Assessment Exam 2 Rationale Flashcards by Miguel Acosta

The primary site of infection with Entameoba histolytica in humans is the

a. skin
b. duodenum
c. cecum and colon
d. liver
e. pericardium

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The one species among the following that is associated with anemia is

a. Strongyloides stercoralis
b. Diphyllobothrium latum
c. Ancylostoma duodenale
d. Trichuris trichiura
e. all of the above

c - IDA

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A skin biopsy taken from the lesion of an individual with mucocutaneous leishmaniasis is most likely to show

a. flagellated promastigotes in polymorphonuclear neutrophils
b. schizonts
c. amastigotes undergoing binary fission
d. eosinophilic granuloma formation
e. extensive tissue necrosis with only rare protozoan forms

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Which statement is true concerning molecular-based paternity testing?

a. Paternity testing is typically performed using VNTR loci in the mother, child and alleged father

b. Single mismatch between an allele in the child (that must have come from the father of the child) and the alleged father is sufficient to exclude the alleged father

c. Match between the alleged father and the child at a rare allele carries less weight in paternity than does a match involving a higher frequency allele

d. Paternity index is calculated for the alleged father using all loci tested, even if one of the loci does not directly match the child.

1-2 mismatches allowed

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A cestode that competes with its definitive host for dietary vitamin B12 is

a. Taenia saginata
b. Taenia solium
c. Diphyllobothrium latum
d. Hymenolepsis nana
e. Echinococcus granulosus

Dibothriocephakus latus new name

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Which organism is associated with blood in the urine and chronic urinary tract obstructions?

a. Schistosoma mansoni
b. Schistosoma haematobium
c. Schistosoma japonicum
d. Dracunculus medinensis
e. Paragonimus westermani

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The developmental form of Leishmania transmitted to humans is the

a. trypomastigote
b. epimastigote
c. promastigote
d. amastigote
e. nomastigote

The infective stage

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Ingestion of ova followed by larval migration to the lung characterizes the life cycle of

a. Strongyloides stercoralis
b. Ancylostoma duodenale
c. Wuchereria bancrofti
d. Ascaris lumbricoides
e. Necator americanus

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The adult stage of the cestode life cycle does NOT take place in humans infected with

a. Taenia saginata
b. Taenia solium
c. Diphyllobothrium latum
d. Echinococcus granulosus
e. none of the above

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Natural resistance to malaria caused by Plasmodium vivax has been demonstrated in populations who are

a. blood group antigen-positive
b. glycophorin A-positive
c. glucose-6-phosphate dehydrogenase-deficient
d. Duffy blood group antigen-negative
e. none of the above

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Diagnosis can usually be established by examination of the stool in persons infected with

a. Ascaris lumbricoides
b. Strongyloides stercoralis
c. Taenia saginata
d. Schistosoma mansoni
e. all of the above

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Coccidian protozoan restricted to production of intestinal disease and especially in acquired immunodeficiency syndrome patients

a. Toxoplasma gondii
b. Trypanosoma cruzi
c. Naegleria fowleri
d. Cryptosporidium
e. Plasmodium falciparum

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Generally, humans are infected by eating raw beef.

a. Wuchereria bancrofti
b. Onchocerca volvulus
c. Taenia saginata
d. Hymenolepsis nana

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Adult parasites are usually in the parenchyma of the human lung

a. Necator americanus
b. Taenia solium
c. Clonorchis sinensis
d. Paragonimus westermani

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Entamoeba histolytica.

a. sporozoan intestinal disease in acquired immunodeficiency syndrome patients

b. interstitial pneumonitis in an immunosuppressed patient

c. fulminant hemorrhagic meningoencephalitis acquired during swimming

d. flatulent diarrhea after travel to Moscow

e. hepatic abscess

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Over the past 3 months a 12-year-old boy heated home made pork sausage lightly and had it for dinner on many occasions. Now he has developed periorbital eosinophilia and severe muscular pains.

