PaBi (17): immunoepidemiology of macroparasites Flashcards

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1
Q

Give examples of some macroparasites.

A

Fleas, ticks, lice, helminths

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2
Q

What is epidemiology?

A

The study of the incidence and distribution of a disease and how it can be controlled.

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3
Q

What are some features of macroparasites?

A

large multicellular organisms- visible to the eye, antigenically complex, don’t multiply in the host- increase in parasites within the host caused by reinfection, complex life cycle, long generation times.

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4
Q

Briefly, what is the Ro of macroparasite?

A

The number of offspring produced and reaching maturity in an ideal world i.e. no competition, no immune response.

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5
Q

What is the exact Ro definition?

A

The average number of female offspring produced throughout the lifetime of a mature female parasite which themselves achieve reproductive maturity, in the absence of density-dependent constraints on the parasite establishment, survival or reproduction.

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6
Q

How are levels of macroparasites measured?

A

Either directly by counting the number on the skin or indirectly for endoparasites by taking faeces/ urine samples, passing them through a filter so the eggs stick and counting the eggs under the microscope.

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7
Q

What are the epidemiological patterns of ticks?

A

Tend to affect older cows more and in December

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8
Q

What is the benefit of knowing the epidemiological patterns and seasonal variations of a parasite?

A

Allows you to know when is best to treat and which animals are best to treat if you have little money and can’t treat them all.

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9
Q

What is the statistic for the frequency distribution of schistosomiasis?

A

The 20-80 rule- 20% of the people have 80% of the infection so it’s best to try and treat that 20%

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10
Q

Why is it beneficial to look for the age group that is most infected?

A

Allows identification and easier treatment of the people who carry most of the infection.

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11
Q

What is peak shift?

A

This is a relationship between age and peak levels of infection- at high transmission rates, peak infection will be at a younger age compared to lower transmission rates.

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12
Q

Who is most predisposed to re-infection after treatment?

A

The same group that had the highest incidence of infection the first time because they still have the highest exposure e.g. they still drink/ wash with the same infected water.

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13
Q

How can you assess peoples exposure to an infective agent?

A

Identify exposure sites and people’s behaviour e.g. who uses the contaminated sites and what for- boys/girls, men/women, swimming/washing/drinking. Look at exposure history by using questionnaires or taking blood samples to test for antibodies.

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14
Q

In lambs, what factor accounts for 30% of their susceptibility to helminths?

A

Genetic factors- can breed for certain resistant genotypes.

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15
Q

What are the benefits of herd immunity?

A

When large numbers of the population are immune, it is harder to carry on the chain of transmission in diseases passed from person to person.

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