GASTROINTESTINAL INFECTION TREATMENT RECOMMENDATIONS




BACTERIAL DIARRHEA


Infection Treatment Other
Bacterial
diarrhea
Shigella species

Salmonella species (nontyphoidal)
  • Pediatric
    • Mild-Moderate disease - treatment is not routinely recommended
    • Severe disease or high-risk patients (see below)
      • Azithromycin - 20mg/kg/day given once daily for 7 days [CTE] ($)
      • Ceftriaxone - 100mg/kg/day IV given in 2 divided doses for 7 - 10 days [CTE] ($)
      • Sulfamethoxazole-trimethoprim -10mg/kg/day (trimethoprim component) given in 2 divided doses for 5 - 7 days [IDSA] ($)
  • Adult
    • Mild-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


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


E. Coli hemorrhagic species (Shiga toxin-producing, E. coli O157:H7)
  • Antibiotics are contraindicated


E. Coli enterotoxigenic species
  • Pediatric
    • Azithromycin - 10mg/kg/day (max 500mg/day) given once daily for 3 days [CTE] ($)
    • Ceftriaxone - 50mg/kg/day IM/IV given once daily for 3 days [CTE] ($)
  • Adults


Vibrio vulnificus
  • Pediatric
    • Azithromycin - 10mg/kg/day (max 500mg/day) given once daily for 3 days [CTE] ($)
    • Ceftriaxone - 50mg/kg/day IM/IV given once daily for 3 days [CTE] ($)
  • Adults


Yersinia enterocolitica

Clostridium difficile (C. diff)
  • Pediatric
    • Metronidazole - 7.5mg/kg/dose (max 500mg/dose) 3 times a day for 10 - 14 days [CTE] ($)
    • Vancomycin - 10mg/kg/dose (max 125mg/dose) by mouth 4 times a day for 10 - 14 days [CTE] ($$$$)
  • Adults
    • Initial episode, mild-to-moderate
      • Metronidazole - 500mg 3 times a day for 10 - 14 days [IDSA] ($)
    • Initial episode, severe (WBC > 15,000; elevated serum creatinine)
      • Vancomycin - 125mg by mouth 4 times a day for 10 - 14 days [IDSA] ($$$$)
      • Fidaxomicin (Dificid®) - 200mg two times a day for 10 days [CTE] ($$$$)

Infectious diarrhea
  • Acute diarrhea - < 14 days
  • Persistent diarrhea - 14 - 29 days
  • Chronic diarrhea - ≥ 30 days

    • Common causes of diarrhea in the U.S. - annual cases/100,000 people
      • Noroviruses - most common cause of diarrhea in adults
      • 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

  • 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 diarrhea; fever and bloody diarrhea 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
  • Traveler's diarrhea - typically caused by Campylobacter jejuni or enterotoxigenic E. coli
  • Diarrhea accompanied with significant vomiting - typically caused by a viral gastroenteritis [1,2,3,4,5]

Stool cultures
  • 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

    • 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

  • 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 typically test for:
      • Salmonella
      • Shigella
      • Campylobacter
      • Enterohemorrhagic E coli (detects Shiga toxin)

  • For patients with recent antibiotic exposure, testing for C difficile toxin A and B (EIA test) should be performed. Other tests for C difficile include detection of glutamate dehydrogenase (GDH), an enzyme secreted by C difficile, and C difficile gene tests (PCR or NAAT).
  • Yersinia and Vibrio are not included in a standard stool culture 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 [1,2,3,4,5]



