Download Eukaryotic Parasites - UAB School of Optometry

FUNDAMENTALS 2 10:00-11:00
OCTOBER 28, 2010
BENJAMIN
EUKARYOTIC PARASITES
Scribe: ANGI GULLARD
Proof: KRATIKA PAREEK
Page 1 of 7
I.
Dental Optometry Parasitology [S1]
a. These are eukaryotic – harder to treat because more difficult to target unique features
II. Important points for parasites [S2]
a. Life cycles - very important, but do not need to focus on too much
b. Definitive host – host where sexual stage of organism occurs; usually does not cause problems for host
c. Reservoir host - where organism hides out and wait for that host to be eaten; not that important
d. Vector – how organism gets from one host to another, transmission
i. EX: mosquito is vector for malaria
e. Important - Understand how humans are infected
f. Migration and where adults go; tissue invasion, etc.
g. Important – diagnostic forms
h. Important to think about - geographic distribution
III. Sedimentation concentration [S3]
a. Way to look for organisms: take fresh stool, filter through gauze into glass tube, spin in centrifuge, parasites
go to bottom, extract fats
IV. Floatation concentration [S4]
a. If have microscope but no centrifuge, take NaCl concentrated solution, mix with stool, fill to top of tube
i. If worms are present, they will float to top, take sample from top part of meniscus with cover slip – look at
slide with or without iodine
V. Classification of Parasites [S5]
a. 2 main divisions of parasites
i. Protozoa – single-celled eukaryotes, like amoeba
1. Mastigophora (term is not important) - Giardia lamblia –flagellate has tails to swim
2. Sarcodina – Entamoeba histolytica causes amoebic dysentery
3. Sporozoa – Toxoplasma, Cryptosporidium, Plasmodium
ii. Helminths- multi-celled worms; more important
1. Remember names of groups
a. Nematodes are round worms (major one is Ascaris)
b. Platyhelminthes are flat worms
c. Trematodes are flukes, such as Schistosoma sp.
d. Cestodes are tapeworms, such as Taenia sp. (pork tapeworm)
VI. Entamoeba histolytica [S6]
a. Classically most important parasite- can cause deaths, large outbreaks
b. Rarely see it (or most other parasites) in US
c. Infectious form is cyst that is 20-30 microns across
i. Has 4 nuclei
d. When ingested by someone, exists in duodenum (small intestine)
e. 4 Amoebae come out, multiply by binary fission, and cause amebic dysentery (small volume stools, bloody
mucus)
f. Trophozoites – invade tissue; can be a diagnostic form
i. Before being expelled, trophozoites transform to cysts (this is the infectious form – can survive in water)
g. Stained specimen: 20-30 microns (bacteria) across; 3 or4 nuclei; food body
VII. Entamoeba histolytica/dispar [S7]
a. Humans are only host – can get liver or brain abscesses; very uncommon here
b. Two different species – histolytica and dispar
c. Read slide
VIII. Entamoeba histolytica/dispar [S8]
a. With molecular techniques, we can differentiate the pathogenic histolytica species from the nonpathogenic dispar species
i. Identify histolytica in stool
FUNDAMENTALS 2 10:00-11:00
Scribe: ANGI GULLARD
OCTOBER 28, 2010
Proof: KRATIKA PAREEK
BENJAMIN
EUKARYOTIC PARASITES
Page 2 of 7
b. If diagnosed with morphological histolytica, can do molecular test to determine if the pathogenic strain is
present
IX. Non pathogenic ameba [S9]
a. We report cases from lab and differentiate nonpathogenic from pathogenic
b. Find out if person eats something not well-cooked
c. Have to identify and measure all present Histolytica species – Entamoeba coli looks like Entamoeba
histolytica – only histolytica is pathogenic (coli is non-pathogenic human commensal)
d. Entamoeba hartmanni – a small histolytica
e. Entamoeba coli- looks like histolytica
f. Of all species listed, only histolytica species is pathogenic
X. Entamoeba coli cysts [S10]
a. Entamoeba coli Cysts look a lot like histolytica; coli cyst could be present with histolytica cyst
b. Dual infection is common in parasitic infection, so need to distinguish and identify all forms
XI. Giardia lamblia [S11]
a. One of most commonly diagnosed and important parasites in US is Giardia
b. Not only in humans; also very common in beaver (contaminated river, streams)
i. Board questions – person drinking from stream - Giardia
ii. Daycare centers- Giardia can be transmitted very quickly by fecal-oral route
c. 50% of those affected are asymptomatic
d. Symptoms: stools are very characteristic fatty, frothy because Giardia stops nutrient absorption
e. Kids are more susceptible; adults develop immunity over time
f. Reservoir hosts - beaver and other animals
g. Diagnostic forms are cysts and trophozoites in stool, but is noninvasive (versus Entamoeba histolytica which
causes tissue damage
XII. Giardia lamblia [S12]
a. Photo of cyst, the infecting form; survives in water, food; cyst formed before it is expelled from host
b. Organism has 2 nuclei, divides by binary fission, has suction cup shape that attaches to small intestine
c. Diarrhea stools have trophozoites, but more formed stools have cysts
XIII. Giardia lamblia [S13]
a. Cysts
XIV.