a. Wuchereria bancrofti
b. Trichinella spiralis
c. Plasmodium malariae
d. Enterobius vermicularis
e. Entamoeba coli

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Members of the genus Babesia are sporozoan parasites of the red blood cell that have recently been found to cause human infections. Infection usually results in a febrile illness associated with hemolysis. Humans become infected from

a. ticks
b. mosquitoes
c. fleas
d. mites
e. none of the above

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Assuming that a variety of microorganisms might cause pneumonia in AIDS patients, which of the following combination of stains would optimally differentiate the major causes of the pneumonia if a piece of lung tissue was available?

a. Gram’s stain and methylene blue stain
b. Direct fluorescent antibody stain and acid-fast stain
c. Acid-fast stain and Albert’s stain
d. Methylene blue and calcifluor white stain
e. Lactophenol cotton blue and Giemsa’s stain

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The diagnostic characteristics of Plasmodium falciparum are best described by which one of the following statements?

a. A period of 72 h is required for the development of the mature schizont, which resembles a rosette with only 8 to 10 oval merozoites

b. An important diagnostic feature is the irregular appearance of the edges of the infected red blood cell

c. The signet-ring-shaped trophozoite is irregular in shape with ameboid extensions of the cytoplasm

d. Except in infections with very high parasitemia, only ring forms of early trophozoites and the gametocytes are seen in the peripheral blood

e. Schuffner stippling is routinely seen in red blood cells that harbor parasites

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Which of the following techniques is employed most successfully for recovering pinworm eggs?

a. Sugar fecal flotation
b. Zinc-sulfate fecal flotation
c. Tap-water fecal sedimentation
d. Direct fecal centrifugal flotation
e. Anal swabbing with cellophane tape

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A man coughed up a long (4 to 6 cm) white worm and his chief complaint is abdominal tenderness. He reports that he goes to sushi bars at least once a week. The following parasites have been observed in people who eat raw fish: Anisakis, Pseudoterranova, Eustrongylus, and Angiostrongylus. Which of the following would best differentiate the specific parasitic agent?

a. Identification of specific species of fish involved
b. Study of distinctive morphology of the parasite
c. Specific antibody tests
d. Antigen detection in tissues
e. Characteristic signs and symptoms

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In the United States, certain enteric protozoan and helminthic infections were previously considered to be exotic illnesses related to foreign travel or to contaminated food or water. However, sexual transmission of these diseases has produced a “hyperendemic” infection rate among male homosexuals. The most common infection seen in this group is

a. giardiasis
b. ascariasis
c. amoebiasis
d. enterobiasis
e. trichiuriasis

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An AIDS patient complains of headaches and disorientation. A clinical diagnosis of Toxoplasma encephalitis is made. Which one of the following antibody results would be most likely in this patient?

a. IgM nonreactive, IgG nonreactive
b. IgM nonreactive, IgG reactive (low titer)
c. IgM reactive (low titer), IgG reactive (high titer)
d. IgM reactive (high titer), IgG reactive (high titer)
e. IgM reactive (high titer), IgG nonreactive

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Trypanosoma cruzi initially penetrates through the mucuous membranes on the skin and then multiples in a lesion known as a chagoma. In the chronic stage of the disease, the main lesions are often observed in the

a. spleen and pancrease
b. heart and digestive tract
c. liver and spleen
d. digestive tract and respiratory tract
e. heart and liver

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A woman recently returned from Africa complains of having paroxysmal attacks of chills, fever, and sweating; these attacks last a day or two at a time and recur every 36 to 48 h. Examination of a stained blood specimen reveals ringlike and crescentlike forms within red blood cells. The infecting organism most likely is a. Plasmodium falciparum b. Plasmodium vivax c. Trypanosoma gambiense d. Wuchereria bancrofti e. Schistosoma mansoni

