Parasitology Quiz: Hookworm and Ascaris

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Questions and Answers

Which of the following is NOT a symptom of hookworm infection?

Epigastric pain

Diarrhea (correct)

Weight loss

Iron deficiency anemia

Which species of hookworm causes cutaneous larva migrans?

Ancylostoma caninum (correct)

Ancylostoma duodenale

Necator americanus

Schistosoma mansoni

How are hookworm eggs typically diagnosed?

Fecal examination (correct)

Skin biopsy

Blood test

Sputum culture

What is the most likely route of infection for the patient described in the text?

Skin penetration by larvae in soil Signup and view all the answers

Which of the following medications is commonly used to treat hookworm infections?

Albendazole Signup and view all the answers

What is the characteristic appearance of a hookworm egg?

Round and clear, with a smooth shell Signup and view all the answers

Which parasitic worm is known for causing a condition called 'creeping eruption'?

Ancylostoma caninum Signup and view all the answers

What is the primary mechanism of infection for hookworm larvae?

Skin penetration by larvae in soil Signup and view all the answers

Which of the following is NOT a symptom of Ascaris lumbricoides infection?

Weight gain Signup and view all the answers

What two body systems are primarily affected in the migratory phase of Ascaris lumbricoides infection?

Respiratory and digestive Signup and view all the answers

How is the diagnosis of Ascaris lumbricoides infection typically made?

Stool examination Signup and view all the answers

What is the most common route of Ascaris lumbricoides transmission to humans?

Ingestion of contaminated water Signup and view all the answers

Which of these groups is most vulnerable to severe complications from Ascaris lumbricoides infections?

Children Signup and view all the answers

Which of the following is NOT a type of nematode?

Diphyllobothrium latum Signup and view all the answers

What is the primary form of Entamoeba histolytica that is infectious in the environment?

Cyst Signup and view all the answers

What is the most common site for extraintestinal infection of Entamoeba histolytica?

Liver Signup and view all the answers

Which of the following is a characteristic feature of Entamoeba histolytica trophozoites?

They inhabit walls of the large intestine and can be cytotoxic. Signup and view all the answers

Which symptom is LEAST likely to be associated with intestinal amebiasis?

Weight gain Signup and view all the answers

What is a characteristic feature of fulminant Entamoeba histolytica infection?

Rapidly progressing infection with a 40% mortality rate. Signup and view all the answers

In which clinical presentation of amebiasis is the presence of blood and mucus visible in the stool most likely seen?

Dysentery Signup and view all the answers

Which group is more likely to experience extraintestinal infection caused by Entamoeba histolytica?

Adult males Signup and view all the answers

Which characteristic is most indicative of Cryptosporidium cysts?

Acid-fast, 5µm size Signup and view all the answers

What is the primary mode of transmission for Diphyllobothrium species?

Ingestion of raw or undercooked freshwater fish Signup and view all the answers

What is the most significant concern regarding Taenia solium larval infections?

Neurocysticercosis Signup and view all the answers

A patient is diagnosed with a Diphyllobothrium infection. Which symptom is strongly associated with the chronic phase of this infection?

Megaloblastic anemia due to Vitamin B12 deficiency Signup and view all the answers

What is the treatment of choice for a Diphyllobothrium infection

Praziquantel Signup and view all the answers

Which of the following is NOT a common symptom of intestinal Taenia solium infection?

Seizures Signup and view all the answers

Which of the following is a common risk factor for Cryptosporidium infection?

Contact with chlorinated swimming pool water Signup and view all the answers

Which diagnostic method would be most useful in identifying a Diphyllobothrium infection?

Microscopic examination of stool for operculated eggs Signup and view all the answers

A patient with HIV presents with chronic watery diarrhea that is unresponsive to standard treatments. What would be the most appropriate intervention to directly address the cause of the diarrhea?

Restoring immune function with HAART therapy Signup and view all the answers

In what way does a Cryptosporidium infection differ from a Diphyllobothrium infection?

Cryptosporidium reproduces inside cells forming a unique intracellular environment. Signup and view all the answers

What is the leading cause of seizure disorders worldwide?

Neurocysticercosis Signup and view all the answers

What percentage of adult epilepsy cases in endemic areas are due to Taenia solium?

29% Signup and view all the answers

In which type of disease can proglottids be found in feces?

Intestinal disease Signup and view all the answers

What is the primary treatment modality for Taenia solium infection?

