L8: Introduction to Parasites Flashcards
Risk factors for parasitic disease? 7
- Traveler to endemic zones
- Raw food
- Barefoot exposure to soil
- Exposure to fresh water
- Injections
- Sexual activity
- Immunocompromised
Vectors and intermediate hosts of parasites?
Disease for each
- Mosquitos: Malaris, filariasis
- Flies: Leishmaniasis, trypanosomiasis, onchocerciasis
- Snail: Schitosomiasis
- Kissing bugs: Chagas disease
- Fish: Diphyllobothrium latum
- Large animals
What can be a vector?
Insect
2 categories of parasites?
- Protozoa: Single celled
2. Metazoa: Multi-celled
4 types of protozoa?
Amoebas
Flagellates
Ciliates
Sporozoans
2 categories of metazoa?
Nemathelminths
Platyhelminths
Another word for metazoa?
Helminth
Protozoans can be divided by location in body, what is this? (2)
- Lumen dwelling: don’t invade
2. Tissue dwelling: invade
3 types of metazoa? with common name
- Nematode: Round worm
- Cestodes: Flatworms or Tapeworms
- Trematodes: Flukes
Are protozoa pro or euk?
Eukaryote
Protozoa are found where?
Free living in marine, fresh water and terrestrial habitats
How are protozoa helpful?
Essential decomposers and part of food chain.
Do protozoa have a cell wall?
Are they eukaryotes?
Do they have chloroplasts?
How do they move?
No
Yes
No
Specalized structures: cilia, flagella, pseudopodia
Two forms a protozoan can exist as?
Define each
- Trophozoite: vegetative/feeding form
2. Cyst: resting form
What is the most common mode of protozoan reproduction?
Specifically what form?
Is this sexual or asexual?
Binary fission
Schizogony
Asexual
Is a protozoan has a definitive host, how does it reproduce?
Sexually
What is schizogony?
Many fissions in which the nucleus divided numerous times and then the cell produces numerous single-celled organisms
Mechanisms of entry of protozoa?
- Ingestion
- Sexual transmission
- Arthopod vectors
Example of direct inoclulation of protozoa?
Malaria
Example of indirect inoculation of protozoa?
Chagas’ disease
2 mechanisms of protozoan pathogenesis?
- Tissue damage
2. Release of toxins from tissue and parasite
Amoebas move by what object?
Pseudopodia
How many nuclei in amoebas?
1-2
How do amoebas replicate?
Binary fission
How do amoebas ingest?
Endocytosis
What do amoebas form under adverse conditions?
Cysts
Old designation of amoebas?
New designation of amoebas?
- Sarcodina
2. Amoebozoa
Flagellates old designation?
Mastigophora
How do flagellates move?
Flagella, 1 or more
How many nuclei do flagellates have?
1-2
How do flagellates reproduce?
Binary fission
What do flagellates form under adverse conditions?
Cysts
Are flagellates life cycles simple or complex?
Both.
Hemoflagellates have a complex life cycle of how many forms?
4, 1 of which is intracellular
Hemoflagellates are transferred by who?
Insect Vectors to trypansoma and leishmania
Trypanosoma can cause what diseases? 2
- African sleeping sickness
2. Chagas’ disease
Ciliates are known as what?
Ciliophora
Ciliates move how?
Cilia rotating
How many nuclei in ciliates?
1-2
How do ciliates replicate?
Binary fission
How do ciliates ingest nutrients?
Through cytosome
Excrete waste through anal pore.
Sporozoans are known as what?
Apicomplexans?
What type of parasite is sporozoans?
Intracellular parasites.
How do sporozoans move? (2)
- Flagella
2. Pseudopodia
How many nuclei do sporozoans?
1 or multiple nuclei
Sporozoans have how many developmental stages?
Several
Are sporozoans only able to have one host?
No
Sporozoans use what type of reproduction?
Sexual: Fusion
Asexual: Fission
End product of sporozoans sexual reproduction is what?
Oocyst
What is difference between intermediate host and definitive host
Intermediate host: Larval forms, asexual
Definitive host: Adult forms, sexual
What are the health strategies against protozoan parasites?
- Control presence in environment
- Prevention of infection
- Treatment of infection
Prevention of infection is through what? 3
- Hygiene
- Vector avoidance
- Immunization
Helminths/Metazoa have what common characteristics?
- Multicellular and complex
- Rudimentary nervous systems
- Outer covering of cuticle that is shed
- Use sexual reproduction (although some are hermaphroditic)
- Highly allergenic (Type 1)
Nematodes have what sexual identity?
Male and female
Nematodes in the GI system do what?
Ova passes out
Nematodes in circulatory must be what?
Be ingested by vector
Nematodes in other tissues must be what?
