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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.
zoonoses
What is the definition of a "dead end host".
A host that is not required for a developmental stage of a parasite.
Name five medically important protozoal species.
1. Plasmodia (malaria)
2. Giardia
3. Cryptosporidium
4. Leishmania
5. trypanosomes
Where does replication of plasmodia occur?
RBCs
Where does replication of Leishmania occur?
macrophages
Where does replication of Giardia occur?
lumen of GI tract
Because many protozoa are unable to withstand dessication, they sometimes alternate between two distinct forms. What are they?
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
Formless cells that move purposefully by extending pseudopods toward an attractive stimulus and then streaming their cytoplasm in the desired direction.
Amebas (or Sarcodina)
Intestinal and blood protozoa that use one or more flagellae for locomotion.
Flagellates
Protozoa covered with tiny cilia that provide locomotion.
Ciliates
Very important pathogens that include the agents of malaria, toxoplasmosis, and several common intestinal parasites.
Apicomplexans (or sporozoa)
These helminths are circular in cross section.
Roundworms
These helminths are asymmetric in cross section.
Flatworms
Schistosoma and Fasciola are relatively short flatworms with nonsegmented bodies known as what?
Flukes
These segmented worms vary in size from millimeters to several meters in length.
Tapeworms
T/F Most helminths complete their life cycle within a single human host.
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.
What species of mosquito is the vector for malaria?
female Anopheles mosquito
What is the vector for sleeping sickness?
tsetse flie
What is the vector for the tissue roundworm infection called river blindness?
black flies
This vector transmits Chagas disease.
reduviid "kissing" bugs
Sources of parasites in the environment that do not participate directly in transmission to humans.
Reservoirs
Give two examples of parasites that are transmitted by the fecal-oral route.
amebiasis and ascariasis
Give two examples of parasites that are transmitted by direct penetration of unbroken skin.
hookworm and schistosomiasis
Give two examples of parasites that are transmitted by the bites of arthropod vectors.
malaria and filariasis
These parasites can coat themselves with host plasma proteins and are thus not recognized as foreign by the host's immune system.
adult schistosomes (blood flukes)
These parasites evade host immune systems by varying their surface antigens.
trypanosomes
What is the mechanism by which Leishmania species are protected by macrophages?
They secrete a superoxide dismutase that protects them from the toxic superoxide produced in the phagolysosome.
What is the name of the antigen present on the surface of RBCs that is necessary for the entry of Plasmodium vivax?
Duffy factor antigen
Give two examples of parasitic diseases which cause chronic inflammation.
schistosomiasis and cutaneous filariasis
Give an example of a parasitic disease in which the host inflammatory response may cause persistent disease even after the parasites have died.
trichinosis
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?
interleukin-5 (IL5)
To pursue the most effective diagnostic strategies, it is important to understand what?
the parasite's life cycle
Antiparasite strategies fall into these three general categories:
1. drugs for prevention and treatment
2. immunization
3. control measures in the field
One example of successful chemoprophylaxis is the use of _______ to prevent malaria.
chloroquine
Mass treatment may be an effective control strategy for diseases that depend on what?
humans as a reservoir
In general, treatment of symptomatic parasitic infections is usually an efficient or inefficient strategy for controlling transmission and why?
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.
What is a major problem in designing vaccines to parasites?
Evasion of the host immune response
What is another problem in designing vaccines?
Parasites typically have different proteins or polysaccharides on their surfaces at different stages of their life cycles.
The best control measures are based on what?
the mode of transmission defined by the parasite's life cycle