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26 Cards in this Set

  • Front
  • Back
Case Presentation

A 3 year old child in Haiti has abdominal pain and a swollen abdomen

Examination reveals distension with a mass.

Intestines reveal lots of worms...
Ascaris lumbricoides
Ascaris lumbricoides

Infection pathway:
Females longer than males because they harbor eggs

Feces powder gets in dirt, may get on food, or aspirated, gets into pulmonary capillaries from gut absorption or from alveoli, embolize there, crawl back to airspaces, into trachea, and then are swallowed into intestine, then they mature.
Ascaris: a “soil-transmitted helminth”

Occasionally seen in __________ USA

Eggs hardy?

Migrating larvae can cause ________ ____________

Migrating larvae can cause?

Symptoms?

Ascaris worms can cause _______ or __________ obstruction

Treatment?
Occasionally seen in Southeastern USA

Female worms produce large numbers of eggs that can survive in the environment.

Migrating larvae can cause eosinophilic pneumonia

Infections are often asymptomatic.

However, Ascaris worms can cause biliary or intestinal obstruction.

Easily treated with mebendazole.
PARASITIC HELMINTHS

__________
(e.g., Ascaris, trichinella, filaria, strongyloides, trichuris,etc.)

_________
a) Trematodes (e.g., schistosomes, clonorchis, other flukes)
b) Cestodes (tapeworms)
Roundworms (nematodes)
(e.g., Ascaris, trichinella, filaria, strongyloides, trichuris,etc.)

Flatworms
a) Trematodes (e.g., schistosomes, clonorchis, other flukes)
b) Cestodes (tapeworms)
Helminths: General features

Host specificity (_____ and _____ hosts)

Lack of ___________ in human host

Infection vs. infestation?

Disease often related to _________ intensity

Polyparasitism
Host specificity (definitive and intermediate hosts)

Lack of multiplication in human host

Infection vs. infestation: Many infections are asymptomatic

Disease often related to infection intensity

Polyparasitism - if you have one, you can have another one
Helminths: Pathogenesis

(4)
Tissue invasion

Deprive host of essential nutrients

Mass effect or physical obstruction

Stimulate harmful immune responses - immunopathology
Diagnostic Options in Parasitology

Name several
Traditional Methods
- Microscopy, Xenodiagnosis, Skin Tests

Enhanced Microscopy

Antigen Detection

Antibody Assays

DNA Detection
Therapy of Helminth Infections

General themes
- Neurotransmission?
- Motility - ?

Which one is agonist for both mammalian / worm chloride channels)

Which ones bind tubulin?
Shared metabolic pathways (causes toxicity issues)

Drug delivery to site of infection

General themes
- Neurotransmission - Ivermectin vs. Nematodes (agonist for both mammalian / worm chloride channels)

- Motility - Mebendazole / Albendazole bind Tubulin

- Interaction with Host Immune System - Praziquantel in Schistosomiasis
“Scotch tape test” shows?
“Scotch tape test” shows bean-shaped eggs of Enterobius vermicularis
A 3 year old child in rural China has growth retardation and lassitude

hook worm found in stool (thin delicate shell)
Ancylostoma duodenale egg
Relationship between hookworm infection intensity and hemoglobin levels (old data from Dominican Republic)
Positively correlated - more severe infection --> more severe anemia
Hookworm: Clinical features?
- due to larval invasion
- due to worms reaching small intestine
- due to worms action at small intestine

Treat with? all these worms are so bendy....
Ground itch (larval invasion)

Abdominal pain (when worms reach small intestine)

Anemia

Treat with mebendazole / albendazole
Host specificity: Cutaneous larval migrans

Can dog and cat hookworm larvae complete migration in humans?
No,

Dog and cat hookworm larvae are unable to complete migration in humans.
Strongyloidiasis: Clinical summary

Epidemiology similar to _______, but higher/lower?______ infection rates.

Symptoms?

_____________* patients may have the hyperinfection syndrome with disseminated infection and sepsis.
Epidemiology similar to hookworm, but lower infection rates.

Clinical manifestations are variable: many asymptomatic

Some people have lower abd rash, “larva currens”

Abdominal bloating, sometimes with diarrhea, weight loss

Immunosuppressed* patients may have the hyperinfection syndrome with disseminated infection and sepsis.

