Parasitic Infections, Bites and Stings Practice MCQs- DPAP Fall 2026

Which of the following best defines a parasite?

A. An organism that benefits both itself and its host

B. An organism that lives on or obtains nourishment at the expense of a host

C. A free-living microorganism

D. An organism that cannot infect humans

B. An organism that lives on or obtains nourishment at the expense of a host

Which parasite class consists of microscopic single-celled organisms?

A. Helminths

B. Ectoparasites

C. Protozoa

D. Arthropods

C. Protozoa

Which parasite class includes roundworms, flatworms, and thorny-headed worms?

A. Protozoa

B. Helminths

C. Ectoparasites

D. Arachnids

B. Helminths

Which statement about helminths is correct?

A. They are single-celled organisms.

B. They commonly multiply within humans.

C. They are multicellular organisms visible to the naked eye.

D. They are all transmitted by insects.

C. They are multicellular organisms visible to the naked eye.

Ectoparasites are best described as organisms that:

A. Live only in the intestinal tract

B. Burrow into or feed on the skin

C. Infect only animals

D. Cause disease exclusively by toxins

B. Burrow into or feed on the skin

Envenomation refers to:

A. Infection after a bite

B. Injection of toxic venom into tissue

C. Infestation by mites

D. Hypersensitivity to saliva

B. Injection of toxic venom into tissue

CRAB stands for:

A. Cutaneous Reaction to Arthropod Bite

B. Chronic Reaction After Bite

C. Cutaneous Rash After Bacteria

D. Chronic Rash from Arthropods and Bugs

A. Cutaneous Reaction to Arthropod Bite

Which component of CRAB refers to the visible bite mark?

A. Redness

B. Allergic reaction

C. Burning

D. Central punctum

D. Central punctum

In CRAB, the "A" represents:

A. Atrophy

B. Allergic reaction

C. Angioedema

D. Arthropod

B. Allergic reaction

Which lesion is most characteristic of many arthropod bite reactions?

A. Wheal

B. Comedone

C. Nodule

D. Plaque

A. Wheal

Which arthropod is classified as an arachnid?

A. Flea

B. Bedbug

C. Tick

D. Louse

C. Tick

Which of the following is considered an insect?

A. Tick

B. Spider

C. Bedbug

D. Mite

C. Bedbug

Tick bite granulomas may develop:

A. Only within hours

B. Days to months after a bite

C. Only years later

D. During active attachment only

B. Days to months after a bite

The most important management step after finding an attached tick is:

A. Apply topical steroids

B. Start antihistamines

C. Immediate complete removal

D. Cover with petroleum jelly

C. Immediate complete removal

Lyme disease in the United States is caused by:

A. Rickettsia rickettsii

B. Borrelia burgdorferi

C. Babesia microti

D. Ehrlichia chaffeensis

B. Borrelia burgdorferi

Which tick stage is the most common source of Lyme disease transmission?

A. Egg

B. Larva

C. Nymph

D. Adult male

C. Nymph

The hallmark skin lesion of early localized Lyme disease is:

A. Eschar

B. Erythema migrans

C. Petechiae

D. Wheal

B. Erythema migrans

Transmission of Lyme disease is uncommon when tick attachment is:

A. Less than 48 hours

B. Less than 72 hours

C. Less than 1 week

D. Less than 10 days

A. Less than 48 hours

Which medication is commonly used to treat early Lyme disease?

A. Fluconazole

B. Acyclovir

C. Doxycycline

D. Clindamycin

C. Doxycycline

Rocky Mountain spotted fever is caused by:

A. Borrelia burgdorferi

B. Rickettsia rickettsii

C. Sarcoptes scabiei

D. Pulex irritans

B. Rickettsia rickettsii

The rash of Rocky Mountain spotted fever classically begins on the:

A. Trunk

B. Face

C. Wrists and ankles

D. Chest

C. Wrists and ankles

Which areas may be involved by the RMSF rash?

