2-33 Introduction to Parasitic Diseases

Question 1

why do we have a harder time clearing parasitic diseases compared to bacterial or viral?

Answer 1

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

Question 2

obligate parasite

Answer 2

completely dependent on host, can’t survive without it

Question 3

facultative parasite

Answer 3

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

Question 4

accidental parasite

Answer 4

Affects an unusual host (e.g. Toxocara canis (a dog parasite) in man).

Question 5

temporary parasite

Answer 5

vists the host only for feeding and then leaves

Question 6

permanent parasite

Answer 6

lives in/on host without leaving until removed (lice, crabs)

Question 7

opportunistic parasite

Answer 7

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).

Question 8

zoonotic parasite

Answer 8

Primarily infects animals and is transmittable to humans (e.g. Cryptosporidium parvum).

Question 9

many parasitic infections are characterized by…

Answer 9

eosinophilia and high levels of IgE

normal eosinophil levels are 1-2%
parasitic infection - 10-15%

Question 10

describe the role of IgE in parasitic diseases

Answer 10

IgE binds mast cells and basophils. When specific antigen-antibody combos occur, mast cells degranulate and releases chemotactic factors, histamine, prostaglandinds, and other mediators.

Question 11

what does eosinophil chemotactic factor do?

Answer 11

attracts eosinophils to infected areas

Question 12

1 parasite worldwide?

Answer 12

malaria

Question 13

highest mortality rates to parasites?

Answer 13

children under 5

Question 14

what caused the decrease in hookworm infections?

Answer 14

wearing shoes

Question 15

parasites don’t often kill hosts (TF)

Answer 15

True, except malaria

Question 16

what has caused the spread of parasites to new areas?

Answer 16

-global warming = parasite range increasing. Along with human behavior and population movement

Question 17

Chagas disease

Answer 17

infected with tryponosoma cruzi via reduviid bug

Question 18

cysticercosis/neurocysticercosis

Answer 18

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

Question 19

toxocariasis

Answer 19

found in cats and dogs

humans accidentally ingest eggs, parasite tries to exit incorrect host via the retina

Question 20

toxoplasmosis

Answer 20

cat feces and undercooked meat

In particular stage of pregnancy, crosses placenta to enters fetus that leads to several issues.

Question 21

trichomoniasis

Answer 21

an STI, 85% asymptomatic, can cause Pelvic Inflammatory Disease

Question 22

ectoparasite

Answer 22

parasite lives on outside of host

Question 23

endoparasite

Answer 23

parasite that lives within the host. ussually helminths

Question 24

definivite Vs intermediate host

Answer 24

definitive - parasite can multiply within the host

intermediate - most human parasites, host harbors the larval or sexually inmmature form

Question 25

most parasites enter humans through

Answer 25

injestion of eggs

Question 26

parasitic infections are ussually diagnosed through

Answer 26

direct examination of feces, urine, blood, or tissue.