Parasitic diseases Flashcards
1
Q
What is a parasite and what are some examples?
A
Parasite- organisms that infect and cause disease in other animals
protozoa, helminths, and arthropods
2
Q
Protozoa
mobile or not?
transmission
A
- most are mobile by flagella, cilia, or ameboid motion
- direct or indirect transmission by fecal oral route, direct transmission through sexual contact or arthropod vector, and contaminated water
3
Q
Helminths
transmission
what organs can it infect?
3 main groups
A
*wormlike
transmission- ingestion of fert eggs or penetration of infective larval stages through the skin (feet)
what organs can it infect? liver, lungs, urinary and intestinal tract, circulatory and nervous systems, and muscles
3 main groups-
- -flatworms (platyhelminths)
- -thorny-headed worms (acanthocephalins)
- -roundworms (nematodes)
4
Q
Arthropods
common vectors
transmission
A
vectors- flies, fleas, ticks, mosquitoes, and lice
transmission- mechanically or biologically
5
Q
Does a parasite directly kill its host?
A
No. the stress placed on the hosts resources can affect its growth, ability to reproduce, and survival. This can sometimes lead to death.
6
Q
Parasitic Infectious process
A
- parasitic organisms attack a host and begins to multiply
- multiplication interferes with normal life functions of a host
- host begins to feel ill as a sx of parasite invasion
* most host immune systems are able to destroy parasite and are asymptomatic
7
Q
Protozoa
multi or unicellular?
causes what deadly diseases
A
- unicellular
- malaria and african sleeping sickness
8
Q
What is a trophozoite?
A
a term for the live adult protozoa
- cysts, spore, or “eggs” are non-adult forms
- most of these diseases are spread by the fecal oral route
9
Q
Giardiasis
- what is is?
- infects what organ?
- transmission
A
- Giardia lamblia is a flagellated pathogenic protozoan
- infects the duodenum and jejunum
- oral-fecal route! Usually contaminated water or food, may be direct person to person contact (day care). Also infected by rodents, deer, cattle, sheep, horses, or household pets.
10
Q
Giardiasis
-life cycle
A
cyst is the infectious form of parasite, excreted in the stool, survives in the atmosphere for a long time. Excyst in the small bowel where they open up, release 2 trophozoites that can adhere to mucosa or be free and cause irritation and low-grade inflamm of duodenal or jejunal mucosa, encyst once they get to the colon. (they form back into cyst form.) The cysts get flushed out into the stool. Sx appear in 1 week or more.
11
Q
Giardiasis
- dx
- sx
- stool appearance
A
dx- If you can’t dind cyst in the stool, do biopsy
–bx will show: crypt hypertrophy, villous atrophy or flattening, epithelial cell damage
sx- asymptomatic, acute or chronic diarrhea, malabsorption syndrome
-malaise, steatorrhea (excretion of fat), abd cramps, bloating, flatulence, n/v, weight loss, depression
- stools may be watery, semisolid, greasy, bulky, foul-smelling (and contain cysts!)
- sx appear 7-14 days after infection and last 2-4 weeks
12
Q
Giardiasis
- work up
- tx
- prevention
A
Stool sample-fecal smear- to look for ova and parasites
- a series of three or more stool examinations on alternate days is therefore recommended
- can do stool ELISA
Examination of duodenal contents may be necessary
tx:
- metronidazole (flagyl) 250mg twice daily for five days (both adults and children)
- could become lactose intolerant during infection and usually goes away after tx.
prevention:
- avoid contaminated water sources
- boil water or use iodine or filtration
- adequate disposal of diapers
- antibacterials are ineffective against cyst forms (wash your hands)
13
Q
Cryptosporidiosis
- what is it?
- transmission
- what organ do the affect
- life cycle
A
- coccidian protozoan parasite (cryptosporidium hominis) which causes this disease
- contaminated water supply
- infect stomach or intestine, but can affect other areas (resp tract and conjunctiva)
- Ingestion of cryptosporidium contaminated water, adhere just under the lining of the stomach or intestine, release 4 sporozites, and cause cell death
14
Q
What are the common causes of waterborne illness in the US?
A
Cryptosporidiosis and giardia
15
Q
What is the infectious dose of cryptosporidium?
Incubation period?
A
less than 10 organisms but only need one to initiate because the reproduced asexually
-incubation period is 7-10 days
16
Q
Crytposporidium sx dx tx prevention
A
sx-stomach cramps, pain, watery diarrhea, dehydration, vomiting, fever
severe sx- profuse watery diarrhea, severe malabsorption, electrolyte imbalance, and weight loss
dx-
- made by examining 3 stool specimens
- microscopy with acid fast
- Enzyme immunoassy
- PCR
tx-
-Nitazoxanide (adults and peds)
prevention
- water purification and filtration
- drink bottled water when traveling
- wash hands
- avoid swimming pools 2 weeks after diarrhea has resolved, otherwise you might infect the pool
17
Q
Intestinal Amebiasis
- what is the most common parasite in the large intestine?
