Lyme Disease Flashcards

1
Q

dead end host

A

a host from which infectious agents are not transmitted to other susceptible hosts
(infected human can’t transmit the disease to other unaffected ticks = level of bacteria circulating in blood = too low)

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2
Q

ecosystem service

A

the quantifiable services than an ecosystem provides to humans

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3
Q

lyme disease

A

zoonotic disease vectored by ticks - small mammals are the main reservoir species

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4
Q

what bacteria cause LD

A

spirochete bacteria

gram-negative

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5
Q

even though there are a number of animals hosts for the pathogen what is the main reservoir

A

mice

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6
Q

what is the vector for the disease

A

ticks

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7
Q

what do ticks need to do in their lives

A

need to malt between different life stages

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8
Q

what must a tick do to become infected

A

feed on an infected host (not human)

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9
Q

what are LD symptoms

A

within a few days: skin rash after bite
days/weeks: fatigue, chills, fever, headache, muscle/joint aches (due to inflammation), swollen lymph nodes, Bell’s Palsy
long term neurological problems: problems with concentration, short-term memory loss, severe arthritis/joint pain

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10
Q

what happens once the bacteria enter the BBB

A

enter the brain - harder to treat as harder to reach

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11
Q

what must happen for human outbreak of LD to occur

A

human must be bitten by infected ticks = need lots of ticks = need to feed on infected hosts

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12
Q

is LD treatable if so with what

A

the earlier you catch it the easier it is to treat - treated by antibiotics - not beta-lactam as gram-negative bacteria

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13
Q

what are vertebrate hosts for larval and nymphal ticks

A

rodents, lizards, birds

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14
Q

what are hosts for adult ticks

A

deer

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15
Q

how do you get infected by LD

A

bacteria found in salivary glands of a tick, enter the body at the site of the bite (compounds in ticks saliva = suppress the immune system), bacteria then migrate out of site of the bite

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16
Q

how would you recognize LD

A

distinctive rash - inflammatory response of the body

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17
Q

who has chronic LD

A

largely in people who have had LD - treated and no longer test positive = treatment worked but still have symptoms

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18
Q

what are 3 explanations of chronic LD

A
  1. hidden infection - (not positive)
  2. autoimmune response - (triggered by initial infection)
  3. something else (psychological factors/immune system problems)
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19
Q

what is the problem associated with chronic LD

A

no evidence: symptoms of chronic LD being caused by bacteria - people convinced of hidden infection = want treatment > long term antibiotics (evolution)

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20
Q

if you increase the awareness of a disease

A

people are more likely to get tested - as science develops, advanced way of testing = increase in no of cases

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21
Q

how and when did we discover LD

A

1921 - joint problems associated with ticks
1975 - cluster of cases of rashes/swollen joints in Lyme
1982 - bacteria discovered

22
Q

could the medical establishment do anything in regards to antibiotic misuse

A

cannot do anything to doctors even if they are harming the patient

23
Q

what is required for an increase in tick density

A

heavy acorn production > increase in mice and deer

24
Q

what happen in the 1960s

A

Watts riot LA (1965) and Detroit riot (1967) = people left city for suburbs - lots of farmland/contact with animals

25
Q

what happen when there was a change in land use

A

reduction of predators = increase in deer = increase in tick density = increase in contact with ticks = LD outbreak

26
Q

what are ticks and what do they do to survive

A

arthropods - malt between different life stages and feed on blood

27
Q

are tick born infected

A

no but they maintain the infection between life stages

28
Q

explain the tick life cycle

A

larvae hatch from eggs take meal > nymphs hatch take meal > adult takes meal

29
Q

how do ticks detect good hosts

A

heat and CO2

30
Q

adult ticks are noticeable but nymphs are not what is the danger

A

harder to detect to eye as they are tiny = can be infected

31
Q

differences between LD on East/West Coast

A
  1. different tick species
  2. different host community
  3. different timing of life cycle (2vs3)
32
Q

why is the larval stage feeding the most important

A

one chance to pick up Borrelia infection before nymphal stage

33
Q

what does the host for tick larval stage determine

A

nymphal infection prevalence

34
Q

what feed are humans at risk

A

nymphal stage feeding

35
Q

the risk to humans is determined by:

A
  1. density of nymphal ticks
  2. infection prevalence in nymphal ticks
  3. human behaviour (walk through vegetation/animals bring back ticks)
36
Q

describe the tick life cycle in the East coast

A

infected nymphs feed in spring = infect small birds and mammals
larvae feed in summer = infected from previous year

37
Q

describe the tick life cycle in the West coast

A

nymphs and larvae both feed in spring = reduce risk of LD - less infected

38
Q

how can altering the host community affect the disease risk

A

can either increase (amplification)
or
decrease (dilution)

39
Q

amplification

A

adding a species to a community increases the total abundance of hosts for a pathogen = increasing the disease risk to the target host

40
Q

dilution

A

adding a species to a community decreases the abundance of competent hosts = decreasing the disease risk to the target host

41
Q

competence (for hosts)

A

the efficiency with which a host acquires and spreads a pathogen

42
Q

as humans move into an area

A

decrease in different species - community becomes simpler - easier for ticks to replicate (in the northeast more nymphs)

43
Q

what happens in the east coast as other species are lost

A

white-footed mice do well
are preferred host of the ticks = more ticks
are a competent host = more infected ticks

44
Q

what is reservoir competence

A

hosts differ in their efficiency at acquiring and spreading borrelia spirochete

45
Q

which host is highly competent

46
Q

which host is somewhat competent

A

deer mouse

47
Q

which host is totally incompetent

A

western fence lizard

48
Q

are lizards good hosts

A

yes but not competent host

49
Q

why are cases for LD so low in CA

A

lizards can’t transmit the disease
when an infected tick bites lizard = leaves uninfected = have complementary protein = destroys bacteria and cleanses tick of infection

50
Q

what are some human behaviours that increase LD risk

A

leaning against a log
carrying wood
sitting on a log