Parasitology and Helminthology

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the primary intermediate host of Hymenolepis diminuta?

Arthropods like cockroaches, flour moths, and beetles

Which tapeworm has proglottids that look like a cucumber?

Hymenolepis nana

Taenia saginata

Dipylidium caninum (correct)

Hymenolepis diminuta

Dwarf tapeworm, Hymenolepis nana, causes mild gastrointestinal complaints such as nausea, anorexia, abdominal pains, and diarrhea due to ingestion of ________ containing the infective larva.

grain products

What is the infective stage of Trypanosoma cruzi?

Metacyclic trypomastigote Signup and view all the answers

Trypanosoma brucei causes Gambian Sleeping Sickness.

False Signup and view all the answers

Which sign is associated with Chagas' disease and involves unilateral eyelid swelling?

Romana's Sign Signup and view all the answers

The bug bites an infected person and ingests _____ (stage that travels in blood).

trypomastigotes Signup and view all the answers

What is the infective stage of Leishmania spp. transmitted by sandflies?

Promastigotes Signup and view all the answers

Which disease is caused by Leishmania tropica?

Urban (dry) Leishmaniasis Signup and view all the answers

Sandflies become infected by biting an infected person and taking in infected cells. In the sandfly, amastigotes turn back into ___________.

promastigotes Signup and view all the answers

Match the liver fluke with its common name:

Fasciola hepatica = Sheep Liver Fluke Fasciola gigantica = Tropical Liver Fluke Clonorchis sinensis = Chinese/Oriental Liver Fluke Signup and view all the answers

What is the common name of Opisthorchis felineus?

Cat liver fluke Signup and view all the answers

Dicrocoelium dendriticum infects the ______ or liver.

bile duct Signup and view all the answers

Which host acts as the 2nd intermediate host for Echinostoma ilocanum?

Pila luzonica Signup and view all the answers

Paragonimus westermani is also known as the Oriental blood fluke.

True Signup and view all the answers

What is the habitat of Eurytrema pancreaticum?

Pancreas Signup and view all the answers

What is the life stage of Schistosoma japonicum that happens 1-3 months after the initial phase?

mesenteric fluke Signup and view all the answers

What parasite is found in the mesenteric veins and can lead to chronic infections such as Hepatosplenic Schistosomiasis?

Schistosoma Signup and view all the answers

Which Schistosoma species is associated with kidneys and has manifestations similar to Schistosoma japonicum but less severe?

Schistosoma mansoni Signup and view all the answers

What is the primary host for Raillietina garrisoni tapeworm?

Rat Signup and view all the answers

Diphyllobothrium latum is commonly known as ____________ tapeworm.

Broad Signup and view all the answers

Match the following parasites with their primary hosts:

Diphyllobothrium latum = Humans Taenia solium = Pigs Schistosoma japonicum = Mesenteric veins Signup and view all the answers

Which larval stage is present in the proglottids of Raillietina garrisoni tapeworm?

Cysticercoid Signup and view all the answers

Stool examination is typically performed to diagnose infections by Raillietina garrisoni tapeworm.

False Signup and view all the answers

Echinococcus granulosus worm primarily affects the __ and .

Liver, Lungs Signup and view all the answers

Match the following structures/stages with the correct parasitic worm:

Armed rostellum, Proglottids containing egg capsules = Raillietina garrisoni tapeworm Hydatid cyst, Protoscolex = Echinococcus granulosus worm Signup and view all the answers

Study Notes

Hemo flagellates: Trypanosoma spp.

Trypanosoma spp. infective stage: Metacyclic trypomastigote
Vector: Reduviid bug (Triatoma) for T. cruzi and Tse tse fly for T. brucei
Reservoir hosts: Armadillos, opossums, and woodrats for T. cruzi, and domestic cattle, bushbuck, and hartebeest for T. brucei
Morphology:
- Amastigote stage: Found in tissues
- Promastigote stage: Found in vector (V)
- Epimastigote stage: Found in vector (V)
- Trypomastigote stage: Found in blood
Pathogenesis:
- Chagoma: Local inflammation, reddish nodule, furuncle-like lesions associated with central edema, and regional lymphadenopathy
- Romana's Sign: Periorbital swelling (edema of eyelid and conjunctiva) and unilateral swelling (only one eyelid affected)
Disease manifestation:
- Acute phase: Fever, lymphadenopathy, and diffuse or focal inflammation affecting myocardium
- Chronic phase: No characteristic symptoms, but prominent lymphadenopathy and CNS invasion
Diagnosis:
- Thick and thin smears
- Buffy coat concentration technique by Strout method
- Culture by NNN medium
- Serology: IFAT, CF test, ELISA, Western Blot, IHA

Trypanosoma cruzi

Life cycle:
- Bug bites an infected person and ingests trypomastigotes
- Trypomastigotes transform into epimastigotes and multiply in the bug
- Epimastigotes further transform into metacyclic trypomastigotes (infective stage)
- Bug bites again and defecates near the bite wound
- Metacyclic trypomastigotes enter the person through the bite or mucous membranes
- Trypomastigotes transform into amastigotes (multiplying stage) inside cells
- Amastigotes multiply and then transform back into trypomastigotes
- Cycle repeats if another bug bites an infected person and picks up the parasite

Trypanosoma brucei

Life cycle:
- Similar to T. cruzi, but with a Tse tse fly as the vector
Disease manifestation:
- Gambian or West African Sleeping Sickness (chronic disease)
- Rhodesian or East African Sleeping Sickness (acute disease)

Hemo flagellates: Leishmania spp.

