Parasitology Flashcards
(163 cards)
1
Q
Name the helminth that causes perianal pruritus
A
Enterobius
2
Q
What findings on blood smear confirm a diagnosis of malaria?
A
Trophozoite ring forms within red blood cells and schizonts containing merozoites
3
Q
A patient has unilateral, nontender periorbital swelling after recent travel to Bolivia. What is the likely diagnosis?
A
Acute Chagas disease (Romaña sign)
4
Q
How can Cryptosporidium infection be prevented?
A
With water filtration
5
Q
What is the treatment for Loa loa infection?
A
Diethylcarbamazine
6
Q
What lab finding might be expected on complete blood count in a patient with hookworm infection?
A
Microcytic anemia
7
Q
In what region of the world is Babesia infection most common?
A
Northeastern United States
8
Q
What organism causes scabies?
A
Sarcoptes scabiei
9
Q
What is the treatment for leishmaniasis?
A
Amphotericin B, sodium stibogluconate
10
Q
Which fluke (trematode) is transmitted in undercooked fish?
A
Clonorchis sinensis
11
Q
All intestinal nematodes can be treated with which medication?
A
Bendazoles
12
Q
What is the specific treatment for a dormant form of malaria?
A
Primaquine
13
Q
What 2 methods are used to diagnose an Entomoeba histolytica infection in a blood sample?
A
Serology and serum antigen testing
14
Q
How is Naegleria fowleri transmitted?
A
Acquired from warm freshwater lakes; enters the central nervous system through the cribriform plate
15
Q
How are diarrhea-causing protozoans transmitted?
A
Via oocysts/cysts in contaminated water
16
Q
What is the most appropriate diagnostic test for Naegleria fowleri?
A
Test for amoebas in the cerebrospinal fluid
17
Q
Before using chloroquine to treat malaria, what should be verified about the patient’s particular strain of malaria?
A
Sensitivity to chloroquine; some have developed resistance to this drug
18
Q
What are the commonly seen symptoms in patients infected withToxocara canis?
A
Myocarditis, hepatitis, visual impairment/blindness, seizures, and coma (patients also often asymptomatic)
19
Q
On what continent is Chagas disease predominantly found?
A
South America
20
Q
Why should pregnant women avoid cat litter boxes?
A
Cat feces may contain Toxoplasma oocysts, which can cross the placenta and cause birth defects
21
Q
What are the common symptoms of Strongyloides stercoralis infection?
A
Duodenitis, dry cough, hemoptysis, and cutaneous symptoms
22
Q
Where on the body are Pediculus humanus and Phthirus pubis commonly found?
A
Scalp/neck (head lice), waistline/axillae (body lice), or pubic/perianal regions (pubic lice)
23
Q
How do you treat an infection with Strongyloides stercoralis?
A
Ivermectin or bendazoles
24
Q
How does the fever pattern differ in malaria caused by Plasmodium vivax, P ovale, P falciparum, and P malariae?
A
P malariae: every 72 hours (quartan); P vivax/P ovale: every 48 hours (tertian); P falciparum: irregular
25
What is the common name for Ancylostoma duodenale and Necator americanus?
Hookworms
26
What are 2 other classic findings associated with the infection causing river blindness?
Skin changes and loss of elastic fibers (Onchocerca volvulus infection)
27
How is Cysticercosis transmitted?
By ingestion of food contaminated with human feces containing Taenia solium eggs
28
How is Entamoeba histolytica transmitted?
Via cysts in the water
29
How is Toxoplasma gondii acquired?
Either by ingesting meat infected with cysts or from exposure to oocysts in cat feces
30
A man bitten by a female black fly experiences skin hyperpigmentation and blindness. What is the diagnosis?
Onchocerca volvulus infection (black flies, black skin nodules, "black sight")
31
How does Cryptosporidium present in immunocompromised hosts with AIDS?
Severe diarrhea
32
How is Ascaris lumbricoides transmitted?
Fecal-oral route
33
How is Schistosoma transmitted to humans?
Through penetration of the skin by cercariae (larval form) in contaminated freshwater
34
What is the treatment for Diphyllobothrium latum?
Praziquantel, niclosamide
35
What is the common name for Ascaris lumbricoides?
