L25 People parasites and pets

Question 1

Define Parasite

Answer 1

‘A parasite is an organism living in or on another living organism, obtaining from it part or all of its organic nutrition, commonly exhibiting some degree of adaptive structural modification and potentially causing some degree of damage to its host’

Question 2

What is commensualism

Answer 2

one species benefits and the other is unharmed

Question 3

What is mutualism

Answer 3

Mutually beneficial symbiotic, can be essential

Question 4

What is parasitism

Answer 4

One species benefits, the other is harmed

Question 5

What is meant by prevalence

Answer 5

The proportion (%) of a population infected,

Question 6

What is meant by incidence

Answer 6

The frequency of a population acquiring infection in a unit of time

Question 7

What is meant by intensity

Answer 7

Measure of the number or density of parasites per host

Question 8

What is morbidity

Answer 8

The level of ill-health or disability among all cases of infection, or among the general population

Question 9

What is Mortality

Answer 9

The number of deaths in a given time, or the % of deaths among all cases of infection

Question 10

What are DALYs

Answer 10

Disability Adjusted Life Years
A measure of overall disease burden. Number of healthy years lost to disease, disability or early death

Question 11

Where do these diseases come from: Ascaris, Schistosomiasis, Malaria, Sleeping sickness

Answer 11

Ascaris is directly transmitted through faecal contamination of soil
Schistosomiasis is snail-borne
Malaria is mosquito-borne
Sleeping sickness is tsetse fly-borne

Question 12

Types of parasites

Answer 12

Protozoa
Helminths
Arthropods

Question 13

Types of parasitic protozoa

Answer 13

Amoeboid
Kinetoplastid
Apicomplexa

Question 14

Types of Helminths

Answer 14

Nemetoda
Platyhelminthes

Question 15

Types of ectoparasites

Answer 15

Insects (lice and fleas)
Arachnids (ticks)

Question 16

What is zoonosis

Answer 16

An infection or disease that is transmissible from animals to humans under natural conditions

Question 17

Toxicara Canis: target organism and how its infected, what it does

Answer 17

Dogs and foxes
infection by ingesting eggs from soil
Invades liver, causes fevers, can impair sight

Question 18

Toxicara Canis life cycle

Answer 18

Adult females release eggs in faeces
Eggs hatch in stomach releasing larvae
Larvae migrate (lungs, liver, brain)
In dogs, move to small intestine and mature to adult worms

Question 19

What happens to Toxicara Canis during dog pregnancy

Answer 19

larvae is reawakened
Larvae travel cross placenta to infect pups or migrate into colostrum to infect milk

Question 20

What is the Echinococcus granulosus’ definitve and intermediate host

Answer 20

Definitive host: dog
Intermediate host: sheep

Question 21

Echinococcus granulosus cycle in the body

Answer 21

Embryonated egg in feces
Onconosphere hatches; penetrates intestinal wall
Hyatid cyst in various organs

Question 22

Toxoplasma gondii key features

Answer 22

Protozoan parasite
Zoonotic
Cosmopolitan
Definitive host: cats

Question 23

What do oocysts develop into to disseminate infection in the host

Answer 23

Tachyzoites

Question 24

Toxoplasma gondii cycle

Answer 24

Oocysts -> oral ingestion -> Tachyzoites (acute infection) -> Bradyzoites (chronic infection)-> can reactivate

Question 25

What are the pathological consequences of toxoplasma infection

Answer 25

Cysts in brain (mice loose aversion to cats)
Tachyzoites invade foetus (infection of brain)

Question 26

What parasites spread lyme disease

Answer 26

Ticks