DIVERTICULITIS

Infection Treatment Other
Diverticulitis Diverticulitis, uncomplicated
  • Diverticulitis
    • Pathology - diverticulosis is a condition where outpockets form along the surface of the colon (typically the sigmoid colon). The outpocketings have a narrow neck that may become obstructed by fecal material. When obstruction occurs, inflammation of the outpocketing may develop (diverticulitis). Diverticulitis may lead to complications such as abscess, perforation, obstruction, and fistula.
    • Epidemiology - The presence of diverticulosis increases with age with a prevalence of 10% in people < 40 years old, and 50 - 70% among people ≥ 80 years old; 80% of diverticulitis occurs in patients who are ≥ 50 years old; it is estimated that 20% of people with diverticulosis will develop diverticulitis over the course of their lifetime;
    • Risk factors - age; low dietary fiber; family history; lack of exercise; obesity; use of NSAIDs; smoking; constipation; red meat consumption
    • Symptoms and findings - left lower quadrant pain; constipation; fever; elevated white count (leukocytosis) present in 55% of cases
    • Diagnosis - in mild cases, clinical diagnosis is often made; for more severe cases or when there is concern for complications, CT scan has a sensitivity of 93 - 97%, and a specificity close to 100%;
    • Recurrence - recurrence rates after first episode of uncomplicated diverticulitis are between 10 - 30% over ten years; recurrent attacks of uncomplicated diverticulitis are no longer an indication for elective colectomy as diverticulitis does not appear to be a progressive disease
    • Follow-up
      • Complicated diverticulitis - colonoscopy is recommended 6 - 8 weeks after resolution
      • Uncomplicated diverticulitis - colonoscopy after uncomplicated diverticulitis does not appear to be necessary in most patients

    • Prevention of recurrent diverticulitis - no preventive strategies have been proven effective in large randomized controlled trials

      • High-fiber diet
      • Smoking cessation
      • Weight loss
      • Exercise
      • Avoidance of nuts, corn, and popcorn (found to have no benefit in a large prospective study)

    • References [22,23,24,25,26]



HELICOBACTER PYLORI

Infection Treatment Other
Helicobacter pylori

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

Adult
  • First-line (ACG 2017 recommendations)
  • Resistant cases (First-line failures)
    • In general, a regimen should be selected that uses different antibiotics than the failed regimen
    • In most cases, the bismuth regimen or the levofloxacin regimen will be appropriate

*Proton pump inhibitors (PPI) - dosing for H. pylori treatment only
  • Omeprazole (Prilosec®)
    • Children ≥ 1 year: 1 - 1.2mg/kg/d given in 2 divided doses [PMID 9200377, 16285942]
    • Adult - 20mg twice daily
    • How supplied - 2.5, 10mg powder for susp; 10, 20, 40mg cap
  • Lansoprazole (Prevacid®)
    • 13 - 22kg - 15mg once daily
    • 23 - 45kg - 15mg twice daily [PMID 19166421]
    • Adult - 30mg twice daily
    • How supplied - 15, 30mg cap; 15, 30mg disintegrating tablet
    • Capsules and tablets can be mixed or dissolved in food - See Prevacid® PI sec 2.3 for instructions
  • Esomeprazole (Nexium®)
    • Children (> 15kg) ∼ 1.5mg/kg/day (max 40mg/day) given once daily [PMID 21407111]
    • Adult - 40mg once daily
    • How supplied - 20, 40mg cap; 2.5, 5, 10, 20, 40mg powder for susp
  • Pantoprozole (Protonix®)
    • Adult - 40mg twice daily
    • How supplied - 20, 40mg tab; 40mg granules for susp
  • Rabeprazole (Aciphex®)
    • Adult - 20mg twice daily
    • How supplied - 20mg tab; 5, 10mg sprinkle cap