Praziquantel Signup and view all the answers

What symptoms are associated with acute hookworm infections?

Dermatitis and pneumonitis Signup and view all the answers

Which environmental conditions are most conducive to hookworm distribution?

Warm and wet climates Signup and view all the answers

What long-term effects can result from chronic hookworm infection?

Anemia and protein deficiency Signup and view all the answers

What is the mechanism by which praziquantel acts on taenia solium?

It kills adults and larvae Signup and view all the answers

What are the common symptoms associated with Strongyloides infection?

Watery diarrhea and epigastric pain Signup and view all the answers

What is the primary method of diagnosing Strongyloides stercoralis?

Microscopy with O & P exam Signup and view all the answers

What is a potential consequence of immunosuppression in Strongyloides infection?

Increased risk of hyperinfection Signup and view all the answers

How does the larva of Strongyloides stercoralis move?

At a rate of 5-15 cm in one hour Signup and view all the answers

Which of the following is NOT a treatment option for Strongyloides infection?

Antibiotics Signup and view all the answers

What type of rash is associated with the infection via skin penetration of Strongyloides?

Serpiginous rash Signup and view all the answers

Chronic infections of Strongyloides can lead to which of the following complications?

Malnutrition and impaired growth Signup and view all the answers

What is a common characteristic of helminthic infections, including Strongyloides?

Complex multicellular organisms Signup and view all the answers

Study Notes

GI Pathogens: Helminths and Protozoa

This presentation covers GI pathogens, specifically helminths (worms) and protozoa (single-celled organisms), focusing on their life cycles, transmission, distribution, symptoms, diagnostic techniques, and treatment.

Conflict of Interest Disclosure

The presenter has no financial or other conflicts of interest to disclose.

Learning Objectives

Understand the life cycle of each pathogen, including the course of infection in the human body, and how it relates to risk factors.
Know the geographic distribution of each pathogen.
Recognize the symptoms and pathology of each type of infection.
Identify diagnostic techniques for detecting these pathogens (including recognizing images).
Understand the treatment and prognosis for each pathogen.
Understand how to recognize medical cases of illness caused by the pathogens.

Parasitic Diseases

The presentation provides a resource URL for accessing a free, downloadable 6th Edition of Parasitic Diseases.

Select GI Pathogens: Parasites

Protozoa (single cell):
- Amebas: Entamoeba histolytica, Cyclospora cayatanensis, Giardia duodenalis, Cryptosporidium spp.
Helminths (worms):
- Cestodes (tapeworms): Taenia saginata, Taenia solium, Diphyllobothrium latum
- Nematodes (roundworms): Enterobius vermicularis, Ascaris lumbricoides, Strongyloides stercoralis, Hookworm (Ancylostoma duodenale and Necator americanus).

Review: Parasite Diagnosis

The gold standard is a stool exam.
Multiple stool samples are needed.
Examining the whole specimen, including large worms or fragments, is important.
Eggs are concentrated using techniques such as floatation (for most nematode and some cestode eggs) and sedimentation (for most trematode eggs and some cestode eggs).

Review: Protozoa – overview

Protozoa are unicellular.
Protozoan morphology (structure) changes throughout their life cycle (e.g., cyst vs. trophozoite).
Some protozoa can have multiple nuclei.
Various protozoa are listed as examples with their names and diagrams.

Review: Intestinal Protozoa Life Cycle

The lifecycle of intestinal protozoa involves alternating between a trophozoite (feeding) stage and a cyst/oocyst (dormant) stage.
A host ingests or ingests contaminated food or water with cysts.
Cysts excrete in the environment with feces.

Entamoeba histolytica

Causes intestinal amebiasis, which can be invasive.
Distributed worldwide, more common in areas with poor sanitation.
Only 10-20% of infected people show symptoms.

Entamoeba histolytica Life Cycle

Entamoeba histolytica has a life cycle that involves cysts passing with feces.
Trophozoites invade tissues of the colon causing various pathologies.
Cysts are ingested along with food or water.
Pathologies can cause, liver abscess, brain abscess, and flask-shaped ulcers.

Entamoeba histolytica Life Cycle (Alternative)

Trophozoites inhabit walls of the large intestine.
They feed on live cells (cytotoxic).
They create flask-shaped ulcers.
They can perforate the intestine and enter the bloodstream.