There are five varieties of cockroaches; the German cockroach, the brown-handed cockroach, the oriental cockroach, theAmerican cockroach, and the smoky brown cockroach. A characteristic of cockroaches is their a. Transmission of Salmonella b. toxic sting c. function as a vector for Borrelia burgdorferi d. function as a secondary host for rickettsiae e. easy eradication

a And Ascaris / other enteric organisms

A medical technologist visited Scandinavia and consumed raw fish daily for 2 weeks. Six months after her return home, she had a routine physical and was found to be anemic. Her vitamin B12 levels were below normal. The most likely cause of her vitamin B12 deficiency anemia is a. excessive consumption of ice-cold vodka b. infection with parvovirus B19 c. infection with the fish tapeworm Diphyllobothrium latum d. nfection with Yersinia e. cysticercosis

Scabies is caused by a small mite that burrows into the skin. The disease is described by all the following statements EXCEPT a. it is caused by a species of Sarcoptes b. it is often complicated by secondary bacterial infection c. it is synonymous with Kawasaki syndrome d. it is best diagnosed by morphological identification of the mite e. allergic (asthmalike) reactions to mites are often reported

Schistosomiasis is a disease characterized by granulomatous reactions to the ova or to products of the parasite at the place of oviposition. Clinical manifestations include all the following EXCEPT: a. calcifications in the bladder wall b. pulmonary arterial hypertension c. splenomegaly d. splenomegaly e. arthropathies

Microscporidia are spore-forming, obligate, intracellular parasites. All of the following statements about microsporidia are true EXCEPT: a. there are four genera of microsporidia b. microsporidia have been detected only in patients with AIDS c. Microsporidia can be observed in stool specimens by the use of special stains d. Microscoporidia are found in a variety of vertebrate and invertebrate hosts e. A serologic test is available for microsporidia

Giardia lamblia a. Sigmoidoscopy and aspiration of mucosal lesions b. Baermann technique c. Dilution followed by egg count d. Enzyme immunoassay (EIA) e. Examination of a cellophane tape swab

A fur trapper complains of sore muscles, has swollen eyes, and reports eating bear meat on a regular basis a. Trichinosis b. Schistosomiasis c. Toxoplasmosis d. Visceral larva migrans e. Giardiasis

Amoebae that inhabit the gastrointestinal tract of man have which stage that is nonmotile, nonfeeding and infective? a. pseudopod b. cyst c. trophozoite d. cryptozoite

A retired Air Force colonel has had abdominal pain for 2 years; he makes yearly freshwater fishing trips to Puerto Rico and often wades with bare feet into streams a. Trichinosis b. Schistosomiasis c. Toxoplasmosis e. d. Visceral larva migrans e.Giardiasis

Strongyloides larvae a. Sigmoidoscopy and aspiration of mucosal lesions b. Baermann technique c. Dilution followed by egg count d. Enzyme immunoassay (EIA) e, Examination of a cellophane tape swab

A protozoan with characteristic jerky motility can be found in: a. Vaginal secretions b. Duodenal content c. Blood d. Biopsied muscle e. Sputum

A tissue dwelling trematode that may be found in feces can also be found in which of the following specimen: a. Vaginal secretions b. Duodenal contents c. Blood d. Biopsied muscle e. Sputum

A parasite that infects both animals and humans and is carried by the same tick that transmits Borrelia burgdorferi, the bacterium that causes Lyme disease can be isolated from which of the following samples? a. Vaginal secretions b. Duodenal contents c. Blood d. Biopsied muscle e. Sputum

The eggs of this tapeworm have an operculum at one end and a small abopercular knob at the other. The eggs are undeveloped a. Diphyllobothrium b. Dipylidium c. Paragonimus d. Hymenolepis

Which of the following is a true ameba? a. Endolimax nana b. Entamoeba hartmanni c. Dientamoeba fragilis d. Iodamoeba butschlii

Either B (True) or C (Flagellate)

The mature cyst of Entamoeba histolytica has how many nuclei? a. one b. two c. four d. more than four

Fine even peripheral nuclear chromatin is characteristic of which of these amoebae? a. Entamoeba coli and Endolimax nana b. Entamoeba hartmanni and Entamoeba histolytica c. Entamoeba polecki and Entamoeba coli d. Iodamoeba butschlii and Endolimax nana