Prepackaged treatments
  • Prevpac® - lansoprazole (Prevacid®) 30mg twice a day + amoxicillin 1000mg twice a day + clarithromycin 500mg twice a day for 14 days ($$$$)
  • Pylera® - omeprazole (Prilosec®) 20mg twice a day + Pylera® capsule (bismuth 140mg / metronidazole 125mg / tetracycline 125mg) 3 capsules 4 times a day for 10 days ($$$$)
Helicobacter pylori (H pylori)
  • Epidemiology and pathology - 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. At least 50% of the world's population is infected with H. pylori. is more common in Asians and people from Central and South America.
  • Duodenal and gastric ulcers - ulcers occur in 1 - 10% of patients infected with H. pylori. H. pylori eradication in patients with gastric or duodenal ulcers greatly reduces the recurrence rate of these ulcers (by about 30%)
  • Gastric cancer - gastric cancer occurs in 0.1 - 3% of patients infected with H. pylori. It is unclear if treating H. pylori infection decreases the risk for gastric cancer.
  • Gastric MALT lymphoma - MALT lymphoma occurs in < 0.01% of patients infected with H. pylori. Treating H. pylori achieves tumor regression in 60 - 90% of patients with localized MALT lymphoma.
  • GERD and dyspepsia - there is no conclusive evidence that treating H. pylori infection improves GERD or dyspepsia symptoms
  • Iron deficiency anemia - some studies suggest an association between iron deficiency anemia and H. pylori infection. A causal link has not been established.
  • Symptoms - most patients with H. pylori infection have no symptoms
  • Who to test (ACG 2107 recs)
    • Testing recommended - history of PUD; early gastric cancer; MALT lymphoma; patients initiating chronic treatment with NSAIDs; patients with unexplained iron deficiency anemia; adults with immune thrombocytopenia
    • Consider testing - < 60 years old with dyspepsia; patients taking long-term daily aspirin therapy
    • Routine testing not recommended - patients with typical GERD symptoms; asymptomatic patients with family history of gastric cancer; patients with hyperplastic gastric polyps
  • Diagnosis
    • H. pylori antibody (IgG) - tests for IgG antibodies to H. pylori; sensitivity 85% and specificity 79% in some studies; 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 reported as 95%; when testing for cure, urea breath test should be performed ≥ 4 weeks after completion of therapy
    • Fecal antigen test - detects H. pylori antigen in the stool; sensitivity and specificity reported as 95% for monoclonal antibody test; when testing for cure, test should be performed ≥ 4 weeks after completion of therapy
    • NOTE: Patients taking the breath test or fecal antigen test should stop proton pump inhibitors and bismuth preparations 2 weeks before the test, H₂ antagonists 24 hours before the test, and avoid antimicrobial agents 4 weeks before the test. These medications may lead to a false-negative result.
    • Endoscopic testing - tests are performed on biopsies taken during endoscopy; tests include urease-based testing, histological assessment, and culture
  • Failed treatment - retreatment is appropriate in patients with peptic ulcer disease, MALT lymphoma, and gastric cancer; the benefit of retreatment in other patients is unclear [19,20,21,27]

    • Eradication rates

    • Treatment Eradication rate
      (% cured)
      PPI + clarith + amoxil or metro 70 - 85%
      Bismuth + metro + tetra + PPI 75 - 90%
      Levo + amoxil + PPI 87%
      Sequential therapy 84 - 93%




PROTOZOAL INFECTIONS

Infection Treatment Other
Giardia intestinalis

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

Adult
  • Metronidazole
    • 250mg - 750mg 3 times a day for 7 - 10 days [IDSA] ($)
    • 500mg twice a day for 5 - 7 days [CTE] ($)
  • Nitazoxanide (Alinia®) - 500mg twice a day for 3 days [CTE/PI] ($$$$)
  • Tinidazole - 2000mg given as a one time dose [CTE/PI] ($)

  • Giardia intestinalis (also called G. duodenalis and G. lamblia)
    • Epidemiology - Giardia is a flagellated protozoan that is primarily passed through water that has been 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; symptoms 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 performed on stool; test has high sensitivity (> 90%) and specificity (95 - 100%) [6,9,10,11]

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

Adult
  • Mild-to-moderate disease - treatment is not routinely recommended
  • Severe disease
    • Nitazoxanide (Alinia®) - 500mg twice a day for 3 days [CDC/PI] ($$$$)
  • Cryptosporidium parvum
    • 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 Unites 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]