Entamoeba histolytica Clinical Presentation

Asymptomatic stage (80% of cases)
Watery diarrhea (can last weeks to years).
Dysentery (blood and mucus in stool, abdominal pain).
Fulminant infection (rapidly progressing, high mortality).
Extraintestinal infections (amebae enter the bloodstream, liver abscesses, lung involvement, brain abscesses are possible).

Entamoeba histolytica Pathology

Images of the pathology of Entamoeba histolytica infections in various tissues.

E. histolytica Ectopic Pathology

Hepatic abscess due to bloodstream dissemination.
Brain abscesses due to bloodstream dissemination.
Ocular amebiasis due to direct contact with trophozoites.

Entamoeba histolytica Diagnostics and Treatment

Microscopy for cysts and trophozoites in stool.
Antigen ELISA test on stool.
Nucleic acid amplification tests (PCR).
Treatment with metronidazole.

Cyclospora cayetanensis

Worldwide cause of watery diarrhea. − Similar to Cryptosporidium outbreaks in the U.S. − Important cause of illness in travelers.

Cyclospora Life Cycle

The life cycle of Cyclospora cayetanensis includes stages of sporulation and ingestion.

Cyclospora Clinical Course

Watery diarrhea with abdominal pain, bloating, flatulence, and nausea.
Duration is 2 weeks to several months.
Symptoms are intermittent.

Cyclospora Diagnosis and Treatment

Microscopy for oocysts in stool samples (8-10 micrometers).
Acid fast or autofluorescence under UV light.
PCR tests.
Treatment with trimethoprim-sulfamethoxazole (and nitazoxanide).

Cyclospora Summary

Causes chronic watery diarrhea.
Often foodborne.
Diagnosis via acid-fast cyst (8-10 micrometers).
Treated with trimethoprim-sulfamethoxazole.

Giardia lamblia

Widespread parasite; US cases due to local animal reservoirs and travel.

Giardia Life Cycle

Cysts are ingested, trophozoites emerge in small intestine.
Trophozoites encyst in small intestine, pathogens live on surface of villi.
Pathologies include flat villi and flattened villi.

Giardia Pathogenesis

Adheres to upper small intestine epithelium.
Sucking disk present.
High numbers cause malabsorption: flat villi, cover surface.

Giardia Clinical Presentation

Asymptomatic carriers.
Watery diarrhea (greasy, foul-smelling, steatorrhea, cramps, bloating, and flatulence).
Biphasic diarrhea/constipation.
Acute and self-limiting or chronic episodes with weight loss.

Giardia Diagnosis and Treatment

Microscopy (cysts: 10µm, 4 nuclei, oval; trophozoites: 13µm, tear-drop shaped, 2 nuclei).
Rapid antigen tests.
Direct fluorescent antibody tests.
Nucleic acid amplification tests (PCR).
Treatment: metronidazole or tinidazole. (Resistance becoming more common)
Other treatment: nitazoxanide.
Post-treatment side effects: lactose intolerance due to tissue damage.

Giardia Epidemiology

Animal reservoirs (beavers, muskrats, guinea pigs, ferrets, dogs, cats, and camelids).
Risk factors: travel to regions with fecal contamination of food/water; hikers drinking from open water sources, daycare.

Giardia Summary

Causes watery diarrhea with steatorrhea, abdominal cramping, bloating, and flatulence.
Worldwide occurrence.
Travel and open water sources are risk factors.
Diagnosis by microscopy (cysts and trophozoites).
Treated with metronidazole/tinidazole.

Cryptosporidium sp.

Watery diarrhea, worldwide common cause.
Several species; Cryptosporidium parvum = cause in humans.

Cryptosporidium Life Cycle

Parasite attaches to columnar epithelial cells forming a unique membrane complex, which creates a unique intracellular environment.
Difficult to treat due to intra-cellular replication and apoptotic induction.

Cryptosporidium Clinical Picture

Asymptomatic carriers.
Watery diarrhea with abdominal pain, nausea, vomiting.
Self-limiting in healthy patients (1-2 weeks, though can recur up to 30 days).
Chronic infections in immunocompromised patients (untreatable). − Worldwide leading cause of diarrhea in immunocompromised/HIV.

Cryptosporidium Epidemiology

Important risk factors include cysts being environmentally resistant to chlorination; swimming pools; drinking water supply; and zoonotic transmission from cattle/calves.

