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Fungi and Parasites > Helminths > Flashcards

Helminths Flashcards

1
Q

List the helminths (9)

A 
Clonarchis sinesis
Diphyllobothrium latum
Echinococcus granulosus
Loa Loa
Onchocera volvulus 
Enterobius vermicularis (Pinworm)
Schistosoma 
Strongyloides stercoralis
Taenia solium
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2
Q

Which helminths are trematodes (flukes)? (2)

A

Clonarchis

Schistosoma

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3
Q

Which helminths are nematodes (roundworms)? (4)

A

Loa Loa
Onchocera
Enterobius
Strongyloides

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4
Q

Which helminths are cestodes (tapeworms)? (3)

A

Diphyllobothrium
Echinococcus
Taenia

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5
Q

Clonorchis transmission

A

Undercooked fish - contracted by eating fish that is undercooked.

Fish are an intermediate host for the parasite - they burrow into the fish muscle and wait as cysts.

At this point they escape the cysts and infect humans when they consume the fish

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6
Q

Clonorchis presentation

A

Clonorchis is a liver fluke - it affects livers and gallbladders

1) Biliary tract inflammation

Once digested by human, the parasite burrows from SI to liver. From liver they feed on bile and travel to bile duct.

Clonarchis induces an inflammatory reaction from the body within the bile ducts and liver

2) Pigmented gallstones

Stones are typically brown in pigment and consist of cholesterol and calcium soaps of fatty acids.

These stones are seen in patients with mechanical obstruction to bile flow (like when this parasite induces inflammation in bile duct)

Associated with cholangiocarcinoma - it’s an oncogenic microbe

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7
Q

Clonorchis Tx

A

Praziquantel

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8
Q

Diphyllobothrium transmission

A

Ingestion of larvae from raw fish

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9
Q

Diphyllobothrium pathogenesis/presentation

A

It competes for Vitamin B12 - 80% of patients infected are asymptomatic and can go years without having their infection detected. Parasite then absorbs 80% of host’s B12 intake, leading to:

Megaloblastic anemia - indistinguishable from pernicious anemia - can also translate to subtle demyelinatie neuro symptoms

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10
Q

Diphyllobothrium Tx

A

Praziquantel (not FDA approved here)

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11
Q

How large is echinococcus?

A

tapeworm. 2-7mm in length

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12
Q

Echinococcus transmission

A

Ingestion of eggs from dog feces - proper hygiene helps prevent spread

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13
Q

Echinococcus presentation

A

1) Hydatid cysts in liver:

Infection causes slow-growing cysts in liver (rarely in lungs, spleen, heart too). These are the hydatid cysts - filled with clear fluid containing antibodies

Depending on the size, the cysts may be asymptomatic or present as an uncomfortable mass

2) Fibrosis and necrosis - how body reacts to the cyst growth
3) Anaphylaxis if antigens are released - if cysts rupture while in the body (during surg or trauma), the patient will go into anaphylactic shock - develop high fever, pruritis, edema, breathing trouble

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14
Q

Echinococcus Tx

A

Albendazole - usually combined with surgical removal of cysts (if accessible)

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15
Q

What disease does Loa Loa cause?

A

Subcutaneous filariasis

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16
Q

Loa Loa transmission

A

Fly bite - fly is the vector - When fly bites, the loa loa larvae penetrate the subQ tissue and are able to cause disease

17
Q

Loa Loa presentation

A

SubQ filariasis

1) Calabar swellings in skin - worm travels through subQ tissue leading to inflammation wherever it goes. When it stops for a while, local inflammation (Calabar swelling) happens.

Presents as localized, tense, inflammatory edema in joints for 1-3 days

2) Conjunctiva - It can travel through and infect the eye causing eye swelling. It can often be seen when it enters the eye since it moves subcutaneously in the conjunctiva

18
Q

Loa Loa Tx

A

Diethylcarbamazine (DEC): Treatment of choice for microfilariae and adult worms. Surgical removal of the worms can be done as well. Patients with serious infections may experience brain inflammation after DEC treatment.

Albendazole - sometimes used AFTER multiple DEC treatments. It causes death in adult worms, but not in microfiliariae. Fewer side effects than DEC.

19
Q

Onchocera transmission

A

Female blackfly bite

It is in microfilarial form when it is in its vector (female blackfly). When they seek a bloodmeal, biting humans, the microfilaria are transmitted to us. These larvae then mature into adults in host’s subQ tissue.