Infection Treatment Other
Entamoeba
histolytica


(Amebiasis)
Pediatric
  • Treatment includes systemic agent followed by luminal agent
    • Systemic agents
    • Luminal agents
      • Paromomycin - 25 - 35mg/kg/day (max 1500mg/day) given in 3 divided doses for 5 - 10 days [PI] ($-$$)

Adult
  • Treatment includes systemic agent followed by luminal agent
    • Systemic agents
      • Metronidazole - 750mg 3 times a day for 5 - 10 days [IDSA/CTE] ($)
      • Tinidazole - 2000mg once daily for 3 days [PI] ($-$$)
    • Luminal agents
      • Paromomycin - 500mg 3 times a day for 7 days [IDSA] ($-$$)

Asymptomatic intestinal colonization may be treated with a luminal agent only
  • Entamoeba histolytica (Amebiasis)
    • 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]

Infection Treatment Other
Cyclospora
cayetanensis
Pediatric
Adult
  • Cyclospora cayetanensis
    • 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]



HELMINTH INFECTIONS

Infection Treatment Other
Pinworms

Enterobius
vermicularis


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

Adult
  • Albendazole - 400mg given as a one time dose. May repeat in 2 weeks. [CTE] ($$$$)
  • Ivermectin - 200mcg/kg given as a one time dose and repeated in 10 days (PMID 15344847, 18452885, 2929853) ($)
  • Mebendazole - 100mg one time dose. May repeat in 2 weeks. [PI] (currently unavailable in U.S.)
  • Pyrantel pamoate (Pin-X®, Reese's Pinworm medicine®, etc.) - available over-the-counter in numerous products. Treat according to product labeling. ($)
  • Enterobius vermicularis (Pinworms) (Enterobiasis)
    • Epidemiology - Enterobius vermicularis is a helminth (worm). Eggs from the worm are deposited around the anus of infected individuals. The eggs may then be carried to common surfaces like hands, toys, bedding, etc. through direct contact. Individuals who come into contact with these surfaces may ingest the eggs and become infected; pinworm eggs can survive in the indoor environment for 2 - 3 weeks; pinworm infections typically affect children and their caregivers; pinworms are the most common type of helminth infection in the U.S.; enterobiasis is a term meaning pinworm infection
    • Pathology - once ingested, eggs hatch in the stomach and upper intestine; the female worm then matures and migrates to the colon; at night, the female migrates outside the anus and deposits her eggs on the perianal skin; the time from egg ingestion to female deposition of eggs around the anus is about 1 month
    • Symptoms - 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 morning, prior to 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. The slide is then observed under a microscope to look for eggs and/or parts of female worms. Test should be performed on three consecutive mornings to increase sensitivity.
      • Fingernail samples - if patient has scratched 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]

Infection Treatment Other
Taenia saginata,
T. solium,
T. asiatica


(Tapeworms)
NOTE: treatment recommendations are for taeniasis infections, not cysticercosis

Pediatric
  • Praziquantel - 5 - 10mg/kg given as a one time dose [CDC] ($$$)
  • Niclosamide - 50mg/kg given as a one time dose [CDC] (currently not available in U.S.)

Adult
  • Praziquantel - 5 - 10mg/kg given as a one time dose [CDC] ($$$)
  • Niclosamide - 2000mg given as a one time dose [CDC] (currently not available in U.S.)