Cryptosporidium Diagnosis and Treatment

Microscopy - small round cysts (5µm), acid-fast.
Rapid stool antigen tests.
Nucleic acid amplification tests (PCR).
Treatment: Nitazoxanide (healthy immune systems), HAART (HIV).

Cryptosporidium Summary

Chronic watery diarrhea with abdominal pain, nausea, and vomiting.
Usually 1-2 weeks symptomatic.
In HIV patients can be longer and be virtually untreatable without restoring immune function.
Transmitted through consuming contaminated food/water, swimming pools, or contact with animals.
Diagnosis by Microscopy or rapid antigen.
Treated by Nitazoxanide.

Diphyllobothrium species

Broad fish tapeworm.
Several species; Diphyllobothrium latum common.
Lifespan ~20 years.
20 million people worldwide infected.
Spread via consumption of raw/undercooked fish.

Diphyllobothrium Life Cycle

Involves eggs passing in feces of human, embryonation and ingestion by first intermediate host (crustacea/fish), and ingestion by the definitive host (human), then the adult worms live in small intestine..

Diphyllobothrium Clinical Manifestations

Often asymptomatic
Abdominal pain, diarrhea, constipation, and weight loss.
Megaloblastic anemia, Vitamin B12 deficiency (in chronic infections).
Intestinal obstruction (in heavy infections).

Diphyllobothrium Diagnosis and Treatment

Eggs in feces, large (75 x 50 μm), oval, operculated.
Also observe passing of worm segments.
Treatment with Praziquantel.

Taenia solium

Pork tapeworm.
Adult tapeworms cause intestinal disease; and larval tapeworms (Cysticercosis) causes CNS/occular disease − spread via ingesting eggs in feces via oral-fecal route

Taenia solium Life Cycle

Eggs/Gravid proglottids in feces to environment.
Embryonated eggs ingested by human host.
Oncospheres penetrate intestinal wall, circulate to musculature.
Oncospheres develop into cysticerci.
Cysticerci may develop any organ, most commonly subcutaneous tissues, brain, and eyes.
Humans acquire intestinal tapeworm infection via consumption of cysticerci in meat.
Adults live in the small intestine.

Taenia solium Clinical Manifestations

Intestinal disease: nonspecific intestinal symptoms, abdominal pain, and loss of appetite.
Cysticercosis, depends on cyst localization: - CNS-Neurocysticercosis (most serious), seizures, headaches, behavioral changes, confusion, and loss of balance.

Taenia solium Diagnosis

Cysticercosis: imaging (MRI/CT scans)
Intestinal disease: Proglottids in feces (proglottids visible in stool)

Taenia solium Treatment

Praziquantel (kills adults and larvae)
Surgical removal of larvae.

Hookworms of Humans

Necator americanus.
Ancylostoma duodenale. − Acute: dermatitis, pneumonitis, epigastric pain, vomiting and diarrhea. − Chronic: anemia, blood loss, physical weakness, pale skin, physical/mental stunting, failure to thrive.

Hookworm Distribution

Prevalence in warm, wet climates.

Hookworm Life Cycle

Larval stage begins in the soil before penetrating human skin.
Larvae migrate through lungs and then to small intestine.
Adults mature in the small intestine.

Hookworm Diagnosis and Treatment

Eggs in feces (65-75 µm).
Treatment includes albendazole or mebendazole.

Cutaneous Larva Migrans

Dermatosis due to ancylostoma caninum, creeping eruption, red pruritic skin eruptions.

Hookworm Summary

Infection occurs in warm, wet climates.
Intestinal phase causes rash at penetration site, epigastric pain, weight loss, iron deficiency.
Can cause cutaneous larva migrans in some cases (hookerms from animals/dogs), or if humans migrate to areas in their life and do not treat these symptoms.
Treatment involves albendazole or mebendazole.

Other GI Pathogens (with summaries)

Ascaris lumbricoides; large round worms, widespread, usually in regions with poor sanitation, symptoms depend on infection dose (asymptomatic to serious symptoms) most common in pigs.
Strongyloides stercoralis: Strongyliasis, geographic distribution in tropical and subtropical regions ~100 million cases per year, possible autoinfection, symptoms range from dermatitis to severe GI issues.

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Description

Test your knowledge on hookworm and Ascaris lumbricoides infections with this quiz. Delve into symptoms, diagnosis, treatment, and transmission routes of these parasitic infections. Perfect for students studying parasitology or infectious diseases.