A cyst is described as 8 microns in diameter, oval, with four large blot-like karyosomal chromatin masses outlined by clear spaces. What amebic cyst does this describe? a. Entamoeba polecki b. Dientamoeba fragilis c. Endolimax nana d. Iodamoeba butschlii

A cyst that possesses a single nucleus and a large glycogen vaucole staining deeply with iodine belongs to a. Endolimax nana b. Iodamoeba butschlii c. Dientamoeba fragilis d. Entamoeba coli

A soil and water amoebae isolated from cases of meningoencephalitis is usually a. Naegleria b. Dientamoeba fragilis c. Isospora belli d. all of the above

Which of the following organisms demonstrates an amoebaflagellate stage? a. Acanthamoeba b. Dientamoeba c. Entamoeba d. Naegleria

Infections with Dientamoeba fragilis can show which of the following symptoms? a. Diarrhea b. abdominal discomfort without diarrhea c. asymptomatic d. all of the above

Which flagellate can be a pathogen of the small intestine? a. Giardia b. Trichomonas c. Chilomastix d. Strongyloides

Red and white blood cells in stool specimens are characteristic of a. meningoencephalitis b. bacillary dysentery c. giardiasis d. none of the above

In what type of specimen can the atrial flagella survive? a. stool b. vaginal secretion c. blood d. spinal fluid

A pear-shaped flagellate with jerk motility, found in a urine specimen, is identified as a. Trichomonas hominis b. Trichomonas vaginalis c. Escherichia coli d. Leptospira

The only bilaterally symmetrical protozoan is a. Trichomonas b. Dientamoeba c. Giardia d. Balantidium

Chagas’ disease a. is caused by Trypanosoma cruzi b. is characterized by C-shape trapanosomes in blood c. affects the cardiac muscle d. all of the above

African sleeping sickness is caused by Trypanosoma a. cruzi b. gambiense c. rhodesiense d. b and c

Which of the following is found within the reticuloendothelial cells? a. Leishmania donovani b. Histoplasma capsulatum c. Toxoplasma gondii d. ll of these can be found in the R-E cells

A Chagoma is a lesion in infections with a. Trypanosoma gambiense b. . Trichomonas vaginalis c. Trichuris trichiura d. Trypanosoma cruzi

In the laboratory diagnosis of Leishmania donovani what is the preferred specimen in which to find Leishman-donovan bodies? a. bone marrow b. blood c. vaginal secretion d. cerebrospinal fluid

Which of the following structures are used for motility of Balantidium coli? a. flagella b. cilia c. pseudopodia d. undulating membrane

Which of the malarial organisms preferentially invades reticulocytes? a. P. falciparum b. P. malariae c. P. vivax d. all of the above

Which malarial organism characteristically has a band form trophozoite stretching across the red cell? a. P. malariae b. P. ovale c. P. vivax d. P. falciparum

Which malarial organism features ring trophozoites that have double chromatin dots, applique forms, and often have multiple parasites in the infected red cells? a. P. vivax b. P. falciparum c. P. malariae d. P. ovale

In which type of malaria is there synchronized rupture of the red blood cells every 72 hours? a. P. vivax b. P. falciparum c. P. ovale d. P. malariae

Which hemoglobin is incompatible with malaria parasite survival? a. Hb – CC b. Hb – F c. Hb – SS d. Hb – A

Man becomes infected with Babesia by a. mosquito – Mansoni b. oocyst in feces c. pseudocysts in tissue d. tick – Ixodes

What is both the definitive and intermediate host of Toxoplasma gondii? a. dog b. cattle c. cat d. poultry

What constitutes a positive result in the Sabin-Feldman dye test? a. Toxoplasma becomes nonmotile b. Toxoplasma can no longer be demonstrated as an intracellular organism c. Toxoplasma loses its affinity for methylene blue d. The mouse into which the immune serum is injected does not die from toxoplasmosis

