Abdominal parasitic infection

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Mohammed Abdelwahed M.D[2]

Abdominal parasitic infection Main page
Overview
Causes
Ascaris lumbricoides
Necator americanus
Giardia lamblia
Fasciola Hepaticum
Schistosoma
Strongyloidis Stercoralis
E. Histolytica (Amebiasis)
Taeniasis
Trichuris trichiura
Hymenolepis Nana

Overview

An intestinal parasite infection is a condition in which a parasite infects the gastro-intestinal tract of humans and other animals. Mode of transmission of infection can be due to ingestion of undercooked meat, drinking infected water, fecal-oral transmission and skin absorption. There are many types of parasites that can cause abdomial infections but the most common types are caused by Ascaris lumbricoides, Necator americanus, Fasciola, Schistosoma, Trichuris trichiura, Strongyloides stercoralis, Taenia, Hymenolepis nana, and Entamoeba histolytica. Ascaris lumbricoides is a common in Asia and during six to eight weeks after egg ingestion, symptoms of ascariasis are abdominal discomfort, anorexia, nausea, vomiting, and diarrhea. Stool microscopy is the most common diagnostic tool for evaluation of Ascaris ova and albendazole is the drug of choice for treatment. Necator americanus is common in rural areas of the US and presents with nausea, diarrhea, vomiting, and epigastric pain. Giardiasis is common in children and mountains hikers who drink water that has not been boiled. Most of the cases are asymptomatic but acute giardiasis symptoms include diarrhea, malaise, steatorrhea, abdominal cramps, bloating, nausea, and weight loss. ELISA is sensitive for detection of giardiasis and stool examination is specific. Tinidazole and nitazoxanide are the preferred drug for Giardiasis. Fasciola appears with fever, anorexia, nausea, vomiting, myalgia, cough, right upper quadrant pain, hematomas of the liver, jaundice, and hepatomegaly. Complications include focal neurologic changes, pericarditis, arrhythmia, and right-sided pleural effusion. Computed tomography and magnetic resonance imaging radiographic findings in fascioliasis are vmultiple small nodules, thickening of the liver capsule, subcapsular hematoma, or parenchymal calcifications or tortuous tracks due to migration of the parasite through the liver. The treatment of choice is triclabendazole. Dosing consists of 10 mg/kg orally for one or two days. Bithionol and nitazoxanide are alternative choices. Intestinal schistosomiasis is caused by infection due to S. mansoni, S. japonicum, and S. haematobium. The most common symptoms include chronic or intermittent abdominal pain, poor appetite, bleeding from colonic ulcers that may cause anemia if heavily infested. The left lobe of liver is enlarged with splenomegaly that may extend below the umbilicus. Increased portal hypertension is due to high resistance in the hepatic circulation. The predominant pathological process consists of collagen deposition in the periportal spaces causing periportal fibrosis. Identification of schistosome eggs is the gold standard for the diagnosis of schistosomiasis with low sensitivity and high specificity. Serology is used as screening mainly because of low sensitivity. Praziquantel is the drug of choice for schistosomiasis. It increases calcium ion permeability. Calcium accumulate in the cytosol leading to muscular contractions and subsequent paralysis. Hymenolepis Nana is most common in temperate zones, and is one of the most common cestodes infecting humans, especially children. Most infections are asymptomatic. The diagnosis is generally established by identifying eggs in the stool. Praziquantel is the treatment of choice for hymenolepiasis. Most infections with T. trichiura are asymptomatic. Main symptoms are loose stool which may contain mucus and blood. The diagnosis of trichuriasis is made by stool examination for eggs. Mebendazole is the drug of choice for trichuriasis.

Causes

• Ascaris lumbricoides
• Necator americanus
• Ancylostoma duodenale
• Fasciola
• Schistosoma (S. mansoni, S. haematobium, S. japonicum)
• Trichuris trichiura
• Strongyloides stercoralis
• Taenia (solium, saginatum)
• Hymenolepis nana
• Entamoeba histolytica
• Giardia lamblia
• Entamoeba dispar
• Entamoeba moshkowskii
• Entamoeba coli
• Entamoeba hartmanii
• Endolimax nana
• Iodamoeba butschlii
• Chilomastix mesnili
• Blastocystis hominis 

Abdominal Parasitic infections

The following table summarizes all the abdominal parasitic infections.