Giant roundworm
36
What are the characteristics of a clinically significant infection with Trichuris trichiura?
Loose stools, rectal prolapse (usually in children), and anemia
37
How is babesiosis treated?
With atovaquone and azithromycin together
38
What are the 4 tissue nematodes?
Toxocara, Onchocerca, Loa loa, Wuchereria
39
What 2 treatments are used in life-threatening forms of malaria?
IV quinidine or artesunate
40
What is the mechanism of anemia in hookworm infestations?
The worms suck blood through the intestinal walls, leading to a microcytic anemia
41
How are acute infections of Trypanosoma cruzi treated?
Benznidazole or nifurtimox (cruzing in my Benz in my fur coat)
42
How are Necator americanus and Ancylostoma spp transmitted?
Larvae enter through the skin (usually from soil to soles of the feet)
43
How is Trypanosoma cruzi transmitted?
Fecal transmission from "kissing bug" that bites and defecates near the mouth or eyes
44
How can you diagnose babesiosis?
With a blood smear (look for "Maltese cross" or ring forms) or polymerase chain reaction test
45
What parasite causes brain cysts and seizures?
Taenia solium (neurocysticercosis)
46
What is the appropriate treatment for visceral larva migrans caused by Toxocara canis infection?
Bendazoles
47
How are infections with Clonorchis sinensis treated?
Praziquantel
48
What is visceral larva migrans?
A clinical syndrome where Toxocara canis nematodes migrate to the blood via the intestinal wall causing inflammation of heart, liver, eyes, and central nervous system
49
Name the parasite that is associated with the development of hematuria and squamous cell bladder cancer
Schistosoma haematobium
50
A woman from a rural area has new-onset skin swelling and conjunctival worms. What is the causative organism?
Loa loa nematode
51
How is Trichomonas vaginalis transmitted?
Sexually (Trichomonas vaginalis exists only in the human body due to inability to form cysts)
52
How can you distinguish Schistosoma mansoni from Schistosoma haematobium?
S mansoni = egg with a lateral spine; S haematobium = egg with a terminal spine
53
What is the typical treatment for infections from Ancylostoma spp and Necator americanus (hookworms)?
Bendazoles or pyrantel pamoate
54
What symptoms are associated with infection by Schistosoma mansoni?
Liver and spleen enlargement, fibrosis, inflammation, portal hypertension
55
What 3 infectious organisms can Pediculus humanus and Phthirus pubis transmit to humans?
Rickettsia prowazekii (typhus), Borrelia recurrentis (relapsing fever), and Bartonella quintana (trench fever)
56
How does hyperinfection syndrome occur with Strongyloides stercoralis?
Via autoinfection by larvae entering the bloodstream through the colonic wall
57
A patient with a past medical history of a trematode infection has painless hematuria. Why is this concerning?
Chronic Schistosoma haematobium infection is associated with squamous cell carcinoma of the bladder
58
What is the treatment of choice for Wuchereria bancrofti infection?
Diethylcarbamazine
59
A man is bitten by a sandfly and develops spiking fevers, hepatosplenomegaly, and pancytopenia. What is the likely diagnosis?
Visceral leishmaniasis (kala-azar)
60
What group of people are at risk for severe infections of babesiosis?
Patients with asplenia
61
What symptoms are typical of infection by Sarcoptes scabiei?
Pruritis that is worse at night and with serpiginous burrows between fingers and toes
62
Name the helminth that causes vitamin B12 deficiency.
Diphyllobothrium latum
63
How does an infection with Diphyllobothrium latum cause megaloblastic anemia?
The tapeworm competes for vitamin B12 in the intestines
64
Which 5 nematodes are transmitted by fecal-oral route?
Enterobius, Ascaris, Toxocara, Trichinella, Trichuris (don't EATTT these!)
65
What form of the nematode is excreted in the stool of an individual infected with Strongyloides stercoralis?
Rhabditiform larvae
66
What is the mode of transmission of intestinal Taenia solium?
Consumption of undercooked pork containing encysted larvae
67
How is an Entamoeba histolytica infection diagnosed from a stool sample?
Stool antigen testing and/or presence of trophozoites or cysts
68
How is Strongyloides stercoralis transmitted?
