Parasitology Exam 1

parasites ewwww but they cool too

What are parasites?

organisms that feed/thrive only on it’s host

Why might fecal samples need to be inspected by a doctor or vet?

for intestinal parasites OR eggs

What are the major groups of parasites discussed?

• protozoa

• helminths

• arthropods

Which major group of parasites is known as a single celled eukaryotic microorganisms?

protozoa

What does “helminths” mean?

worm

What does endohelminth mean?

parasitic worm that lives inside the body

What’s an example of a parasitic arthropod?

ticks

What is an ectoparasite?

parasite that lives OR burrows on/in the surface of the skin of host

What does hyperparasitism mean?

ectoparasites that can also carry parasites

Is scientific name the same as species name?

yes

How do you properly construct a species name?

Genus + specific epithet (italics when typed, underlined when written)

Genus is capped and epithet is lowercased

TRUE OR FALSE: Genus cannot be used alone but the specific epithet can be.

FALSE. The Genus can be used alone but NOT the epithet

What are additional rules to the binomial nomenclature?

Use full name when first used in a sentence after that it can be abbreviated, except if used as the first word in a sentence then you have to use the full name again.

If you have two species w the same specific epithet, use the first two letters in the Genus when abbreviating

Why do we study parasites?

Provide bio phenomena not found in living organisms

• medical importance

• veterinary

• economical

Common parasitic diseases in the US include

• neglected tropical diseases

• species cosmopolitan & native to the US

• species that move from other areas of the world due to moving persons

• species transmitted from animals to humans

__% of ALL organisms can be hosts

100

At least 50% of all organisms are parasites and probably as many as __% of all organisms

80

Over ___ species of parasites infect humans

370

Parasites are found in all major groups of organisms

• Bacteria

• Fungi*

• Plants*

• Protozoa

• Animals

* = economically important to crops

Parasitism is a form of what?

Symbiosis

What is symbiosis?

A close relationship between two living organisms

• Symbionts: interacting organisms

• Parasitism: parasites gain, but the host is negatively affected

Predator is typically ___ than prey (exceptions) and parasites are typically ____ than host

larger; smaller (relating to body size)

Predator population grows ___ than prey and parasite population grows ___ than host

slower; faster

Predators use many prey items during their life span, how does this compare to parasites?

parasites use 4 OR less hosts to complete a generation

• often very specific interactions are involved

Mosquitoes, ticks, and leeches are what kind of predators?

micropredators

Mosquitoes, ticks, leeches, ect. are also considered intermittent parasites. What does this mean?

prey on many hosts, OR single hosts intermittently

What is a parasitoid? What are some examples?

• Adults are free-living, and they have other ways to feed themselves

• Immature stages feed on the host’s body (usually another insect

• ex. wasps & flies

What are endoparasites?

inside the body

• endohelminths, worms, nematodes

What are obligate parasites?

needs host to survive

• won’t usually kill host as they NEED them.

  • most of the parasites discussed will be this kind

What are facultative parasites?

Do okay on their own but won’t mind being a bit parasitic time to time >;)

• infections are usually fatal as they are not naturally parasites

What are accidental OR incidental parasites?

Parasites in wrong host

• do not usually survive

What are permanent parasites?

Live entire life/life stages on one host

What are temporary parasites?

Live in or on several hosts during a life-cycle stage

What are zoonotic parasites?

Develops on other animals but can infect humans

What are the types of hosts?

• Definitive host

• Intermediate host

• Vector

• Paratenic host

• Reservoir host

What is the biologist/ecologist definition of definitive host? what is the medical field definition?

Biologist/Ecologist: Parasite reaches sexual majority

Medical: Where parasite is most detrimental to humans

What is an intermediate host?

Required host but maturity (sexual) does not occur

• often asexual repro. happens here

What is a vector?

TRANSMITS parasite from one host to another host (biting or blood-sucking)

What is a paratenic host?

Parasite does not develop at all (stays the stage it entered in the host as) but remains infective to another host

What is a reservoir host?

Host that harbors infection that can be transmitted to humans ( zoonotic host)

• may be the definitive host for non-specific parasites

True OR False: Parasites must infect subsequent hosts to surivive

True

What do life cycle’s describe?

• Parasite development

  • Transmission mode

What is needed when drawing life stages?

• Reproduction

• Transmission

• How

• Who

• Host

What is a monoxenous parasite?

Complete life cycle within a single host

• infective stage enters host & the same stage leaves the host

What is a heterogeneous parasite?

Require several hosts to complete life cycle

• stage entering host differs from stage leaving the host

Review the example life cycles given in the Chapter 2 PowerPoint: Enterobius vermicularis and Fasciola hepatica

True or False: Hosts are simple as there is only one environment parasites like to reside, usually the intestinal tract.

False.

• Hosts are complex and contain many environments, such as:

  • blood stream, intestinal tract, muscles, intracellular environment, etc.

Each parasite species is adapted to a specific host _____

environment

What are coelozoic parasites?

reside in host’s hollow organs or lumen of intestine

What are histozoic parasites?

Parasite reside within host tissue (body wall of organs)

______ exists within regions of hosts

Microhabitats

DIfferent parasite species reside in the various ______

Microbahbitats

• niche partitioning

• may result from:

  • current competition

  • the “ghost of competition past”

What is niche partitioning?

Different parasites species living in different regions of the intestine!!

• what they are physiology attracted to

Explain infrapopulation

All individual of a parasite species in one host individual

• ex. count all individual of species A in a host & measured

What is intensity?

The measure of an infrapopulation

• # od parasites in a single host

What is metapopulation?