  • After treatment, stools should be collected for 3 days to search for tapeworm proglottids for species identification
  • Stools should be re-examined for Taenia eggs 1 and 3 months after treatment to be sure the infection is cleared
  • Taenia saginata, T. solium, and T. asiatica (Tapeworms)
    • Epidemiology - Taenia saginata, T. solium, and T. asiatica are tapeworms that infect humans through the consumption of undercooked beef (T. saginata) or pork (T. solium, T. asiatica); the worm attaches to the wall of the small intestine and can live there for years; eggs and proglottids from the worm are shed in the stool; Taeniasis is a term for intestinal tapeworm infection; T. solium may also cause an infection called cysticercosis (see below) which is different than taeniasis
    • Cysticercosis - Cysticercosis is an infection caused by T. solium. It occurs when larval cysts infect brain (neurocysticercosis), muscle, and other tissues. Cysticercosis infection occurs when humans consume food contaminated with the feces of individuals with intestinal T. solium infections. Cysticercosis infection does not occur from eating raw or undercooked pork; cysticercosis can lead to seizures, muscle damage, and eye damage
    • Symptoms - Taeniasis typically has no symptoms or very mild symptoms (abdominal pain, distension, diarrhea); T. solium tapeworm segments often go unnoticed in stools where T. saginata segments are typically seen because they are much larger
    • 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]

Infection Treatment Other
Ancylostoma duodenale and Necator americanus

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

Adult
  • Albendazole - 400mg given as a one time dose [CDC] ($$$$)
  • Mebendazole - 100mg twice daily for 3 days or 500mg given as a one time dose [CDC] (currently unavailable in U.S.)
  • Pyrantel pamoate (available over-the-counter) - 11mg/kg/day (max 1000mg/day) given once daily for 3 days [CDC] ($)
  • Ancylostoma duodenale and Necator americanus (Hookworm)
    • Epidemiology and pathology - hookworm is a helminth that is 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 and invade the skin of bare-footed humans (or other skin surfaces that come in contact) 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]

Infection Treatment Other
Ancylostoma braziliense

Ancylostoma caninum

Uncinaria stenocephala

(Zoonotic Hookworms)
Pediatric
Adult
  • Albendazole - 400mg once daily for 3 - 7 days [CDC] ($$$$)
  • Ivermectin - 200mcg/kg as a single dose [CDC] ($)
  • Ancylostoma braziliense, Ancylostoma caninum, Uncinaria stenocephala
    • Epidemiology and pathology - Zoonotic hookworms are spread from dogs and cats to humans. Infected dogs and cats shed eggs in their 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 in the skin (cutaneous larva migrans). The eruption may move in the skin as the larvae migrates. 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 - 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 eosinophilic pneumonitis, respectively
    • Diagnosis
      • Signs and symptoms - 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, therefore the infection is usually self-limited. Treatment with ivermectin and albendazole may be indicated to control symptoms. [6]

Infection Treatment Other
Strongyloides
stercoralis


(Strongyloidiasis)

(Roundworm)
Pediatric Adult
  • First-line
    • Ivermectin - 200mcg/kg given once daily for 1 - 2 days [CDC] ($)
  • Alternative
    • Albendazole - 400mg twice a day for 7 days [CDC] ($$$$)

Repeat stool exam should be performed 2 - 4 weeks after treatment to confirm clearance of infection
  • Strongyloides stercoralis (Strongyloidiasis)
    • Epidemiology and pathology - Strongyloides stercoralis is a roundworm that is spread through contaminated soil. Strongyloides infection affects an estimated 30 - 100 million people worldwide. In the U.S., 0 - 6.1% of persons sampled are infected, and up to 46% of immigrant populations are infected; humans infected with strongyloides shed larvae in their feces. When soil contaminated with feces comes in contact with human skin, the larvae attach and invade the skin. 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. In the intestine, they become threaded within the intestinal lining and produce eggs which turn into larvae. These 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, transient lung infiltrates may be seen
      • Intestinal symptoms - typically asymptomatic; stomach pain, heartburn, bloating, intermittent diarrhea, nausea, 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]

Infection Treatment Other
Ascaris lumbricoides

(Ascariasis)

(Roundworm)
Pediatric
  • Albendazole (≥ 6 years old) - 400mg given as a one time dose [CDC] ($$$$)
  • Ivermectin - 150 - 200mcg/kg given as a one time dose [CDC] ($)
  • Mebendazole - 100mg twice daily for 3 days or 500mg given as a one time dose [CDC] (currently unavailable in U.S.)
Adult
  • Albendazole - 400mg given as a one time dose [CDC] ($$$$)
  • Ivermectin - 150 - 200mcg/kg given as a one time dose [CDC] ($)
  • Mebendazole - 100mg twice daily for 3 days or 500mg given as a one time dose [CDC] (currently unavailable in U.S.)

