Blood-suck­ing par­a­sites that com­mand re­spect

Wicklow People (West Edition) - - LIFESTYLE - PETE WEDDERBURN

MOST peo­ple have a strong aver­sion to ticks, but to me, they are the most ap­peal­ing of all par­a­sites. I have a great deal of re­spect for these hardy, su­per-adapt­able spi­der-like crea­tures. They’ve been around for a long time: even di­nosaurs had ticks. And they’ll be around when hu­mans are ex­tinct.

As part of a re­search project as a young vet, in Africa, I put ticks in a deep freeze to pre­serve them for ex­am­i­na­tion by a spe­cial­ist. A month later, when I thawed them out, they woke up and crawled around.

Ticks hide in the un­der­growth of mead­ows and forests, at­tach­ing to pass­ing an­i­mals, plung­ing their tiny, drill-like mouth parts into the skin, lo­cat­ing a tiny blood ves­sel, and suck­ing blood. They swell up with blood, changing from the size of a lentil to a large pea. Once they are full, they fall off the an­i­mal, land­ing back in the un­der­growth, spend­ing 90% of their life­times off the an­i­mals that they feed from.

Tick life cy­cles in­volve eggs, then three stages, lar­vae, nymphs, then fi­nally, the adult. All stages suck blood. The ticks fall off the an­i­mals in be­tween each stage. It takes be­tween two days and two weeks for a tick to fill with blood, de­pend­ing on the life stage (adults take long­est be­cause they are biggest). Adult male ticks do not swell up with blood and may not even at­tach to an­i­mals at all. Adult fe­males lay hun­dreds of eggs when they fall off, and the eggs then hatch into young lar­vae, and so the cy­cle con­tin­ues.

Ticks used to have spring and au­tumn peaks (so-called “rises”) but in re­cent years, due to the changing cli­mate, they have be­come ac­tive all sum­mer too.

Ticks cause two is­sues for pet own­ers. First, the di­rect harm by the ticks them­selves, and sec­ond, the dis­eases that they can carry.

In gen­eral, the di­rect harm is min­i­mal: they cause a mi­nor ir­ri­ta­tion. Some­times, the tick bite wound can be­come in­fected, caus­ing a painful ab­scess, es­pe­cially if the tick is brushed off or care­lessly re­moved, break­ing off the tiny mouth­parts and leav­ing them em­bed­ded in the skin. If a high num­ber of ticks at­tach, the blood­suck­ing can cause anaemia due to blood loss (sim­i­lar to an an­i­mal bleed­ing from a wound for days on end). And with some ex­otic tick species (not seen in Ire­land) there is a nasty neu­ro­log­i­cal con­di­tion of dogs called Tick Paral­y­sis caused by sali­vary neu­ro­tox­ins pro­duced by the ticks (sim­i­lar to snake venom).

The dis­eases car­ried by ticks are a much more se­ri­ous prob­lem. When they suck a blood meal, ticks also in­ject small amounts of tis­sue fluid and saliva from their own bod­ies, and this of­ten in­cludes dis­ease-caus­ing mi­cro-or­gan­isms.

In Ire­land, the most com­mon tick species is the cas­tor bean tick, Ix­odes rici­nus, which at­taches to rep­tiles, birds and mam­mals. This is the tick most com­monly seen on dogs. Cats are more likely to have a dif­fer­ent species, known as the hedge­hog tick or Ix­odes hexagonus. Both of these ticks also af­fect rep­tiles, birds and farm an­i­mals. Other species of tick are far less com­mon in Ire­land.

Farm an­i­mals can be af­fected by three com­mon tick borne dis­eases: Loup­ing ill (a brain dis­ease caused by a virus, mostly af­fect­ing lambs), Anaplas­mo­sis (known as tick-borne fever, caused by a bac­te­rial in­fec­tion from ticks), and Babesio­sis (or red­wa­ter), seen in cat­tle. Babesio­sis doesn’t af­fect dogs in Ire­land, but the ca­nine ver­sion is com­mon in some Eastern Euro­pean coun­tries. Some im­ported dogs in Ire­land have been re­ported to bring this dis­ease back with them.

The biggest worry for Ir­ish pet own­ers is a tick borne dis­ease that can af­fect hu­mans as well as dogs: Lyme Dis­ease, caused by bac­te­ria called Bor­re­lia burgdor­feri. This causes arthri­tis, as well as heart dis­ease and kid­ney prob­lems,in dogs, and in hu­mans. While still rarely di­ag­nosed in dogs, this has be­come in­creas­ingly com­mon in hu­mans in re­cent years, with about 300,000 cases in the USA each year and an­other 200,000 seen in Europe. The in­crease is thought to be caused by higher tick pop­u­la­tions due to cli­mate change, as well as in­creased lev­els of hu­man ac­tiv­ity in tick-in­fested ter­ri­tory, be­cause of the pop­u­lar­ity of out­door ac­tiv­i­ties (in­clud­ing dog walking). Stud­ies have found no cor­re­la­tion be­tween dog own­er­ship and risk of Lyme Dis­ease in­fec­tion, and in­fected dogs pose lit­tle or no di­rect risk to hu­mans. The risk to hu­mans comes from di­rect con­tact with ticks, so if a dog comes home with lots of ticks, their hu­man is also likely to get ticks them­selves, and they should be aware of this dis­ease.

The risk of in­fec­tion of dogs with Lyme Dis­ease can be re­duced sig­nif­i­cantly by prompt re­moval of the tick, and the use of rou­tine pre­ven­ta­tive prod­ucts that rapidly kill or re­pel ticks is the safest ap­proach. These come as tablets, to be given once a month or ev­ery 3 months, as well as top­i­cal in­sec­ti­cides like spot-on drops or col­lars. Own­ers should also check their dog for ticks at least ev­ery 24 hours, re­mov­ing any ticks us­ing a sim­ple “twist and pull” ac­tion, with a spe­cially de­signed re­mover like the O’Tom Tick Hook. Ticks should be han­dled with care, us­ing gloves, and dis­posed of safely (e.g into fire, or squash­ing while in­side plas­tic bag then into bin). I re­spect ticks, but I still see them as an en­emy!

Ticks are a tiny but re­silient en­emy

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