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39 Cards in this Set
- Front
- Back
Parasitic infections of humans that are caused by agents that infect animals such as birds, reptiles, and other mammals.
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zoonoses
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What is the definition of a "dead end host".
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A host that is not required for a developmental stage of a parasite.
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Name five medically important protozoal species.
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1. Plasmodia (malaria)
2. Giardia 3. Cryptosporidium 4. Leishmania 5. trypanosomes |
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Where does replication of plasmodia occur?
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RBCs
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Where does replication of Leishmania occur?
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macrophages
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Where does replication of Giardia occur?
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lumen of GI tract
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Because many protozoa are unable to withstand dessication, they sometimes alternate between two distinct forms. What are they?
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1. trophosoite form that grows and replicates by binary fission with the host.
2. dormant, non-replicating cyst form that is adapted for survival in various environmental extremes |
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Formless cells that move purposefully by extending pseudopods toward an attractive stimulus and then streaming their cytoplasm in the desired direction.
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Amebas (or Sarcodina)
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Intestinal and blood protozoa that use one or more flagellae for locomotion.
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Flagellates
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Protozoa covered with tiny cilia that provide locomotion.
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Ciliates
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Very important pathogens that include the agents of malaria, toxoplasmosis, and several common intestinal parasites.
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Apicomplexans (or sporozoa)
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These helminths are circular in cross section.
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Roundworms
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These helminths are asymmetric in cross section.
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Flatworms
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Schistosoma and Fasciola are relatively short flatworms with nonsegmented bodies known as what?
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Flukes
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These segmented worms vary in size from millimeters to several meters in length.
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Tapeworms
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T/F Most helminths complete their life cycle within a single human host.
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False. With rare exceptions, no helminthic parasite completes its life cycle within a single human host. Therefore, the parasitic burden is directly related to the number of helminthic parasites that the host acquires form the environment.
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What species of mosquito is the vector for malaria?
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female Anopheles mosquito
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What is the vector for sleeping sickness?
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tsetse flie
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What is the vector for the tissue roundworm infection called river blindness?
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black flies
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This vector transmits Chagas disease.
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reduviid "kissing" bugs
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Sources of parasites in the environment that do not participate directly in transmission to humans.
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Reservoirs
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Give two examples of parasites that are transmitted by the fecal-oral route.
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amebiasis and ascariasis
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Give two examples of parasites that are transmitted by direct penetration of unbroken skin.
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hookworm and schistosomiasis
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Give two examples of parasites that are transmitted by the bites of arthropod vectors.
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malaria and filariasis
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These parasites can coat themselves with host plasma proteins and are thus not recognized as foreign by the host's immune system.
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adult schistosomes (blood flukes)
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These parasites evade host immune systems by varying their surface antigens.
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trypanosomes
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What is the mechanism by which Leishmania species are protected by macrophages?
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They secrete a superoxide dismutase that protects them from the toxic superoxide produced in the phagolysosome.
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What is the name of the antigen present on the surface of RBCs that is necessary for the entry of Plasmodium vivax?
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Duffy factor antigen
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Give two examples of parasitic diseases which cause chronic inflammation.
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schistosomiasis and cutaneous filariasis
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Give an example of a parasitic disease in which the host inflammatory response may cause persistent disease even after the parasites have died.
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trichinosis
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Eosinophils are leukocytes that participate in neutralizing infections with parasitic worms. Eosinophilia is typically accompanied by increased levels of IgE and is driven by elevated levels of what?
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interleukin-5 (IL5)
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To pursue the most effective diagnostic strategies, it is important to understand what?
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the parasite's life cycle
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Antiparasite strategies fall into these three general categories:
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1. drugs for prevention and treatment
2. immunization 3. control measures in the field |
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One example of successful chemoprophylaxis is the use of _______ to prevent malaria.
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chloroquine
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Mass treatment may be an effective control strategy for diseases that depend on what?
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humans as a reservoir
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In general, treatment of symptomatic parasitic infections is usually an efficient or inefficient strategy for controlling transmission and why?
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inefficient because a long delay often occurs between the initial infection and the onset of symptoms. During the long asymptomatic interval, infected humans are able to transmit the infection.
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What is a major problem in designing vaccines to parasites?
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Evasion of the host immune response
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What is another problem in designing vaccines?
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Parasites typically have different proteins or polysaccharides on their surfaces at different stages of their life cycles.
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The best control measures are based on what?
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the mode of transmission defined by the parasite's life cycle
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