  • Ascaris lumbricoides (Ascariasis)
    • Epidemiology and pathology - Ascaris lumbricoides is a roundworm that is spread through contaminated soil. Ascaris lumbricoides infection affects an estimated 30 - 100 million people worldwide. Humans infected with Ascaris shed eggs in their feces. The infection is spread when food sources contaminated with feces are consumed. The eggs turn into larvae in the intestine. They then invade the wall of the intestine and are carried to the lung via the bloodstream. In the lungs, larvae penetrate the aveoli, 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 between 2 - 3 months from egg ingestion to mature worm. Adult worms may live for 1 - 2 years and can reach lengths of up to 35cm
    • Symptoms - typically asymptomatic; lung migration may cause cough, shortness of breath, and other nonspecific respiratory symptoms; 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]

Infection Treatment Other
Trichuris trichiura

(Trichuriasis)

(Whipworm)
Pediatric
  • Albendazole (≥ 6 years old) - 400mg given once daily for 3 days [CDC] ($$$$)
  • Ivermectin - 200mcg/kg given once daily for 3 days [CDC] ($-$$)
  • Mebendazole - 100mg twice daily for 3 days [CDC] (currently unavailable in U.S.)
Adult
  • Albendazole - 400mg given once daily for 3 days [CDC] ($$$$)
  • Ivermectin - 200mcg/kg given once daily for 3 days [CDC] ($$)
  • Mebendazole - 100mg twice daily for 3 days [CDC] (currently unavailable in U.S.)

  • Trichuris trichiura (Trichuriasis) (Whipworm)
    • Epidemiology and pathology - Trichuris trichiura is a whipworm that is spread through the fecal-oral route. An estimated 600 - 800 million people are infected worldwide. Infected persons shed eggs in their stools. Eggs mature in the soil and become infective in 15 - 30 days. Infection occurs when food or other sources contaminated with feces are consumed. After consumption, eggs hatch in the small intestine and release larvae that mature in the colon. Adult worms are about 4cm in length, and they live in the cecum and ascending colon. Females begin producing eggs about 60 - 70 days after infection. The worms live for about 1 year. The swine whipworm Trichuris suis does not mature in humans, although the larvae can briefly colonize the colon. T suis larvae are 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 causing 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]

Infection Treatment Other
Schistosoma species

S. mansoni,
S. haematobium,
S. japonicum


(Schistosomiasis)

(Bilharzia)

(Flatworm)
Pediatric (≥ 4 years old)
  • S. mansoni, S. haematobium, S. intercalatum
    • Praziquantel - 40mg/kg/day given in 2 divided doses for 1 day [CDC] ($$$)
  • S. japonicum, S. mekongi
    • Praziquantel - 60mg/kg/day given in 3 divided doses for 1 day [CDC] ($$$)
Adult
  • S. mansoni, S. haematobium, S. intercalatum
    • Praziquantel - 40mg/kg/day given in 2 divided doses for 1 day [CDC] ($$$$)
  • S. japonicum, S. mekongi
    • Praziquantel - 60mg/kg/day given in 3 divided doses for 1 day [CDC] ($$$$)

  • 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

  • Schistosoma mansoni, S. japonicum, or S. haematobium (Schistosomiasis)
    • Epidemiology and pathology - Schistosomiasis is caused by a flatworm. An estimated 230 million people are infected worldwide. Infected individuals shed eggs in their feces and urine. Eggs that reach freshwater will hatch releasing ciliated miracidia that can 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. In humans, cercariae migrate through several tissues eventually reaching the portal blood in the liver where they mature into worms. Worms migrate to the mesenteric veins where they produce eggs. Schistosoma mansoni and S. 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. 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 may 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]