- What are the three stages of amebiasis?
- transmission
A
-most common is Entamoeba histolytica
- three stages
- -active amoeba
- -inactive cyst
- -intermediate precyst
-Transmission is fecal-oral route
18
Q
Life cycle of an ameoba
A
- cyst ingestd
- trophozoite emerges in the stomach and duodenum and divides into 8 small trophozoites per cyst.
- these pass to the cecum and produce a population of lumen dwelling trophozoites
- cause discrete ulcers with a pinhead-sized center and raised edges from which mucus, necrotic cells, and amoebas pass.
- trophozoites may penetrate the muscular coats and occasionally the serosa leading to perforation into the peritoneal cavity.
- extraintestinal infection is metastatic (amoebas spread through the blood) to liver, brain, and lungs
- before the amoeba exit through the feces they encyst once again.
19
Q
What is the most common form of amoebic extraintestinal infection?
A
hepatitis or liver abscess.
20
Q
Symptoms of Amoeba
A
- sx vary greatly depending upon the site of intensity of lesions.
- -extreme abdominal tenderness
- -fulminating dysentery and dehydration
- -in less acute disease:
- –episodic diarrhea, abd cramps, nausea and vomitting, urgent desire to deficate.
21
Q
Amoeba Diagnostic Lab tests and treatment
A
-Stool specimen
- -fluid feces; fresh and warm for immediate examination for trophozoites
- after a saline purge for cysts and trophozoits
–formed feces for cysts
–Serology is available (EIA)
- Tx: treat all cases of proven E. histolytica regardless of symptoms.
- -Asymptomatic: Paromomycin 10days
- -Symptomatic: Paromomycin 10 days after Metronidazole 5-10days followed by diloxanide to eradicate any potential intestinal reservoirs
22
Q
Amoeba Prevention
A
- avoid contaminated food and water
- wash and cook vegetables
- hand washing
23
Q
Malaria
- vector
- most serious vector
- once in the body, where does this parasite multiply?
A
- mosquitoes of the genus Anopheles
- most serious vector is Plasmodium falciparum, very often lethal.
- once in the body, parasites multiply within the liver cells and RBC
24
Q
Malaria Sx
A
- onset 10-14days up to 1 mo
- chills
- night sweats
- fever
- HA
- muscle pain
- cough and chest pain
- splenomegaly- chronically infected patients
- hepatomegally- chronically infected patients
25
Congenital Malaria
- when do you suspect this in newborns, what are their sx?
- how does a newborn contract this?
- suspect congenital malaria in febrile newborns who could have been infected during their pregnancy.
- malaria infection during pregnancy can result becausee the mother became infected during her pregnancy, but it can ALSO result from an infection acquired month or YEARS before.
26
Malaria Prevention
- vector control; reduce stagnant water, spray with insecticide
- apply deet
- mosquito nets
27
Malaria Tx and Prophylaxis
Tx:
- chloroquine* or Atovoquine* with Doxycycline if multi drug resistant
* *in area of high transmission of P. facliparum DOC=Atovaquone
- Mefloquine and Chloroquine are safe with pregnancy
* In areas of high transmission, it should be presumed that ALL cases of fever are d/t malaria. First loading dose of chloroquine or atovaqoune should be given immediately after collecting blood specimen even without waiting for its report.
-Prophylaxis:
chloroquine phosphate weekly, continue 6weeks after leaving the area. Add Fansidar weekly in areas with chloroquine resistant P. Falciparum
OR
Primiquine phosphate daily, begin 2 days before travel and 7 days after leaving the area.
28
Toxoplasmosis
- what protozoa causes this?
- life cycle of host and human.
- transmission
- Toxoplasma gondii is a coccidian protozoan
- Life cycle:
- -oocysts develop in the cat GI tract, pass into the gut lumen of the cat and pass out via the feces.
* these cysts can be ingested by other creatures, including humans (changing cat litter box)
Human Life Cycle:
- oocyst opens in human doudenum and releases sporozoites that pass through the gut wall circulate in the body, and invade various cells; esp. mfs.
- They multiply, break out, and spread the infection to lymph nodes and other organs. Especially penetrate the nerve cells of the brain and eye.
-transmitted by cats, raw pork, or lamb
29
Toxoplasmosis Sx
- immune competent pts: asymptomatic
- immune compromised patients: hepatitis, pneumonia, blindness, and sever neurologic disorders, body aches, swollen lymph nodes, HA, fever, fatigue, sore throat.
30
Congenital Toxoplasmosis
- how do you get this?
- SE
develops only when non-immune mothers are infected during pregnancy. The incidence and severity of congenital toxoplasmosis varies with trimester during which infection was acquired
- SE:
- still birth, chorioretinitis, intracerebral calcifications, hydrocephaly or microcephaly.