Chilomastix mesnili: non-pathogenic flagellate [S14]
a. Rare flagellate – reported but shouldn’t be treated
XV. Toxoplasma gondii [S15]
a. Another important parasite - cats are definitive host (housecat, lions, etc.)
b. Vancouver outbreak in a lake– cougar could have been infected, contaminated water supply
i. Cat is infected by eating infected rodent or an oocyst that comes from cat that grows in gut
c. Toxoplasma cysts is not eliminated by chlorine, so need filter to remove organisms from water
d. Life cycle is like that of malaria but occurs in gut cells instead of red blood cells
e. Cysts are passed, are very resistant to environment
f. Concern is severe congenital malformations and spontaneous fetal abortions when pregnant women become
infected
i. Expectant mothers are told not to change cat litter box due to Toxoplasma exposure
g. If have infected cat that sheds cysts- cysts are not infectious after first passed, takes a few days to weeks for
cysts to become infectious, so regular cleaning of litter box would reduce chance of pregnant women to get
infected
h. 1% per year of people in US are infected
i. Get infected by eating cyst from cat, or by eating meat from animal that is infected – 50/50 cat source, meat
source (uncooked beef, pork, etc.)
i. When people have acute infections – usually asymptomatic, 10% have swollen lymph nodes - looks like
mononucleosis, can resemble lymphoma
FUNDAMENTALS 2 10:00-11:00
Scribe: ANGI GULLARD
OCTOBER 28, 2010
Proof: KRATIKA PAREEK
BENJAMIN
EUKARYOTIC PARASITES
Page 3 of 7
XVI.
Untitled [S16]
a. Children can get infected transplacentally and result is severe disease – spontaneous abortions
b. Can get infected by organ transplants – always do serology on people before do organ transplant
i. 10% have lymphadenitis, myocarditis; 90% asymptomatic; latently infected for rest of life - brain can be
affected – personalities may change a bit
c. If infected person is immunosuppressed, disease is more likely; can get reactivation and brain lesions
d. In pregnancy, problem occurs during early pregnancy
e. Old French custom – raw meat juice consumption during pregnancy; high rate of congenital toxoplasmosis
XVII.
Congenital Toxoplasmosis [S17]
a. We have 400-4,000 cases per year; we don’t know how many cases really, not often diagnosed
b. 750 deaths per year: 50% food-borne, 50% cat litter
c. 1st trimester – if mother is infected, rare transmission to child
d. 3rd trimester - 59% of transmission to fetus, but almost no problems for fetus; early on infection is worse
XVIII.
CNS lesions found in immunosuppressed patients [S18]
a. Huge lesion in frontal cortex - from HIV positive patient
XIX.