Infective oocysts of Isospora belli contain(s) a. sporozoites b. tachyzoites c. pseudocysts d. a sporoblast

Eggs that average 60 microns in length, are oval with one flattened side, and contain a motile larva, are those of a. Enterobius b. Taenia c. Ascaris d. hookworm

The best way to demonstrate a pinworm infection is by which technique? a. Rectal biopsy b. Third portion of urine volume c. Scotch (cellophane) tape preparation d. flotation

The Helminth egg that is most resistant to changes in moisture and temperature is that of a. Enterobius b. Ascaris c. Taenia d. hookworm

Muscle biopsy is a diagnostic technic employed to detect a. trichinosis b. taeniasis c. trichuriasis d. ascariasis

A roundworm that inhabits the small intestine, and usually is demonstrated a larvae in the fecal specimen, is a. hookworm b. Ascaris c. Trichinella d. Strongyloides

One of the differential characteristics of the microfilariae is a. the number of somatic nuclei b. the presence or absence of a sheath c. the presence or absence of a dorsal curvature of the posterior end d. the presence or absence of a hexacanth embryo

Which microfilaria causes a severe eye disease and is seen as a sheathed larva with terminal nuclei? a. Brugia b. Wuchereria c. Loa d. Dracunculus

A Hexacanth embryo is enclosed in a radially striated shell this egg belongs to the genus a. Trichuris b. Taenia c. Trichostrongylus d. Trichinella

During the G2 phase of the cell cycle, the DNA content of a cell is a. Haploid b. Diploid c. Triploid d. Tetraploid

Which is considered an epigenetic modification of DNA? a. A transversion of an A nucleotide to a T in an exon of a gene b. A transition of an A to a G in an intron of a gene c. Methylation of CpG islands in the promoter region of a gene d. Insertion of a nucleotide into the coding region of a gene

Reverse transcriptase would best be described as a: a. DNA-dependent DNA polymerase b. DNA-dependent RNA polymerase c. RNA-dependent DNA polymerase d. RNA-dependent RNA polymerase

The term that best describes males regarding X-linked genes is: a. Heterozygous b. Homozygous c. Haplozygous d. Hemizygous

Which statement concerning the resolution of DNA on an agarose gel is true? a. The polymerization of agarose is initiated by adding TEMED and ammonium persulfate to agarose monomer in solution. b. Agarose gel electrophoresis can resolve smaller molecules of DNA compared to acrylamide gel electrophoresis c. As the concentration of agarose in the gel increases, the smaller the size of DNA that can be resolved on the gel. d. DNA must be denatured before being loaded into the sample wells of an agarose gel

The methodology of performing a reverse dot blot is best described as: a. Attaching many patient DNA samples to a nitrocellulose membrane and hybridizing the patient samples with a single labeled probe b. Attaching multiple patient samples to a nitrocellulose membrane and hybridizing multiple labeled probes to the patient samples c. Attaching multiple labeled probes to a nitrocellulose membrane and hybridizing a patient sample to the multiple labeled probes d. Attaching multiple probes to a nitrocellulose membrane and then hybridizing a single labeled patient sample to the multiple probes

The Klenow fragment of E coli DNA polymerase I is used: a. To make cDNA from an RNA template b. To label DNA probes by random primer labeling c. In quantitative real time PCR d. To label a DNA probe by nick translation

Which probe is most often used to detect trisomy 21 by interphase FISH? a. Locus-specific probe b. Alpha satellite DNA probe c. Chromosome paint probe d. Spectral karyotyping probe

Chelex® 100 resin is used to: a. Purify mRNA from total RNA b. Extract total RNA from cells c. Extract DNA from cells d. Remove unincorporated primers from PCR reactions prior to gel analysis of PCR products

Which statement is true concerning the analysis of short tandem repeats (str)? a. Str are detected by RT-PCR b. Str alleles are determined by Southern blotting c. Str alleles are determined by PCT product size d. Str analysis requires that high molecular weight genomic DNA be available in samples to be tested

