Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
283 Cards in this Set
- Front
- Back
|
definitive host
|
host undergoes Sexual Reproduction - humans and other animals
|
|
|
reservoir hosts
|
animals that harbor a parasite that is pathogenic for ANOTHER species
(is more difficult to eradicate) |
|
|
intermediate host
|
animal in which larval or asexual stages are found
|
|
|
transfer host
|
a "not necessary" host but utilized host
|
|
|
incidental host
|
accidentally infected and not needed for the parasite's survival or development
may not allow the full development |
|
|
vectors
|
usu. arthropod
carries an agent from one host to another |
|
|
biologic vector
|
if parasite develops or multiplies in the vector
e.g.: mosquito in malaria |
|
|
mechanical vector
|
just carries the organism from host to host
|
|
|
major routes of parasite transmission
|
oral fecal rout
vector borne direct skin invasion needle transfer |
|
|
how are nematode eggs transmitted?
|
oral-fecal
|
|
|
structural characteristics of protozoa
|
flagella
nuclei cilia |
|
|
structural charcteristics of nematodes
|
cylindrical worms
|
|
|
structual characteristics of cestodes
|
elongate ribbone like
segmented body |
|
|
structual characteristics of trematodes
|
flat or leaf-shaped
|
|
|
4 forms of protozoa
|
ameba
trypoanosome malaria parasite leishmania |
|
|
sarcodina group
locomotion diseases |
ameboid like locomotion
amebic dysentery |
|
|
mastigophora
locomotion diseases |
flagella locomotion
Chagas' disease, African sleeping sickness, giardiasis, trichomoniasis, leishmaniasis |
|
|
Ciliata
locomotion diseases |
cilia locomotion
Balantidiasis |
|
|
Sporozoa
locomotion disease |
no locomotion
malaria, babesiosis |
|
|
3 types of helminths
|
nematodes
cestodes trematodes |
|
|
nematodes
|
elongate, cylindrical worms
stiff cuticle pseudo-coelomic cavity structures at both ends (mouth, uterus, uterine opening, anus) digestive tract separate sexes |
|
|
cestodes
|
tape worms
elongate and ribbonlike segmented body segments have both male and female organs scolex (attachment organ) with suckers around this structure no digestive tract eggs are operculated |
|
|
trematodes
|
leaf-shaped
flat, bilaterally symmetrical bodies most are hermaphroditic have suckers |
|
|
examples of trematodes
|
liver flukes - fasciola
lung flukes - paragonimus blood flukes - schistosoma |
|
|
5 types of ectoparasites
|
lice
mites fleas ticks flies |
|
|
crustacae
|
ecotoparasite
cyclops --> guinea worm |
|
|
arachnida
|
ectoparasite
mites --> typhus ticks --> many infections, eg: Rocky Mtn Spotted Fever |
|
|
Insecta
|
ectoparasite
lice --> epidemic typhus fleas --> plague bugs --> Chagas' ds beetles --> hymenolepis flies --> onchocerciasis, loaisis, etc |
|
|
5 factors in epidemiology
|
hygiene (oral-fecal transmission)
vector presence human contact and closeness environment (temp, moisture, etc.) sexual contact (trich, crabs,etc) |
|
|
2 examples of parasites that immunocompromised people are particularly susceptible to
|
strongloides
scabies |
|
|
parasite leading to river blindness
|
onchocerciasis
if killed in the eye (rather than on the skin), then causes blindness |
|
|
which worms tend to present such that they "make an agreement with the host," but the host reacts violently to anti-worm treatment?
|
helminths
|
|
|
types of GI tract parasite symptoms
|
diarrhea
blockage (worm moves from low to high part of bowel and curl up into a ball, blocking intestine) irritation ("don't feel good" is common presentation) |
|
|
allergic responses to parasites
|
cyst fluid released (cyst with parasite inside it)
responses to dead or dying parasites hypersensitivity (reinfection, ascaris sensitivity) |
|
|
parasitic cyst
|
egg w/ tough outer surface
can survive outside host |
|
|
what cell type is central to allergic reaction at death of parasite?
|
eosinophils
|
|
|
3 major classes of parasite-related pathophysiological upsets
|
GI tract
allergic reaction debility and malnutrition |
|
|
pathogenic mechanisms of parasites
|
space occupying lesions (cysts)
degernative effects irritation/psychological effects tracking through the body sclerosing (scarring) blood vessel & blood pathology cancer immunological conditions |
|
|
where do parasitic cysts tend to occur?