Parasitic Infection		Mode of infection		Epidemiology	Clinical manifestations	Diagnosis	Treatment
Disease	Parasite		Incidence	Geographic distrubution
Ascariasis	Ascaris lumbricoides	Ingestion of Ascaris eggs secreted in the feces of humans or pigs. Ingesting uncooked pig or chicken liver with the larvae.	Ascariasis affects at least 1 billion people worldwide and about 4 million people in the United States.	Asia Africa South America	Abdominal discomfort Anorexia Nausea and vomiting Diarrhea Intestinal obstruction	Stool microscopy Peripheral eosinophilia Barium swallow	Albendazole Mebendazole Ivermectin
Necatoriasis	Necator americanus	Skin contact	Approximately 800 million people are infected with hookworms worldwide.	Brazil Texas Africa China Southwest Pacific islands India Southeast Asia	Acute Nausea and vomiting Diarrhea Epigastric pain Increased flatulence  Chronic Bloody stools Anemia LBW in pregnant women	Stool microscopy Peripheral eosinophilia	Albendazole Mebendazole Pyrantel pamoate
Giardiasis	Giardia lamblia	Ingestion of raw or undercooked food contaminated with cysts.	Approximately, 15,223 cases were reported in the United States in 2012.	Worldwide infection Among mountains hikers	Asymptomatic Acute Diarrhea Malaise Steatorrhea Abdominal cramps Bloating Nausea Weight loss. Chronic Lose stools Malabsorption Steatorrhea Weight loss Fatigue	Antigen detection assays  Fluorescein-tagged monoclonal antibodies Immunochromatographic assays Enzyme-linked immunosorbent assays  Nucleic acid amplificationassays (NAAT) Stool microscopy	Tinidazole Nitazoxanide
Fasciolosis	Fasciola Hepaticum			Central and South America Asia (China, Vietnam, Taiwan, Korea, and Thailand) Europe (Portugal, France, Spain, and Turkey) Africa The Middle East.	Acute liver phase Fever Anorexia Nausea and vomiting Myalgia Cough Right upper quadrant pain Hematomas of the liver Jaundice Hepatomegaly. Chronic biliary phase Asymptomatic Common bile duct obstruction Pancreatitis	Microscopy Stools Bile Duodenal aspiration Peripheral eosinophilia may disappear. Serology Indirect hemagglutination Complement fixation Enzyme-linked immunosorbent assay	Triclabendazole Bithionol Nitazoxanide
Schistosomiasis	S. mansoni S. japonicum S. haematobium	Infection can occur by: Penetration of the human skin by cercaria Handling of contaminated soil Consumption of contaminated water or food sources (e.g, unwashed garden vegetables)	Approximately 200 million people are infected annually with 200,000 deaths per year.	Sub-Saharan Africa.	Acute schistosomiasis syndrome  Fever and chills Urticaria Angioedema Myalgias Arthralgias Dry cough Diarrhea Abdominal pain Headache. Chronic schistosomias Intestinal schistosomiasis Hepatosplenic schistosomiasis Pulmonary schistosomiasis Genitourinary schistosomiasis	Stool microscopy Serologic tests include: Indirect hemagglutination Complement fixation Enzyme-linked immunosorbent assay PCR	Praziquantel Oxamniquine
Strongyloidiasis	Strongyloidis Stercoralis	Infection is contracted via direct contact with contaminated soil during agricultural, domestic, and recreational activities	Approximately 30–100 million infected persons worldwide	Tropical and subtropical regions	Hyperinfection syndrome Fever Nausea and vomiting Anorexia Diarrhea Abdominal pain Dyspnea Wheezing Hemoptysis Cough	Aspiration of duodenojejunal fluid is sometimes used to detect  Stool microscopy PCR, ELISA	Ivermectin Albendazole
Amoebiais	E. Histolytica	Transmitted by the fecal-oral route through contaminated drinking water or food. Direct contact with infected individuals.	Annual incidence of amoebiasis is approximately 50 million cases.	India Africa Mexico Parts of Central and South America	Asymptomatic Mild diarrhea to severe dysentery. Fulminant amebic colitis. Weight loss Amebic dysentery	Stool microscopy Antigen testing PCR	Metronidazole Tinidazole  Paromomycin  Diloxanide furoate  Iodoquinol
Taeniasis	Taenia saginata (beef tapeworm) Taenia solium, ( pork tapeworm).	Consumption of undercooked beef	Approximately 50 million human have cysticercosis.	Europe Parts of Asia.	Most human carriers are asymptomatic. Symptoms may include Nausea Anorexia Epigastric pain	Stool microscopy Peripheral eosinophilia ELISA PCR	Albendazole
Trichuriasis	Trichuris trichiura	Ingestion of embryonatedeggs from contaminated drinking water and food.		Endemic in tropical and subtropical countries.  Southern United States Incidence and prevalence rates are highest in children living in Sub-Saharan Africa Asia Latin America Caribbean	Asymptomatic Loose stool which may contain mucus and blood Nocturnal stooling Rectal prolapse	Stool microscopy Proctoscopy Demonstrates adult worms protruding from the bowel mucosa. Eosinophilia Polymerase chain reaction	Mebendazole 500 mg PO q24h X 3 day (or) 100 mg PO q12h x 2 days Albendazole 400 mg POq24h
Hymenolepiasis	Hymenolepis nana	Ingestion of infected eggs		Most common in temperate zones South Europe Russia India US Latin America.	Asymptomatic Heavy infections with >1000 worms can occur Crampy abdominal pain Diarrhea Anorexia Fatigue Pruritus ani	Stool microscopy FLOTAC method	Praziquantel Prompt family screening or empiric treatment

