Exam 3 - (1) Parasites Flashcards
Some of the most prevalent diseases in developing countries?
Parasitic
(T or F) Parasitic infections cause clinical infections
False
(T or F) Parasitic infections are distinct from parasitic disease
True
most common parasitic infection worldwide
Toxoplasmosis
Prolonged, repeated, or high burden infections are:
- usually subacute or chronic
- rarely fatal (except for malaria P. falciparum which is rapidly fatal 3-5)
Many parasitic agents are _____ meaning they infect animals.
zoonoses
Many human parasites require _______ and ______ hosts to complete their life cycles.
- human
- non human
What are the two parasite types?
- protozoa
- helminths
What are Protozoa?
One celled eukaryotes that cause disease when present in large numbers
What are 5 common protozoa?
1-Plasmodium 2-Giardia 3-Cryptosporidium 4-Leishmania 5-Trypanosomes
Where can protazoa manifest themselves during an infection?
- intracellular (RBCs, macrophages)
- extracellular (GI tract)
what are two forms protozoans w/in the GI tract take?
active trophozoite
dormant cyst
There are ~65,000 spp. of protazoa and few are parasitic. Where are most spp. found?
water + soil
What is the term for flagellated protozoa?
Mastigophora
What are some characteristics mastigophora?
- single nucleus
- sexually reproduce by syngamy
- divide by longitudinal fisson
- parasitic form have no mitochondria or golgi
- form cysts and are free living + solitary
what are 4 examples of Mastigophora?
1-Trypanosoma
2-Leishmania
3-Giardia and Cryptosporidium
4-Trichomonas
Where/why was a major Cryptosporidium outbreak/ how many were affected/ what was the total cost?
- Milwaukee, water treatment failure
- 400,000 people
- $96.2 million
What are Apicomplexa/sporozoa?
non-motile protozoans that produce sporozoites following sexual reproduction
What are some general characteristics of apicomplexa?
- not motile save for male gametes
- complex life cycles
- most form oocysts
- entire group is parasitic
What are two examples of apicomplexians?
1-Plasmodium
2-Toxoplasma gondii
What are helminths?
multicellular (metazoa) worm parasites
What are two common types of helminths?
1-Roundworms
2-Flatworms
What are some general helminth characteristics?
- They remain extracellular (large)
- they have a complex life cycle that doesn’t typically complete within the human
- development happens outside the human definitive host and in animal vector intermediate hosts
(T or F) Helminths chronic infections cannot be tolerated by human hosts
False - most are
(T or F) disease is a consequence of parasitic replication
False - it is not
What is a parasitic burden?
a term for the number of parasites that the host initially acquires from the environment
When do established helminth infections resolve themselves?
when the adult worms reach senescence (old age degradation)
(T or F) Adult helminths are large enough to see with the naked eye
True
(T or F) Helminth eggs and larvae can be seen with the naked eye
False- a microscope is required
What are some general characteristics of Flatworms?
- they’re part of the phylum platyhelminthes
- thin and often segmented
What are the 2 subdivisions of Flatworms?
1-Cestodes (tapeworms)
2-Trematodes (flukes)
What are some general characteristics about roundworms?
- they’re part of phylum Aschelminthes
- they are elongate, cylindrical and unsegmented
What are roundworms also known as?
nematodes
what class of animals are vectors for most parasites?
arthropods
What are some common arthropodic parasite vectors?
- Female anopheles mosquito
- flies (black and tsetse)
- kissing bugs
- ticks
(T or F) Arthropod vectors are not involved in any essential steps within a parasites life cycle
False
(T or F) Parasites are prevalent in areas conducive to arthropod breeding
True
What are parasite reservoirs?
sources of parasites that do not participate DIRECTLY in transmission
Name three broad parasite reservoir classifications
- humans
- animals
- environment
What are three routes of parasite entry?
1-oral ingestion
2-penetration of skin
3-arthropod borne bite wound
what constrains parasite transmission?
- special life cycle requirements
- presence of intermediate hosts
parasite disease manifestation is dependent on:
size of inoculum and varies between spp.
survival of a parasite within its host is largely dependent on it’s ability to
circumvent the host’s antibody and cell-mediated immune responses
a parasites life cycle is determined by
species and tissue tropisms
a specific conditional variable on a parasite’s ability to thrive is
temperature
clinical manifestations of a parasitic infection may include
- direct tissue damage from a parasite
- effects of a host immune response
- a mix of both
clinical complications such as those seen in schistosomiasis and pork tapeworms can occur ______ after initial infection
years
Chagas disease or American trypanosomiasis begins with a trivial asymptomatic or mildly symptomatic _____.
skin lesion
Chagas disease can be acute or chronic. Acute infections result in:
- a swollen eyelid (Romaña’s sign)
- swollen lymph nodes
- possible death in immunocompromised or young children
Chronic Chagas disease results in
lesions on various internal organs.
three ways to treat/prevent/eradicate parasitic infections
1-preventative drugs (chemoprophylaxis)
2-Immunization
3-field control measures
What are some problems with immunizing against parasitic pathogens?
- parasites masquerade as “self” by coating in host antigens
- some parasites (trypanosomes) continually alter surface antigens
- different proteins or polysaccharides displayed on surfaces at different life stages
What red blood cell parasitic disease is the most important of all protozoan diseases?
malaria
approximately how many named species of plasmodium (that infect various species of vertebrates) exist?
156
What four plasmodium spp. infect humans/what is their RBC preferences?
1 - P. falciparum/all age RBCs (most mortality)
2,3 - P. vivax/P. ovale/reticulocytes and young RBCs
4 - P. malariae/older RBCs