|
brain
chest abdomen muscle |
|
|
describe parasitic degenerative effects
|
reactions to dying parasites
wearing out of host tissues due to repeated cycles |
|
|
examples of clinical presentations of sclerosing conditions
|
nodules
liver fibrosis |
|
|
two examples of conditions that include blood vessel and blood pathology
|
elephantiasis
anemia |
|
|
cancers associated with pathogenic mechanisms
|
liver cancer - Asia
bladder cancer |
|
|
examples of parasites tracking through the body
|
wandering larvae
eye-worms moving across conjunctiva |
|
|
components of host responses and immunity to parasites
|
antibodies: IgE, IgG
cellular mechanisms TH2 type responses (?) mast cells, esoinophils, T cells |
|
|
characteristics of host responses and immunity to parasites
|
allergies
acute inflammation - IgE (promote inflammation and healing) & IgG (attack parasites) sclerosis and fibrosis |
|
|
avoidance mechanisms of parasites
|
blocking antibodies
immunosuppression (T cell suppression) proteolytic cleavage of antibody and complement host antigen acquisition |
|
|
what parasite turns muscle cells into nurse cells by taking over their genomes?
|
trichinella spiralis (nematode)
|
|
|
3 major anti-parasitic (anti-helminth) drugs
|
albendazole
praziquantel ivermectin |
|
|
diagnositic approaches to parasites
|
clinical presentation and knowledge of transmission (risk factors)
laboratory tests - parasitological - find the parasite in stool/blood - immunological/molecular - Ab or Ag presence & DNA presence |
|
|
generic name for Flagyl
|
metronidazole
|
|
|
Human onchocerciasis
|
river blindness
nematode (filarial worm) blindess b/c worm dying in eyes dermiatitis due to inflammation Mectizan is donated to rid endemic areas of this infection |
|
|
drug used to treat river blindness
|
Mectizan
|
|
|
onchocerciasis vector
|
simulium - black fly vector
|
|
|
head nodules seen in onchocerciasis contain what?
|
adult worms
|
|
|
transmission of guinea worm
|
year long cycle
female emerges to spread new large in water for the intermediate host (IH) person drinks water + IH emerging of female causes secondary infections, pain, etc. |
|
|
intermediate host of guinea worm
|
cyclops
|
|
|
clinical presentations of guinea worm
|
worm blisters in feet
dracunculiasis - rotting away around blister from immune response to breaking off part of worm (see CP 43) |
|
|
control of guinea worm
|
filter water - linen material covered "pipe straws"
education number dramatically dropping in all endemic countries (except Sudan) |
|
|
most important waterborn pathogen in US
|
giardia lambila
|
|
|
structural characteristics of giardia lambila
|
flagellate protozoan parasite - 8 flagellae
"trophoozoite" pear-shaped |
|
|
in what human organ does giardia lambila reside?
|
small intestine (of mammals in general)
predilection for proximal jejunem |
|
|
pathogenic mechanism of trophozoite
|
trophozoite adheres to enterocytes of small intesting by a sucking disk, producing low grade intestinal disease
|
|
|
how do giardia lambila multiply?
|
binary fission
|
|
|
giardia lambila trophozoites develop into...
|
oval cysts 10-12 um which are passed in feces
|
|
|
pathogenicity of giardia
|
10 cyst minimum required to produce an infection
|
|
|
TRUE/FALSE: giardia is commonly asymptomatic?
|
true
|
|
|
characteristics of giardia cysts
|
12 mm diameter
4 nuclei may be seen gastric acid induces excystation |
|
|
characteristics of giardia trophozoites
|
8 flagella per trophozoite
spiral motion, epithelium attaches by suction to villus |
|
|
occurrence of giardia
|
all parts of the world
highest incidence where fecal contamination is common |
|
|
transmission of giardia
|
ingestion of viable cysts
fecal-oral route prepatent period 7.5 days children are particularly susceptible (b/c of hygiene) |
|
|
predisposing factors to giardia infection
|
children who are malnourished
day-care centers (contact-contact) surgery hypo-gammaglobulinemic individuals NOT thought to be important in HIV diarrhea |
|
|
stages of giardia infection
|
2-7 weeks incubation
diarrhea for 2 weeks recovery malabsorption, steathorrhea --> relapsing condition stages: ingestion, colonization, adhesion |
|
|
diarrhea of giardia infection
|
not well understood
damage to microvilli at enzymatic transport site accumulation of active molcules in gut lumen altered malabsoption of fat, microbial imbalance |
|
|
clinical presentation of giardia
|
widely varied presentation, even within same strain
anorexia, nasuea, lassitude and diarrhea - offensive, frequent, yellow stools abdominal distension, bad taste in mouth, flatulence systemic upset does not generally occur |
|
|
giardia complications or lack of recovery after 2 weeks generally relates to...