Ascaris lumbricoides adult worms, source: By SuSanA Secretariat - https://www.flickr.com/photos/gtzecosan/15701719491/in/set-72157648708895830, CC BY 2.0, https://commons.wikimedia.org/w/index.php?curid=37077525

+/−, Public Domain, https://commons.wikimedia.org/w/index.php?curid=781546

Necator Americanus, source: By Jasper Lawrence - I took the photograph using a Nikon E200 Trinocular microscope, an M99 microscope adaptor from the Martin Microscope Company (S/N3734), a D10NLC C-Mount manufactured by Diagnostic Instruments and a Sony HDV-A1U HD digital video camera., GFDL, https://commons.wikimedia.org/w/index.php?curid=4335265

Hookworm life cycle , source: By The original uploader was Sonett72 at English Wikipedia - CDC - Department of Parasitic Diseaseshttp://www.dpd.cdc.gov/dpdx/HTML/ImageLibrary/Hookworm_il.htmhttp://www.dpd.cdc.gov/dpdx/images/ParasiteImages/G-L/Hookworm/Hookworm_LifeCycle.gifOriginally from en.wikipedia; description page is/was here., Public Domain, https://commons.wikimedia.org/w/index.php?curid=1860052

Giardia lamblia

• The prevalence of giardiasis is 20 to 40 percent in endemic areas.
• The highest risk group for infection are children <5 years.
• Approximately, 15,223 cases were reported in the United States in 2012.
• Giardiasis is a major cause of diarrhea among mountains hikers who drink water that has not been boiled.
• Transmission of giardiasis can occur via ingestion of raw or undercooked food contaminated with cysts.
• Giardiasis can be transmitted via anal-oral sexual contact.

Clinical presentation

Asymptomatic infection 

• Most of the cases are asymptomatic.

Acute giardiasis

• Symptoms of acute giardiasis include diarrhea, malaise, steatorrhea, abdominal cramps, bloating, nausea, and weight loss.

Chronic giardiasis

• Symptoms of chronic giardiasis may include loose stools, malabsorption, steatorrhea, weight loss, and fatigue.

Complications

• Persistent infection occur in small number of patients causing malabsorption and weight loss.

Laboratory diagnosis

Antigen detection assays 

• Fluorescein-tagged monoclonal antibodies, immunochromatographic assays, and enzyme-linked immunosorbent assays are studies using antibodies against cyst or trophozoite antigens. These methods have greater sensitivity.

Nucleic acid amplification assays

• Nucleic acid amplification assays (NAAT) detect Giardia in stool samples.

Stool microscopy

• Stool microscopy to detect Giardia can be specific but needs expert to examine the stool and needs intermittent excretion of Giardia cysts.

