1. Ingestion: Oral (nasopharyngeal) in food, water or aerosols, etc. 2. Active penetration: Through host tissues, skin or mucous membranes (Cercarial Dermatitus) 3. Injection: Through host tissues by vector or agent 4. Congenital: Transmission of parasites across the placental barrier from mother to fetus

Microblock 5 Flashcards by Anroux Mey

Facultative parasite:

Obligate parasite:

Incidental parasite:

Facultative parasite: Normally free living organism, but may become an opportunistic parasite

Obligate parasite: Cannot survive in a free living state

Incidental parasite: Establishes itself in a host in which it does not normally live (dog flea bites a human).

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Definitive host:

Intermediate host:

Reservoir host:

Paratenic host:

Definitive host: The host that harbors the adult or sexually reproducing stages of a parasite

Intermediate host: That host which harbors the immature, larval, or asexually reproducing forms of a parasite

Reservoir host: A host which replaces man in the life cycle of the parasite

Paratenic host: A host that serves as a transport host in which the parasitic forms undergo no development, but passes on to the final host

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Routes of infection

Ingestion: Oral (nasopharyngeal) in food, water or aerosols, etc.
Active penetration: Through host tissues, skin or mucous membranes (Cercarial Dermatitus)
Injection: Through host tissues by vector or agent
Congenital: Transmission of parasites across the placental barrier from mother to fetus

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Describe the morphology of a cestode (tapeworm)

Head = Scolex for attachment

Body= Proglottids (segments) / Strobili (chain)

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What is the specimen shown?

Taenia solium

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What are the two issues that Taenia solium can cause?

T. solium infection

Cause: Eating undercooked pork

Symptoms: Indigestion, diarrhea, WORM

Diagnose: stool exam

Prevention: Cook pork until grey

Cysticercosis

Cause: Eating T. solium eggs (human feces)

Symptoms: cyst location dependent

Diagnose: imaging of calcified cysticerci, visualize after excision, CT/MRI. Serology

RX: Steriods for inflammation

Prevention: sanitation

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What is the specimen shown?

Taenia saginata

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If you are the definitive host of a tapeworm what would you suffer from vs the intermediate host?

Definitive: Adult tapeworm in system

Intermediate: cysticercosis, echinococcosis, sparganosis

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What is shown

Diphyllobothrium latum

(Fish Tapeworm)

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Common source of Diphyllobothrium latum?

What are some of the symptoms?

Gefilte Fish

asymptomatic, nausea, Low B12

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What is caused when larval tapeworms penetrate the skin when swimming in cold lakes

Sparganosis

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What population is at danger of contracting Echinococcus granulosus

What are the routes of transmission?

Rate of growth?

Diagnosis?

Treatment?

Sheep Farmers

route: ingestion of contaminated water/veg, hand to mouth canine feces

Slow growing (5-20 years), pressure ofter first sign

Imaging, aspiration is an option but risk of rupter

Rx: aspirate add formalin

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What population is at risk for Echinococcus multilocularis?

What animals are intermediate hosts?

What animals carry the eggs?

Where do the oncospheres usually attack the human body?

Trappers (Handle fur pelts and inhale fecal dust)

Rodents

Fox, dogs, and cats

Liver and Lungs (possibly the brain)

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What type of cyst mimics a carcinoma?

Echinococcus multilocularis

years before symptoms appear

liver enlargement and obstruction of biliary and portal pathways

metastasizes to the lungs and brain

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What tapeworm is able to auto-reinfect?

What is the intermediate host?

Hymenolepsis nana

Beetles

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What is known as the dwarf tapeworm?

Hymenolepis nana

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What is different in the life cycle between the two Hymenolepis?

Nana: able to auto-reinfect

Dimunta: Requires insect for reinfection

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What is shown?

Dipylidium caninum

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What are the hosts of Dipylidium caninum

Fleas on cats and dogs

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What is this the egg for?

Taenia

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What is this the egg for?

Diphyllobothrium latum

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What is this the egg for?

Hymenolepis nana

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What is this the egg for?

Hymenolepis diminuta egg

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What type of sex are Trematodes (Flukes)?

*What is the exception*

Hermaphrodites

Schistosomes = cylindric bodies and separate male/female

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What type of shape are Trematodes (Flukes)

Leaf-shaped

What do Flukes require as their first intermediate host?

Mollusks (Snails / clams)

What is the most prevalent Fluke? What food are they associated with?

Fasciolopsis Buski What veg = Water Chestnuts

What is the stage at which humans ingest Fasciolopsis buski?

Metacercaria (Encysted Larva)

What is shown?

Fasciolopsis buski or Fasiolopsis hepatic

What is associated with watercress consumption?

Fasciola **hepatica**

What fluke is associated with upper right quadrant pain?

Fasciola hepatica (Sheep Liver Fluke) Clonorchis sinesis (Chinese Liver Fluke)

What Fluke requires **_two_** intermediate hosts?

