Parasitology TYK 2

The absence of which of the following can help distinguish Babesia from Plasmodium?

-Malarial pigments (hemozoin) -Schüffner's dots -Maurer's dots

Giemsa stock solution is diluted with buffered water. The recommended pH is?

6.8

What is the diagnostic form for the Leishmania parasites?

Amastigotes

A 15-year-old boy spent most of the summer at the northern Minnesota family cabin on a lake in a densely wooded area. After returning to school in the fall, he was frequently tired and listless with periods of fever and chills. A blood sample taken at the physicians office revealed the following organism. The most likely identification is:

Babesia microti

A thin blood film from a patient with no travel history outside of the United States shows multiple delicate ring forms of a parasite. The most likely identification of this parasite is

Babesia microti

Which of the following parasites has been linked to splenectomized patients and transfusion transmission in the eastern United States?

Babesia spp.

Five members of a family develop a sudden onset of watery diarrhea, nausea, vomiting, headache, and cramps. They go to the family physician who orders fecal cultures and complete ova and parasites (O&P) analysis. Each sample reveals the presence of organisms about 5microns in size seen below. The most likely cause of the infection is:

Cryptosporidium parvum

Which of the following requires non traditional methods of stool concentration without the use of formalin fixative

Cyclospora

Oocysts of which of the following will autofluoresce in UV light microscopy ?

Cyclospora cayetenensis

What is the best anticoagulant to use for blood specimens for parasitology (venipuncture)?

EDTA

Which morphologic characteristic may help in distinguishing P. vivax from P. ovale?

Formation of merozoite rosettes

The testing method recommended for detection and diagnosis of Toxoplasma gondii is:

IgM ELISA

Which of the following is the vector known to transmit Babesia?

Ixodes

Oocysts of Cryptosporidium spp. can be detected in stool specimens using:

Modified acid-fast stain

Which of the following diseases is caused by the Leishmania braziliensis complex?

Mucocutaneous leishmaniasis

The infective stage for Toxoplasma gondii in humans is the:

Oocysts

Cryptosporidium parvum and Cyclospora cayetenensis can be differentiated on the basis of the following?

Oocysts of Cyclospora autofluoresce in UV microscopy and are larger that Cryptosporidium whose oocysts will not autofluoresce

A 27 year old female backpacker recently returned from Northern Thailand presents at a clinic with a high fever, nausea, vomiting and severe epigastric pain. Her doctor suspects malaria. The trophozoites shown below were seen on a Giemsa stained thin smear of her blood and were quite numerous. No other stages were observed. What species of Plasmodium is the most likely cause of the infection?

P. falciparum

Cerebral malaria is most commonly seen as a complication of:

P. falciparum

It is important to identify Babesia infections in blood smears as the parasites can mimic malarial infections. It is believed that several cases of babesiosis have been misdiagnosed as;

P. falciparum

The malarial parasite with the longest paroxysm time frame (periodicity) is:

P. malariae

Which species of Plasmodium is characterized by a rosette arrangement of merozoites and the presence of Schüffner's dots in the red blood cells?

P.ovale

A mature schizont is described as having 8 merozoites arranged around the excess malarial pigment and is seen in an infected RBC that is relatively small in size. The Plasmodium species is most probably which of the following:

Plasmodium malariae

Band-shaped trophozoites are characteristic of;

Plasmodium malariae

The high power photomicrograph is of a stained peripheral blood smear that includes two erythrocytes that are infected with malarial parasites. This infection commonly does not involve humans. Based on this microscopic observation, select the species identification from the multiple choices listed below.

Plasmodium ovale

A patient with fever every 48 hours is evaluated in the emergency room. The patient has a history of travel to Guatemala in the past month and did not take any preventive measures against malaria. An organism is seen inside the patients RBC that demonstrates single ring forms and other parasite stages in the cells, which are enlarged. The RBCs have Schuffner's dots and hemozoin pigment. This patient is mostly likely infected with:

Plasmodium vivax.

The main benefit of the thin blood film is

RBC morphology is preserved

What is the vector for the Leishmania braziliensis complex?

Sand fly

Which morphologic characteristic may help in distinguishing P. vivax from P. falciparum?

Schuffner's dots

What is the primary method of diagnosing toxoplasma gondii infection?

Serologically in blood samples

The following are diseases caused by the Leishmania species EXCEPT:

Sleeping sickness

The crescent-shaped actively proliferating trophozoite form of Toxoplasma gondii seen in early more acute infections are referred to as;

Tachyzoites

After returning from a 2-year stay in India, a patient has eosinophilia, an enlarged left spermatic cord, and bilateral inguinal lymphadenopathy. The most likely clinical specimen and organism match is:

Thick blood films—microfilariae

A young man returns to the US after a trip to Mt. Kilimanjaro in Africa. Although he has been compliant with his malarial prophylactic treatment, he develops a high fever, confusion, and lethargy. He is taken to the emergency room, where blood samples reveal a hemoflagellate organism in the routine blood smear. Considering this history, the most likely organism involved is:

Trypanosoma brucei

The disease commonly called West African sleeping sickness is caused by which of the following parasites?

Trypanosoma brucei gambiense

A young man from rural Brazil is visiting family in the United States when he becomes ill with muscle pains, high fever, and hepatosplenomegaly. A blood sample taken in the emergency room reveals the following organism. The most likely identification of this organism is:

Trypanosoma cruzi

What is the vector for Trypanosoma brucei gambiense?

Tsete fly

Mosquitoes serve as intermediate hosts and vectors for;

Wecheria bancrofti

A patient who just returned from Western Africa is suspected of having malaria. The patient has had fever episodes every 48 hours. To optimize the potential to detect the parasite, the next blood sample collected should be:

between paroxysms

The definitive host for Toxoplasma gondii is

cat

A patient who is known to have malaria may be treated with which of the following medications?

chloroquine

The main benefit of the thick blood film is

the volume of blood is larger than the thin blood film