Parasitology Introduction Flashcards
WHAT IS A PARASITE?
any organism that takes metabolic advantage of another organism, could cause mental or physical harm
(exclude negative impact)
animals, plants, fungi, bacteria, and viruses, which live as
host-dependent guests
Parasitism is one of the most
successful and widespread ways of life
What are the different forms of parasitism?
- Facultative parasites: can be free living and don’t require host
- Obligate parasites: can’t live outside host
- Endoparasites: live inside host
- Ectoparasites: surface of host
what does PARASITOLOGY study?
protozoans and eukaryotic multicellular organisms
what is PHYLOGENETICS?
THE STUDY OF EVOLUTIONARY RELATIONSHIPS AMONG BIOLOGICAL ENTITIES
what
HOW ARE PARASITES ORGANIZED?
- protozoa: single cell microscopic eukaryotes
- helminths: parasitic worms, macroscopic, multicellular eukaryotes
- arthropods: insects, macroscopic, multicellular eukaryotes
WHY ARE THERE SO MANY PARASITIC DISEASES?
- We must drink to survive
- We must eat to survive
- we must interact with our environment
does parasitic relationship indicate transmission of disease?
no, not all parasitic relationships transmit disease
effects on parasites?
high climate = more parasites bc insects prefer warm climate
contaminated water
lower economy
Over — species of protozoa have been described so far and many have been —; ~ — currently living
200,000
fossilized
35,000
what type of organism is a protozoan?
eukaryotic single-celled organisms
characteristic of free living species?
occupy every conceivable ecological niche (high temp, high salt)
~ __ different protozoams are parasitic to humans
70
what does it mean to be a heterospecific host?
can’t infect their own species – infect other vertebrates/invertebrates
how are parasites classified by motility?
- flagelletes
- amebae: squish and push protoplasm towards one end
- sporozoa: move by worm-like gliding
- ciliates: hair-like cillia
mechanism of parasitic entry?
- oral
- sexual
- inhalation
- direct contact
- arthropod vectors
how do parasites divide and reproduce?
asexual, sexual, or both
what is a monoxenous parasite?
lives within a single host during its whole life cycle (asexual or sexual depending on species)
what is diheteroxenous parasite?
lives within a two host during its life cycle
* final/diffinitive host and intermediate host
what is triheteroxenous parasite?
lives within 3 hosts in life cycle
first intermediate, second intermediate, and final host
what occurs in a diffinitive host?
usually sexual reproduction of parasitic organism
what occurs in an intermediate host?
usually asexual reproduction of parasite
what are the factors that ensure parasitic survival?
- immune evasion: antigenic variation, niche selection, inhibition of host immune response, entering long lasting dormant stage
- non-immune evasion: enter environmentally resistant stage (survuve in area they don’t usually survive)
What is parasitic pathogenesis?
- host cell death
- secrete virulence factors
- biproducts of metabolism are toxic to host
how is malaria transmitted?
3 ways
infected human gets mosquito bite -> mosquito has parasite -> next human bit gets infected
- can also be in utero if pregnant and get infected by malaria (congential)
- contamination through blood transfer, organ transplant, needles if infected with malaria - transfer merozoite stage
What is the malaria causing parasite?
what type of parasite, molility?
a single celled parasite from plasmodium genus (endoparasite, obligative, sporozoan) that can infect humans and animals
what are the 5 human infecting plasmodium parasites?
- P. falciparum: most severe, Africa
- P. vavx: relapse of infection Asia + Africa
- P. ovale: similar to vavx, more in Africa bc negative more duffy blood group
- P. malariae: chronic infection lifelong
- P. knowlesi: new, zoonotic from monkey, quick 24hr life cycle!
What is the vector for malaria transmission?
why does canada have less malaria cases
female ANOPHELES MOSQUITOES
uncommon mosquito in canada
why are only female anopheles mosquitos infectious vectors?
- femals take blood meals for egg production
- blood meals contain malaria
blood not main food source – sugar is, so males do not take male meals
factors that effect malaria global distribution?
climatic factors such as temperature, humidity, and, standing water to lay eggs, rainfall
what type of reproduction occurs for plasmodium falciparum?
diheteroxenous: humans intermediate host and mosquitoes definitive host
what do merozoites eat when in humans? What is the effect on humans?
when merozoites are in RBCs, they eat hemoglobin but heme grp is toxic on its own for parasite and humans
enzyme that eats globulin part and stacks heme groups on top of each other in a crystal structure called hemozoan (metabolic structure that is a toxic byproduct for humans)
malaria symptoms?
- anemia (RBC destruction)
- jaundice (liver infection)
- flu like symptoms
malaria diagnosis?
- blood smears: take blood sample look at microscope (diff structure for which type of malaria parasite)
- PCR
malaria steps of treatment?
- determine which species of malaria
- clinical status of patient (pregnant, child, immunocompromised?)
- determine drug susceptibility/resistance (CDC)
WHY HAVEN’T WE GLOBALLY ERADICATED MALARIA?
- sporozoites are good at hiding from immune system
- overlap of sickle cell trait (not ideal for parasite to thrive)
- ecosystem relationship between humans and mosquitos
malaria prevention?
- case management
- insecticide treated nets
- indoor spraying
- antimalarial drug: prophylaxis
- children vaccine in Africa