Larvae from soil penetrate skin
69
What is the treatment of choice for a blood-borne Trypanosoma brucei infection (African sleeping sickness)?
Suramin (versus melarsoprol for CNS disease); “I sure am mellow when I’m sleeping”
70
With which 3 anti-malarials is it important to screen for glucose-6-phosphate dehydrogenase (G6PD) deficiency prior to use?
Quinidine, artesunate, primaquine
71
How is Trichuris trichiura transmitted?
Via fecal-oral route
72
What are the 6 intestinal nematodes?
Enterobius, Ascaris, Strongyloides, Ancylostoma/Necator, Trichinella, Trichuris
73
How do you treat Onchocerca volvulus infections?
Ivermectin (for river blindness)
74
What is the pathogensis of lympatic filariasis?
Elephantiasis: worms invade lymph nodes → inflammation → lymphedema over the course of 9-12 months
75
Name the parasite that forms hydatid liver cysts.
Echinococcus granulosus
76
What disease is associated with a Clonorchis sinensis infection?
Cholangiocarcinoma
77
What will a blood smear show of a patient diagnosed with visceral leishmaniasis?
Macrophages containing amastigotes
78
How is African sleeping sickness transmitted?
Trypomastigotes are transmitted through the bite of a tsetse fly
79
What is the mode of transmission of Diphyllobothrium latum?
Ingestion of larvae in uncooked freshwater fish
80
What are the typical complications of chronic Chagas disease?
Dilated cardiomyopathy with apical atrophy, megaesophagus, and megacolon
81
Name the 2 helminths that classically cause microcytic anemia.
Ancylostoma and Necator
82
What are 3 possible intestinal complications associated with Ascaris lumbricoides infections?
Ileocecal valve obstruction, intestinal perforation, biliary obstruction
83
Which 3 nematodes are transmitted cutaneously?
Strongyloides, Ancylostoma, Necator (they get into your feet from the SANd)
84
What is the treatment for toxoplasmosis?
Sulfadiazine and pyrimethamine
85
What is the mode of transmission of the Plasmodium species that cause malaria?
Bite of the female Anopheles mosquito
86
What are 2 different presentations of leishmaniasis?
1) Cutaneous: skin ulcers; 2) Visceral (kala-azar): spiking fevers, hepatosplenomegaly, pancytopenia
87
What acid-fast organism causes watery diarrhea in healthy patients?
Cryptosporidium
88
What are the presenting signs and symptoms of Pediculus humanus and Phthirus pubis infections?
Severe pruritus with excoriations on the head, torso, or pubic regions
89
What is the treatment of choice for African sleeping sickness with involvement of the central nervous system?
Melarsoprol (versus suramin for blood-borne disease); “I sure am mellow when I’m sleeping”
90
Which 3 nematodes are transmitted through bites?
Loa loa, Onchocerca volvulus, Wuchereria bancrofti (lay LOW to avoid getting bitten)
91
How is an Enterobius vermicularis infection diagnosed?
Tape test to look for the presence of eggs stuck to the tape
92
What is the treatment for pinworm infection?
Pyrantel pamoate or bendazoles (bendy worms)
93
How is Wuchereria bancrofti transmitted?
Via female mosquito
94
How is Toxocara canis transmitted?
Via the fecal-oral route
95
How is Babesia transmitted?
By Ixodes ticks
96
How do you treat neurocysticerosis?
Albendazole
97
How is Cryptosporidium diarrhea treated in immunocompetent patients?
Nitazoxanide; otherwise, prevent by water filtration
98
Which 2 species of Plasmodium form dormant hypnozoites in the liver, leading to relapsing malaria?
P vivax and P ovale
99
What parasite causes myalgias and periorbital edema?
Trichinella spiralis (trichinosis)
100
What is the intermediate host of Schistosoma flukes?
Snails
101
How is giardiasis treated?
Metronidazole
102
What is noted in the blood smear of patients with African sleeping sickness?
Trypomastigotes (Trypanosoma brucei)
103
What are the key aspects of treating Trichomonas vaginalis infections?
