5_Helminthes 2 Flashcards
Nematodes (Round worms):
characteristics
- cylindrical
- structure
- body wall composed of outer cuticle, thin hypodermis, and musculature
- tubular intestine w/ excretory gland
- sexual reproduction: testes & ovaries; copulation is necessary for fertilization
pathogenesis of Nematodes
- diseases are caused by direct damage from worm activity and immune rxn to them
- large worms can physically block the intestine
- Infxn is related to the # adn the infective stages encountered
how do humans respond to infxn by Nematodes?
- children are more susceptible than adults
- waning of immune competence w/ age increases infxn
- Immunosuppressive therapies may inc. susceptibility
- immune defense thru production of IgE and action of mast cells and eosinophils
what are the common nematodes to know?
- Pinworm (Enterobius cermicularis)
- Trichinella (Trichinella spiralis)
- Toxocariasis (Toxocara canis, Toxocara cati)
- Whipworm (Trichuris trichura)
- Ascariasis (Ascaris lumbricoides)
- Hookworm (Necator ameicanus, Ancylostoma duodenale)
lifecycle for Enterobius vermicularis (Pinworm)
life cycle of Trichinella spiralis
name 2 worm infxns that one can contract by eating undercooked pork?
Taenea (tapeworm) and Trichinellosis
which two species cause Toxocariasis,
and which animal causes it?
- Toxocara canis from dogs
- Toxocara cati from cats (less common)
Life cycle of:
Toxocara species
the eyes are affected by which worm infections?
- Toxocariasis - granuloma, ocular larva migrans
- Trichinella spiralis - swelling
Which worm can cause splinter hemorrhages of the fingernails , or a cough?
Trichinella spiralis worm movement
life cycle and transmission:
Trichuris trichiura
life cycle of:
Ascaris lumbricoides
which of the following nematode (round worms) infect w/in the GI tract only?
- Pinworms
- Whipworms
- Trichinellosis
- Ascariasis
Pinworms, and Whipworms
Where do adult Schistosoma mansoni reside and is it in a round worm?
Veins that drain the intestine
S. mansoni is a type of flatworm (*NOT a roundworm)
Hookworm infection:
causal agents,
how frequent?
transmission?
- causal agents:
- Necator americanus - predominates in the Americas (north, central, and south america) and australia
- Acylostoma duodenale - occurs in the middle east , southern europe, and north america
- 2nd most common human worm infection
- transmssion: soil-transmitted helminth (STH) - often occur in areas where human feces are used as fertilizer, or where degacation onto soil happens
Life cycle of Hook worm
Hookworm:
presentation
- infxn is not common in adults
-
cutaneous larva migrans - red, intensely pruruitic (itchy), very painful, creeping eruption, ambiguously known as “ground itch”
- usually heals spontaneously over wks to months
- scratched may allow a secondary bacterial infxn to develop
High intensity Hookworm:
affects which groups?
which symptoms?
- *High intensity hookworm infxns: occur in school-age children
- Sxs: development of anemia & protein deficiency caused by blood loss @ site of intestinal attachment
- When continuously infected by many worms, children have loss of iron and protein, can lead to retarded growth and mental development
Zoonotic hookworms?