A PCR reaction in which 4 different sets of primers are used to simultaneously amplify 4 distinct loci in the same reaction tube is known as a: a. Multiplex PCR reaction b. Heteroplex PCR reaction c. Polyplex PCR reaction d. Quadraplex PCR reaction

Denaturation of DNA during a PCR reaction refers to breaking a. Hydrogen bonds between nitrogenous bases in base-paired nucleotides b. Phosphodiester bonds between nitrogenous bases in base-paired nucleotides c. Covalent bonds between nitrogenous bases in base-paired nucleotides d. Peptide bonds between nitrogenous bases in base-paired nucleotides

When quantifying the amount of genomic DNA in a sample by spectrophotometry, an OD 260 of 1.0 corresponds to what concentration of DNA? a. 10 μg/mL b. 20 μg/mL c. 50 μg/mL d. 100 μg/mL

Probes are often used during real time PCR to quantitate the formation of specific amplicons during the reaction. Which system involves the use of 2 distinct probes to generate a fluorescent signal? a. TaqMan® b. Molecular beacon c. FRET d. Scorpion™

What is the purpose of the enzyme uracil-N-glycolase in a molecular diagnostics laboratory? a. Comparative genome hybridization b. Allele-specific PCR c. Real time PCR d. Single-strand conformational polymorphism

Choices to the 91 in AE 1

What is the best method to rule out the possibility of genomic DNA giving a false-positive result in an RT-PCR reaction? a. Use of upstream and downstream primers that span an exon-intron-exon region of the target b. Treatment of RNA that will be used in the RT reaction with RNase c. Addition of uracil-N-glycolase to the RT reaction d. Omission of Taq DNA polymerase from the PCR reaction

A common use for pulsed-field gel electrophoresis is: a. DNA fingerprinting b. Mitochondrial DNA typing d. Tumor cell phenotyping c. Epidemiological typing of bacterial strains d. d. Tumor cell phenotyping

A human actin gene may be used as an amplification control when performing PCR testing for Mycoplasma pneumonia in a bronchoalveolar lavage taken from a human patient. The type of amplification control is described as: a. Homologous extrinsic b. Homologous intrinsic c. Heterologous extrinsic d. Heterologous intrinsic

DNA-based testing for the presence of MRSA uses PCR with primers specific for which gene? a. vanA b. inhA c. mecA d. rpoB

The molecular-based diagnostic test for Mycobacterium tuberculosis uses ribosomal RNA as the target. Primers are made to be specific for which RNA subunit? a. 5.8S b. 16S c. 18S d. 28S

After performing interphase FISH with X chromosome-specific and Y chromosome-specific alpha satellite probes, it is determined that nuclei in cells from your phenotypic female exhibit only 1 bright fluorescent spot with the X chromosome-specific probe and do not react at all with the Y-specific probe. Assuming all controls have worked correctly, what is the most likely diagnosis for this patient? a. Patient is a genetically normal female b. Patient is a female with Turner syndrome c. Patient is a female with fragile X syndrome d. Patient is a male who suffers from androgen insensitivity syndrome due to the lack of a Y chromosome

A molecular-based test commonly used in testing donors and recipients prior to organ transplantations is: a. Sequence-specific PCR b. Allele-specific PCR c. Real time PCR d. Reverse transcriptase PCT

DNA sequencing of hypervariable regions I and II is used to: a. Detect polymorphisms in human TP53 b. Genotype strains of Mycoplasma c. To monitor chemotherapy for B cell lymphoma d. Detection of polymorphisms in human mitochondrial DNA

An 18-month-old child passed a “big worm” that resembles an earthworm. The most likely diagnosis is that it is a. Trichuris trichiura b. Enterobius vermicularis c. Ascaris lumbricoides d. Strongyloides stercoralis e. Necator americanus

The life cycle of all clinically important flukes involves some species of a. reduviid bug b. mosquito c. microcrustacean d. snail e. tsetse fly