|
nutritional status of the host
|
|
|
3 severity levels of giardia presentations
|
asymptomatic - normal absorption and gut histology
mild - reduced xylose absorption and mild histological abnormalities severe - malabsorption of fat, xylose, vit B12, villus hight down, interepithlial lymphocytes increased |
|
|
TRUE/FALSE: in giardia, severe villus atrophy is rare
|
True
|
|
|
protective immunity against giardia
|
non-specific: a bile salt-dependent mild lipase is toxic to Giardia
specific - humoral antibody important - IgM and IgA both kill Giardia - surface antigens are called Giardins |
|
|
4 methods of giardia diagnosis
|
stool examination
duodenal aspiration tests antibodies |
|
|
diagnosis of giardia by stool examination
|
intermitten shedding occurs
tophozoites in stool cysts in stool antigen detection - IFA, ELISA |
|
|
diagnosis of giardia by duodenal aspiration
|
micelles on biopsies
smears for trophozoites and cysts |
|
|
diagnosis of giardia wrt antibodies
|
80% symptomatic patients have antibodies
persist 6 months after eradication |
|
|
giardia treatment and recovery
|
Flagyl - metronidazole
- long course vs. short course - alcohol contraindicated diarrhea stops in 1-2 weeks cyst exretion stops 2 days after tx begins histology takes 1-2 months to restore |
|
|
giardia prevention
|
clean drinking water
- not killed by normal water disinfection chloride concentrions at 21*C, cysts reamin viable in water for 5 weeks heating to 50*C kills encysted tophozoites sterilze using tincture of iodine |
|
|
cryptosporidia parasite
|
C. parvum - tiny intracellular parasite
4-5 mm oocytes multiple fission, massive replication destroys enterocytes sporozoites: 1-2um: banana shaped |
|
|
describe cryptosproridia life cycle
|
"Coccidian" type of life cycle
- sexual and asexual reproduction - furable oocyst in environment - zoonotic potential via an infective oocyst |
|
|
cryptosporidia transmission
|
readily spread to contacts
important cause of infant diarrhea in developing countries less common in breast fed children NOT HOST SPECIFIC |
|
|
disease caused by cryptosporidia
|
waterborne enteritis
paritcularly susceptible: - immunocompromised - recovery requires T cells - vet students interacting with calves short incubation (2-4 days) patent 10 days, then self cure |
|
|
symptoms caused by cryptosporidia
|
intestinal infection - jejunum primary target
enterotoxic effect with weight loss self-limiting to torrential diarrhea with malabsorption and severe wt loss in AIDS pts |
|
|
No recovery from cryptosporidia with these factors
|
immunocompromised
AIDS excessive weight loss |
|
|
Cryptosporidia incidence
|
infections from calves
sewage-contaminated domestic water daycare centers cause of "Treveler's diarrhea" - when stressed |
|
|
parasitology of cryptosporidia
|
no cilia or flagellae
oocysts 2-8 um (in enterocytes) life cycle has 6 major stages pathogenic dose: 10 oocysts little host specificity |
|
|
effects of cryptosporidia on host jejunum
|
villous atrophy
lamina propria infiltration of inflammatory cells mechanism underlying malabsorption not clear |
|
|
which two intestinal parasites are often transferred simultaneously?
|
giardia and cryptosporidia
|
|
|
for how long after cessation of diarrhea are cryptosporidia excreted in feces?
|
2 weeks
|
|
|
2 clinical statuses of cryptosporidia infection
usually, but not always, based on what? |
acute vs. chronic diarrhea illness
usually related to host's immunostatus |
|
|
cryptosporidia - acute diarrhea illness
|
self-limited attack 3-12 days
incubation: 1-2 weeks no blood in stool NO WBCs in stool transient "flu-like" illness abdominal cramps, N/V, low fever, HA bloating and faltus less common than with giardia shedding of oocytes 8-50 days |
|
|
crytposporidia chronic diarrhea illness
|
AIDS or hypogammaglobulinemia
torrential diarrhea - major mortality factor slim disease in African AIDS pts |
|
|
extraintestinal cryptosporidiosis
|
seen in the immunocomprosmised
bilary tract disease (Gangrenous cholecystitis) mixed cryptosporidium/CMV --> sclerosing cholangitis respiratory tract involvement is reported in the immunocompromised |
|
|
diagnosing cryptosporidiosis
|
oocysts seen or detected
stool oocytes need the right stain diarrhea stools have more parasites than well formed stool |
|
|
testing strategies for diagnosisng cryptosporidiosis
|
concentration techniques
IFA important must be distinguished from yeasts experienced technician needed |
|
|
clinical management of cryptosporidiosis
|
with intact immune response - no Rx, only oral rehydration
AIDS pts - spiramycin (marcolide ABS) |
|
|
sarcodina
|
amoebae (unicellular)
multiply by binary fissuion tough cystic wall pseudopod movement most free living |
|
|
most important sarcodina type
|
entamoeba
(rare in US) |
|
|
entamoeba histolytica
|
causes the disease "amoebiasis"
areas of high risk: Mexico, S. America |
|
|
invasive forms of entamoeba histolytica cause...
