Flashcards in 2-33 Introduction to Parasitic Diseases Deck (26)
why do we have a harder time clearing parasitic diseases compared to bacterial or viral?
1. the life cycles of parasites are short and express different antigens
2. antigen mimicricy - parasite expresses epitopes similar to host molecules
3. antigenic shedding - shed antigens to conceal from immune system
4. antigenic variation - generate novel antigens by random mutations
5. antigen concealment - antigen hides antigens by being intracellular
completely dependent on host, can't survive without it
Can change its life style between free-living in the environment and parasitic according to the surrounding conditions and does not absolutely require a host for survival
Affects an unusual host (e.g. Toxocara canis (a dog parasite) in man).
vists the host only for feeding and then leaves
lives in/on host without leaving until removed (lice, crabs)
Capable of producing disease in an immunodeficient host (like AIDS and cancer patients). In the immuno-competent host, it is either found in a latent form or causes a self-limiting disease (e.g. Toxoplasma gondii).
Primarily infects animals and is transmittable to humans (e.g. Cryptosporidium parvum).
many parasitic infections are characterized by...
eosinophilia and high levels of IgE
normal eosinophil levels are 1-2%
parasitic infection - 10-15%
describe the role of IgE in parasitic diseases
IgE binds mast cells and basophils. When specific antigen-antibody combos occur, mast cells degranulate and releases chemotactic factors, histamine, prostaglandinds, and other mediators.
what does eosinophil chemotactic factor do?
attracts eosinophils to infected areas
#1 parasite worldwide?
highest mortality rates to parasites?
children under 5
what caused the decrease in hookworm infections?
parasites don't often kill hosts (TF)
True, except malaria
what has caused the spread of parasites to new areas?
-global warming = parasite range increasing. Along with human behavior and population movement
infected with tryponosoma cruzi via reduviid bug
caused by larval pig tapeworms (taenia solium)
-frequent cause of seizures in low-income countries
wild boar/pigs are resovoir
creates significant lesions in brain that cause destruction
found in cats and dogs
humans accidentally ingest eggs, parasite tries to exit incorrect host via the retina
cat feces and undercooked meat
In particular stage of pregnancy, crosses placenta to enters fetus that leads to several issues.
an STI, 85% asymptomatic, can cause Pelvic Inflammatory Disease
parasite lives on outside of host
parasite that lives within the host. ussually helminths
definivite Vs intermediate host
definitive - parasite can multiply within the host
intermediate - most human parasites, host harbors the larval or sexually inmmature form
most parasites enter humans through
injestion of eggs