Ingested by predator
Cestodes have what sexual identity?
Hermaphroditic
Do cestodes/proglottids exit under their own power or disintegrate?
Both
Trematodes are usually what sexual identity?
Hermaphroditic
Difference between cestodes and trematodes in terms of fertilization?
Cestodes: Self fertilize
Trematodes: Cross-fertilize
Trematodes in GI system do what?
Ova exit in feces
Trematodes in circulatory do what?
Erode to lumen
Trematodes in pulmonary system do what?
Exit in sputum or feces
What is a definitive host?
Harbors adult worms and is site where sexual reproduction takes place
What is an intermediate host?
Harbors larval forms and asexual reproduction may take place.
Helminth entry into body is by what means?
Intermediate host: Ingestion of larvae in tissue
Fecal-oral: Ingestion of eggs or larvae from feces of infected host
Skin penetration: Larval forms burrow through the skin
Injection by blood-sucking insect
Two broad categories of helminths?
- Nemalthelminths (Roundworms)
2. Platyhelminths: Flatworms
What is the group of roundworms called?
Nematodes
What are the two subdivisions of flatworms?
- Cestodes: Tapeworms
2. Trematodes: Flukes
Nematode body?
Long, cylindrical, narrow
After hatching how do nematodes develop?
Molt through 1 or more larval stages
Which is larger in nematodes, males or females?
Females
Do nematodes have digestive tracts?
Some do
For transmission of nematodes, what can be the infectious unit?
Which passes easily?
Egg: Pinworm (easily passes)
Larva: Hookworm
How does a larval/hookworm act as infectious unit?
- Penetrate bare skin, enter blood stream
- Carried to lungs, and travel up trachea to esophagus
- Kids swallow them into intestine and they lay eggs here
- Poop out eggs
- Ova hatch in soil into first larval stage. and molt into second
Should you pull tissue nematodes out?
No
Tissue nematodes larvae are released into what?
Bloodstream or Exterior of body and are taken up by insects or intermediate hosts
How are tissue nematodes acquired? 5
- Larvae ingested by copepods
- Drink copepods from bad water
- Larval migrate through tissues and mature
- Female adults go to subcutaneous tissue on extremities to release larva into water
Platyhelminths have what shape?
Flattened
Platyhelminths are of what sexual identity?
Hermaphroditic
Which platyhelminths HAVE a digestive tract?
Flukes do
What do platyhelminths use for attaching to tissues?
Tapeworms: Hooks
Tapeworms AND flukes: Suckers
Cestodes have what two main parts?
- Strobila
2. Scolex
The strobila is made up of what?
- Proglottids
2. Gravid proglottids
Proglottids have what fnction?
Reproductive: Wil twitch and then dissolve releasing egg
Gravid proglottids have what?
Eggs
In intestinal cestodes, humans are what host?
Definitive host: Infected by larvae. Adult worms live in humans
In tissue cestodes, humans are what host?
Intermediate host: Ingest eggs to get infected. Larvae live in tissues
What is beef tapeworms lifecycle?
- Ova are ingested by cattle (intermediate host)
- Larvae ingested by humans (definitive host)
- Proglottids and eggs in intestine.
- Ova are shed in human feces
How does the pork tapeworm’s lifecycle compare to the beef tapeworms?
Same
What happens if humans ingest pork tapeworm ova?
Cysticercosis: Larvae encyst in tissue
Trematodes have what symmetry?
What shape?
Bilateral
Leaf-shaped
What do suckers do in trematodes?
- Hold on
2. Suck fluid
What are the trematodes to worry about?
Blood flukes
Definitive hosts of trematodes/flukes?
Humans, livestock
Intermediate hosts of trematodes/flukes?
Snails
What is lifecycle of trematode/fluke? 5
- Larvae burrow into snails
- Larvae multiply asexually and released into water
- Larvae form cyst in second intermediate host or water vegetation
- Cysts or larvae infect vertebrae host, mature and lay eggs
- Ova passed from vertebrae host to hatch inw ater
Health strategies for parasitic helminths?
- Control presence in environment
- Prevention of infection
- Treatment of infection
What are the treatment challenges to parasites?
- Diagnosing
- Effective medications (penetration and resistance)
- Toxicity of medication
- Expense of medication
- Elimination of pathogen
Adult arachnids have how many legs?
4 pairs
What are the most important arachnid vectors?
Ticks
Insects have how many legs?
How many body regions?
3 pairs of legs
3 body regions
3 entomology relationships in humans?
- Parasitic (live on/in us) Mites, lice
- Predatory (feed on us sometimes): Fleas, mosquitos, ticks, (great vectors)
- Polluting: Houseflies spreading germs