|
flask-like ulcers
|
|
|
disease presentations of invasive entamoeba histolytica
|
intestinal - diarrhea
systemic - liver abscesses - lung, heart, others sites |
|
|
amebiasis
|
fecal-oral transmission of tough cysts
humans = main reservoir rate is LOWER in children invasive form is seen more in males |
|
|
pathology of amebiasis
|
lower bowel hemorrhage, dysentery
extraintestinal migration leads to hepatic abscesses, occasionally in the CNS lungs involved in some cases |
|
|
diagnosis of amebiasis
|
fetal microscopy
antigen detection |
|
|
treatment of amebiasis
|
iodoquinol
boiling water kills cysts (cysts live over a month at 4*C) |
|
|
entamoeba coli
|
benign
colonic normal flora cyst transmission |
|
|
coccidian protozoa
|
cryptosporidia
isospora microsporidium cyclospora |
|
|
isospora
|
only has an enteric stage (small bowel mucosa)
causes disease in immunocompromised persistent diarrhea and peripheral eosinophilia |
|
|
microsporidium
|
usually only in the immunocompromised
peristent diarrhea, bronchiolitis commonly parasitzes lower animals (silkworms, bees) oral ingestion |
|
|
cyclospora
|
may be common cause of diarrhea in travellers
outbreak from strawberries in MI |
|
|
Life cycle of nematodes
|
5 stages:
L1 - newborn form L2 - often in the vector L3 - infective form (in human) L4 - developing form in host L5 - adult |
|
|
Parasitology of nematodes
|
biggest class of helminths
multicellular transmission by oral intake, skin or via vector |
|
|
What stage of nematode life cycle is inside the human host?
|
L3
|
|
|
only nematode infection that is exacerbated in immunosuppression
|
strongyles
|
|
|
where are nematodes found in host?
|
adults in gut, blood/lymphatics or in subcutaneous tissues
usu. larvae cause pathology in various tissues |
|
|
enterobiasis
|
enterobius vermicularis = "pinworms"
worldwide distribution fecal/oral transmission |
|
|
enterobiasis
what does it do in human host? |
larvae mature in small intestine
adults live in colon and rectum NO PATHOLOGY IN INTESTINE females lay tough eggs on perianal skin sticky eggs --> itchiness successful transmission via durable eggs |
|
|
conditions of enterobiasis transmission
|
1000 eggs/female
high density living conditions greatest prevalence in children handling kids' bedding/clothes --> risk infection adult is small, whitish, pinshaped. lives 13 weeks immunity is acquired |
|
|
ascaris, aka:
|
human roundworms
|
|
|
largest parasitic nematode
|
ascaris
|
|
|
highest and second highest prevalence of ascaris (geographically)
|
Asia
Africa |
|
|
where are ascaris eggs found?
|
soil
(eggs mature in soil) |
|
|
Where are adult ascaris worms found?
|
small intestine
|
|
|
when are ascaris larvae released?
|
upon ingestion
|
|
|
pathogenesis of ascaris
|
larvae penetrate bowel, go to liver, lungs
larvae are coughed up from lungs and return to gut larvae can generate allergic reactions 6-8 weeks until adulthood symptoms produced by tissue invasion (wandering worms) |
|
|
pulmonary phase of ascaris infection
|
migration of larvae through the lung
|
|
|
intestinal phase of ascaris infection
|
asymptomatic themselves except for:
gut interference gut blockage |
|
|
toxocara
|
dog and cat roundworms
zoonotic problem, primarily causing ocular and CNS problems in children can't complete cycle in humans, but causes disease during migration phase eggs present in moist soil |
|
|
Mneumonic for toxocara
|
Remember: "all puppies infected"
(as a general rule. doesn't stand for anything) |
|
|
toxocara in dogs
|
larvae hatch from infected eggs eaten by dogs
female dogs harbor larvae in tissue, pass to fetus to cause congenital infection puppies release eggs in feces and children may ingest mature eggs |
|
|
visceral larva migrans (VLM)
|
VLM
larvae migrating in body's tissues |
|
|
ocular larva migrans (OLM)
|
larvae migrating in the eye (and CNS)
|
|
|
two types of hookworms
|
NECATOR americanus - New World Hookworm
ANCYLOSTOMA duodenale - Old World Hookworm |
|
|
Hookworms
|
small intestinal NEMATODES
blood suckers major cause of anemia, esp. in children no autoinfection. eggs, once laid, hatch quickly. warm, wet weather is favorable bare feet = risk facctor |
|
|
life cycle of hook worms
|
eggs in soil from fecal materal
infective larvae develop larvae migrate through blood to lungs larvae coughed up and swallowed larvae develop in intestinal tract |
|
|
strongyloides
|
threadworms
tiny, small intestine dweller less common, but more severe than hookworm can be life threatening males mate with females, produce larvae that pass in feces soil maturation can produce a free living cycle |
|
|
pathogenesis of strongyloides
|
infective larvae penetrate skin
travel via venule, right heart and lungs to be coughed up and swallowed mature in gut larvae may penetrate lower bowel, enter venule (i.e.: autoninfection) live for decades in humans multiply indirectly outside host |
|
|
two names for infective stronglyloides larvae pentrating skin
|
creeping urticaria
eosinophilic lung |
|
|
3 pathologic events in strongyloides infection
|
skin penetration
pulmonary migration intestinal penetration (minimal pathology) |
|
|
causes of pathology in strongyloides infection
|
damage to tissues in migration
death of parasites --> inflammation |
|
|
unique characteristic of strongyloides
|
only autoinfection phenomenon in helminths
can therefore persist for many years |
|
|
what US population is most commonly seen with *old* strongyloides infections?
