Parasitology Exam 1

What are the three ways that organisms generally interact?

Predation, Competition, Symbiosis

Parasites are

Symbiotes

Symbiosis

When two dissimilar organisms live together in more or less intimate association or close union

Mutualism

An interaction between two organisms where each species benefits

Commensalism

An interaction between two orgnisms where one benefits and the other neither benefits nor is harmed

Parasitism

An interaction between two organisms where one benefits and the other is harmed in some way.

Definitive Host

A host that supports the adult or sexually active stage of a parasite.

This is necessary for parasite survive and completion of the life cycle.

Intermediate Host

A host that supports the immature or non-sexual reproductive forms of a parasite.

There can be asexual reproduction.

This stage is necessary for parasite survival and life cycle completion

Not all parasites have this kind of host

Transfer Host

A host that can move or relocate parasite stages from one location to another (most often in reproductive stages such as eggs)

Insects such as flies and cockroaches are good transfer hosts.

Vector Host

A host that acts as a definitive or intermediate host and can also transfer that host

e.g. mosquito and malaria, flies and African sleeping sickness

Reservoir Host

A host that serves as a source of infection and potential reinfection of humans

Acts as a means of sustaining a parasite within a population and ecosystem

Exposure

When someone comes into contact with an infectious organism

Colonization

When an infectious agent is present in or on a body surface without causing infection in the person

Infection

When infectious agents invade and grow in/on the body

Sign

When any objective evidence of a disease can be observed by others

Quantitative

Symptom

When a subjective evidence is observed by the patient

Qualitative

Incubation Period

The time between exposure to an infection and the appearance of the first signs and symptoms

Latency

The time it takes from infection to become infectious

Disease

When the cells in your body are damaged as a result of infection

What are the three virulence factors that influence disease and pathogenicity?

Infectivity

Invasiveness

Pathogenicity

Infectivity

The ability of an organism to establish an infection

Invasiveness

Ability of an organism to spread to adjacent or distant tissues

Pathogenicity

The ability to produce substances that damage tissues

T/F: Most parasites feed on the food you ingest

False

Hookworms go through ____ micro liters of blood per day (population size does matter)

A. 350

B. 400

C. 250

D. 300

C. 250

Lytic Necrosis feeders

Digest tissue of host

e.g. entamoeba hystolytica

Traumatic damage

mechanical damage to host tissue

e.g. hookworm

Obstruction of Lumens

Blockage of tubes within the body

Penetration of host tissues

Ascaris lumbricoides and E. histolytica

Common intestinal nematodes inefective in egg state

Pinworm

Whipworm

Giant Roundworm

Pinworm scientific name

Enterobius vermicularis

Whipworm scientific name

Trichuris trichura

Giant Roundworm scientific name

Ascaris lumbricoides

T/F: Pinworm will normally migrate to the female genitalia and appendix

False

T/F: Pinworm has both direct and indirect transmission

True

Direct Pinworm Trasmission

Anus to mouth via fingers

Indirect Pinworm transmission

Airborne eggs or fomites

Fomite

An inanimate object that can transmit infectious organisms to another person

T/F: Cold makes pinworm eggs dormant

True

Pinworm lifecycle in appendix

Migration to appendix

Irritation of appendix

Bacterial infection

Inflamation

Vaginitis (abnormal life cycle)

Migration to Vagina

Migration to fallopian tubes

Salpingitis

Scarring of fallopian tubes

What drug treats pinworm

Mebendazole (Emverm)

T/F: Whipworm eggs can remain viable for long periods in warm moist areas

True

Who is most susceptible to whipworm?

young school aged children

Whipworm is common where unprocessed ____ is used as fertilizer

night soil

Where does whipworm manifest in the body

Large intestine and Rectum, burrowed into the mucosa

Which part of whipworm burrows into the gut wall to feed on gut tissue?

Anterior end (thin end)

What results from a mild to normal whipworm infection?

Tissue injury/necrosis, hemorrhage, bacterial infection, pain, loss of appetite

What results from a heavy whipworm infection?

Anemia, dysentery, fever, rectal prolapse

How to diagnose whipworm

Fecal smear

Proctoscopic exam

Colonoscopy

What shape are whipworm eggs?

Barrel like

What is the whipworm treatment?

Mebendazole, 100 mg twice a day for 3 days

Dysentery

Diarrhea with blood in stool

What is the best climate for Giant Roundworm survival

warm moist climate

Giant Round Worm egg

Thick shell around embryo

Clinical manifestations of Giant Roundworm

Occurs in lungs (larvae stage)

Petechial hemorrhage

Sero-cellular exudate

Cough

Can have allregic reactions to molting fluid

Symptoms are asthma like

Adult Giant Roundworm Clinical Manifestations

Reside in lumen of gut (small intestine)

swim against gut peristaltic movement

Feed on instestinal contents (ingested food not you)

Abnormal/dangerous outcomes for Giant Roundworm

intestinal obstuction

Appendecitis

Abnormal migrations (pancreatic duct, bile duct, esophagus → trachea → lungs, mouth, ears)

gut penetration