Parasites

Question 1

Broadly define parasites

Answer 1

An organism living on or in another living organism to which it takes benefits from whilst actively harming the host.

Question 2

define the prevalence of infection

Answer 2

The proportion (%) of a population infected

Question 3

Define the Incidence of infection.

Answer 3

The frequency of a population acquiring infection in a unit of time e.g. 3% per week

Question 4

Define Intensity of an infection

Answer 4

A measure of the number or density of parasites per host e.g. % of red blood cells infected with malaria.

Question 5

Define mortality in terms of disease

Answer 5

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

Question 6

Define morbidity in terms of infection

Answer 6

The level of ill health or disability among all cases of infection

Question 7

What does DALY stand for?

Answer 7

The Disability Adjusted Life Years

Question 8

Define DALyY in terms of impact on an organism.

Answer 8

Number of healthy years lost to disease, disability or early death.

Question 9

Name two ectoparasites

Answer 9

Insects and Arachnids

Question 10

What is polyparasitism?

Answer 10

When one organism is a host to multiple different parasites

Question 11

how is lyme disease transmitted?

Answer 11

Through Tick bites

Question 12

How was the Black death transmitted?

Answer 12

Via Fleas on animals like rats.

Question 13

Why can toxoplasma Gondii considered the worlds most successful parasite?

Answer 13

It currently infects 30% of all humans, and migrates to the brain to alter behaviour.

Question 14

What are “Neglected Tropical Diseases”?

Answer 14

A group of diseases which cause substantial illness for more than 1 billion people globally.

Question 15

Briefly describe the lifecycle of Ascaris lumbricoides

Answer 15

Fertilized egg ingested –> Adult eggs in intestinal void –> adults produce more eggs which leave the host back onto soil.

Question 16

How is Ascaris lumbricoides treated?

Answer 16

Regular oral ingestion of medicine which prevents worm growth.

Question 17

Name a downside of current treatment of helminths

Answer 17

The drugs do not stop reinfection

Question 18

Name the life stages of schistosomiasis in order.

Answer 18

Eggs, miracidiae, cercariae, schistosomulae, worms.

Question 19

Name the life stages of bacteria in mosquitos of malaria

Answer 19

Microgametes grow into macrogametes and then zygotes when fertilised. In the mosquito gut, the ookinete grows into an oocyst which then bursts releasing sporozoites.

Question 20

Name the life stages of malaria in humans

Answer 20

Merozoites –> erythrocytes –> tropnozoites –> erythrocyte –> Gametocyte

Question 21

Where do malaria cells multiply?

Answer 21

The red blood cells

Question 22

What is “people who have the sickle cell trait being protected against malaria” an example of?

Answer 22

Balanced polymorphism due to Heterozygote advantage

Question 23

What are some ways to prevent the infection of malaria?

Answer 23

Mosquito nets, Vaccines, fumigation of mosquito nests near humans, sterilising males

Question 24

Name the three types of malaria vaccine and which parts of the life cycle they target

Answer 24

Sporozoite Vaccine - when the mosquito has just bitten the human. Merozoite Vaccine - targets proteins required for the invasion of cells. Gametocyte Vaccine - Blocks transmission to new host i.e. mosquito that bites wont pick up the gametocytes.

Question 25

Name the reasons why we dont have 100% effective vaccines against many parasites.

Answer 25

Complex life cycles, high levels of antigenic variation, immune evasion strategies, ability to supress human immune systems