Helminths Flashcards

Learn all about helminths

1
Q

What are the 3 nematodes (roundworms) that are acquired thru ingestion of eggs?

A
Ascaris lumbricoides
Trichuris trichura (whipworm)
Enteribius vermicularis (pinworm)

To remember: TRIplet oSCAR ENTER in EGG form

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2
Q

What are the 2 nematodes (roundworms) that are acquired thru penetration of skin?

A
Necator americanus (hook work)
Strongyloides stercoralis

To remember: Capt. HOOK is a STRONG AMERICan.

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3
Q

What nematode (roundworms) is acquired thru ingestion of pork meat?

A

Trichinella spiralis

To remember: TRICky PORK

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4
Q

Which nematodes migrate into the human lungs in larval form?

A
Ascaris lumbricoides (can produce 200K eggs per day in the small intestine)
Nescator americanus (lives in the soil as a larva. When inside the human body, goes to the lungs as larva. Travels to the small intestines as an adult. Attaches to the intestinal wall and sucks blood, copulate and releases more eggs.)
Strongyloides stercoralis (eggs don't pass to the stools but can cause auto-infection, direct cycle and indirect cycle).

To remember: the AMERICAN oSCAR has STRONG LUNGS.

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5
Q

What is the medicine for nematodes?

A

Mebendazole, albendazole, Thiabendazole.

To remember: Worms BEND a lot.

Pyrantel pomoate (alternative for ascaris, necator and enterobius.)

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6
Q

What are the symptoms of hookworm infection?

A
Diarrhea 
Abdominal pain
Weight loss
Iron deficiency anemia
Itchiness and rash (at penetration site)
Cough 
Local infiltrate in the lungs
Eosinophilia

Note: relate the symptoms to the life cycle of hookworm

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7
Q

Describe the infection caused by Trichinella spiralis.

A

Encysted larvae in pork meat is ingested.

The cysts travel to the small intestines where larvae leave their cysts.

Larvae mature and copulate.

Adult males pass on to feces while adult females penetrate intestinal mucosa and prduce thousands of larvae.

The larvae pass into the blood stream, reaching other organs and skeletal muscles.

Larvae can get encysted in the skeletal muscles and stay there for decades.

To remember: TRICky pork is MUSCULAR.

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8
Q

These are the two mildest worm infections.

Note: mild means no lung and muscle invasions. They stay only in the intestinal track.

A
Trichuris tricura (whip worm)
Enterobius vermicularis (pin worm)
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9
Q

The pinworm, Enterobius vermicularis, is known to cause intense perianal itch at night.

Explain the phenomenon.

A

After ingestion of eggs (50-60 micra), they mature in the caecum and ascending large intestines.

The female migrates at night to the perianal area and lays there thousands of eggs which become infective in 4-6 hrs., causing severe Itchiness and lack of sleep.

This infection is more of a nuisance than a danger.

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10
Q

Which nematodes are acquired thru intermediate hosts?

A
Onchocerca volvulus (via black flies) "ONCHOCERCIASIS"
Wucheria bancrofti (via mosquito) "ELEPHANTIASIS"
Brugia malayi (via mosquito)
Dracunculus medinensis (via crustacean - freshwater copepad)

To remember: Cancer (ONChO), like worms, is a WitCH, BRUhA and a DRACUla.

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11
Q

Describe the infection, diagnosis and treatment of ONCHOCERCIASIS.

A

An infected black fly transmits the microfilariae (larvae) to humans. The microfilariae matures into adult form. They can be found coiled up in fibrous nodules in the skin and subcutaneous tissues.

After mating, more microfilariae are produced that migrate through the dermis and connective tissues and eyes.
(This phenomenon causes pruritic skin rash, popular lesions aka interepithelial granuloma and blindness.)

Diagnosis can be done through skin biopsies and slit lamp examination of the eyes to demonstrate the microfilariae or adult worms.

Treatment is through IVERMECTIN that prevent the birth of new microfilariae. Adult worms will eventually die.

Also treated with DIETHYLCARBAMAZINE.

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12
Q

Describe the infection, diagnosis and treatment of ELEPHANTIASIS.

A

An infected mosquito transmits the microfilariae (larvae) to humans. The microfilariae matures into adult form within the lymphatic vessels and lymphatic nodes of the genitals and lower extremities. After mating, microfilariae are produced and enter the nearby blood vessels.
(This phenomenon causes enlarged lymph nodes, acute febrile episodes. Repeated exposures cause fibrous tissues around microfilariaein the lymph nodes, which can plug the ducts, thus causing the swelling of the genitals and legs).

Diagnosed through isolation of microfilariae in blood drawn at night and Immunofluorescence of antibody titers.

Treated with DIETHYLCARBAMAZINE.

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13
Q

Describe the infection, diagnosis and treatment of Guinea worm (Dracuncula medinensis)

A

The ingestion of water with microscopic crustacean (copepods) transmits the larvae to humans. The larvae penetrate the intestines and migrate to subcutaneous tissues where they mature and copulate. The male dies and the female continues to grow for up to a year. It continues to move to the skin, releasing thousands of larvae when it’s uterus touches water.

During the release of larvae, the person experiences nausea, vomiting, hives and breathlessness.

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14
Q

What are the 2 groups of FLATWORMS (PLATYHELMINTHES)?

Note: flat = plat

A

Trematodes or flukes

Cestodes or tapeworm

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15
Q

Describe the infection, diagnosis and treatment of SCHISTOSOMIASIS (Trematodes).