|
veterans of the Asian Wars (WWII, Vietnam)
|
|
|
diagnosing strongyloides infections
|
larvae in feces (intermittent output)
larvae in sputum serology |
|
|
treatment of strongyloides
|
thiabendazole, benzimidazoles
ALBENDAZOLE |
|
|
trichuris, aka:
|
whipworms
|
|
|
trichuris
|
common, blood sucking, parasite of the large bowel, found in the tropics
host = humans, mostly seen in children prevalent in Middle East fecal/oral transmission |
|
|
life cycle of trichuris
|
eggs commonly found in soil, on veggies
female worms 3.5cm, whiplike, lay eggs eggs mature after 12-14 days in environment ingestion --> larvae mature in bowel uneven distribution in a community "wormy people" |
|
|
clinical presentation of trichuris
|
well adapted. ergo, mostly asymptomatic, causing little pathology
attaches to wall of colon/rectum blood suckers --> hemorrhagic diarrhea, anemia damage to colonic mucosa - irritation/inflammation |
|
|
diagnosis of trichuris
|
fecal microscopy
|
|
|
treatment of trichuris
|
benzimidazoles: ALBENDAZOLE
|
|
|
6 major groups of ectoparasites
|
lice
mites fleas bugs ticks flies |
|
|
biting arthropods
|
transient (most), usually winged and highly mobile
hematophagous arthropods - piercing & sucking - Diptera - Bugs - Fleas - Soft ticks Non-hematophagous arthropods - centipedes |
|
|
ectoparasites with longterm host contact
|
fleas
hard ticks lice crab lice |
|
|
endoparasites with longterm host contact
|
tungiasis
myiasis - Diptera |
|
|
Pediculus, aka:
|
lice
|
|
|
pediculus
|
transmit many infectious diseases
diesase is called pediculosis life cycle - only on host, 2 weeks no metamorphosis, nymphs look like adults mult feed daily to survive |
|
|
lice structures
|
legs for clinging to hairs
blood feeding by three stylets nits are glued to hair for some time |
|
|
Vagabond's disease
|
pigmentation of the skin resulting from lice
|
|
|
insecticides used for treatment of headlice
|
Benzene Hexachloride/Pyrethins
|
|
|
Phthirius, aka:
|
crab lice
|
|
|
phtherius
|
venereal transmission
crab-like shape people become sensitized to louse bites no zoonotic lice |
|
|
treatment of phthirius
|
clothes - 55*C for 20 minutes
|
|
|
sarcoptes, aka:
|
mites
|
|
|
burrowing mites cause...
|
mange
|
|
|
sarcoptes life cycle
|
male/females mate on skin and eggs laid in tunnels
nymphs hatch and burrow |
|
|
sarcoptes clinical presentation
|
causes allergic sensitization, itchiness
regional preference (hands, elbows) larvae migrate to skin surface females feed on stratum corneum. secretions/exretions that cause irritations |
|
|
sarcoptes mode of transmission
|
contact
|
|
|
scabies is caused by...
|
sarcoptes/mites
|
|
|
treatmetn of scabies
|
ivermectin/Stromectin,
acaricidal drugs |
|
|
form of scabies that infects HIV+ patients
|
Norwegian scabies
extensive regions of scaling skin |
|
|
demodex
|
follicle mite
species found on all animals, host specific common on human face hair follicles, sebaceous glands disease reare, usually in females |
|
|
fleas
|
blood suckers.