Treatment

Preferred agents

• Tinidazole and nitazoxanide are the preferred drug for Giardiasis.
• Tinidazole has a longer half-life than nitazoxanide and may be administered as a single dose with high efficacy (>90 percent).

Drug	Dose
	Adults	Children
Tinidazole	2 g orally, single dose	Age ≥3 years: 50 mg/kg orally, single dose (maximum dose 2 g)
Nitazoxanide	500 mg orally two times per day for three days	Age 1 to 3 years: 100 mg orally two times per day for 3 days Age 4 to 11 years: 200 mg orally two times per day for 3 days Age ≥12 years: Same as adult dose

Giardia lamblia cytology, source: By Jerad M Gardner, MD - Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=15125058

, source: By CDC/Alexander J. da Silva, PhD/Melanie Moser - NIH, or CDC, or CDC PHIL #3394., Public Domain, https://commons.wikimedia.org/w/index.php?curid=3195726

Fasciola Hepaticum

• Fasciola infection is endemic in Central and South America, Asia (China, Vietnam, Taiwan, Korea, and Thailand), Europe (Portugal, France, Spain, and Turkey), Africa, and the Middle East.
• Children and women are the highest risk groups. It is highly infectious and in some endemic areas to the extent of infecting 100% of the individuals.

Clinical manifestations

• Many infections are mild forms of infection, and include two phases; the acute liver phase and chronic biliary phase.

Acute phase

• The early phase is associated with fever, anorexia, nausea, vomiting, myalgia, cough, right upper quadrant pain, hematomas of the liver, jaundice, and hepatomegaly.
• Acute symptoms last for six weeks.
• Complications include focal neurologic changes, pericarditis, arrhythmia, and right-sided pleural effusion.

Chronic phase

• This phase is usually asymptomatic.
• Common bile duct obstruction can develop, and chronic infection can lead to biliary colic, cholangitis, cholelithiasis, and obstructive jaundice.
• Pancreatitis has been reported in 30 percent of cases. Peripheral eosinophilia may disappear.

Complications

• Ascending cholangitis are biliary obstruction may be developed.

Diagnosis

• Diagnosis of fascioliasis should be associated with evaluation of family members.

Microscopy

• The diagnosis can be established by identifying eggs in stool, duodenal aspirates, or bile specimens.
• Eggs are not detectable in stool during the acute phase of infection.
• Examination of multiple specimens may be needed or concentration of specimens to facilitate egg identification.

Serology

• It is useful for cases of absent eggs in the stool, early cases and ectopic cases.
• Serologic tests include:
• Indirect hemagglutination
• Complement fixation
• Enzyme-linked immunosorbent assay

Imaging

• Computed tomography and magnetic resonance imaging radiographic findings in fascioliasis are vmultiple small nodules, thickening of the liver capsule, subcapsular hematoma, or parenchymal calcifications or tortuous tracks due to migration of the parasite through the liver.
• Necrotic areas may be seen especially in larger lesions. Peri-portal lymphadenopathy and hepatomegaly and/or splenomegaly may be seen, especially in acute fascioliasis.

Treatment

• The treatment of choice is triclabendazole. Dosing consists of 10 mg/kg orally for one or two days. Bithionol and nitazoxanide are alternative choices.

Schistosoma

• The prevalence of schistosomiasis is highest in sub-Saharan Africa.
• Approximately 200 million people are infected annually with 200,000 deaths per year.

Clinical presentation

Acute schistosomiasis syndrome

• Clinical manifestations include sudden onset of fever, urticaria, angioedema, chills, myalgias, arthralgias, dry cough, diarrhea, abdominal pain, and headache.
• The symptoms are usually relatively mild and resolve spontaneously over a period of a few days to a few weeks.

Chronic infection

• Chronic infection related to schistosomiasis is most common among individuals in endemic areas.

Intestinal schistosomiasis

• Intestinal schistosomiasis is caused by infection due to S. mansoni, S. japonicum, and S. haematobium.
• The most common symptoms include chronic or intermittent abdominal pain, poor appetite, bleeding from colonic ulcers that may cause anemia if heavily infested.
• Granulomatous chronic inflammation surrounding eggs in the intestine wall is developed making polyps. Dysplasia is uncommon complication of chronic inflammation.
• Intestinal stricture or obstruction is on the commonest complications.