* Steroids, chemotherapy, transplant recipients, pregnancy, alcohol abuse or malnutrition, HTLV-1
Strongyloidiasis: Clinical summary

Diagnosis: Stool examination does NOT show what? instead it shows?

Treatment:
Diagnosis: Stool examination (larvae, not eggs)

Treatment: Ivermectin
Trichinosis

Host(s)?

Symptoms?

Treatments/Prevention?
Hosts: Broad host range (rodents, pigs, humans)

Symptoms: Fever, myalgia (muscle pain = light bulb), eosinophilia

Albendazole (questionable), steroids to dec. inflammation

Cook meat thoroughly to eliminate cysts in meat muscle
Trichinosis

Life Cycle

Ingestion of _______ _______ (e.g. ____) --> larva released in _____ ________ --> larvae deposited in ________ --> _______ larva in ________ _________ --> Repeat
Ingestion of undercooked meat (e.g. pork) --> larva released in small intestine --> larvae deposited in mucosa --> encysted larva in striated muscle --> Repeat
What is Filariasis?

Target organs?

Intestine involved?
Insect-borne nematode infections
8 species infect humans

Other species infect animals (heartworms)

Target organs: eyes, skin, lymphatics, heart

No intestine involved - mosquito bourne disease
Filariasis Life cycle

_________takes a blood meal (L3 larvae enter skin)--> adults go into lymphatic system --> adults produce _______________ that migrate into lymph and bood channels --> another mosquito takes a blood meal (ingests a ________) ---> __________ shed sheats, penetrate mosquito midgut and migrates to thoracic muscle, --> larvae travel to mosquito head and proboscus -->Repeat
Mosquito takes a blood meal (L3 larvae enter skin)--> adults go into lymphatic system --> adults produce sheathed microfilariae (not eggs) that migrate into lymph and bood channels --> mosquito takes a blood meal (ingests a microfilariae) ---> microfilariae shed sheats, penetrate mosquito midgut and migrates to thoracic muscle, --> larvae travel to mosquito head and proboscus --> mosquito takes a blood meal from human and infects
Bancroftian filariasis?

Bancroftian = Wuchereria Bancrofti
Causes severe hydrocele and genital elephantiasis

A hydrocele denotes a pathological accumulation of serous fluid in a bodily cavity.
Diagnosis:

Treatment of filariasis
Filariasis pregnancy test type thing


Albendazole
Diethylcarbamazine
(emphased in CMMRS)
Ivermectin
Onchocerca. volvulus

Vector: __________

Diagnosis: ____________

Adult worms live in __________ __________

May lead to "__________ ___________"(hallmark manifestation)
Onchocerca. volvulus

Vector: Simulium BLACK flies

Diagnosis: Microfilariae in skin snips

Adult worms live in subcutaneous nodules

May lead to "River Blindness"(hallmark manifestation)
Eye Exam

Onchocerciasis: shows ?

Can cause?

Disease cased by?
Eye Exam

Onchocerciasis: shows Punctate keratitis (snowflakes) or Sclerosing keratitis

Can cause blindness

Disease caused by inflammatory reaction to microfilariae
Other Onchocercal manifestations aside from visual symptoms?

Disease caused by?
Onchocecal dermatitis

Caused by inflammatory response to microfilariae
Onchocerciasis Treatment

____________(Mectizan, donated by Merck)

Interferes with __________ in nematodes

Clears __________ from skin and eyes of oncho patients

This effect is (temporary/permanent) _______; the drug _______ (does/does not) kill adult worms

Safe for use in ______ ___________ ____________

Effective?
Ivermectin (Mectizan, donated by Merck)

Interferes with neurotransmission in nematodes

Clears microfilariae from skin and eyes of oncho patients

This effect is temporary; the drug does not kill adult worms

Safe for use in mass treatment programs

Vector control and ivermectin have have largely eliminated severe disease in many areas in Africa and the Americas
Treatment:

__________ (8 weeks) clears Wolbachia and sterilizes O. volvulus
Doxycycline (8 weeks) clears Wolbachia and sterilizes O. volvulus