Parasitology Test 1 Flashcards
Parasitology is largely a study of____
symbiosis
Any organism spending a portion of all of its life intimately associated with another organism of a different species is known as a ___
symbiont
What are the 4 cateogires of symbiosis?
- Phoresis
- Commensalism
- Mutualism
- Parasitism
What is phoresis?
When 2 symbionts travel together but NEITHER is physiologically dependent on the other
In a phoresis, the host carries a smaller symbiont known as a __
phoront
What is commensalism?
When one symbiont (commensal) benefits from its relationship with host and the host doesn’t benefit or get harmed.
What is a big similarity between commensalism and phoresis?
Neither organism in symbiotic relationship is dependent on the other and CAN survive independently.
What is mutualism?
Both partners in symbiotic relationship are called mutuals and both benefit from the association. Both organisms DEPEND on each other physiologically. Mutuals CANNOT survive without eachother.
What is parasitism?
When symbiont harms its host or in some sense lives at the expense of the host; parasite is usually smaller than host and physiologically dependent on host.
Most parasites are considered___, as they are physiologically dependent upon host and usually cannot survive if kept isolated.
Obligate
What is a facultative parasite?
Not common, free living or not normally parasitic, but becomes so occasionally when accidentally eaten or encountered.
When a parasite enters or attaches to body of host different from its normal host, it is called an ___ or ___
accidental or incidental parasite
What is an ectoparasite?
If parasite lives on the surface of its host or superficially embedded in the body surface
What is an endoparasite?
If the parasite lives internally (alimentary tract, liver, lungs, urinary bladder)
What are the 3 types of host?
- Definitive host
- Intermediate host
- Paratenic host
Define a definitive host?
If the parasite attains sexual maturity and reproduces within host
Define intermediate host?
Some development of the parasite occurrs but in which it does not reach maturity
What is a paratenic?
A paratenic or transfer host is not required for the completion of the parasites life cycle but is utilized as a temporary refuge and a vehicle for reaching the definitive host in the cycle.
What is a reservoir host?
Infected animal that serves as a source of parasites for humans
A wild animal in the role of reservoir host is called a ____
sylvatic reservoir host
A disease of humans caused by pathogenic parasite found in wild and domestic vertebrate animals.
Zoonosis
Anything such as a invertebrate, vertebrate, or disease causing agent like water and air is a _
vector
A parasite that hosts other parasites example: protozoan plasmodium in a mosquito
Hyperparasitism
what does heterotrophic mean? How does it relate to parasites?
Parasites require energy in existing organic molecules and nitrogen in the form of amino acids
What is a coelozoic parasite? Give the major example
parasite that resides within lumen of intestine or hollow organs
example: flukes, tapeworms
What is a histozoic parasite? example?
- parasite that lives within tissues
example: some protozoans and nematodes
What are features of R-selection? (there’s 4)
- high fecundity
- high mortality
- short life-span
- effective dispersal mechanism
What type of environment and population does R-selection favor?
- R selection prevails when selective forces upon organisms are UNSTABLE
- R-selection favors population sizes that are BELOW the carrying capacity of the environment
Give an example of a parasite that is an r-strategist
Any trematode; their environment is HIGHLY VARIABLE with 2 or more different hosts, plus 2 free-swimming stages in water to complete their life-cycle
Most parasites are ___strategist
R-strategist, R-selection
When does K-selection or k-strategist parasites prevail? What sort of conditions?
K-selection prevails when selective forces upon the organisms are RELATIVELY STABLE over a period of time
What are features of K-selection? (there’s 4)
- low fecundity
- low mortality
- longer life-spans
What type of environment and population does K-selection or K-strategist parasites prefer?
-RELATIVELY STABLE population sizes that are CONSTANT over time and are usually below the carrying capacity of the environment
What is an example of a K-strategist parasite?
Free living flatworm
What are the two types of parasitic competition?
- Exploitation
- Interference
Describe the exploitation style of parasitic competition
-joint exploitation of a limiting resource within a host species by 2 or more parasite species
Give example of exploitation competition style
Ascaris and Trichuris may coexist
Describe Interference style of parasitic competition
Antagonistic or hostile mechanisms are used by one species to reduce survival of another or to displace it from a preferred site of attachment, probably caused by production of toxins
What is prevalence?
(%) number of host individuals infected by 1 parasite DIVIDED by # hosts examined
example: 1 person in a group of 5 who were examined was infected, the prevalence would be 20%
What is intensity?
Number of parasites in a single infected host
What is mean intensity?
-average of the number of parasites in infected parasites
What is incidence?
(%) # of new cases of a disease or infection appearing in a population within a given period of time DIVIDED by # of uninfected individuals in the population at the beginning of time period
What is density?
(abundance) # of individuals of a particular parasite per unit are, volume, or weight of infected host tissue or organ
What is infrapopulation?
all of the parasites of a particular species in the body of a single host
What is suprapopulation?
all individuals of a species of parasite in all stages of development within all hosts in an ecosystem
what is epidemiology?
The study of factors responsible for the transmission and distribution of disease
What are the 7 factors that influence epidemiology?
- age
- sex
- social (cultural) and economic status
- diet
- distribution and presence of vectors and reservoir hosts
- host specificity
- densities of host and parasite
Means of transmission of parasite from one host to another
Vector
What organizations monitor epidemiology world wide?
- World Health Organization (WHO)
- Tropical Disease Research Program (TDR)
How did ectoparasites evolve, give example to support this theory?
May have evoloved from non-parasitic omnivores,
Example: Moth in South East Asia that feeds on plant juices, but 1 species sucks tears from orbits of large mammals
How did endoparasites evolve, give an example to support this theory?
Probably found entrance through alimentary tract.
Example: Cyst-forming protozoa and nematodes protected by a tough cuticle most readily survived actions of gastric juices.
What happens as a parasite becomes progressively more specialized?
-It limits its potential host species; increases host specificity
Why study host parasite interactions?
Without knowing the biochemical differences, new chemotherapeutic drugs may not emerge or effective vaccines may not be produced
____is the ability of the host to withstand a parasitic infection and may develop in several ways
Resistance