Metronidazole should be given to both the patient and the sexual partner for prophylaxis; screen for sexually transmitted infections as well
104
What are the findings on colon biopsy of a patient with an Entamoeba histolytica infection?
Flask-shaped ulcers
105
How does treatment of amebiasis differ between symptomatic and asymptomatic patients?
Symptomatic: use metronidazole; asymptomatic: use paromomycin or iodoquinol
106
How does Trichinella spiralis cause muscle inflammation?
Larvae enter the bloodstream and encyst in striated muscle cells
107
How does toxoplasmosis present in immunocompetent adults?
As a mononucleosis-like syndrome but without heterophile antibodies
108
In patients with Plasmodium falciparum infections, red blood cells tend to occlude capillaries in which 3 organs?
Kidneys, lungs, and brain (cerebral malaria)
109
What are 2 diagnostic findings of Trichomonas vaginalis infection?
Motile trophozoites on wet mount and/or punctate cervical hemorrhages ("strawberry cervix") on exam
110
Infection by what parasite is associated with Chagas disease?
Trypanosoma cruzi
111
How is an infection with Schistosoma spp treated?
Praziquantel
112
How does African sleeping sickness present?
Recurrent fevers, somnolence, coma, lymphadenopathy
113
Taenia solium, Diphyllobothrium latum, and Echinococcus granulosus are examples of what type of organism?
Cestodes (tapeworms)
114
What is the mechanism that causes the itching that occurs in scabies?
Mites burrow into the stratum corneum, which causes pruritus
115
What are the characteristics of a Clonorchis sinensis infection?
Biliary tract inflammation leading to pigmented gallstones
116
Toxoplasma causes severe disease in what 2 patient populations?
Patients with AIDS (reactivation) and neonates (congenital toxoplasmosis)
117
What is the treatment for lice infection?
Pyrethroids, malathion, or ivermectin lotion; and nit combing
118
What is the classic triad of congenital toxoplasmosis?
Chorioretinitis, hydrocephalus, and intracranial calcifications
119
Ixodes ticks transmit which 3 diseases?
Babesiosis, Lyme disease (Borrelia burgdorferi), anaplasmosis (Anaplasma spp)
120
Name the 2 helminths that cause portal hypertension.
Schistosoma mansoni and Schistosoma japonicum
121
What vaginal infection is characterized by a foul-smelling, itching, burning vaginitis with green discharge?
Trichomoniasis (Trichomonas vaginalis)
122
In what populations is scabies common?
Children, prison inmates, and nursing home residents (crowded conditions)
123
What protozoan infection is characterized by bloody diarrhea, right upper quadrant (RUQ) abdominal pain, and liver abscesses?
Entamoeba histolytica infection
124
What is the common name for Enterobius vermicularis?
Pinworm
125
How is Trichinella spiralis transmitted?
More often via oral ingestion of undercooked meat, especially pork; less often fecal-oral
126
For school-aged children who are diagnosed with head lice, how is their school attendance generally affected?
Minimally; children with head lice can continue to attend school while receiving treatment at home
127
What is the vector of transmission for cysticercosis and neurocysticercosis?
Ingestion of food contaminated with human feces containing Taenia solium eggs
128
Ingestion of food contaminated with human feces containing Taenia solium eggs
Flies (deer fly, horse fly, mango fly)
129
Where might Plasmodium vivax and P ovale remain dormant in the body?
The liver as hypnozoites
130
Which helminth causes biliary tract disease and is associated with cholangiocarcinoma?
Clonorchis sinensis
131
What is the treatment for Echinococcus granulosus infection?
Albendazole; surgery for complicated cysts
132
What 2 diseases can develop secondary to chronic infection with Schistosoma?
Squamous cell bladder cancer and pulmonary hypertension (with Schistosoma haematobium)
133
By what methods is Sarcoptes scabiei treated?
Permethrin cream, oral ivermectin; laundering of all bedding and clothing, and treating close contacts
134
How is Enterobius vermicularis transmitted?
Fecal-oral route
135
What 2 diagnostic tests can confirm Toxoplasma infection?
Serology and biopsy (tachyzoite)
136
A patient presents with chronic pulmonary hypertension. What is the most likely diagnosis based on the microscopy image below?