Toxoplasma gondii (cysts) [S19]
a. What is found in human tissue - cysts in tissue; each blue spot is an organism
XX. Cryptosporidium parvum [S20]
a. 1st human cases diagnosed in 1979-80
b. Known to occur in cattle
c. Most people who get infected and are not immune-suppressed are usually ok
d. Can identify parasite from stool
e. Ways to diagnosis needed - became very important disease in HIV pandemic
f. No way to cure or treat
g. Cysts are infective; resistant to chlorine (like those of Toxoplasma)
h. Milwaukee – water filters were put in wrong  some suffered chronic diarrhea until death, especially those
who were HIV positive
i. About as common as Giardia in daycare centers
j. Grows in gut epithelium – brush border cells, does not cause much damage but malabsorption diarrhea
i. Causes severe diarrhea in AIDS patients
XXI.
Cryptosporidium parvum [S21]
a. Can stain with acid-fast stain
b. Red balls are organisms; 5 microns
XXII.
Untitled [S22]
a. Grow on outside edge of brush-border of small intestine
b. Person usually becomes immune and gets rid of the parasite quickly
XXIII.
Overview of Malaria Epidemiology [S23]
a. Malaria- one of deadliest infectious diseases in world
i. 2.7 million deaths/year, mostly children in Africa
ii. 300 to 500 million cases annually
iii. Hard to count number of cases- anyone living in area of malaria who has fever is diagnosed with malaria
b. If they get over initial infection, infected people can survive a long time
c. When get treated, lose malaria, lose immunity after a few years, then when get re-infected, it is hard to
survive
d. If a non-immune person has P. falciparum (mostly in Africa), have 5% of dying, so should get treated
e. More than 40% of world’s population lives where malaria naturally occurs
f. Rarely is malaria transmitted in US; few cases of transmission in NJ, MI, FL, CA, but still rare
g. Plasmodium vivax- less virulent
h. Plasmodium falciparum – most deadly
XXIV.
Plasmodium (malaria) [S24]
a. Life cycle of malaria: Mosquito bites and releases sporozoites that go to liver (few 1,000)
FUNDAMENTALS 2 10:00-11:00
Scribe: ANGI GULLARD
OCTOBER 28, 2010
Proof: KRATIKA PAREEK
BENJAMIN
EUKARYOTIC PARASITES
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b. Liver cell invaded  liver releases merozoites penetrate RBC – intracellular parasite – grows into ring form
and then an amoeboid organism in RBC  then divides into merozoites again and infects new RBCs
c. 48 hour cycle - when RBCs lyse, get fever spikes
d. Some merozoites form gametocytes – taken up by mosquito from bloodstream and multiply in mosquito gut
(sexual stage)
e. When mosquito bites, malaria is transmitted again
f. Civil War – lots of malaria, still have vector Anopheles mosquito here in US
XXV.
Malaria fever [S25]
a. Different kinds of fevers
b. 48 hours – fever cycle
XXVI.
Plasmodium vivax [S26]
a. Ring forms with red dots, blue cytoplasm – become trophozoites, destroy shape of RBC
b. Go to schizogony – merozoites form and complete cycle; gametocytes are infectious form for mosquito
XXVII. Plasmodium falciparum: Malignant malaria [S27]
a. Virulent species - can get very high parasitemia with massive hemolysis (23% every 2 days)
XXVIII. Malaria prevention: decreased contact with mosquito [S28]
a. DEET
b. Anopheles mosquitoes only bite at night
c. Insecticide-treated mosquito nets – very effective if used
d. DDT on walls of house - kill mosquitoes
e. Wear lots of clothes and insect repellant to avoid getting malaria
f. Prophylactic drugs
XXIX.
US Cases of Cyclospora [S29]
a. Gut organism found in US from cases in 1996 – traced back to raspberries from Guatemala
b. After outbreak in US, CDC taught Guatemalan farmers how to prevent organism
c. Still had cases the next year; stopped importing raspberries from Guatemala
d. Anesthesiologists at CA meeting severely affected
i. 1 raspberry is an infectious dose
e. It was thought there was an intermediate host , but most likely a human disease transmitted focally-orally
f. Can also get parasite from sweet basil and lettuce
XXX.