Preferentially infects tissues over intestines

20
Q

Onchocera presentation

A

1) Hyperpigmented skin

Since it likes to migrate to subQ tissues, infections usually have derm symptoms - skin nodules, pruritis, inflammation, and hyperpigmentation

2) River Blindness

Patients can develop vision loss - disease most often occurs in Subsaharan Africa blackflies are found near rivers

21
Q

Ochocera Tx

A

Ivermectin

Relieves derm symptoms (itching, nodules, hyperpigmentation) and helps stop progression of blindness

It only kills adult worms, so it usually has to be re-administered

22
Q

Enterobius transmission

A

Pinworm

Ingestion of pinworm egg: fecal-oral through contaminated hands, food, or water.

23
Q

Enterobius presentation

A

Pinworm

1) Intestinal infection

After eating the pinworm eggs, a 4-6 week incubation ensues and patients develop intestinal infection of adult pinworms. Infection is called enterobiasis.

This is asymptomatic in 1/3 of patients

2) Anal pruritis

Most common symptom of enterobius infection is intense anal itching

This happens bc adult pinworms exit the digestive tract to lay eggs around host’s anus at night

Pruritis is seen around perineum and anus - tickling, tingling, even pain

24
Q

Enterobius diagnosis

A

Scotch Tape Test - transparent adhesive tape applied to patient’s anal area. Tape is removed and viewed under low-power microscope to look for pinworm eggs.

25
Q

Enterobius Tx

A

Albendazole - inhibits glycogen metabolism in worms, starving them to death. This kills only adults though so it must be re-administered to fully eradicate.

Pyrantel Pamoate (2nd line) - causes neuromuscular blockage in worm

26
Q

Schistosoma transmission

A

It is a blood fluke

Snail-infested water! Snails are the host - humans develop infection from being exposed to snail-infested water.

27
Q

Schistosoma presentation

A

1) Intense immune response - symptoms of schistosomiasis happen after an intense immune response from host to worms and trapped eggs. This leads to cellular infiltrant that leads to granulomas, inflammation and fibrosis
2) Intestinal disease - As eggs pass through GI, many pathologic events take place

Ulceration, eggs getting lodged in intestines, worms being trapped in mesenteric intestinal veins

3) Hepatosplenic granuloma - parasites usually go to liver sinusoids where they feed on RBCs

From this liver migration, hepatorenal blood flow can become interrupted (through obstruction via worm or egg), leading to hepatosplenic dysfunction and granuloma formation.

Schistosoma mansoni and japonicum are specifically known for this.

4) Squamous cell cancer of bladder - some types can travel to urethral areas or the bladder and kidneys - can lead to urinary granulomas and GU issues in patients. Schistosoma hematobivin can lead to SCC of bladder in those who are chronically infected.

Patients display painless hematuria

28
Q

Schistosoma diagnosis

A

ELISA - look for parasitic antigens

29
Q

Schistosoma Tx

A

Praziquantel

30
Q

Strongyloides transmission

A

This nematode is adapted to living in top 15cm of soil. We get infected when larvae burrow through our skin (usually barefoot)

Once in skin, the larvae burrow into bloodstream where they mature and invade organs

31
Q

Strongyloides presentation

A

Uncomplicated Disease:

1) GI distress - most often it affects GI and leads to intestinal infection. This can be asymptomatic for a while. Sometimes, symptoms like vomiting, diarrhea, epigastric pain are seen
2) Loffler’s Syndrome - a pulmonary eosinophilia which occurs from parasitic invasion (eosinophilic pneumonia)
3) Dermatitis - patients can develop urticarial rashes at the site of larval penetration and other classic areas - feet, buttocks, waist.

Disseminated Disease:

Occurs in immunocompromised - can then cause septicemia, meningitis, maybe death

32
Q

Strongyloides Tx

A

Ivermectin - only kills adults. Re-dose to eradicate

Albendazole - when ivermectin fails or when disseminated disease occurs.

33
Q

What 2 diseases does Taenia cause?

A

Taeniasis (larval ingestion)

Cysticercosis (egg ingestion)

34
Q

Taenia infection transmission

A

Taeniasis - from ingestion of larvae in undercooked pork

Cysticercosis - from ingestion of cestode eggs

35
Q

Taenia infection presentation

A

1) Taeniasis

Ingestion of larvae from undercooked pork. Larvae grow into adults in SI. Infection is generally harmless and can be asymptomatic. Sometimes, GI upset is reported.

2) Cysticercosis

More dangerous. When eggs are ingested instead. Larvae mature in body and form cysts that embed into various parts of the body (skin, muscles, CNS)

Neurocysticercosis - most severe form - affects the brain and is a cause of epilepsy

36
Q

Taenia Tx

A

Albendazole - indicated for neurocysticercosis

Praziquantel - treats intestinal taeniasis and non-neuro forms of cysticercosis

Fungi and Parasites (5 decks)

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