Introduction to Parasites Flashcards
What are the characteristics of protozoa?
Unicellular, aerobic heterotrophs, present where there is a lot of water, reproduce by budding, schizogoy and sex and can produce cysts
What is schizogony?
Multiple division of the nucleus before cell division
Where would you find entamoeba histolytica?
Poorly sanitized environment and around homosexual males
Which amoeba is the only pathogenic among all intestinal amoebae?
Entamoeba histolytica
Mammals can be infected with entamoeba histolytica but;
do not shed cysts with their feces
Where does the trophozoite entamoeba histolytica of exist?
Only in the host and fresh feces
Where do the cysts of entamoeba histolytica survive?
Outside of the host in water and soils and on food
How many nuclei does the trophozoites of entamoeba histolytica have? The cysts?
1, 4
What are the clinical manifestations of entamoeba histolytica?
Asymptomatic carriers
Collitis and deep, tear drop ulcer formation
Watery stool with mucus and blood
Extra-intestinal infection
How is entamoeba histolytica treated?
Metronidazole
Where would you find giardia lamblia and how is it translated?
Lakes, streams, prisons and day cares
Fecal-oral
What is the reservoir for giardia lamblia?
Human and animals where cysts are in the feces
How many nuclei does the giardia lamblia trophozoite have? The cyst?
2, 4
What does giardia lamblia cause and how does it do this?
Malabsoprtion because the organism coats the distal villi
What are the clinical signs of giardia lamblia?
Watery, foul smelling diarrhea Cramps and flatulence Abdominal distention Disaccharidase deficiency (lactose intolerance) Dehydration
What happens with pts who have an IgA deficiency who acquire giardia lamblia?
Predisposed to symptomatic infection
What is cryptosporidium parvum and what is it associated with?
GI protozoa
Diarrhea in the immunocompromised
Where can you find cryptosporidium parvum and why there?
Public swimming pools because its resistant to chlorine
In an immuno-competent person what would cryptosporidium parvum cause?
Mild-self limiting entercolitis (diarrhea, vomiting, ab pain) and spontaneous remission
If an immunocompromised pt acquires cryptosporidium parvum what could happen to them?
50 or more stools per day
Dehydration
Lasts for months
Common in AIDS patients
What is the treatment for cryptosporidium parvum?
Self-limiting in healthy
Lethal in AIDS
No effective therapy
maybe azithromycin
What type of parasite is a toxoplasma gondii?
Apicomplexa
What is the host for toxoplasma gondii?
Kitties
How does toxoplasma gondii reproduce?
Asexually and sexually inside the cells
What is the role of human in toxoplasma gondii?
Intermediate host
In the asexual tissue cycle, toxoplasma gondii enters a phase of motility and can produce disease. It’s called;
Tachyzoites
The non-motile phase of toxoplasma gondii is called;
Bradyzoites
If a pt who is immunocompromised contacts toxoplasma gondii what would you see in terms of symptoms?
Focal neurological deficits, tetinochoroditis or pneumonitis
If a pregnant mother has toxoplasma gondii what could happen to the infant?
Hydrocephalus, heptaospenomegaly, jaundice, fever, anemia, pneumonia
How can toxoplasma gondii be prevented?
Clean litter box daily
Cook meat and fish completely through
What are the two types of Trypansomas?
T. cruzi (america) and T. bruci (africa)
T. cruzi and T. bruci look very similar. Where do they both get their energy from?
A kinetoplast
Where would you be likely to find Tryanosoma cruzi?
Central and South America
What transmits T. cruzi?
Reduviid - kissing bug
What is the inflammation at the site of infection called when made by the thing that transmits T. cruzi?
Chagoma
What is Romana’s sign for T. cruzi?
Painless perobital swelling
What is the clinical manifestation of tryansoma cruzi?
Chaga’s disease
What are the chronic symptoms associated with T. cruzi?
2/3 of patients will have dialated cardiomyopathies
1/3 of patients present with megacolon and megaesophagus
What is the treatment for T. cruzi?
Nifurtimox
What transmits T. bruci?
The glossina fly/ Tse Tse fly
When the lymph becomes englarged due to a T.bruci infection what is it called?
Winterbottom’s sign
What is the clinical manifestion of T. bruci?
African sleeping sickness
How can T. bruci cause CNF problems?
Because it can cross the blood brain barrier
What are the symptoms of African sleeping sickness?
Tremors of tongue and eyelids
Mental dullness and progressive apathy
Neurological symptoms
Rapid weight loss, anemia and coma
What are the cutaneous forms of leishmania?
L. tropica
L. major
L. aethiopica
L. mexicana
What is the visceral leishmania?
L. donovani
What is the mucocutaneous leishmania?
