Parasitology Flashcards
1
Q
How do you test for pinworms?
A
Sticky tape test
2
Q
Pinworm infection is the most common helminth infection seen in the US
A
Generally seen in urban settings under crowded conditions
3
Q
PInworm name
A
Enterobius Vernicularis
4
Q
Pinworm life cycle
A
- Eggs ingested by humans
- Larvae hatch inside small intestine (cecum)
- Adult females migrate to perianal region at night to lay eggs.
- Eggs mature into larvae in 4-6 hours and the kids scratch and get them in their fingernails.
HUMANS ARE DEFINITIVE HOST
SCOTCH TAPE TEST
5
Q
Host
A
Organism in which parasite lives
6
Q
Reservoir
A
Host which maintains the parasite in nature as a source for continued transmission
7
Q
Definitive host
A
Host in which sexual reproduction takes place
Humans are a definitive host for strongyloides because sexual reproduction takes place within us
8
Q
Intermediate host
A
Host in which development occurs, possible asexual …but NOT sexual
9
Q
Accidental Host
A
Host in which parasite cannot complete life cycle
10
Q
Types of endoparasites
A
Metazoan and Protozoan
11
Q
Metazoan characteristics
A
- Multicellular organisms
- Helminths (worms)
- Life cycle includes egg, larval, adult
Roundworms— nematodes
Flatworms— Trematodes and Cestodes
12
Q
Protozoan
A
Single celled eukaryotes
- Flagellates
- Amoebas
- Sporozoea
13
Q
What are the Helminths (metazoans) that are transmitted through the soil
A
- Ascariasis
- Trichuriasis
- Hookworm
14
Q
Whipworm life cycles
A
- Eggs in soil
- Swallowed
- Hatch
- Attach to gut wall/ eggs excreted in feces
15
Q
Hookworm is the one that penetrates the skin through an open wound
A
ok….It is a significant cause of illness around the equator
MOST SIGNIFICANT CAUSE OF ANEMIA IN CHILDREN POOR COUNTRIES
16
Q
Hookworm life cycle
How do you prevent hookworm infection
A
- Eggs are excreted in feces, hatch in the environment. The larvae penetrate the skin and enter the bloodstream where they go to the lungs. THey are then coughed up and swallowed. Go to small intestine where sexual repro occurs. FEEDS BY SECRETING AN ANTICOAGULANT
- Where shoes, treat carriers, sanitation
17
Q
Ascariasis causes
A
Intestinal infection
Global morbidity around 1 billion per year
Large worm burdens can cause intestinal obstruction and perforation.
Can also cause pancreatitis
CAN ALSO INFECT LUNGS AND CAUSE LAOEFLER SYNDROME
18
Q
Toxocara Canis and Toxocara Cati cause
A
visceral Larval Migrans- Larva penetrate into mucosa and enter circulation, carried to the liver, lungs, eyes - cause inflammatory necrosis
19
Q
What is cutaneous larval migrans
A
Also caused by Toxocara Canis and Cati…. larva penetrates skin, migrates in subcutaneous tissue and causes inflammation
20
Q
Strongyloidiasis clinical features
A
- frequently ASYMPTOMATIC EOSINOPHILIA Symptoms related to three phases: 1) skin invasion- purpuric papule 2) Lung migration 3) Gi invasion- abdominal pain and diarrhea
Maintains chronic infection by autoinfection
21
Q
What is strogyloides hyperinfection KNOW
A
When you get a disseminated infection in an immunocompromised host that leads to a massive parastie burden in the lungs which causes respiratory failure. Massive invasion of GI causes sepsis. Absent immune response
22
Q
lab dx of strongyloides infection
A
larvae in stool or sputum
23
Q
Trichinenella infection usually acquired how
A
consumption of undercooked pork or meat which carries the encysted larvae
Larvae are then released in the small intestine of humans, turn into adults where sexual reproduction occurs, more larvae come and enter the circulation where they can go to different parts of the body.
24
Q
Signs, symptoms of trichinosis
A
ranges from asymptomatic to bad
- initially gastroenteritis followed by fever, muscle weakness,
25
What causes elephantitis (Lymphatic filariasis)
Wuchereria Bancrofti----- transmitted by different types of moquitoes.