All infrapopulation of a species of parasites in a single host species in an ecosystem or community

What is mean intensity?

population average of intensity

• # parasite in a population of hosts/ # of infected host (infected individual)

What is suprapopulation?

All parasites of a single species in ALL its host species in an ecosystem or community

Parasites are fundamental components of the ____ ecosystem

mudflat

Different parasites have evolved different ___ of finding hosts & getting inside hosts

methods

Parasite methods can change over evolutionary time, as _____ ______ can favor new methods of infecting host

natural selection

Parasites adapt to host population/community changes, often resulting in new parasite ____ ______

host assocations

• strict host specificity may evolve

Red Queen hypothesis (related to co-evolution)

species must continuously adapt & evolved to survive

Host population evolve in response to _____

parasites

What are some ways parasite population evolve to increase transmission?

• Host finding mechanisms

• Immune response avoidance

• High reproduction output

• Sexual reproduction

• Drug resistance

• Virulence

  • degree or severity of disease

What is one of the hypothesis of virulence?

Parasite should become less virulent over time, as host death has a neg. impact on para, fitness

What is the second hypothesis of virulence?

Parasite should evolve into optimal virulence that maximizes parasite reproduction and transmission

What is virulence?

degree of damage parasite does to a host

True or False. Infection = Disease

False.

What is subliminal infection?

infection with no signs or symptoms

What are some factors infection depends on/relates to?

parasite burden (intensity = # of parasites.), host immune response, host genetics, & pathology of the parasite

Much of the disease caused by parasites is directly related to ___ ____ mechanisms

host defense

• inflammatory response

• 
  

How does infection affect the body?

• can effect cell growth

• block nutrient absorption

• metabolic products (poop) are toxic to tissue

Does this definition describe pathology or symptoms/clinical signs?:

The physical, biological, and/OR cellular damage in the patient

• tissue damage and organ enlargement

Pathology

Does this definition describe pathology or symptoms/clinical signs?:

What the patient reports and/OR outward clues that can be seen and measured

• refusing to eat or nausea, lethargy, coughing, limping, fever, headache, etc

Symptoms OR clinical signs

Does this describe the pathology or the symptoms of malaria?

• anemia

• blocked capillaries

• hypoxia

• kidney malfunction

Pathology

Does this describe the pathology or symptoms of malaria?

• cyclical severe chills

• high fever

• fatigue

• shaking

• headache

Symptoms

Does this describe the pathology or symptoms of dog heartworm?

• mechanical disruption to heart & vessels

• chronic vessel inflammation

• enlarged heart

Pathology

Does this describe the pathology or symptoms of dog heartworm?

• dry cough

• lethargy

• difficulty breathing

• weight loss

Symptoms

What is epidemiology?

study of ecological aspects of disease

• distribution (who, where, when), transmission, prevalence, incidence

What is prevalence? How do you calculate it?

Proportion of hosts infected at a given time, usually expressed as percent

• ( # of infected hosts / # sampled) x 100 = %

What is incidence?

Number of new infections per unit of time

What is abundance? How do you calculate it?

Number of parasites of a species in a host population

• # parasites in a population of hosts / # of ‘hosts’ sampled

• disregards the infection status of the individual sampled

Example problem:

5 mice (M) with a total of 75 pinworms

• Mouse 1: 25 worms, Mouse 2: 10 worms, Mouse 3: 40 worms, Mice 4 & 5: 0 worms

Calculate the prevalence, intensity, mean intensity, and abundance

Prevalence: 60.0%

Intensity: M1: 25, M2: 10, M3: 40

Mean intensity: 25.0 parasites/host

Abundance: 15.0 parasites/host

Parasites of a given species are often overdispersed. What does this mean?

Most populations of hosts have few or no parasites

• Average (mean) # of parasite exceeds the variance of the mean

  • variance / mean > 1

What are the 3 main categories of parasite control?

• Reducing transmission

• Overuse & Resistance

• Vaccines

What is the key to reducing transmission of a parasite?

The life cycles of the parasite

Which parts of the life cycles can we target to try and reduce transmission?

Looking at the hosts, reservoir hosts, and intermediate hosts

• reducing contact of these hosts if possible

What can we do about food safety to reduce transmission of tropically transmitted parasites?

Proper sanitation for fecal-oral route

• disposal of waste

Safe water

What are the two types of anti-parasitic drugs?

Prophylactic and Therapeutic (chemo)

Is chemotherapy only use to describe the treatment for cancer?

No. Chemotherapy is the treating of any disease with a drug

Which drug is used to treat before infection? Which drug is used to treat after infection?

Prophylactic is before and Therapeutic is after

What are some issues that arise when it comes to producing and using anti-parasitic drugs?

• The drugs aren’t made often as the population that needs them are too poor to afford treatment (companies will not turn a profit treating poor people)

• Hard to target the parasite due to it’s different life stages

• Since parasites are eukaryotes, it is difficult to target ONLY the parasite and not the host too

What is an issue that arises when using vaccines?

Few vaccines have been successfully developed as parasites have the same cells as the host

What is One Health?

Recognizes that humans animals, & the environment are ALL related

• promotes well-being of all species

• Integrates human, veterinary, and environmental medicine/Science.

What group of parasites that we will be discussing is considered more diverse than any other group?

Protozoans

Do protozoans have taxanomic significance?

Naur

The phylum Euglenozoa contains which genus of protozoans?

• Leishmania

• Trypanosoma

The phylum Metamonada contains which genus of protozoans?

• Giardia

• Trichomonas

The phylum Apicomplexa contains which genus of protozoans?

• Cryptosporidium

• Sarcocystis

• Toxoplasma

• Plasmodium