Ascaris Flashcards
what is the type of tissues that ascaris infect
intestines
all nematodes that are parasidic in humans have what
-separate sexes aka males are smaller than females
-egg production varies from species to species
how many eggs per day for stongyloides stercoralis
very few
how many eggs per day for ascaris lumbricoides
200 000
what is the life cycle of intestinal nematodes
- Five successive stages: 4 larval stages and the adult
- In most cases, the third-stage larva is the infective stage
- Eggs and larvae living in the intestinal are passed outside in the feces or may be
deposited on the perianal skin by the female worm. - Eggs are fully embryonated or require an extended period of egg embryonation in the
soil.
-In some cases, eggs are infective when swallowed or will hatch
in the soil and initiate infection by skin larval penetration
what is the host and disease of ascaris lumbricoides
man and ascariasis
what is the host and disease of ascaris suum
pig, man
ascariasis
what is Baylisascaris procyonis
-Found in raccoons (Procyon lotor) causes serious disease in humans – North America
-Larva invade the eyes (Ocular larva migrans), spinal cord and
brain (neural larva migrans) and in the intestine (VLM)
-No effective treatment
what is Gnathostoma spinigerum
-Found in dogs and cats. Endemic in China, Philippines
-Humans infected by the ingestion of raw or poorly cooked or pickled freshwater
fish, chicken, birds, frogs or snakes
-Larva migration including pulmonary, GI, urogenital, ocular, and cerebral tissues
toxocariasis is caused by what
-infections of humans with ascarids of dogs aka toxocara canis or cats toxocara catis
what is the mode of transmission of toxocariasis
transmission by ingestion of embryonated toxocara eggs in food or soil
-eggs are long lived
in toxo eggs, if the larvae do not develop to adult stage, what do they do
- they wander through the body
- migrate to soft tissues (liver, brain) or eye
- can cause blindness
epidemiology of toxocara
-worldwide parasite including usa
-highest incidence in kids
true or false: infected dogs/cats increase the risk of infection
-trie
-20% of all adult dogs are infected
-98% of all puppies are infected
-in halifax: 26% of dogs, 25% of cats, 56% of puppies
seroprevalence in kids of toxocara
-7.3% in usa
-34% in ireland
-50-80% in developing tropical countries
systemic visceral larvae migrans: what is the pathogenesis
-due to invasion of soft tissues by wandering larvae
-pathogenesis include:
-hepatomegaly
-pulmonary and neurological problems
-eosinophilia
ocular toxocariasis
-due to invasion of the eye tissues by the larvae
-jeveniles cause chronic infammation
-granulomas of the retina (may cause blindness)
what is the diagnosis for toxocara
-fecal egg counts
-elisa using es antigens
-high eosinophilia is suggestive
treatment of toxocara
mebendazoles
what is the prevention for toxocara
-regular deworming of dogs and cats
-dispose of feces
-clean up after your dogs
what are the risk factors for toxocariasis
-living in southern us
-dogs defecating near parks
ultrasound findings in kids with toxocariasis on 18 cases
-in 2 of the asymptomatic patients, the diagnosis of toxocariasis was confirmed when eosinophilia was found in presurgical hemograms
the 18 case studies of toxocara showed what?
-that most docs don’t think of the possibility of toxocariasis even when there are hapatic nodules
-at the same time, the identification of hepatic nodules by us can aid in the diagnosis of toxocariasis since many of its symptoms are often non specific or nonexistent
how many people are infected by ascaris
1.3 bilion
where is ascaris prevalent
tropical countries and socio-economically depressed areas of europe, latin america and asia
where are most of the ascaris infections
73% are in asia
-in some areas 100% of people are infected
what is the transmission of ascaris
-transmission by ingestion of contaminated food, water/soil
-using human feces as fertilizer means contaminated vegetables
which age group has the highest ascaris infection rate
-in kids
-3.2% of kids in soviet union had eggs in nasal mucus
-in SE usa, 20-60% of kids were infected
when does the intensity of infection of ascaris peajs
5-15yrs
which parasite who’s eggs are resistant. af
-ascaris
ascaris and her resistant eggs
-resistant to 2% formalin and 50% HCL, nitric/sulfuric acid
-due to the lipid layerof the eggshellh
how long do eggs of ascaris love and what are their characteristics
-live up to 15yrs
-eggs are sticky
-found on german banknotes 1949
-eggs can be transmitted by windborn dust
in china 1947, it was estimated that … tons of eggs were excreted by humans and how many /day worldwide
18 000 tons
-10^14/day
development of ascarids
-4 larval stage (L1-L4)
-larval morphology resembles adult worms
-transition from one larval stage to the next requires shedding of the surface cuticle (molting)
-most species undergo 4 molts
life cycle of ascaris
-fertilized egg in soil
-adult eat fertilized
-larvae migrates from intestive to lung and then poop the eggs etc
lung phase of ascaris
-5-6 days after exposure
-pneumonitis (loefflers pneumonia) due to penetration of lung capillaries by juvenile parasite causing hemorrhage
intestinal phase of ascaris
-2-3 months after infection
-abdominal pain, diarrhea
-malabsorbtion of nutrients
-stunted growth, cognitive impairment
-intestinal obstruction by high worm numbers
wandering worms ascaris
-cause of pathogenesis
-intestinal perforation: peritonitis
-blockage of bile conducts
-obstruction of the respiratory tract
-liver abscesses
how many peeps in southern usa adnd apalachia had ascaris
49.4
a survey of ascaris lumbricoides was conducted during 1976 and 1977 in a rural community in nova scotia. Out of the 431 individuals how many had ascaris
-121 aka 28.15 had ascaris and they were all under 20yrs old
what is the other name of ascaris
round worm
how many eggs per day for ascaris
-females make 200 000 eggs/day
-finding eggs is simple
how many eggs to female ascaris make in their lives
60 000 000 eggs
what is the treatment for ascaris
-chemotherapy
-using benzimidazoles
-aka mebendazole or ivermectin
-they bind to tubulin and block muscle action
what does chemotherapy do in kids that had ascaris
increases weight gain and apetite
what are the cytokines made in infected people with ascaris
4 and 5
infection of ascaris increases the ratio of cells producing … response compaired to … response
-th2 to th1
in human ascaris infection causes what in tems of immune response
-more pbmc producing il4-5
-no effect of pbmc producing il 10 and infy
-more th2 than th1
-th2 cytokine secretion among individuals with significant exposure to ascaris lumbricoides might have an impact on susceptibility to pulmonary infections with mtuberculosis
L3/L4 in ascaris are located where
lung