A. Palms and soles

B. Eyelids only

C. Scalp only

D. Back only

A. Palms and soles

If Rocky Mountain spotted fever is suspected, treatment should include:

A. Amoxicillin

B. Doxycycline

C. Permethrin

D. Ivermectin

B. Doxycycline

Flea bites are typically described as:

A. Painful ulcers

B. Grouped pruritic lesions

C. Dermatomal vesicles

D. Burrows

B. Grouped pruritic lesions

Flea bites commonly occur on the:

A. Face and scalp

B. Arms and shoulders

C. Legs and waist

D. Palms and soles

C. Legs and waist

A characteristic pattern of flea bites is:

A. Dermatomal

B. Reticular

C. Zig-zag

D. Annular

C. Zig-zag

Treatment of flea bites often includes:

A. Oral antihistamines

B. Oral antivirals

C. Oral antifungals

D. Isotretinoin

A. Oral antihistamines

Chigger bites occur most commonly during:

A. Winter

B. Spring only

C. Summer and fall

D. Early spring

C. Summer and fall

Chiggers most commonly affect areas such as the:

A. Fingertips

B. Legs and belt line

C. Face and scalp

D. Palms

B. Legs and belt line

Which statement about chiggers is correct?

A. They burrow deeply into skin

B. They transmit Lyme disease

C. They do not burrow

D. They are lice

C. They do not burrow

Chigger bites are characteristically:

A. Painless

B. Severely pruritic

C. Non-inflammatory

D. Vesicular only

B. Severely pruritic

Bedbugs are most likely to hide in:

A. Swimming pools

B. Carpets only

C. Mattresses and box springs

D. Soil

C. Mattresses and box springs

Bedbug bites classically occur in what pattern?

A. Targetoid

B. Linear "breakfast, lunch, dinner"

C. Dermatomal

D. Reticular

B. Linear "breakfast, lunch, dinner"

Which treatment is important in bedbug infestation?

A. Oral antibiotics for everyone

B. Eradication of infestation

C. Oral antifungals

D. Cryotherapy

B. Eradication of infestation

Pediculosis capitis is most common in:

A. Newborns

B. Elderly adults

C. Children

D. Immunocompromised adults

C. Children

Head lice are most commonly spread through:

A. Food contamination

B. Head-to-head contact

C. Water exposure

D. Tick bites

B. Head-to-head contact

Which finding strongly supports pediculosis capitis?

A. Nits firmly attached to hair shafts

B. Burrows

C. Eschars

D. Pustules

A. Nits firmly attached to hair shafts

First-line therapy for pediculosis capitis is:

A. Lindane

B. Oral ivermectin

C. Permethrin 1%

D. Fluconazole

C. Permethrin 1%

Which treatment should generally be avoided because of neurotoxicity?

A. Spinosad

B. Malathion

C. Lindane

D. Permethrin

C. Lindane

Body lice typically lay eggs:

A. On scalp hair

B. In clothing seams

C. On eyelashes

D. In the epidermis

B. In clothing seams

Pediculosis corporis is especially associated with:

A. Swimmers

B. Children in daycare

C. Unhoused populations

D. Gardeners

C. Unhoused populations

Which finding is characteristic of pediculosis pubis?

A. Burrows

B. Maculae cerulea

C. Herald patch

D. Exclamation-point hairs

B. Maculae cerulea

Pediculosis pubis is most commonly transmitted through:

A. Tick exposure

B. Mosquitoes

C. Sexual contact

D. Soil

C. Sexual contact

Scabies is caused by:

A. Ixodes tick

B. Sarcoptes scabiei var. hominis

C. Cimex lectularius

D. Pulex irritans

B. Sarcoptes scabiei var. hominis

The hallmark symptom of scabies is:

A. Pain

B. Burning

C. Intense nocturnal pruritus

D. Fever

C. Intense nocturnal pruritus

Which lesion is most characteristic of scabies?

A. Burrow

B. Comedone

C. Telangiectasia

D. Vesicle only

A. Burrow

Which location is commonly affected by scabies?

A. Finger webs

B. Nose

C. Upper back only

D. Scalp in healthy adults

A. Finger webs

Microscopic examination with mineral oil preparation may reveal all EXCEPT:

A. Mites

B. Eggs

C. Scybala

D. Spirochetes

D. Spirochetes

First-line treatment for scabies includes:

A. Permethrin 5% cream

B. Topical acyclovir

C. Clindamycin

D. Doxycycline

A. Permethrin 5% cream

Which sequence best describes the evolution of a fire ant sting?

A. Wheal → pustule → crust → vesicle

B. Vesicle → ulcer → scar

C. Erythema → wheal → vesicle → pustule → crust

D. Papule → burrow → plaque

C. Erythema → wheal → vesicle → pustule → crust