They ingest microfilaria from an infected host, inject it into another human where it develops into an adult worm in the lymphatics and causes obstruction. Obstruction increases when it dies due to calcification
EARLY INFECTION DETECTED BY MICROSCOPY OF BLOOD OR LYMPH
26
Beef tapeworm is
Taenia Saeginata
27
Pork tapeworm is
Taenia salium
28
What is the proglottid section of a tapeworm?
segments with branched uteri designed to produce thousands of eggs... the proglottids closest to the scolex (head) are immature but those at the terminal end break off and are released along with numerous eggs
29
Tapeworm diseases
Depends on how you ingest the tapeworm, if you ingest the larvae you usually acquire asymptomatic intestinal infection unless extremely heavy.
Ingestion of T Solium eggs can cause cysteriosis (cyst development) in the brain, eye, or muscles. Most common causes of epilepsy in low income countries. SWISS CHEESE BRAIN
Diagnosis involves the recovery of eggs or proglottids from the stool
30
hookworm gastroenteritis symptoms and pathology
They grasp onto the intestinal villi and eat tissue. they produce an anticoagulant which facilitates bleeding. The larval stage is migratory which means it can produce inflammation and eosinophilia
CAUSES A LOT OF ANEMIA IN THE DEVELOPING WORLD BECAUSE IT SUCKS SO MUCH BLOOD
31
Ascaris lumbricoides life cycle
Fertilized eggs ingested by humans, Goes to small intestine where the larvae hatch. They attach to villi, enter bloodstream, go to lungs, are coughed up and and re-swallowed. Eggs are laid in intestines (unfertilized) and shed through feces
32
Toxicara canis and cati are usually like the ascaris of dogs and cats
In humans, the eggs are ingested and larvae enter the intestines, get to the lungs (or liver or eyes), and find that they can't continue their life cycle so they end up sitting in the lungs and cause a massive inflammatory response before being cleared.
HUMANS ARE THE ACCIDENTAL HOSTS IN Toxicara infections
33
What is the most common immune response to parasites
IgE, Eosinophils, TH2
34
WHat is the most common presentation of a toxicara infection
someone, usually a kid, comes to the ER with a massive eosinophilia. Injury in the eye can be very serious.
35
What is unique about the strongyloides life-cycle
It causes permanent auto-infection because larvae that cause the initial infection go through the process of getting into the lungs and then back into the intestines where they become adults. Once in the intestine the females lay eggs which, in this case, HATCH into larvae and some are excreted in teh stool while some migrate back to the lung to continue the regular life-cycle. Can cause persistent disease that really gets bad in an immunocompromised host
36
How is Wucheria Bancrofti identified
They microfilaria move in the blood at night.
37
Echinoccus Granulosus is generally passed between what animals>
Dogs and sheep
Dogs are definitive hosts, sheep are intermediates
Can be passede to humans where larvae spread hematogenously and secrete a membrane. The inner part produces hydatid cysts in various organs
38
Where do the hydatid cysts formed by echinococcus granulosus form?
generally form on tissues that grow slowly over time (liver, brain, etcc) The presentation can be similar to a slowly growing tumor, Big problems arise if the cyst ruptures and causes anaphylaxis. Will cause jaundince in liver and intracranial pressure problems in the brain
39
Sheep dogs = echinococcus granulosus
ok
40
The Schistosomas
S. Hematobium: bladder granulomas, hematuria, bladder cancer
S Mansoni and S japonicum- Periportal fibrosis, PORTAL hypertension, hepatosplenomegaly
S.Mansoni (spine in middle), S Japanicum (no spine), S. Hematobium spine in tip
41
What is the intermediate host of schistosoma?
snails
Human host sheds eggs into urine or stool. On contact with fresh water they hatch and become miracidia. This is the form that go into snail. Become sporocysts within the snail. Snail releases them in a form called cercaria. The cercaria is infective to the human host. The cercaria lose their tails during penetration and become schistosomulae which migrate through the blood to different places.
42
Entamoeba histolytica life cycle
Mature cysts are ingested in fecally contaminated food, water, and hands.
Excystation occurs in small intestines and release trophozoites to the large intestine. The trophozoites produce cysts that are passed in the feces.
43
What are the three potential outcomes of Entamoeba Histolytica infection?
Asymptomatic infection, intestinal disease (AMOEBIC DYSENTERY...bloody), extra-intestinal abscess (flask shaped) (trophozoites pass into liver or brain)
_ look for liver cysts if its not severe bloody diarrhea
44
Netti Pot
Negieria Foweri- migrates through the cribiform plate into the brain and causes primary amoebic meningotis.....survival rate less than 1%
45
Frothy vaginal discharge, punctate hemorrhage at the cervix (strawberry cervix)
Trichomoniasis
46
Morphology of trichomoniasis
single nucleus, 4 anterior flagella, Undulating membrane
In women, prefers a pH of greater than 4.5 with frothy discharge
47
Trichomonas life-cycle
Lives in lower genital tract of women and urethra of men. Transmitted by sexual contact
48
Giardiasis
Most common protozoan intestinal disease. It is a flagellated protozoan.
