Protozoan and helminth parasites L17

Question 1

parasitism

Answer 1

this is where the parasite benefits at the expense of the host, either have obligate of facultative parasites

Question 2

obligate parasites

Answer 2

these are parasites that are required to spend at least part of their life cycle in a parasitic relationship

plasmodium falciparum - causes malaria
ascaris lumbricoides - helminth causes ascariasis

Question 3

facultative parasites

Answer 3

these are generally free living but can become parasitic if they enter a suitable host
naegleria fowleri

Question 4

Ascaris lumbricoides

Answer 4

parasitic roundworm - helminth
causes ascariasis
fecal-oral route through ingestion of eggs in contaimined food
hatch in intestine and larvae move to lungs and then back down to mature

Question 5

Plasmodium falciparum

Answer 5

protozoan parasite
causes malaria
spread by bite of female mosquitoes

Question 6

Naegleria fowleri

Answer 6

brain eating amoeba - free living
accuses PAM
enter body when contaminated water goes up in nose

Question 7

definitive host

Answer 7

this is where the parasite reaches sexual maturity

plasmodium falciparum - the mosquito is the definitive host as sexual reproduction occurs in this host

Question 8

intermediate host

Answer 8

a host that is required for parasite development but where no sexual development takes place

plasmodium falciparum- humans are intermediate host, asexual stages but no sexual reproduction

Question 9

incidental host

Answer 9

a host that can be infected but does not play a role in lifecyle

usually a dead end as parasite cannot complete cycle

toxocara canis - dog roundworm, humans are incidental hosts accidentally infected, larvae can migrate but cannot mature

Question 10

paratenic host

Answer 10

no development takes place but parasite remains alive and infective to another host - used as a bridge to gap between hosts in cycle, remains dormant until next host

toxocara spps. rodents can be paratenic hosts that carry larvae until eaten by dog or cat

Question 11

what is parasite maturity

Answer 11

this is the part of life cycle where parasite becomes capable of reproducing , infect host, produce eggs or spores

Question 12

egg or cyst stage - 1st life stage parasite

Answer 12

dormant and protective stage, survives outside the host and is often how parasite spreads

Question 13

larval or juvenile stage - 2nd life stage

Answer 13

actively invades host and may migrate through tissues, however it is immature and not yet reproducing

Question 14

growing stage - 3rd life stage

Answer 14

feeding or active stage, may cause symptoms in host, can multiply asexually

Question 15

mature adult stage - 4th life stage

Answer 15

fully developed and reproductively active, lives in specific organ and may lay eggs or form cysts to exit host

Question 16

helminths characteristics

Answer 16

these are parasitic worms
multicellular eukaryotic organisms
large - seen with naked eye
have organ and tissues
complex life cycles with multiple hosts and larval stages

examples - nematodes, cestodes trematodes

often transmitted via contaminated food,water, hosts

Question 17

protozoa characteristics

Answer 17

singled celled parasitic organisms
unicellular , euakryotic
microscopic
reproduce asexually and sometimes sexually
live in blood, intestines, tissues

ameoboids, flagellates, ciliates, sporozoans

transmit via contaminated food/water or vectors

Question 18

how do parasites enter a host?

Answer 18

most parasites enter through broken skin, mouth or elsewhere

Question 19

helminths features

Answer 19

highly complex parasites and infections
infect orally through skin or vectors bite
infect a range of different tissues and organs
often form long term chronic infections
generally do not proliferate in host, release eggs in faeces or urine

Question 20

3 taxonomic groups of helminths

Answer 20

nematodes - round worms
cestodes - tapeworms
trematodes - flukes

Question 21

challenges of combating helminth infections

Answer 21

helminths are very good at evading and suppressing host immunity - they ar long lived so do not want to kill the host

the large size makes them difficult for immune system to kill or dislodge
takes decades to develop immunity and protective memory
immune suppression is often associated with reduction in pathology

helminths have co-evolved with us so good at manipulating us

Question 22

the whipworm example

Answer 22

most common helminthic infection

sexual reproduction occur in mammalian host

eggs ingested from environment
larvae emerge in duodenum
adults feed in large intestine and where males and females mate

Question 23

taenia solium - tapeworm

Answer 23

in humans via ingesting infected or raw/undercooked meat from cattle or pigs.

Question 24

route and pathology of ascaris infection

Answer 24

nematodes - helminths

route = ingesting eggs from contaminated food or water

pathology - larvae migrate through lungs —> adult worms in intestines —> abdominal pain and malnutrition

Question 25

route and pathology of schistosoma spp

Answer 25

trematodes route= penetration of skin by larvae in contaminated water. pathology = Liver damage, bladder inflammation, blood in urine or stool.

Question 26

route and pathology of Taenia solium

Answer 26

cestode route = Eating undercooked pork with cysticerci (larval cysts). pathology = Intestinal discomfort; if eggs ingested → cysticercosis (larval cysts in brain/muscle).

Question 27

How is Trypanosoma brucei transmitted?

Answer 27

By the bite of a tsetse fly. African sleeping sickness – fever, lymph node swelling, then neurological symptoms and coma.