**Clonorchis sinesis** **Paragonimus westermani (Lung Fluke)**

What distinguishes Clonorchis sinesis vs Fascioloa Hepatica?

Source: Sinesis = Fish / Hepatica = Water Veg Egg appearance

What is the life cycle of Paragonimus westermani?

Egg -\> snail -\> crustacean -\> human

What is shown?

Clonotchis sinesis (Chinese Liver Fluke)

What is shown?

Paragonimus westermani

What fluke could cause destruction of lung tissue?

Paragonimus westermani

What is an important part of the prevention of Paragonimus westermani?

Pickling and wine soaking of crabs/crayfish do not kill the eggs

What is Schistomomiasis also known as?

Bilhariasis Snail Fever

How are Schistosomes different than flukes?

Male/Female No operculum Obligate **_intravascular_** parasite Skin penetrating cercariae

What allows for Schistosomes to survive in the blood stream for 20-30 years?

Coated in substance that immune system recognizes as self

Where do Schistosomes develop? Where do they migrate?

Portal Vein S. manosi/japonicum = mesenteric veins S. haematobium = urinary bladder

What causes an intense inflammatory reaction with Schistosomes?

The eggs (they also produce enzymes) Adults have a minimal affect

What are the early vs late signs of schistosomes?

Early = rash Late = **_Katayama Syndrom_** fever, cough, urticaria, arthralgias, lmphadenopthay, splenomegaly, and abdominal pain Chonic = fibrosis/scarring from eggs

What are the three types of Schistosomes?

S. masoni S. Japonicum S. Haematobium

What is shown?

S. mansoni

What is shown?

S. Japonicum

What is shown?

S. Haematobium

What are some symptoms of S. Mansoni?

Chronic: hepatosplenomegaly, ascites, eggs in spinal cord, lungs, thick white layer on portal vein (**_Clay pipestem fibrosis_**)

What are the symptoms of S. Japonicum?

Eggs are much smaller than S. mansoni = travel every where including brain ## Footnote **_Neurological deficits_**

What population is most likely at danger for S. Japonicum?

Rice paddies workers

What Schistosoma is associated with the prostate/uterine?

S. Haematobium

Swimmers itch is?

Cercarial Dermatitis non-human schitosomes

Characterized by large cylindric, **_unsegmented_** bodies

Nematodes (roundworms)

What is shown?

Enterobius vermicularis

What test is associated with Enterobius vermicularis?

**_Scotch tape prep_**

What are the symptoms of Enterobius vermicularis?

pruritus and fatigue

What is the most common helminthic in North America?

Enterobius vermicularis (Pinworms)

What is shown?

Ascaris lumbricoides

What can cause Pneumonitis (asthmatic attack)?

Ascaris lumbricoides

Why is Ascarid treated first?

Worms migrate in response to drugs and fevers, which could lead to perforations in the intestine

Life cycle of Ascaris lumbricoides

Ingest egg -\> larva worm penetrates duodenum -\> blood stream -\> liver/heart -\> pulmonary circulation -\> break through aveoli -\> grow in mucus -\> cough/swallowed -\> duodenum

What is a major source of Ascaris lumbricoides?

Human feces Most common helminthic worldwide

What is this showing?

Toxocara / Baylisascaris

What are reservoirs for Toxocara / Baylisascaris?

**Raccoons**, cats, and dogs

What is so dangerous about Toxocara and Baylisascaris?

Larva may invade any tissue of the body Causes bleeding and found in lungs, heart, kidneys, liver, skeletal muscles, eyes, and CNS

What type of drug is important for the treatment of Toxocara and Bayliscaris?

Corticosteroids

What is shown?

Trichuris trichiura | (Whipworm)

What nematod has no animal reservior?

Trichuis trichiura | (Whip worm)

What Nematod causes appendicitis?

Trichuris trichiura | (Whipworm)

Nematode that has no animal reservoir and is only associated with human feces

Trichuris trichiura

Roundworm with a mosquito as a vector

Wuchereria bancroti (no known resevoir): tropical areas Brugia malayi (cats/monkeys): Malaysia, India, Thailand, area

What is used to diagnose Wucheria bancrofti and Burgia malayi?

**_Microfilaria_**e in a **_blood_** smear

What are some symptoms of Wuchereria bancrofti and Brugia malayi?

**Lymhadenitis, Elephantiasis**

What is associated with Chrysops (mango fly) as vector? When should you look for a presence? What's important about the antibody test?

Loa Loa 10AM-2PM IhG test can be used in visitors due to locals most likely having "false" positives

Symptoms similar to L. Loa however the microfilariae in the blood is unsheathed (Edema, Calabar swelling)

Mansonella Perstans (Africa / Central-South America

Roundworm in Congo causes rare form of elenphantiasis

Monsonella Streptocerca

What family of roundworms are associated with midges and blackflies?

Masonella

What three roundworms are sheathed?

**Wucheria bancrofti** **Burgia malayi** **Loa Loa**