttocks, perineum, and thighs
    • Lung symptoms - typically asymptomatic; tracheal irritation, cough, shortness of breath, and transient lung infiltrates may be seen
    • Intestinal symptoms - typically asymptomatic; stomach pain, heartburn, bloating, intermittent diarrhea, nausea, and loss of appetite may be seen
    • Hyperinfection - a disseminated infection may occur in immunocompromised patients that leads to multi-organ infection and has a high mortality rate
  • Diagnosis
    • Stool studies for ova and parasites - larvae may be visualized under a microscope; serial stool exams are often required to increase sensitivity (≥ 3); specialized stool exams may increase sensitivity
    • Duodenal aspirate and biopsy - has a high sensitivity
    • Bronchoalveolar lavage - larvae may be seen on wet mount
    • Serum antibody tests (IgG) - high sensitivity; antibodies cross-react with other parasites (schistosomes, Ascaris lumbricoides) therefore have low specificity; does not necessarily indicate acute infection [6,16]

Treatment

General
  • Repeat stool exam should be performed 2 - 4 weeks after treatment to confirm clearance of infection
Pediatric
Adults
  • First-line
    • Ivermectin 200 mcg/kg given once daily for 1 - 2 days [CDC] ($)
  • Alternative
    • Albendazole 400 mg twice a day for 7 days [CDC] ($$$$)

Tapeworms
Taenia saginata, Taenia solium, Taenia asiatica

Overview

  • Taeniasis - Taeniasis is an intestinal tapeworm infection caused by Taenia saginata, Taenia solium, and Taenia asiatica. Tapeworms infect millions of people worldwide, but in the U.S., they are uncommon, with T. solium being the most prevalent and primarily affecting Latin American immigrants. Tapeworms are acquired through the consumption of undercooked beef (T. saginata) or pork (T. solium, T. asiatica). Once ingested, the worms attach to the wall of the small intestine, where they live for years producing eggs and proglottids (sexually-mature tapeworm segments) that are shed in the stool. Cows and pigs become infected by eating food and vegetation contaminated with human feces.
  • Cysticercosis - cysticercosis is an infection caused by T. solium, but unlike taeniasis, it is not acquired by eating undercooked pork and is instead transmitted when humans consume food or water that has been contaminated with feces from individuals with intestinal T. solium. Eggs hatch in the intestine, invade the intestinal wall, enter the circulation, and migrate to different tissues, primarily the brain (neurocysticercosis), muscles, and eyes. Cysticerci can damage the infected tissues, leading to seizures, muscle damage, and vision loss.
  • Symptoms
    • Taeniasis - taeniasis typically has either no symptoms or very mild ones (abdominal pain, distension, diarrhea). T. solium tapeworm segments often go unnoticed in stools, where T. saginata segments are much larger and typically seen
    • Cysticercosis - cysticercosis is often asymptomatic and discovered incidentally on imaging for other indications. Brain cysts can cause seizures and headaches (see neurocysticercosis). Eye cysts can cause vision loss, and muscle cysts can become tender.
  • Diagnosis
    • Worms in stools - worm and worm segments can be examined if they are found in the stool
    • Stool studies for ova and parasites - Taenia eggs may be visualized under a microscope; 3 consecutive specimens should be obtained; eggs can be difficult to visualize, therefore this test has a low sensitivity
    • Coproantigen detection assays - tests that detect Taenia antigens in stools; have high sensitivity and specificity; not widely available
    • Cysticercosis antibody testing (IgG) - test is performed on serum; detects antibodies to Taenia solium; supports diagnosis of cysticercosis [6,14]

Treatment

General
  • Treatment recommendations below are for taeniasis infections, not cysticercosis (see neurocysticercosis for more)
  • After treatment, stools should be collected for 3 days to search for tapeworm proglottids, which are useful for species identification
  • Stools should be re-examined for Taenia eggs 1 and 3 months after treatment to be sure the infection is cleared
Pediatric
  • Praziquantel 5 - 10 mg/kg given as a one time dose [CDC] ($$$)
  • Niclosamide 50 mg/kg given as a one time dose [CDC] (currently not available in U.S.)
Adults
  • Praziquantel 5 - 10 mg/kg given as a one time dose [CDC] ($$$)
  • Niclosamide 2000 mg given as a one time dose [CDC] (currently not available in U.S.)

Trichuris trichiura (Whipworm)

Overview

  • Epidemiology and pathology - Trichuris trichiura is a whipworm spread through the fecal-oral route that affects an estimated 600 - 800 million people worldwide. Infected persons shed eggs in their stool that mature in the soil and contaminate food sources. After consumption, eggs hatch in the small intestine and release larvae that migrate to the colon and turn into worms. Adult worms are about 4 cm in length and reside in the cecum and ascending colon. Females live for about 1 year and produce eggs 60 - 70 days after infection. The swine whipworm, Trichuris suis, is believed to have anti-inflammatory properties and has been studied in the treatment of Crohn's disease.
  • Symptoms - light infections typically have no symptoms; heavy infections are marked by colitis and the passage of painful, frequent stools that contain mucus, water, and blood; rectal prolapse may occur
  • Diagnosis
    • Stool studies for ova and parasites - eggs may be visualized under a microscope; stool concentration techniques may improve sensitivity [6,17]

Treatment

Pediatric
Adults
  • Albendazole 400 mg given once daily for 3 days [CDC] ($$$$)
  • Ivermectin 200 mcg/kg given once daily for 3 days [CDC] ($$)
  • Mebendazole 100 mg twice daily for 3 days [CDC] ($$$$)

PRICE ($) INFO

  • $ = 0 - $50
  • $$ = $51 - $100
  • $$$ = $101 - $150
  • $$$$ = > $150
  • Pricing based on one month of therapy at standard dosing in an adult
  • Pricing based on information from GoodRX.com®
  • Pricing may vary by region and availability

BIBLIOGRAPHY