key characteristics
- Common in puppies/kittens, esp in areas w/ wamrer climates
- Causal agents: Ancylostoma braziliense, A. caninum, A. tubaeforme
-
Transmitted in dog & cat feces, w/ warm, moist conditions hatch into larvae after several days
- larvae of dog hookworms –> can infect people
- larvae penetrate skin while people walk barefoot, or w/ exposed skin contact w/ contaminated soil/sand
- larvae –> cutaneous larval migrans –> which don’t usually develop into adult hookworms in people –> larvae will die in the skin after several weeks w/o developing any further
*
Strongyloidiasis:
- etiologic agent, hx
- transmission
- causal agent: Stronglyoides stercoralis –> described in French troops stationed in Vietnam during the late 19th century
- Transmission: thru exposed skin, e.g. barefeet
Strongyloidiasis:
typical manifestation
- Manifestation: most infected people remain asymptomatic/undiagnosed
-
Larva currens: intensely itchy creeping raised rash, also known as ground itch
- Allergic response to migrating filariform larvae
- Appears recurrently along the thighs and buttocks, the site of skin penetration & intradermal migration
- May last hours to days but in autoinfxn cycles can recur over weeks, months, & years
- Tracheal irritation & dry cough: as larvae migrate from the lungs up thru the trachea
- GI disturbance: abdominal pain, intermittent diarrhea/constipation, fecal occult blood, massive colonic and gastric hemorrhage
Strongyloidiasis:
more serious manifestation
- More serious manifestations: larvae invades numerous organs
- Severe life-threatening forms of disease (fatality approaches 90%)
- Affects pts receiving high-dose corticosteroids for the tx of asthma or COPD, and in patients getting immunosuppressive drugs bc of transplants (due to impaired host immunity à accelerated autoinfxn & # of migrating larvae)
- Pulmonary infiltrates, acute respiratory distress syndrome (ARDS), small bowel obstruction, & multisystem organ system, & rapid clinical decline
Which of the helminths cause pneumonia by migration to the lung is a step of the life cycle?
- Ascaris lumbricoides
- Anclyostoma duodenale
- Trichinellaosis (Trichinella spiralis)
- Toxocariasis (Toxocara canis, Toxocara cati)
- Strongyloidiasis (Strongyloides steroiralis)
1, 2, and 5
- Ascaris lumbricoides
- Anclyostoma duodenale
- Strongyloidiasis (Strongyloides steroiralis)
Guinea worm disease:
life cycle
Guinea worm:
causal agent,
epidemiology,
sxs,
complications
Prevention and control of
Guinea worm disease
- Safe water –> using water filters
- Health education and community mobilization
- teaching communities about the disease and how it’s spread
- chemically killing worms in water
- identifying infected person w/in 24 hours of worm emerging
- person should receive proper tx and case management by local health provider
- w/in 7 days of worm emerging, GWEP supervisor determines that above criteria has been met
Which of the following worms enter orally and move outside of GI tract?
- Ascariasis
- Hookworm
- Strongyloides
- Guinea worm
- Ascariasis
- Guinea worm
Lymphatic Filariasis - Elephantiasis
life cycle and transmission
Lymphatic Filariasis-Elephantiasis:
causal agent,
epidemiology
transmission
Lymphatic Filariasis-Elephantiasis:
symptoms,
prevention and control
Sxs: Lymphedema of limbs, hydrocoele, chyluria
- Majority of pts are asymptomatic, but virtually all of them have subclinical lymphatic damage
- As many as 40% have kidney damage, w/ proteinuria & hematuria
- Recurrent acute attacks – extremely painful, accompanied by fever
Prevention/Control: take precaution when traveling to an area w/ lymphatic filariasis
- Sleep in air-conditioned room or under mosquito net; wear long-sleeves & trousers
- Use mosquito repellant on exposed skin between dusk and dawn
- Global campaign to eliminate lymphatic filariasis –> annual mass tx, and controlling mosquito
Round worms are not transmitted by insect bites:
TRUE/FALSE
False, can be via insect bites, but can also be transmitted thru soil
(e.g. Filariasis-Elephantiasis)
Define: Neglected parasitic infections
What are the top 5?
- NPI: relatively little attention has been devoted to surveillance, prevention, and/or tx
- Incl:
- Chagas disease
- cysticercosis
- toxocariasis
- toxoplasmosis
- trichomoniasis
Which of the following worms infect by skin penetration?
- Schistosoma haematobium
- Dracunuculus medinensis (GWD)
- Anclyostoma duodenale (Hookworms)
- Anclyostoma braziliense (Dog hookworm)
- Stronglyoides steroralis
- Schistosoma haematobium
- Anclyostoma duodenale (Hookworms)
- Anclyostoma braziliense (Dog hookworm)
- Stronglyoides steroralis
(All except Dracunulus medinensis (GWD), which is transmitted by infected copepods in unfiltered water)
