Epidemiology & Control Flashcards
What is epidemiology?
branch of medical science that studies factors which determine the presence & absence of diseases & disorders
Why is Ascaris a relatively simple parasite to model?
direct, no IH, no amplification
Define per capita reproductive rate.
r: # of eggs produced per worm
Define net reproductive rate.
rA
Define per capita transmission rate.
beta: likelihood eggs will get into a host & develop into adults
Which model components describe parasite reproduction and transmission?
rA = net reproduction & beta = transmission
Which model components describe parasite elimination?
u1 and u2
What balance must be maintained for the parasite to survive in the host population?
reproduction (rA) & transmission (beta) > elimination (u1 & u2)
What host behaviors must be considered in the development of a model?
- contact 2. # of eggs 3. # of hosts
How can our model be applied to the eradication of Ascaris?
increase parasite elimination (Au1 with drugs) and decrease beta (behavior education and drugs)
Would you target parasite elimination or transmission?
transmission
What is Ro?
basic reproductive ratio: avg # of secondary cases that a typical single infected case will cause
How is Ro related to our success in eradication specific diseases?
Ro = 1 is the threshold of parasite survival
Define control.
pathogen continues to exist, but prevalence reduced as consequence of intervention
Define eradication.
pathogen no longer exists anywhere in the world…seldom realistic
Define elimination.
localized eradication: pathogen no longer exists in a specific geographical region
When was smallpox eradicated?
1980
Explain why the smallpox eradication campaign was so successful.
- because Ro is only 2 2. long lasting immunity 3. vaccine 4. absence of animal reservoir 5. gov cooperation 6. funding
What was the one key factor in smallpox eradication?
vaccine: 1. long lasting protective immunity 2. single dose 3. easily administered 4. easy delivery & edu campaign 5. fear of disease -> public acceptance
Have any vaccines against parasites been developed?
no
Why is Dracunculus so close to possible eradication?
education & other control methods
What factors in developed countries have contributed to elimination of many human parasites?
- increased living standards 2. sanitation & hygiene 3. effective waste disposal 4. improved meat inspection
What are the 2 best approaches for most campaigns which are aimed at eliminating or eradication parasites?
education and control
