Parasitology

Question 1

Patient presents with foul smelling diarrhea. History reveals he was out camping and he and his buddies decided to try and sanitize their own water from a nearby stream. He shows you pictures from the trip that include beavers building a dam. What would do to confirm diagnosis of the suspected culprit and how is it treated?

Answer 1

Giardia lamblia
-trophozoites or cysts in stool

Tx: Metronidazole (MOA thought to produce excessive free radicals in parasites leading to death)

Question 2

A patient presents with bloody diarrhea and RUQ pain. Treatment with standard beta lactam antibiotics is ineffective and a biopsy of the liver shows a flask shaped ulcer formation. Serology shows trophozoites in the stool. What is the treatment?

Answer 2

Entamoeba histolytica

Tx: Metronidazole and Iodoquinol

Question 3

A patient presents with severe watery diarrhea. His CD4 count is less than 200 now and he is diagnosed with AIDS. What is the best way to diagnose and best treatment for the most common causative agent?

Answer 3

Cryptosporidium
Dx: Acid fast oocysts
Tx: Nitazoxanide

Question 4

Patient presents with chorioretiniits, hydrocephalus, and X ray shows intracranial calcifications. What is the best treatment?

Answer 4

Toxoplasma gondii

Tx: Sulfadiazine + Pyrimethamine

Question 5

Patient presents with irritability and altered mental status. He reports that “things don’t smell right”. He expires a few hours after admission. What would be revealed in the CSF?

Answer 5

Naegleria fowleri

-amoebas in CSF, no effective Tx

Question 6

An immigrant from Africa presents with intense somnolence and enlarged lymph nodes. He slips into an unarousable coma an hour after admission. What is the mode of transmission of the most likely causative agent and its treatment?

Answer 6

Trypanosoma brucei (African Sleeping Sickness)
-Tsetse fly bite
Tx: Suramin or Melarsoprol

Question 7

Patient presents with fever, headache, anemia, and splenomegaly. History reveals that he returned from a trip to Africa 7 months ago and had similar symptoms then but cannot remember what they gave to treat him, but it was effective. What is the best course of action for this case?

Answer 7

Plasmodium vivax
-malaria that is sequestered in the liver
Tx: chloroquine (for circulating malaria) + primaquine (for the dormant hypnozoite form in liver)

Question 8

Patient presents with intense fever. Blood smear indicates a hemolytic anemia with a maltese cross shape visible in RBCs. What is the mode of transmission and the treatment?

Answer 8

Bebesia microti
-Ixodes tick bite
Tx: quinine, clindamycin

Question 9

Patient presents with difficulty swallowing and constipation. Barium swallow reveals “bird beak sign”. What is the mode of transmission and treatment?

Answer 9

Trypanosomi cruzi (Chagas disease)
-Reduviid Bug
Tx: Nifurtimox

Question 10

Patient presents with spiking fevers and hepatosplenomegaly. CBC reveals pancytopenia and blood smear reveals amastigotes in macrophages. What is the mode of transmission and treatment?

Answer 10

Leishmania donovani
-Sandfly
Tx: Sodium Stibogluconate

Question 11

Patient presents with anal pruritis. What test would confirm diagnosis and what is the treatment?

Answer 11

Enterobius vermicularis (pinworm)
-scotch tape prep
Tx: mebendazole or pyrantel pamoate

Question 12

Patient presents with a funny feeling around the anus. visual exam notes sizable worms exiting the anal canal. What is the treamtne t for this condition?

Answer 12

Ascaris lumbricoides (giant roundworm)
Tx: mebendazole or pyrantel pamoate

Question 13

Patient presents with terrible muscle aches and periorbital edema. What is the treatment?

Answer 13

Trichinella sprialis
-cysts end up in muscle fibers
Tx: mebendazole

Question 14

Patient presents with vomiting and diarrhea. CBC reveals normochromic anemia. What is the treatment?

Answer 14

Strongyloides Stercoralis

Tx: mebendazole or ivermectin

Question 15

Patient presents with abdominal pain and anemia. History reveals he runs barefoot on the beach every morning. What is the treatment?

Answer 15

Ancylostoma duodenale or Necator americanus (hookworms)

Tx: mebendazole or pyrantel pamoate

Question 16

Patient presents with terrible skin ulceration and inflammation. Regular antibiotics and antifungals do not alleviate the rash and topical steroids make the condition worse. What is the next step of treatment?

Answer 16

Dracunculus medinensis

Tx: niridazole

Question 17

Patient presents with progressively worsening vision. PE reveals dark nodules on the skin of the arms and face. What is the mode of transmission and the treatment?

Answer 17

Onchocerca volvulus (African river blindness)
-black flies
Tx: Ivermectin

Question 18

Patient presents with orbital pain and vision changes. PE reveals a worm crawling thru the conjunctiva. What is the treatment?

Answer 18

Loa loa

Tx: diethylcarbamazine

Question 19

Patient presents with progressively enlarged right leg. Diagnosis of elephantiasis is made. What is the pathogenesis and treatment?

Answer 19

Wuchereria bancrofti
-worms invade lymphatic channels and block them
Tx: diethylcarbamazine

Question 20

Patient presents with progressively worsening headaches. History reveals he had a rare-cooked pork chop earlier in the week that gave him an upset stomach. MRI reveals Swiss cheese appearance of the brain. What is the treatment?

Answer 20

Taenia solium (pork tapeworm)
Tx: mebendazole (for neurocysticercosis)
-if cysts aren’t in the brain use praziquantel

Question 21

Patient presents with irritability and mood swings. He also reports being very fatigued and appears pale. CBC reveals megaloblastic anemia. History reveals he likes to eat freshwater fish. What is treatment?

Answer 21

Diphyllobothrium latum (fish tapeworm)
-depletes B12 vitamin store
Tx: praziquantel

Question 22

Patient presents with hepatosplenomegaly along with hematuria. Liver biopsy reveals granuloma and fibrosis formation. What is a risk of chronic infection with this agent?

Answer 22

Schistosoma hematobium
-squamous cell carcinoma of the bladder
Tx: praziquantel

Question 23

Patient presents with cough that produces rust colored sputum. Sputum culture reveals only normal flora and not gram (+) cocci. What is the treatment for the causative agent?

Answer 23

Paragonimus westermani
-undercooked crab meat, migrates to the lungs causing secondary bacterial infection leading to hemoptysis
Tx: praziquantel