49
Symptoms of giardia
uncontrollable flatulence, abdominal distension, foul-smelling bulky diarrhea with excess lipids. Trophozites cover and flatten intestinal epithelium, may lead to malabsorption of nutrients.
50
African sleeping sickness
Trypanosomiasis (T. Brucei) further divided into T Brucei G (gambia- west) and T Brucei R (east africa)
51
T. Brucei infection is carried by what
How does T Brucei get around in the blood?
Tsetse fly
Undulating membrane
52
Variant Surface glycoprotein?
The major characteristic of T. Brucei... prevents it from being killed by the immune system and causes the intermitten fevers
53
West African form more slowly progressive than East African form
ok
54
American Trypanosomiasis
T. Cruzi
55
T. Brucei (african sleeping sickness) really only has a blood form
ok
56
T. Cruzi (american sleeping sickness) has a cellular form
ok
57
WHat spreads T. Cruzi
Reduvid bug....remember, it bites the human and T. Cruzi develops in the gut of the bug, then bites another human and defecates in the bite.
58
T. Cruzi is called what in the blood
Trypamastogote...this is what the fly picks up when it bites and what it transmits
59
T Cruzi is called what in the tissue
Amastigote...multiply by binary fission in infected cells....once they turn into trypamastogotes they burst out of the cell
60
Chagas disease (american trypanosomiasis) includes
- Primary lesion, Chagoma, at the site of infection- usualy on the face. Fever, myalgia, rash.....parasitemia and lymphocytosis
Chronic infection involves the heart (cardiomyopathy), esophagus (megaesophagus) and colon (megacolon)
61
Leshmaniasis life cycle (brief_)
-Sandfly inject promastigate form into the skin.
- Promastigates ingested by macrophages and transform into amastigates...THESE ARE THE DISEASE CAUSERS
Sandflies bite and take up these promastigates which turn into amastigates in the midgut of the sandfly to be injected into other humans
62
How does leshmaniasis cause disease
amasigates in migrate to and multiple in various tissues
63
Three distinct forms of leshmaniasis
1) Visceral- organisms multiply in phagocytes of spleen, liver, nodes, etc
2) mucocutaneous- organisms in skin metastasize to mucoid tissue
3) cutaneous- ulcer develops at lesion site
64
Look at notes for toxoplasmosis life cycle
ok....KNOW THE FOUR WAYS OF CONTRACTING IT:
Life cycle involves a cat eating a small animal with the infection, then pooping out the oocysts which get into livestock muscle and or litter box, Humans then ingest these oocysts. Toxoplasmosis is rarely symptomatic in immunocompetent people but hte congnital form is severe
- congenital
- cat litter
- rare meat
- blood transfusion
65
Know that congenital toxoplasmosis infection can be very dangerous ( 5-10% end up as miscarriages, 10% have brain damage, 10% have visual handicaps, 70% have normal births)....ONLY DANGEROUS IF INFECTION ACQUIRED DURING PREGNANCY...look for IgM, if IgM positive it is probably a recent infection
ok...also know that reactivation of latent infection or new infection in immunocompromised hosts are also bad
66
Cryptosporiduim infection associated with
swimming pools and water parks
67
Cryptosporidium life cycle
Thick walled oocysts are resistant to chlorine, they are ingested and sporozoites are released to infect gastric epithelial cells. Differentiate into merozoites which grow via asexual cycle.
68
Cryptosporidium causes
terrible diarrhea.
In immunocompromised hosts, may disseminate to the gall bladder, biliary tract, lung, etc...
69
Malaria and hypnozoites
Hypnozoites chronically infect liver cells and are not killed off by treating the blood phase of malaria. May recur many years later unless the hypnozoites tehmselves are treated.
70
Classic malaria presentatio n
Fever (becomes cyclic if untreated)Deadliest causative agent of malari, Chills, Rigors along with headache vomitting and diarrhea
- Acute anemia due to RBC rupture
Cerebral disease= decreased conscious state
Respiratory distress
71
Deadliest causative agent of malaria
P.Falciparaum
Vivax and ovale associated with hypnozoites
72
What mosquito spread malaria
anopholes mosquito