carrier of major diseases: Y. pestis, rickettsia, murine typhus, tapeworms voracious blood suckers, will feed on any host in environment jumps from host/host flea bite hypersensitivity - sensitization to salivary allergens |
|
|
most problematic flee
|
cat flea
|
|
|
prevention of flea infections
|
vacuuming, insecticides, growth regulated
|
|
|
flea life cycle
|
larvae, pupate, hatch to form adults - free living, eyeless & wormlike
normally lives on cat/dogs, eggs hatch in coat or in environment |
|
|
ticks
|
periodic blood suckers, usually on mammals, birds
head parts inserted deep, anticoagulant injected engorged ticks drop off, lay eggs in environment most populous in summer |
|
|
type of tick that infests houses in winter
|
Rhipicephalus - borwn dog tick
|
|
|
ticks cause...
|
irritating skin lesions
spread of infectious diseases - Lyme disease - Rocky Mountain Spotted Fever |
|
|
Bugs
|
insects, blood suckers, wingless or prefer not to fly
mouth parts - piercing sucking type |
|
|
Cimex
|
Bug
NOT a vector of HIV (contrary to rumor) bed bug feed on blood at night irritating bites (sheet stains and papule irritation) sensitization to salivary antigens |
|
|
Triatoma
|
kissing bugs, "Reduvid" bugs
feed on other bugs - "assassin bugs" blood suckers, transmit protozoa (Chagas' disease) Parasite in hindgut --> feces --> infection "Romana's sign" swelling |
|
|
Romano's sign
|
indicative of Chagas' disease
unilateral, painless, periorbital swelling |
|
|
Myiasis
|
larvae of flies in the tissues
secondary infections common |
|
|
Myiasis
|
see lecture for details
|
|
|
Nematodes with dermatological presentation
|
pinworms
onchocerciasis guinea worm --> dracunculiasis loa loa --> loiasis |
|
|
Protozoa with dermal presentation
|
leishmaniasis
|
|
|
Leishmaniasis - the disease
|
arthropod transmitted flagellate
intracellular replication chronic disease, organism replicates in macrophages |
|
|
Forms of leishmaniasis
|
Cutaneous - disfiguring
Visceral - fatal (often even if treated) Mucocutaneous - disfiguring |
|
|
Diagnosis of leishmaniasis
|
biopsy
culture |
|
|
treatment of leishmaniasis
|
antimonials (Pentostam)
protracted, toxic regimes |
|
|
leismaniasis life cycle
|
infected female sand fly bites and injects promastigotes into skin
amastigotes form in cells, reproduce and invade tissue sand fly bites and ingests amastigotes promastigotes develop in sand fly |
|
|
trichomoniasis
|
venereal transmission only
symptomatic in female - usu. asymptomatic in male symptoms of allergic inflammation highly site specific pathogen |
|
|
trichomonas vaginalis
|
oval 10-20um diameter organisms
4 anterior flagella with undulating membrane (twitching motion) no cystic forms occur many are actively phagocytic moderately anaerobic conditions for optimal growth binary fission |
|
|
what cell type is infected in trichomoniasis?
|
squamous cells - almost always in vagina - NOT columnar
|
|
|
trichomonas vaginitis
|
discharge contains large numbers of PMNs
organisms are free in vagina or adhering to epithelium, but no tissue invasion micrscopic hemorrhages in 50% cases microulceration occurs under clumps of organisms PMNs & macrophages are capable of killing trichomonads. local IgA response occurs |
|
|
clinical presentation of trichmonas in women
|
up to 90% clinically symptomatic
many symptomatic women have other infections vaginal discharge in 65% of women 50% have vulvar irritation/pruritis abdominal discomfort occurs in 10% symptoms exacerbated following menstrual period vulva is erythematous in 30% of patients |
|
|
clinical presentation of trichomonoas in men
|
nearly always asymptomatic
cause of nongonoccocal urethritis |
|
|
diagnosis of trichomonas
|
microscopic examination of a fresh sample
large numbers of PMN (yellow discharge supports diagnosis) pH < 4.5 supports diagnosis pungent odor supports diagnosis motile trichomonads sometimes detectable DDX: candidiasis (no yellow discharge, no change in pH, no pungent odor) |
|
|
treatment of trichomonas
|
5-nitroimidazoles
Metronidazole: 2.0gm single oral dose cures 7-day regimen for men is used |
|
|
prevention of trichomonas
|
nonoxynal G - spermatoxide is effective, but has not been studied in detial
condoms |
|
|
what organisms undergo initial development in snails?