Hepatosplenic schistosomiasis

• The left lobe of liver is enlarged with splenomegy that may extend below the umbilicus.
• Increased portal hypertension is due to high resistance in the hepatic circulation.
• The predominant pathological process consists of collagen deposition in the periportal spaces causing periportal fibrosis.
• This leads to occlusion of the portal veins, portal hypertension with splenomegaly, portocaval shunting, and gastrointestinal varices.

Pulmonary complications

• Pulmonary manifestations of schistosomiasis occur most frequently among patients with hepatosplenic disease due to chronic infection with S. mansoni, S. japonicum, or S. haematobium.
• Dyspnea is the primary clinical manifestation.
• Chest radiography demonstrates fine miliary nodules.

Genitourinary schistosomiasis

• In early infection, eggs are excreted in the urine and patients present with microscopic or macroscopic hematuria and/or pyuria.
• Blood is usually seen at the end of voiding terminal hematuria, although in severe cases hematuria may be observed for the entire duration of voiding.
• In early chronic infection, the eggs provoke granulomatous inflammation, ulcerations, and development of pseudopolyps in the vesical and ureteral walls, which may be observed on cystoscopy and mimic malignancy.

Laboratory findings

• Eosinophilia is observed in 30 to 60 percent of patients. Eosinophilia is very common among patients with acute schistosomiasis infection.
• Anemia and thrombocytopenia may be observed secondary to splenic sequestration in an enlarged spleen.
• Liver enzymes are near normal even if hepatic fibrosis occurred in most cases.
• Hematuria may occur with S. haematobium infection due to deposition of eggs in the urinary bladder wall.

Microscopy

• Identification of schistosome eggs in a stool or urine sample via microscopy is the gold standard for the diagnosis of schistosomiasis with low sensitivity and high specificity.

Infection intensity

• The intensity of intestinal schistosomiasis is classified as:

Infection Intensity	Egss per gram
Light	100 eggs per gram
Moderate	100 to 400 eggs per gram
Severe	>400 eggs per gram

• The intensity of urinary schistosomiasis is classified as:
  • Light to moderate: up to 50 eggs/10 mL
  • Severe: >50 eggs/10 mL

Serology

• Schistosome antigens including extracts of adult worms, cercarial antigens can develop antibodies that may be used in serology test.
• Serology is used as screening mainly because of low sensitivity.
• Serologic tests include:
  • Indirect hemagglutination
  • Complement fixation
  • Enzyme-linked immunosorbent assay

Molecular tests

• PCR on urine samples noted sensitivity and specificity of 94 and 100 percent, respectively.
• S. mansoni PCR sensitivity is 100 percent and specificity is 90 percent.

Biopsy

• Histopathology of superficial rectal biopsies is more sensitive than stool microscopy and may demonstrate eggs even when multiple stool specimens are negative.

Treatment

• Praziquantel is the drug of choice for schistosomiasis. It increases calcium ion permeability. Calcium ions accumulate in the cytosol, leading to muscular contractions and subsequent paralysis.
• Praziquantel side effects include dizziness, headache, vomiting, abdominal pain, diarrhea, and pruritus.

• Oxamniquine can be used for refractory schistosomiasis infection and may be as effective as praziquantel.

Schistosoma mansoni egg, source: By US federal government - Work of US federal government, Public Domain, https://commons.wikimedia.org/w/index.php?curid=218201

Couple of Schistosoma mansoni, source: CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=55038168

Strongyloidis Stercoralis

• In tropical and subtropical regions, the prevalence of Strongyloidis Stercoralis infection may exceed 25 percent.
• The highest rates of infection in the United States are among residents of the southeastern states and among individuals who have been in endemic areas.

Gastrointestinal symptoms

The most common manifestations of the hyperinfection syndrome include:

• Fever
• Nausea and vomiting
• Anorexia
• Diarrhea
• Abdominal pain
• Dyspnea
• Wheezing
• Hemoptysis
• Cough

Diagnosis

• Aspiration of duodenojejunal fluid is sometimes used to detect Strongyloides larvae in patients with negative stool samples.
• Polymerase chain reaction tests have also been developed for detection of Strongyloides in stool samples and have been found to be more sensitive and more reliable in detection of S. stercoralis.