Leishmania spp. infective stage: Promastigote
Vector: Sandflies (Phlebotomus spp.)
Morphology:
- Amastigote stage: Found in tissues
- Promastigote stage: Found in vector
Disease manifestation:
- Cutaneous Leishmaniasis: Skin lesions, may be urban or rural
- Mucocutaneous Leishmaniasis: Skin and mucous membrane lesions
- Visceral Leishmaniasis: Kala-azar, Dumdum fever, or Post kala-azar dermal leishmaniasis
Diagnosis:
- Demonstration of lesions
- Tissue and skin biopsies for amastigotes
- Montenegro Skin Test for Leishmania donovani
- Formol Gel Test for hypergammaglobulinemia

Leishmania spp. Life Cycle

Sandflies bite an infected person and inject promastigotes
Promastigotes enter immune cells and turn into amastigotes
Amastigotes multiply inside these cells and spread to other cells
Sandflies become infected by biting an infected person and taking in infected cells
In the sandfly, amastigotes turn back into promastigotes
The cycle continues when the sandfly bites another person### Liver Flukes
There are two main species of liver flukes: Fasciola hepatica (Sheep Liver Fluke) and Fasciola gigantica (Tropical Liver Fluke)
Both species have a large, broad, flat body with a cephalic cone and prominent shoulders
They have intestinal ceca that are highly branched

Habitat and Hosts

Fasciola hepatica infects the biliary passages of the liver, and metacercaria are found in aquatic plants (Ipomea)
Fasciola gigantica is found in the bile ducts and liver
Hosts include sheep and humans

Morphology

Fasciola hepatica has a longer but narrower body, with a more developed cephalic cone and shoulders
Fasciola gigantica has a shorter body with a less developed cephalic cone and shoulders
Adult flukes have an attenuated anterior end

Disease Manifestation

Acute stage: due to larval migration and worm maturation, causing fever, chills, fatigue, weakness, weight loss, liver enlargement, and jaundice
Chronic stage: persistence of adult worms in biliary ducts, leading to obstruction and inflammation, and eventually fibrosis or cirrhosis

Infection

Infection occurs through ingestion of undercooked or raw aquatic plants containing metacercaria
Ingestion of livers (cooked) containing eggs can also lead to infection

Diagnosis

Eggs are reported as Fasciola eggs
Diagnosis can be made through stool examination (FECT, Kato Katz, Stoll’s dilution)
Difficult to distinguish from F. buski, but can be differentiated through size and shape of eggs### Liver Flukes
Opisthorchis felineus: Cat liver fluke, adult worms found in the gallbladder and bile duct, ventral sucker bigger than oral sucker, and eggs are dark brown with a thick shell and a large operculum.
Chronic infection leads to periductal fibrosis, cirrhosis, and portal hypertension, and may cause cholangiocarcinoma.
Humans are accidental hosts, and infection occurs through ingestion of raw or undercooked fish containing metacercariae.

Intestinal Flukes

Dicrocoelium dendriticum: Lanceolet/Lancet fluke, adult worms found in the bile duct or liver, and eggs are dark brown with a thick shell and a large operculum.
Humans are accidental hosts, and infection occurs through ingestion of ants or plants contaminated with metacercariae.
Infection can cause periductal fibrosis, cirrhosis, and portal hypertension.
Fasciolopsis buski: Giant intestinal fluke, adult worms found in the small intestine, and eggs are large and operculated.
Humans are the definitive host, and infection occurs through ingestion of encysted metacercariae in aquatic plants.
Infection can cause marked eosinophilia, malabsorption of vitamins, and inflammation at the site of attachment.
Echinostoma ilocanum: Garrison's fluke, adult worms found in the small intestine, and eggs are straw-colored and operculated.
Humans are the definitive host, and infection occurs through ingestion of second snail hosts raw.
Infection can cause local inflammation at the site of attachment, diarrhea, and intoxication due to release of metabolites.
Heterophyes heterophyes: Small intestine fluke, adult worms found in the small intestine, and eggs are light brown and operculated.
Humans are the definitive host, and infection occurs through ingestion of encysted metacercariae in fish.
Infection can cause local inflammation at the site of attachment, and heavy infections can lead to diarrhea and malabsorption.

Pancreatic Flukes

Eurytrema pancreaticum: Pancreatic fluke, adult worms found in the pancreas, and eggs are ellipsoid and yellow-brown.
Humans are accidental hosts, and infection occurs through ingestion of ants or grasshoppers contaminated with metacercariae.
Infection can cause local inflammation, ulceration, and hemorrhage, and heavier infections can lead to abdominal pain, duodenal ulcer disease, and diarrhea.

Lung Flukes

Paragonimus westermani: Oriental lung fluke, adult worms found in the lung, and eggs are reddish-brown and coffee bean-shaped.
Humans are accidental hosts, and infection occurs through ingestion of undercooked crabs containing metacercariae.
Infection can cause lung fluke disease, with symptoms including dry cough, blood-stained or rust-colored sputum, and may mimic signs of TB.

Blood Flukes

Schistosoma spp.: Oriental blood fluke, eggs are oval with a recurved hook or knob, and are found in the mesenteric veins.
Humans are the definitive host, and infection occurs through exposure to water contaminated with cercariae.
Infection can cause acute phase - Katayama syndrome, and chronic infections can lead to hepatosplenic schistosomiasis, intestinal bilharziasis, and pulmonary schistosomiasis.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

This quiz covers various aspects of parasitology, including helminthology, infection, and diagnosis. It includes topics such as snail and Kato Katz methodology.