|
trematodes
|
|
|
schistosomiasis
|
flatworms - blood flukes
waterborne, via snails adults in visceral blood vessels, eggs shed in feces or urine |
|
|
types of schistosome that sheds eggs in feces
|
schistosomiasis mansoni
|
|
|
types of schistosome that sheds eggs in urine
|
schistosomiasis haematobium
|
|
|
bird schistosomes in Michigan
|
contaminate fresh water
penetrating larvae of these cause swimmer's itch |
|
|
pathogenesis of schistosomiasis - overview
|
dermatitis
migratory phase --> pulmonary lesions hepatic, urinary or pulmonary stages (vascular system)( acute phase (antigen Ab complexes) chronic phase (granulomas, cancer) |
|
|
schistosomiasis pathogenesis
|
skin penetration on water contact
egg - granulomas, biliary passage, bladder granulomatous changes around eggs in tissues gastrointestinal disease, cirrhosis (S. mansoni) bladder bleeding, thickening, cancer |
|
|
schistosomiasis diagnosis
|
eggs in feces
|
|
|
schistosomiasis treatment
|
parziquantel treatment
no vaccine as yet |
|
|
5 parasites with pulmonary presentations
|
malaria
paragonomiasis trichinella nematodes filariasis |
|
|
Pneumocystis carinii
|
4-6mm cyst
multiple fission - no resistant cysts known lung inhabitant, intracellular or free in superficial cells of airway |
|
|
immunity to PCP
|
70% of children have serum Abs to PCP by 4 years
|
|
|
pathogensis of PCP
|
usu. well controlled in normal host
|
|
|
diagnosis of PCP
|
microscopy, PCR, DFA - silver stains
|
|
|
treatment of PCP
|
aerosolized pentaminidine
without tx, fatal in immunocompromised hosts |
|
|
Paragonamiasis
|
trematode
living predominantly in the lungs Latin America and Asia |
|
|
House dust mites
|
allergies
asthma |
|
|
Trichinella
|
zoonotic infection passed by carnivorism
tiny enteric nematode larvae migrate and invade muslce cells (nurse cells), lives here for years exposure by eating poorly cooked pork or other carnivores pigs get infected from garbage feeding - contains infected meat |
|
|
trichinosis
|
disease caused by trichinella
|
|
|
clinical picture of trichinosis
|
larvae mature quickly
enteritis symptoms, followed by muscle invasion, muscle pain, periodic fever hx of exposure, gut pain, diarrhea, muscle pain CNS and mycardial complications convalescent phase in 2nd month larvae lie for years, then die and calcify disease severity proportional to number of larvae ingested allergic reactions complicate the disease |
|
|
diagnosing trichinosis
|
biospy (muscle - intercostal, diaphragm are highest)
serology radiology |
|
|
treatment of trichinosis
|
Mebendazole, Thiabendazole
anti-inflammatory agents |
|
|
parasites that present in CNS
|
cysticercosis
malaria acanthamoeba naegleria |
|
|
toxoplasma
|
coccidian parasite
common infection, BUT uncommon as disease (except in immunocompromised) about 35% US pop. infected |
|
|
toxoplasmosis life cycle
|
infection occcus either w/ fecal oocysts or with ingestion of tissue stages
intracellular replication. replication in enterocytes of cats results in resistant oocysts predator/prey cycle keeps organism going everywhere ingested oocysts produce sporozoites in humans, then tissue stages |
|
|
transmission of toxoplasmosis
|
transplacental
oral ingestion of oocytes from cats oral ingestion of tissue cysts (eg: meat) 3 important reservoirs: - cats - soil - intermediate host uncontrolled proliferation occurs in AIDS cases |
|
|
pathogenesis of toxoplasmosis
|
all cells can be infected, including macrophages and neurocytes
rapid proliferation occurs until immunity sets in |
|
|
initiating event for inflammation in toxoplasmosis
|
rupturing of toxoplasma cyst
|
|
|
toxoplasma disease
|
invation of maternal tissues during pregnancy --> invasion of fetus --> congenital abnormalities
toxoplasma gondii - most important infectious cause of congenital abnormalities primary infection in normal people --> flu like symptoms and cervical lymphadenitis pet cats and meat are major sources of infection |
|
|
diagnosis of toxoplasma
|
tests - serological tests as indicators of infection
- seropositive = immune or infected - DNA probe tests, biopsy also used |
|
|
treatment of toxoplasma
|
treatment difficult
sulfonamides/pyrimethamine fetotoxicity |
|
|
prevention of toxoplasma
|
hygiene
cooking of meat |
|
|
Naegleria
|
free-living amoebae, prevalent in US water
warm fresh water or brackish water highly motile, has flagellate stage. thermophilic, tough cysts. 5-7 day incubation invades via olefactory epithelium --> olfactory nerve --> brain, inducing purulent meningitis causes PAM fata, no treatment |
|
|
PAM
|
primary amebic meningoencephalitis
caused by naegleria |
|
|
Acanthamoeba
|
Acanthamoeba castellani common in water