Serology

• ELISA against strongyloides antigens has been proven as useful in diagnosis of immunocompetent individuals.
• ELISA results can be falsely negative in immunocompromised hosts.

Endoscopy

• Upper endoscopy is not usual diagnostic test.
• Strongyloidiasis has a broad range of endoscopic features:
  • In the duodenum, the findings include edema, brown discoloration of the mucosa, erythematous spots, subepithelial hemorrhages, and megaduodenum.
  • In the colon, the findings include loss of vascular pattern, edema, aphthous ulcers, erosions, serpiginous ulcerations, and xanthoma-like lesions.
  • In the stomach, thickened folds and mucosal erosions are seen.

Treatment

• Ivermectin is the preferred drug for treatment.
• Administered as two single 200 mcg/kg doses of ivermectin administered on two consecutive days.

Albendazole

• Albendazole (400 mg by mouth on empty stomach twice daily for three to seven days) also has activity against Strongyloides.

Strongyloides Stercoralis, source: Public Domain, https://commons.wikimedia.org/w/index.php?curid=219824

E. Histolytica (Amebiasis)

• Areas with high rates of amebic infection include India, Africa, Mexico, and parts of Central and South America. The overall prevalence of amebic infection may be as high as 50 percent in some areas.

Clinical presentation

• The majority of entamoeba infections are asymptomatic; this includes 90 percent of E. histolytica infections.

• Clinical amebiasis generally has a subacute onset, usually over one to three weeks.
• Symptoms range from mild diarrhea to severe dysentery, rarely fulminant amebic colitis.
• Weight loss occurs in about half of patients, and fever occurs in up to 38 percent.
• Amebic dysentery is diarrhea with visible blood and mucus in stools and the presence of hematophagous trophozoites (trophozoites with ingested red blood cells) in stools or tissues.
• Fulminant colitis with bowel necrosis leading to perforation, and peritonitis has been observed in approximately 0.5 percent of cases; associated mortality rate is more than 40 percent. Toxic megacolon can also develop.
• Amebic colitis has been recognized in asymptomatic patients.

Diagnosis

Stool microscopy

• The demonstration of cysts or trophozoites in the stool suggests intestinal amebiasis, but microscopy cannot differentiate between E. histolytica and E. dispar or E. moshkovskii strains. In addition, microscopy requires specialized expertise and is subject to operator error.

Antigen testing

• Stool and serum antigen detection assays that use monoclonal antibodies to bind to epitopes present on pathogenic E. histolytica strains (but not on nonpathogenic E. dispar strains) are commercially available for diagnosis of E. histolytica infection.
• Antigen detection kits using enzyme-linked immunosorbent assay (ELISA), radioimmunoassay, or immunofluorescence have been developed.
• Antigen detection has many advantages, including ease and rapidity of the tests, capacity to differentiate between strains, greater sensitivity than microscopy, and potential for diagnosis in early infection and in endemic areas.

Serology

• Antibodies are detectable within five to seven days of acute infection and may persist for years.
• Approximately 10 to 35 percent of uninfected individuals in endemic areas have antiamebic antibodies due to previous infection with E. histolytica.
• Negative serology is helpful for exclusion of disease, but positive serology cannot distinguish between acute and previous infection.

Molecular methods

• Techniques can detect E. histolytica in stool specimens.
• Studies have shown that PCR is significantly more sensitive than microscopy and that it was 100 percent specific for E. histolytica.
• PCR is about 100 times more sensitive than fecal antigen tests.

Treatment

• All E. histolytica infections should be treated, even in the absence of symptoms, given the potential risk of developing invasive disease and the risk of spread to family members.
• The goals of antibiotic therapy of intestinal amebiasis are to eliminate the invading trophozoites and to eradicate intestinal carriage of the organism.

Amebiasis life cycle , source: By CDC - https://www.cdc.gov/dpdx/amebiasis/index.html, Public Domain, https://commons.wikimedia.org/w/index.php?curid=41751982

Amoebic cyst, source: By CDC’s Division of Parasitic Diseases - http://dpd.cdc.gov/DPDx/HTML/ImageLibrary/Amebiasis_il.htm, Public Domain, https://commons.wikimedia.org/w/index.php?curid=5030067

Taeniasis

Taeniasis

• There are two main species of human Taenia; Taenia saginata (the beef tapeworm) and Taenia solium, (the pork tapeworm).
• T. saginata occurs worldwide but is most common in areas where consumption of undercooked beef is customary, such as Europe and parts of Asia.