Cyclospora cayetanensis [S30]
a. We think only reservoir is humans
b. Affects small intestine epithelial cells; profuse watery diarrhea for 3-7 days with relapses
c. Treatable, unlike Cryptosporidium
d. Harder to diagnose, not seen often
XXXI.
Cyclospora cayetanensis [S31]
a. 10 microns in diameter
b. Stain with acid-fast stain
XXXII. Helminth species - table [S32]
a. List of helminths and millions of cases in world
b. Billion cases or 1/6 of world is infected with Ascaris
i. Red – roundworms (nematodes)
ii. Blue- flukes/ trematodes
iii. Black – tapeworms
c. Still we are having a lot of these organisms – lots of cases in world
XXXIII. Helminth species - table [S33]
XXXIV. 58,000 specimens from 601 US laboratories [S34]
a. Listing of parasites found in 58,000 stool samples – 700 Giardia found with greatest occurrence
FUNDAMENTALS 2 10:00-11:00
Scribe: ANGI GULLARD
OCTOBER 28, 2010
Proof: KRATIKA PAREEK
BENJAMIN
EUKARYOTIC PARASITES
Page 5 of 7
XXXV. Ascaris lumbricoides: large roundworm [S35]
a. Ascaris – large roundworm, has worldwide distribution
b. Humans are definitive host
c. Embryonated eggs are infected, so eggs have to be in soil before they are infectious
d. Person who has one worm that puts out 200,000 eggs per day, person is not infectious
i. Person can handle food because eggs have to be in soil for a few weeks
e. Eggs hatch in duodenum, larvae penetrate intestine, enter bloodstream, migrate through lungs, get coughed
up and swallowed
f. Case in 1970s – 5 roommates in Canada; 1 person fed others eggs from pig Ascaris – great potential of
having lung damage
i. Students got bad pneumonia, worms were seen in Gram stain of sputum samples
g. Adult worms life in small intestine, worm lasts 6 months to a year
h. Have seen only 1 case in last 20 years at UAB
i. Diagnostic form is eggs in stool or adult worms passed
XXXVI. Ascaris lumbricoides [S36]
a. Life cycle: embryonated egg in soil for a few weeks eggs eaten  larvae hatch, go through circulation,
lung, trachea, swallowed, then grow in small intestine
b. Worms move up and down especially when host has a fever
XXXVII. Ascaris lumbricoides: Roundworm [S37]
XXXVIII. “Vomit worm” - Ascaris lumbricoides [S38]
a. Child diagnosed with tuberculosis thanks to presence of Ascaris worm in stomach
XXXIX. Strongyloides stercoralis [S39]
a. Worm found here
b. Penetrates skin - Not a hookworm but closely related, infects the same way
c. People walking barefoot can get these worms, which can live a lifetime
d. Infected people had ground itch, when larvae burrow through skin
i. Host is asymptomatic until decades later when host becomes immune-suppressed
e. Worms get to be 2 mm long, females only
f. Worms can cause disease when they go through lungs, are coughed up, swallowed, and grow in small
intestine  lay eggs in mucosa, eggs hatch, larvae burrow out and are found in stool
g. Takes a few weeks for a person to be infectious, can be transmitted
h. If someone is immune-suppressed or takes steroids, can get hyperinfection syndrome
i. Lung damage that appears to be asthma
i. Can see worms in sputum  get diagnosis
j. 1 or 2 cases per year in UAB
XL. Strongyloides stercoralis [S40]
a. Mainly tropical distribution
b. To complete life cycle, need to pick up eggs
c. Dogs can be infected, but it is rare
d. Dogs do have hookworms that can burrow through skin
e. Infection can be subclinical for decades
f. Eosinophilia is common (50% eosinophilia in blood)
XLI.
Strongyloides stercoralis [S41]
a. Motile in fresh stool
b. 300 microns long, fairly easy to see
XLII.