free living in water as trophs or cysts v. sluggish - no flagellate stage invasive usu. only in immunocompromised affects the CNS and other tissues ocular infection |
|
|
ocular infection of acanthamoeba
|
invasive to cornea --> amoebic keratitis
contact lens users if no tx, is fatal in all cases |
|
|
cestodes
|
ribbon-like segmetned tabeworms of small intesting
do not have body cavity complex life cycles - worm stage and cyst stage 4-30 meters in length sometimes egresses from body |
|
|
scolex of tapeworm
|
attachment organ on the head associated with 2 or 4 suckers
|
|
|
TRUE/FALSE: most tapeworms that infect humans require at least one intermediate host
|
TRUE
|
|
|
symptoms associated with infection by tapeworm in the adult stage
|
symptomless, only causing nutrient deprivation in the host
|
|
|
symptoms associated with infection by tapeworm in the larva stage
|
serious or fatal pathology
|
|
|
tapeworms - life cycle
|
Definitive host: adult worm in gut lumen
--> ingestion of eggs in feces --> Intermediate host Intermediate host: larval cyst in viscera --> ingestion of tissue cyst--> Definitive host |
|
|
Beef tapeworm
|
taenia saginata
large, 25-30 feet, lives in small bowel distal segments shed in feces, contain eggs eggs eaten by cattle larval form encysts in mucle humans infected by eating beef |
|
|
Diagnosis of taenia saginata/beef tapeworm
|
segments visible
fecal microscopy |
|
|
treatment for cestods
|
praziquantel
albendazole |
|
|
taenia solium
|
pork tapeworm
large worm in small bowel (<40ft) segments exit, shedding eggs eggs hatch in pig gut - larvae encyst in pork muscles transmission via rare pork |
|
|
serious CNS problem caused by taenia solium
|
Neurocysticerosis
|
|
|
What happens when taenium solium eggs hatch in humans?
|
larvae invade eye, CNS, muscle, skin
|
|
|
neurocysticercosis diagnosis
|
space occupying CNS lesion
images seroloyg |
|
|
treatment for neurocysticercosis
|
surgery
chemotherapy albendazole |
|
|
Trypanosomiases - two types
|
Trypsansoma brucei
Trypanosoma cruzi |
|
|
Trypanosoma brucei
|
tsetse fly vector
transmitted, AFrica sleeping sickness, replication in CNS tissues |
|
|
trypanosoma cruzi
|
triatomic bug vector
transmitted in S. America replication in heart muscle, nerves chronic heart disease, bowel disease |
|
|
3 parasites that present vascularly
|
malaria
schistosomiasis lymphatic filariasis |
|
|
Elaphantiasis
|
skin changes caused by Wuchereria, Brugia infections - FILARIAL WORM
general term to cover range of disease presentations seen in lymphatic filariasis |
|
|
Filariasis
|
mosquito borne nematodes
live in lymphatics; microfilariae in blood lymphadenopathy, lymphedema |
|
|
lymphedema
|
seen in filariasis
accumulation of lymph fluid in tissue of limbs, etc. |
|
|
hydrocele
|
accumulation of lymph in scrotal sac
seen in filariasis |
|
|
parasites with systemic presentations
|
strongyloides
hookworm malaria toxoplasmosis |
|
|
two parasites that cause anemia
|
hookworm
malaria |
|
|
malaria's life cycle
|
coccidian
mosquito borne intracellular replication, RBCS, hepatocytes |
|
|
plasmodium falciparum
|
most important malaria species
periodic fevers, debilitation cerebral syndrome - can be fata anemia chronic attacks lead to renal complications |
|
|
malaria is most severe in what demographics?
|
children from endemic areas
adults from non-endemic areas |
|
|
diagnosis of malaria
|
blood stages
serology, DNA probes |
|
|
treatment of malaria
|
primaquine, cholorquine
fancidar, mlarone, artemesin |
|
|
immunity to malaria
|
controversial - parital in endemically exposed
|
|
|
malaria vaccine available?
|
no
|
|
|
malarial pathogenesis of anemia
|
autoimmune
|
|
|
2 parasites that cause hepatosplenomegaly and corresponding abdominal distention
|
malaria
leishmaniasis |
|
|
parasites that present general multi-organ
|
leishmaniasis
amebiasis ecchinococcus cysticercosis |
|
|
what condition is correlated with a high seroconversion rate to Toxocara?
|
epilepsy
|
|
|
Echinococcus granulosus
|
tapeworm
causes "Hydatid disease" small tapeworms fo dog gut, eggs hatch in herbivores and invade viscera cystic form, proliferative, "hydatids" cystic larvae eaten by dog, to complete the cycle eggs will hatch in human gut, cycsts form in internal organs space occupying lesions |
|
|
treatment for echinococcus
|
surgery
antihelminthics |
|
|
echinococcus multilocularis
|
zoonotic disease
adult form in foxes, cats larvae in rodents cystic larval stages can infect humans, grow fast, rapidly fatal treatment requires surgery |
|
|
Chagas' disease, aka:
|
American trypansomiasis
trypanosoma cruzi |
|
|
Triatomid bugs, aka:
|
reduvid or kissing bugs
cause Chagas' disease |
