Name: PowerPoint Presentation
Uploaded: 2022-09-22
Duration: 5 min
Description: Lyme disease: Be aware of different tick life stages.

Across Western Europe, just one species of tick carries Borrelia - a spirochete bacteria which can cause Lyme disease in humans.. 

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Lyme disease: Be aware of different                                                   tick life stages

In other regions of the Northern Hemisphere, three other very closely related species also transmit  Borrelia . The biology, behaviour and disease-transmitting attributes of these are, to all but the specialist, identical with that of our European tick.

Across Western Europe, just one species of tick carries Borrelia  - a spirochete bacteria which can cause Lyme disease in humans.

Its Latin name is  Ixodes ricinus  – here it shall simply be referred to it as ‘tick’  or  ‘ticks’

Websites and public health-related documentation relating to Lyme disease frequently use images of adult female ticks on their banners and front pages. 

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Websites and public health-related documentation  relating to Lyme disease frequently use images of adult female ticks on their banners and front pages

The adult female is relatively large, visually striking and therefore easier to photograph and film.

But the real danger from the viewpoint of Lyme disease is the much smaller  nymph

The tick has three active life stages :. - Larva. 

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The tick has three       active life stages :

So, a tick with say, a  minimum life-cycle length of 18 months spends just 19 days feeding on host animals – 3.5% of its time on the host and 96.5% on the ground, digesting, moulting, not moving (quiescent) or questing

The likelihood of being bitten by an infected adult male tick is remote in the extreme.

There is no  hard  evidence that larvae can transmit   Borrelia .

So, it is the nymph and the adult female tick that pose the  real  risk of disease transmission.

Lyme disease: Be aware of different tick life stages. 

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Once a tick has taken a blood meal from a host, its appearance changes and it becomes bigger and more rounded as distinct from the flat shape of unfed ticks

Walker – shorts, bare legs, no tick repellent

Nymph will feed for 3 to 4 days and then detach and drop to the ground

Now – watch the tick (nymph) ambushing the unsuspecting walker

Note  – ticks are tiny.  Tick  s ize relative to human leg is exaggerated here for the purpose   of visualisation

Nymph. Adult female. Lyme disease: Be aware of different tick life stages. 

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The se  video clip s  below show the true  relative  sizes of nymph and adult female  ticks   on  a human forearm

Oil barrier painted on wrist - tick turns and walks parallel to it

In these video clips, the human subject was able to feel the movement of the adult female on the skin but did NOT feel the nymph. 

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In these video clips, the human subject was able to feel the movement of the adult female on the skin but did NOT feel the nymph

And the small size of the nymph means it can be easily overlooked

Remember that the vast majority of Lyme diseases cases result from bites by nymphs -  not  by adult ticks.

So - be particularly watchful for the tiny nymph  when examining yourself, your children, your clothing  and any dogs you may have, after being outdoors in a  “tick risk” area.

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