Immunology of Parasitic Infections Flashcards
The function of the immune system
To protect the body from invasion by potential pathogens
How does parasitic infections in humans and animals occur?
Parasitic infections in humans and animals occur when the parasite successfully establishes itself in the host and is not eliminated by many host defense systems and is able to continue its life cycle
How does the ability of the parasites to cause infections has evolved
Natural selection
It constitutes the body’s first line of defense against pathogens
Natural physical barriers
Provides effective surface protection against invasion from parasites that initiate infection through skin penetration
Skin
How does Hookworm and Strongyloides penetrate skin?
The filariform larvae of hookworms and Strongyloides can synthesize a protein that aids in the entry through the skin
How does Schistosoma spp. cercariae penetrate skin?
They are capable of skin penetration because of the presence of glands in the anterior part of the parasite that secrete lytic enzymes
Does the mucous membranes lining the respiratory, gastrointestinal, and genitourinary tracts provide external barriers to parasite entry?
Yes
Function of tight junctions between epithelial cells
Serve to prevent passage of all but the smallest molecules
How does the low pH of vaginal secretions and gastric juices contribute to killing parasites?
They present a hostile environment to many microorganisms
How does the trophozoites of Trichomonas vaginalis survive the acidic environment of the vagina?
Trophozoites of Trichomonas vaginalis are unable to survive the acidic environment of the vagina
How does intestinal secretions affect Giardia lamblia
Once intestinal secretions envelope Giardia lamblia, its motility is greatly diminished reducing injury to the host
How does intestinal parasites/protozoa evade acidic type environment inside the host?
The embryonated eggs of parasites are protected from the acidic environment by thick egg shells and the cystic wall of intestinal protozoa are resistant to acidic pH
How does the lipase content of breast milk affect Giardia lamblia?
It has been found to be toxic to Giardia lamblia in vitro
How does the lysozyme found in tears and saliva affect different microorganisms?
Lysozyme found in tears and saliva is able to destroy microorganisms, along with secreted IgA immunoglobulins in these fluids
