Parasitology - EXAM 1

Intro and Nematodes - Lectures 1-5

Mutualism

Both species in the relationship benefit. (e.g. bird gets food between alligator’s teeth)

Commensalism

1 species benefits and the other doesn’t lose or gain anything (e.g. pilot fish feed off shark’s leftovers)

Parasitism

Parasite lives in/on organism (host) and thrives from it. (e.g. tick feeds off humans blood.)

Facultative Parasite

Acts like a parasite, but doesn’t always need a host.

Obligatory

Requires host to complete life cycle.

Endo-parasite

Lives IN a host, causing infection.

Ecto-parasite

Lives ON a host, causing infestation

Definitive Host

Host helps the parasites adult/reproductive stage.

Intermediate Host

Host helps the parasite’s larval/egg/asexual reproduction stage.

Vector

Can be either definitive or intermediate. Its goal is to transmit a parasitic pathogen from an infected host to an uninfected one.

Reservoir (host)

Animal/plant/environment that harbors a parasite/pathogen indefinitely, may not always show symptoms. Continuous source of infection.

Colonization

Infection agent in or on body, but not causing infection (e.g. lash mites).

Incubation

Time between exposure and appearance of first signs/symptoms.

Latency

Time from infection to being able to transmit infection.

Infection

Infectious agents (bacteria/fungi/parasites) entering your body and may cause infection.

Disease

Occurs after infection, being characterized by signs/symptoms of illness. Can also cause tissue damage, leading to pathological features/conditions.

Lytic Necrosis

Host tissue destruction where the parasite may penetrate the gut wall. In severe cases, it can penetrate the body wall.

Most parasites feed on the host’s body to survive.

True

Hookworms feed on 250μl of host blood daily.

True

Traumatic damage

Larva/adult migrating through the body and damaging host tissue.

Obstruction of Lumens

Blockage of tubes within the body (e.g Ascaris lumbricoides).

Eosinophilia

Increased production of eosinophils (WBC’s) to defend against parasitic infections.

Erythropoiesis

Increase production of RBC’s due to anemia caused by parasitic feeding.

Neoplasia

Uncontrolled proliferation of cells due to excessive tissue damage & repair caused by parasites.

Factors influencing intestinal helminth infections

• Poor hygiene

• Socioeconomic factors (e.g. poverty)

• Host’s biological factors (e.g. health, immuno-competence)

• Infrastructure issues (e.g. sewage, waste disposal)

• Demographic factors (e.g. family size, population density)

• Environmental factors (e.g. humidity, rainfall, intermediate hosts)

How many eggs do Ascaris lumbricoides females produce daily?

200,000

How does Entamoeba histolytica hyper-reproduce?

Nuclear division in reproductive cyst stage.

Helminths

Nematodes - Roundworms

Intestinal Helminth

Hookworm (Necator americanus OR Ancylostoma duodenale)

Blood & Tissue Helminth

Firey serpent (Dracunculus medinensis)