Parasites Flashcards
Broadly define parasites
An organism living on or in another living organism to which it takes benefits from whilst actively harming the host.
define the prevalence of infection
The proportion (%) of a population infected
Define the Incidence of infection.
The frequency of a population acquiring infection in a unit of time e.g. 3% per week
Define Intensity of an infection
A measure of the number or density of parasites per host e.g. % of red blood cells infected with malaria.
Define mortality in terms of disease
The number of deaths in a given time or the % of deaths among all cases of infection
Define morbidity in terms of infection
The level of ill health or disability among all cases of infection
What does DALY stand for?
The Disability Adjusted Life Years
Define DALyY in terms of impact on an organism.
Number of healthy years lost to disease, disability or early death.
Name two ectoparasites
Insects and Arachnids
What is polyparasitism?
When one organism is a host to multiple different parasites
how is lyme disease transmitted?
Through Tick bites
How was the Black death transmitted?
Via Fleas on animals like rats.
Why can toxoplasma Gondii considered the worlds most successful parasite?
It currently infects 30% of all humans, and migrates to the brain to alter behaviour.
What are “Neglected Tropical Diseases”?
A group of diseases which cause substantial illness for more than 1 billion people globally.
Briefly describe the lifecycle of Ascaris lumbricoides
Fertilized egg ingested –> Adult eggs in intestinal void –> adults produce more eggs which leave the host back onto soil.
How is Ascaris lumbricoides treated?
Regular oral ingestion of medicine which prevents worm growth.
Name a downside of current treatment of helminths
The drugs do not stop reinfection
Name the life stages of schistosomiasis in order.
Eggs, miracidiae, cercariae, schistosomulae, worms.
Name the life stages of bacteria in mosquitos of malaria
Microgametes grow into macrogametes and then zygotes when fertilised. In the mosquito gut, the ookinete grows into an oocyst which then bursts releasing sporozoites.
Name the life stages of malaria in humans
Merozoites –> erythrocytes –> tropnozoites –> erythrocyte –> Gametocyte
Where do malaria cells multiply?
The red blood cells
What is “people who have the sickle cell trait being protected against malaria” an example of?
Balanced polymorphism due to Heterozygote advantage
What are some ways to prevent the infection of malaria?
Mosquito nets, Vaccines, fumigation of mosquito nests near humans, sterilising males
Name the three types of malaria vaccine and which parts of the life cycle they target
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.
Name the reasons why we dont have 100% effective vaccines against many parasites.
Complex life cycles, high levels of antigenic variation, immune evasion strategies, ability to supress human immune systems