A

Schistosomes (cercariae form), found in water, penetrate the skin and invade the venous system where they mate and lay eggs. The eggs may enter the intestines or the bladder and eventually be excreted into a nearby lake or stream. The eggs only hatch in water. The larva emerges and finds its way to freshwater snail. In it, they mature. They are called cercariae which look like tadpoles with suckers and tails . Upon release from the snails, they are already infective to humans.

Systemic syndromes

  1. Dermatitis in the area of penetration
  2. Katayama fever during the laying of eggs
  3. Chronic Fibrosis of the organs and blood vessels from chronic inflammation surrounding the deposited eggs.

Diagnosed by the presence of eggs in the stool or urine; high eosinophil in the blood.

Treated with Praziquantel ( a drug for both cestodes and trematodes.)

Control measures: management of human fecal waste disposal; elimination of snails.

To remember: 4S
Schistosomiasis
Snail
Skin
Syndromes
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16
Q

Describe tapeworms (Cestodes)

A

Long, flat, segmented (a boxlike segment is called peoglottid)

Live in the intestines of their hosts.

No digestive tract (really dependent on the nutrients digested by the host).

Hermaphrodite (possess both male and female sex organs

17
Q

Name the parts of a tapeworm

A

Scolex (with hooks and suckers)
Immature proglottids
Mature glottids (with both sex organs)
Gravid proglottid (contain the fertilized eggs)

To remember: the gluttons don’t use their skull (scolex/head), but feast on sex and gravy.

18
Q

How do you treat tapeworms

A

Praziquantel, niclosamide

To remember: a pretzel and a nickel are taped together.

19
Q

Types of tapeworms

A

Pork (Taenia solium)
Beef (Taenia saginata)
Fish (Diphyllobothrium latum)
Dwarf (Hymenolepsis nana)

20
Q

Describe the infection, diagnosis and treatment of pork tape worm (Taenia solium).

A

An undercooked pork meat with the larvae (CYSTICERCUS) can infect if ingested by humans. The tapeworm can attach itself to the host’s intestinal mucosa and grow from its nutrients. Eggs can be released into the feces and can be eaten by grazing pigs. Then begins a new cycle when the egg develops into larvae and disseminate into the pig’s intestines and muscles.

CYSTERCUS is the larval form of the tape worm that us round, with fluid-filled bladder.

CYSTERCOSIS happens when men ingests the eggs (oro-fecal). The eggs hatch in the small intestine and larvae migrate throughout the body, penetrating the tissues to encyst (forming cysterci), more commonly in the brain (aka neurocystercosis) and skeletal muscles.

Symptoms: seizures, obstructive hydrocephalus, focal neurologic deficits.

Diagnosis: presence of eggs or/and proglottids in feces. CAT scan, biopsy of infected tissue for cystercosis.

Treatment: Praziquantel, Dibendazole for cystercosis

21
Q

How does T. Saginata differ from T. Solium?

A

Beef is the intermediate host.

No effect when egg is ingested by humans.

22
Q

What is peculiar with the fish tapeworm (Diphyllobothrium latum)?

A

Has 2 intermediate hosts (di/both): crustacean and fteshwater fish (trout, salmon, pike, etc.)

Can grow up to 45m. (No wonder, can cause Abdominal pain and absorb Vit B)

23
Q

What is the novel method for helminth egg analysis?

A

KATO KATZ is highly accurate and rapid for Ascaris lumbricoided, T. Trichiura, schistosome by stai nn ING a sieves fecal sample and examining under the microscope. It counts the no. of eggs per gram.

24
Q

What’s an effective method for egg analysis in stool exam?

A

Kato-Katz. It involves staining a sieved fecal sample and examining it under a microscope. The total number of eggs is counted and used to calculate v the number of eggs per gram.

Accurate method for ascaris, tricura and schistosomes and not for delicate hookworm eggs.

25
Q

What PH Programs are implemented to reduce prevalence of soil transmitted helminths?

A

Mass drug administration for children of 1-15 yra old in endemic communities.

Albendazole (400 mg) or Mebendazole (500mg)

26
Q

Who are commonly affected by STH?

A

Preschoolers, school-age children, women of child-bearing age, special groups (farmers, soldiers, food handlers, indigenous people

27
Q

Social and environmental factors of STH

A

Poverty, poor living conditions, poor sanitation, inadequate water supply, soil quality, climate, poor personal and environmental hygiene, poor health awareness

28
Q

Describe a pinworm (Enterobius vermicularis)

A

It is D-shaped, with a lateral expansion in the mouth (cephalic alae) and enlarged esophagus. Males are distinguished by a curved end; females have straight ends that are longer and wider.

29
Q

Describe the infection, diagnosis and treatment of PINWORM

A

Eggs can be ingested from contaminated fomites. They then invades and mature in the cecum and lower epithelium where they develop into larval forms. The adult form develop in the intestine within 15-26 days. Afterwhich, they are ready for mating and reproduction.

Females migrate to analyze area to deposit eggs (4-17k).

Symptoms: catarrhal inflammation. Extra intestinal migration (reproductive organs and peritoneal cavity).

Diagnosed by tape swabs (scotch adhesive or perianal cellulose)

Treated by aldendazole, mebendazole and pyrantel pamoate. All are given in single dose and repeated after 2 weeks.

Prevented through WASH and vacuum, boiling of linens.y