L. brazilliensis
What is the the treatment for T. bruci?
Suramin
How is Leishmania transmitted?
Sand flies
Animal to human
Human-sandfly-human
What are the clinical manifestations of cutaneous leishmaniasis?
Most common form, relatively benign self-healing skin lesions
What are the clinical manifestations of muscocutaneous leishmaniasis?
Simple skin lesions that metastasize to mucosae (nose and mouth)
What is the clinical manifestation of viseral leishmaniasis?
Kala-Azar fever
Skin, lymph, bone marrow, liver and spleen invovlement
Generalized infection of the reticuloendothelial system, hepatosplenomegaly
High mortality
If you saw a helmenth what clues would let you know it was a cestode?
Segmented plane
No body cavity or digestive tube
Hermaphroditic
Oral suckers, botridias and double rostellar hooks
What features would be expected of a trematode?
Unsegmented plane No body cavity Digestive tube ending in a cecum Hermaphroditic except Schistosoma Oral suckers and ventral suckers
What features would be expected from a nematode?
Cylindrical
Body cavity and digestive tracks that ends with anus
Dioecious
Lips, teeth, extremities and dentary planes
What is the colloquial name for cestodes?
Tapeworms
What are the general characteristics of cestodes?
Scolex (head)
Segmented body and suckers
Eosinophillia
What specific features would you see of taenia saginata (beed tapeworm)?
Scolex with 4 suckers
No hooks
Usually asymptomatic
Where would you find the cysticosis for Taenia saginata?
Cow muscle which are infected by human waste
Humans are the host only to the adult worm
What specific features would you see of Taenia solium (pork tapeworm)?
Scolex with 4 suckers and circle of hooklets
What is the treatment for taenia saginata?
Praziquantel
Albendazole
At what stage of the taenia solium life cycle are humans the host?
Definitive or intermediate host
What are the clinical manifestation of taenia solium?
Adult worms generally asymptomatic
Larvae penetrate intestines, enter blood and encyst the brain leading to hydrocephalus, motor spasm, loss of vision, meningitis, seizures
Larvae that encyst other organs are generally asymptomatic
Where is taenia solium prevalence high?
Mexico
What is the treatment for taenia solium?
Praziquiantel and Albendazole can kills cysts but death of larvae may cause inflammation
Corticosteroids vs. edema and inflam
How could Diphyllobothrum latum (fish tapeworm) be visualized?
Yellow with dark markings
3 -15 m long
Long life span
Scolex with 2 sucking grooves
How do crustaceans aquire D. latum and who becomes a host?
Ingest eggs in fresh water
Humans and dogs
What is the host cycle for D.latum?
1st intermediate - crustacean
2nd intermediate - fish
Definitive - human
What are the specific life stages of the D. latum?
Coracidium (egg in feces)
Procercoid (in crustacean)
Plerocercoid larvae (in fish)
What are the clinical signs of D. latum?
Asymptomatic mostly
Abdominal discomfort and cramps
Diarrhea and constipation cycles
Megaloblastic anemia - dec B12
What is the treatment for D. latum?
Praziquantel
What are the general properties of Echinococcus granulosus (dog tapeworm)?
Found in dogs and sheep
Scolex with 3 proglottids
Rostulum 4 suckers
2 rows of hooks
What are the clinical manifestation of E. granulosus?
Hydatid cysts
Occurs when hyadid cyst is 8-10cm
Travel from liver to brain to and once big enough can compress vital structures and erode into biliary tact or bronchus
Fever and hypotension
What is the most common tape worm in the US?
Hymenolepsis nana (dwarf tapeworm)
Where does H. nana complete its life cycle?
Both larval and adult forms maybe be found in humans
What is the direct transmission of H. nana?
Ingestion of effs that hatch in duodenum (autoinfection)
What is the indirect transmission of H. nana?
Ingestion of ingested arthropod
What are the symptoms of H. nana?
Praziqantel
How would nematodes (round worms) be characterized?
Unsegmented, bilaterally symmetric, body “cuticle”, triploblastic (fluid filled cavity, psudeocoelom, hydrostatic skeleton)
Can be free living
What does the digestive tract of a nematode look like?
Complete
Nematodes are dioecious, but how do you tell a man wiggly from a lady wiggly?
Males have a bent tail and females do not
Which is one of the largest nematodes in the world?
Ascaris lumbricoides
How could an infection of ascaris lumbricoides be obtained?
Soil contaminated with human feces
What is the pathogenesis of ascaris?
Ingestion of eggs > Eggs hatch in small intestine > Larvae released > Penetrate intestinal wall > Portal circulation > Liver > Heart > lungs > from lungs coughed up and swallowed > back to intestines as adult
What are the clinical signs for ascaris lumbricoides?