Schistosoma sp. (blood flukes) [S42]
a. Schistosoma species are blood flukes - there are 3 species
b. Adults live in venules in mesentery- around gut or bladder
c. Cercaria penetrate skin
d. Anyplace where there are water and snails, in bodies of water outside US, could become infected by putting
your feet in water
e. Also found in animals
FUNDAMENTALS 2 10:00-11:00
OCTOBER 28, 2010
BENJAMIN
EUKARYOTIC PARASITES
f. S. haematobium – around urinary bladder, so get urine sample for diagnosis
g. Diagnostic form is eggs in stool or urine depending on species
Scribe: ANGI GULLARD
Proof: KRATIKA PAREEK
Page 6 of 7
XLIII.
Schistosoma species - Blood flukes [S43]
a. Eggs are large, with a hook on side
b. Eggs are laid in tissue, and the spine helps egg wander through tissue – want to enter gut to replicate
c. Organisms multiply in snails
d. Flukes appear as paper fibers in water and can penetrate host very easily
XLIV.
Schistosoma mansoni eggs [S44]
a. Large eggs with spike
XLV.
Schistosoma mansoni [S45]
a. Adults can live in mesentery venules
b. Infectious cercariae in image on right
XLVI.
Taenia solium: pork tape worm [S46]
a. Taenia = tapeworms
b. Taenia solium – pork tapeworm
c. People get infected when eat uncooked pork or where pigs are allowed to scavenge human waste
d. Humans can be definitive host, so we can have the tapeworm by eating uncooked pork or if we eat eggs from
infected person, can get cysticerci
e. Cysticerci cause cysts in brain - person has seizures, identify cysts by CAT scan, MRI
XLVII.
Adult Taenia (tapeworm) [S47]
a. Tapeworm has numerous units known as proglottids, which can be passed via excretory system
XLVIII.
Measly pork- Source of Taenia solium (Pork tapeworm) [S48]
a. Cysts in pork – head of tapeworm invaginated in cyst
XLIX.
Other cestodes – tapeworms [S49]
a. Taenia saginata – beef tapeworm, from raw or undercooked beef
b. Diphyllobothrium latum - broad fish tapeworm, from raw or undercooked fish (sushi)
c. Hymenolepis nana - dwarf tapeworm, from raw or undercooked insects (intermediate host is roach or flower
weevil)
d. Hymenolepis diminuta - rat tapeworm
L. Dracunculus medinensis: Guinea worm [S50]
a. On edge of distinction, nearly eradicated
b. Worm wanders around subcutaneously for a year, about 1 meter long
c. If worm dies, whole tract of worm becomes necrotic, so to remove the worm, need to pull it out, 5 cm per day
LI. Number of dracunculiasis cases by country 1999 3.5 million 1985 [S51]
LII. Cuterebra sp. [S52]
a. Adult flies do not bite or feed, but squirrels, rats, and rabbits can get botflies – look like “tumors”
b. Squirrel hunters wait for colder months when squirrels should not have “tumor” bumps anymore
LIII. UAB Botfly in eye [S53]
a. If consume botfly eggs (grass for example), they can burrow through skin
b. Rare for people to get this
c. Several species exist in South America and Africa where people get botflies
d. Images of botfly-infected eye: fly eradicated by laser, person lost eye
LIV.
Acanthamoeba sp. [S54]
a. Free-living ameba that can grow in contact lens cleaning fluid  can lead to corne
b. Can be isolated from almost any place
c. Cysts form in tissue
d. Can cause amoebic meningo-encephalitis – swimming in water, they go up nose and enter brain
FUNDAMENTALS 2 10:00-11:00
OCTOBER 28, 2010
BENJAMIN
EUKARYOTIC PARASITES
e. Resistant to chlorine, most susceptible to salt
f. Naegleria goes into brain – diagnosis upon autopsy
Scribe: ANGI GULLARD
Proof: KRATIKA PAREEK
Page 7 of 7
LV. River blindness: Oncocerca volvulus [S55]
a. River blindness caused by Oncocerca volvulus, which is transmitted by black fly bite
b. In South America, small foci in Brazil, common in large part of western Africa
c. Organisms have endogenous bacteria in their cells
d. Bacteria LPS causes inflammation and damage to eye  river blindness
e. With antibiotics – kill bacteria in worm, still have worm but is not problematic
f. Diagnosis is by skin snips – cut off clipping of skin, put in saline, and look for worms coming out
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