Clinical presentation

• Most human carriers of adult tapeworms are asymptomatic.
• Symptoms may include nausea, anorexia, or epigastric pain.
• A peripheral eosinophilia may be observed.

Diagnosis

• The diagnosis is generally established by identifying eggs in the stool.
• Enzyme-linked immunosorbent assay for the detection of T. solium antigens in fecal samples and DNA hybridization can be used in case of failed eggs detection.
• Polymerase chain reaction assays targeting various genomic regions have been developed for distinguishing between species of human Taenia infections.

Treatment

• Praziquantel is the treatment of choice for taeniasis.
• Dosing for taeniasis is 5 to 10 mg/kg orally (single dose), although excellent efficacy against T. saginata infections has been reported at doses as low as 2.5 mg/kg.
• Niclosamide is an acceptable alternative treatment for tapeworms if praziquantel is not available.

Taenia Saginata life cycle , source: By Centers for Disease Control & Prevention, National Center for Infectious Diseases, Division of Parasitic Diseases - Centers for Disease Control & Prevention, National Center for Infectious Diseases, Division of Parasitic DiseasesThe work compiled from original Life cycle of Taenia spp. - http://www.dpd.cdc.gov/dpdx/html/Taeniasis.htm, Public Domain, https://commons.wikimedia.org/w/index.php?curid=26668532

Trichuris trichiura

• Trichuris trichiura is a round worm that causes trichuriasis when it infects a human large intestine.
• It is commonly known as the whipworm due to the shape of the worm.

 Clinical manifestations

• Most infections with T. trichiura are asymptomatic.
• Main symptoms are loose stool which may contain mucus and blood.
• Nocturnal stooling is common. Colitis and dysentery occur most frequently among individuals with >200 worms, and secondary anemia with pica may occur.
• Rectal prolapse can occur in heavily infested patients.
• Children who are heavily infected may have impaired growth and cognition.

Diagnosis

• The diagnosis of trichuriasis is made by stool examination for eggs.
• Proctoscopy can be performed and frequently demonstrates adult worms protruding from the bowel mucosa.
• Polymerase chain reaction assays targeting various genomic regions are becoming available and are able to detect T. trichiura worms.
• CBC shows peripheral eosinophilia of up to 15 percent and anemia.

Treatment

• Mebendazole is the drug of choice for trichuriasis: 500 mg once daily for three days or 100 mg orally twice daily for three days.
• Albendazole is second-line treatment: 400 mg orally on empty stomach once daily.

Trichuris Trichiura, source: By Delorieux for Johann Gottfried Bremser - XIX tabulae : Anatomiam entozoorum illustrantes, congestae, nec non explicatione praeditae, Public Domain, https://commons.wikimedia.org/w/index.php?curid=11412733

Hymenolepis Nana

• Hymenolepis Nana is a species most commonly in temperate zones, and is one of the most common cestodes infecting humans, especially children.
• The prevalence of Hymenolepis Nana is higher in warm parts of South Europe, Russia, India, US and Latin America.
• Prevalence is 97% in Moscow children and 34% in Argentina children. It has been reported to affect 4 percent of schoolchildren in rural southeastern United States.

Clinical manifestations

• Most infections are asymptomatic.
• Heavy infections with >1000 worms can occur and are often associated with crampy abdominal pain, diarrhea, anorexia, fatigue, and pruritus ani.

Diagnosis

• The diagnosis is generally established by identifying eggs in the stool.
• The sensitivity of stool microscopy can be increased by using concentration techniques such as the FLOTAC method.
• Diagnosis of hymenolepiasis should prompt family screening or empiric treatment, given the potential for person-to-person spread.

Treatment

• Praziquantel is the treatment of choice for hymenolepiasis.
• Dosing for hymenolepiasis is 25 mg/kg orally (single dose), followed by repeat dose 10 days later.

Hymenolepis Nana life cycle , source: Public Domain, https://commons.wikimedia.org/w/index.php?curid=2936828