Migration - hemorrhagic/ eosinophillic pneumonia, cough (loeffler’s syndrome)
Intestinal obstruction - intestinal rupture
Parasite proteins that are allergenic - asthma, hives
How could you acquire Ancylostoma duodenale?
Larvae can penetrate skin, generally through people walking barefoot
Where would Ancylostoma duodenale be found in the body and what does it cause?
It attaches to GI mucous causing blood and fluid loss
microcytic hypochromic iron deficiency anemia
Pot-belly, finger clubbing and PICA (eats dirt)
Which species does Enterobius Vermicularis (pin worms) infect?
Humans
Where do the Enterobius Vermicularis infect and where do they migrate to?
Colon and travel to the perianal region at night to lay eggs
How is a person reinfected by Enterobius Vermicularis?
By scratching the infected area
“Pruritus ani”
What is the test that determines an Enterobious Vermicularis infection?
Scotch tape test
What is the treatment for Enterobious Vermicularis?
Albendazole kills adults
How could Anisakis be acquired?
Infection due to infected water or raw saltwater seafood
What are the symptoms associated with Aniskais?
Gastroenteritis, Eosinophilia, occult blood in stool
How is a person infected with Trichuris trichiura (whipworm)?
Infection from soil contaminated with human feces
Where does the adult form of trichuris trichiura inhabit in the host?
Cecum and large intestine
What are the symptoms of a trichuris trichiura infection?
Tenesmus, malnutrition, diarrhea
Prolapse of rectum
Where would Strongyloides strocrailis most likely be found and how is its contracted?
Tropical areas
Infection through ingestion or larval penetration
How would Strongyloides be diagnosed and what are the clinical signs?
Larva in stool, no eggs present
Itching, blotching, wheezing (pneumo), diarrhea, weight loss
What parasite is associated with under-cooked pork or bear?
Trichinella spiralis
How is Trichinella spiralis diagnosed and what are the clinical signs?
Encysted larva in striated muscle (adult intestines)
Trichinosis - gastroenteritis, fever, muscle pains, periorbital edema, eosinophilia
What would you treat Trichinella spiralis with?
Thiabendazole
How is Wuchereria bancrofti transmitted?
Larvae transmitted though female Anopheles mosquito bite
What are the clinical signs of Wuchereria bancrofti?
Filarisasis - obstruction of lymphatics leading to edema, lymphangitis, cellulites
Elephantiasis - result from chronic and repeat infection
tropical pulmonary eosinophilia
Chlyuria (microfilariae in urine)
What is the treatment for Wuchereria bancrofti?
Diethycarbamazine and Ivermedtin (microfilariae)
Where would Oncocerca volvulus be found and what transmits it?
Africa and Central America
Transmitted by female blackfly
What are the clinical signs of Oncocerca volvulus?
Subcutaneous inflam and pruritus
River blindness due to microfilariage
How is Oncocerca volvulus treated?
Ivermectin
What is Dracunculus medinensis referred to as?
Guinea Fire Worm disease
How can you attain Drancunculus medinensis and how do you remove it?
Drinking infected water where little crustacenas live
Use a stick which they wrap around over the course of a few days
What are the characteristics of trematodes?
Dorso-ventrally flattened, unsegmented, snails are always intermediate, hermaphroditic (except blood flukes), 2 radial striated suckers, incomplete digestive tract
Most made of reproductive organs
Where does Fascioloa hepatica (sheep liver fluke) live in the host?
Bile ducts of sheep
What is the defining feature of Fasciola hepatica?
Prominent cephalic cone
What is the life cycle of Fasciola hepatica?
Eggs hatch and become miracidium in water which does into snails, then free swimming cercariae are released and collects on plants which are then eaten by humans
What are the clinical signs of Fasciola hepatica?
Biliary obstruction
Gall stones
Elevated blood bilirubin
Cirrhosis
Where would you find Clonocrchis sinensis (chinese liver fluke) on the earth and in the body?
Far east, southeast Asia, Russia
Adult worms in intrahepatic biliary tract
How could Chonocrchis sinensis be contracted?
Eating undercooked fish
What are the clinical signs of Chonocrchis sinesis?
RUQ pain
Jaundice
Heptatomegaly
Adenomatus hyperplasia (Cholangiocarcinoma)
What is the defining visual feature of the Paragonimus westermani egg and adult?
Operculum around egg
Adults encapsulated in a granuloma
If a Paragonimus westermani cyst ruptures what symptoms may occur?
Cough and chest pain
What are the clinical signs of Paragonimus westermani?
Cerebral paragonimiasis
Head aches, fever, nausea, visual disturbances and convulsive seizures