- blindness, hepatosplenomegaly, diarrhea, feeding probs, jaundice, low birth weight, vision problems,, hearing loss.
31
Toxoplasmosis Diagnostic Lab Tests and Tx, prophylaxis
Test:
- Serology; Sabin-Feldman dye test ***GOLD STANDARD
- ELISA
Tx:
-combo of pyrimethamine and either sulfadiazine or clindamycin
Prophylaxis:
-BACTRIM** OR any of the aforementioned drugs usedin treatment.
32
Helminths
| -what are the types?
Nematodes:
- pin worms
- hook worms
- round worms
Cestodes:
-tape worms
Trematodes:
-Flukes
33
Nematode: Pinworm
- what species?
- transmission
- sx
- most common in who?
- life cycle
- Diagnosis
- Tx
- Enterobius vermicularis
- Fecal Oral Route; self contamination and internal reinfection
- sx: itchy butt (Pruritis anii)
- occurs in school age children 5-10, uncommon
34
Nematode: Round Worms
- causes what disease?
- common among what age?
- transmission
- life cycle
- sx
- diagnosis
- Treatment
- Prevention
- Ascariasis
- 2-10years old
Transmission::
-ingestion of contaminated food/water, children playing in contaminated soil
Life Cycle:
- ingested ova hatch in small intestine and release larvae
- larvae migrate in blood or lymphatics to lungs within 4 days, may also migrate to the kidneys and brain.
- after 10days in the lung they mature, ascend to bronchial tree and get swallowed
- mature worms hatch in jejunum
Sx:
- cough (when they have migrated to the lung)
- abdominal pain; anorexia, nausea, diarrhea
- intestinal obstruction
- biliary colic
-Diagnosis: microscopic examination of eggs in stool sample
- Tx:
- Mebendazole, albendazole, pyrantel, or ivermectin
- Prevention:
- -proper disposal of feces
- -good handwashing
35
Nematode: Hook Worm
- what species?
- transmission
- life cycle
- Nector americanus
- Transmission: walking barefoot on soil, enter through legs or feet.
- Life Cycle:
- migrate to blood vessels and are carried by blood to lungs. Migrate to alveoli and up the bronchi and trachea, then are swallowed.
- Develop into adults in the small intestine attaching to the wall with cutting plates (hooks)
- feed on blood from capillaries of the intesinal villi.
*6-8weeks following infection do the eggs become detectable, takes 1-2years before adult worms die off.
36
Nematode: Hook Worm
- sx
- diagnosis
- Treatment
- Prevention
Sx:
-loss of blood at site of their attachment.
weakness and pallor accompany the microcytic anemia
-skin penetration produces focal pruritic maculopapular eruption at site "Ground itch" (usually on toes)
-mild cough and pharyngeal irritation
-n/v diarrhea
Dx:
-microscopic examination of eggs in stool, occult blood is seen, EOSINOPHILIA***
Tx:
-albendazole and mebendazole are effective
Prevention:
-disposing of sewage properly and wearing shoes
37
Nematode: Trichinosis
- caused by what species of nematode?
- reservoirs
- transmission
- life cycle
- trichinella spiralis (round worm)
- pigs are reservoirs
- transmitted by eating raw or undercooked meat containing encysted muscle
Life Cycle;
- larvae encyst in small intestinal mucosa
- eggs hatch and larvae are released into the blood stream to many organs, however they develop only in STRIATED MUSCLE CELLS.
- nurse cells encapsulate the larvae and can remain viable for several years but eventually calcify
38
Trichinosis;
- sx
- diagnosis
- tx
Sx:
- few days after infection pt experience diarrhea
- 1-2weeks later, fever*, muscle pain*, periorbital edema*, and eosinophilia*
- signs of cardiac and central nervous system disease are frequent because the larvae migrate here as well.
Dx:
- muscle biopsy reveals larvae within striated muscle*
- Elisa
Tx:
- often self-limited and not required
- symptomatic: steroids plus albendazole or mebendazole
Prevention:
-cooking pork or freezing meat and by feeding pigs cooked garbage.
39
Cestodes: Tapeworm
- two human pathogens??
- morphology
- life cycle
pathogens: Taenia solium (pork tapeworm) and Taenia saginata (beef tapeworm)
Morphology:
- head, neck, and segmented body
- each segment has proglittid, each proglottid can produce eggs, its asexual...this is how they grow as long as they do.
Life cycle:
-cattle or pigs ingest vegetation that is contaminated with eggs or proglottids
-human become infected by eating undercooked meat
-attach to small intestine and develop proglottids
-
40
Cestode: Tapeworm
- Sx
- Diagnosis
- Tx
- Prevention
- most are asymptomatic but malaise and mild cramps may occur
- proglottids appear in stool and may protrude the anus
Diagnosis:
-finding gravid proglottids with 15-20 uterine branches in the stool
Tx:
-praziquantel
Prevention:
-cooking meat adequately and disposing of waste properly so cattle cannot consume feces