Schistosoma haematobium infection (egg with a terminal spine)
137
What protozoa can cause a ring form or "Maltese cross" on blood smear?
Babesiosis
138
What protozoa shown below can cause bloating, flatulence, and fatty diarrhea?
Giardia lamblia; these are Giardia cysts; shown are multinucleated trophozoites
139
A patient develops the pruritic rash (image) after walking barefoot at a beach. Which parasite is likely responsible?
Hookworm (diagnosis: cutaneous larva migrans)
140
A sheepherder presents with acute-onset anaphylaxis. His abdominal CT scan findings are shown (image). What is the causal organism?
Echinococcus granulosus (cestode)
141
What is the structure shown in the blood smear below?
Trophozoite ring form of Plasmodium (malaria)
142
A sheep farmer is found to have cysts in his liver. One such cyst is shown (image). How did he likely acquire this infection?
Ingestion of food contaminated with dog feces containing Echinococcus granulosus eggs → hepatic hydatid cyst formation
143
Which gastrointestinal infection causes fatty, foul-smelling diarrhea (steatorrhea) and is pictured below?
Giardia lamblia cysts (think fat-rich Ghirardelli chocolates for fatty stools of Giardia)
144
A patient ingests an organism (image) after handling dog feces. What clinical conditions can be caused by this organism?
Hydatid cysts in liver, anaphylaxis if the cysts rupture (Echinococcus granulosus)
145
What is the treatment for asymptomatic cyst passers of Entamoeba histolytica?
Iodoquinol or paromomycin
146
What is the most appropriate treatment for Naegleria fowleri?
Amphotericin B
147
How does Trypanosoma brucei shown in the blood smear (image) cause recurrent fevers?
Antigenic variation on the surface of the organism
148
What does this blood smear from a recently migrated South American with unilateral periorbital swelling show?
A trypomastigote; characteristic of a Trypanosoma cruzi infection (endemic to South America)
149
What organism is shown in the image?
Pediculus humanus (lice)
150
A child presents with intense pruritus and rash on the hand (image). How is the causative infection transmitted?
Through skin-to-skin contact (more common) and via fomites (Sarcoptes scabiei )
151
Wet mount results from a vaginal culture are shown below. What is the likely infectious entity?
Trichomonas vaginalis
152
The egg from this tapeworm (image) is found in the stool of a patient after eating food that was contaminated with dog feces. What are the intermediate hosts for this tapeworm?
Sheep (Echinococcus granulosus)
153
What infection is most commonly associated with the findings of Schüffner stippling (image) in the blood smear?
Malaria, specifically caused by the Plasmodium vivax/ovale species only
154
A patient has an intestinal infection with the tapeworm shown in the image. What is the treatment?
Praziquantel (Taenia solium infection)
155
A patient who recently returned from an international trip developed the ulcerated rash shown below. What is the likely diagnosis?
Cutaneous leishmaniasis
156
This egg (image) was found on the anal canal of a child complaining of anal pruritus. Which organism is this?
Enterobius vermicularis (pinworm)
157
A recent visitor to Mexico develops fever, vomiting, periorbital edema, and muscle pain. A muscle biopsy is shown (image). What organism has he been infected by?
Trichinella spiralis nematodes
158
A man moved to a rural, swampy area with poor health care access. A year later, he presents with the findings shown (image). Which organism causes this presentation?
This is elephantiasis caused by Wuchereria bancrofti
159
Name the structure shown below from a patient with Entamoeba histolytica.
A trophozoite with engulfed RBCs in the cytoplasm (diagnosis: Entamoeba
histolytica Eats Erythrocytes)
160
A 40-year-old man has new-onset seizures and is found to have cystic brain lesions (image). What is the most likely diagnosis?
Neurocysticercosis (Taenia solium)
161
A patient presents with cough, gallstones, and abdominal pain. A microscopic fecal exam is shown (image). What organism is most likely responsible?
Ascaris lumbricoides (giant roundworm) characterized by "knobby-coated" eggs visible in feces under a microscope
162
What is the organism shown in the image?
Schistosoma mansoni (egg with lateral spine)
163
A blood smear is shown from a patient diagnosed with visceral leishmaniasis. Describe the findings.
Amastigotes within a macrophage
