Lice transfer via shearers

By Deb Maxwell, ParaBoss Operations Manager

December 2017

With crutching coming up at home my shearer informed me that the place he was currently on had lice, and did I want to have a day’s gap before he came to my shed?

This was a significant biosecurity issue. I wondered: How likely is it that he might bring lice with him? Was a day’s gap going to solve the problem? What could we actively do to ensure no lice were introduced from the previous shed?

LiceBoss Technical Committee member, Dr Peter James, and Honours student Sarah Crawford, did research on this problem in the late 90s, which provided the answers.

How likely could lice be introduced on shearers' clothing?

Dr James’s work demonstrated that lice could remain alive on moccasins and that the surviving lice were viable and could reproduce when again provided with suitable living conditions. As there is a high death rate in the lice off sheep, the risk is greatest with heavier lice infestations where plenty of lice transfer to the moccasins, rather than with lightly infested sheep.

The study used a moderately louse-infested sheep held in the shearing position for 3½ minutes over well-worn moccasins. In that time, up to 124 lice transferred onto each moccasin.

Was a day’s gap going to solve the problem?

The moccasins in the experiment were then left in mild temperatures (between 16.5 and 23ºC) with some lice surviving for 10 days. Clearly, a single day’s gap, if conditions were mild, is insufficient time for the lice to die.

What could we actively do to ensure no lice were introduced from the previous shed?

If lice could survive so long on moccasins, it is reasonable that other clothing, particularly the lower legs of the shearer’s jeans, could harbour some lice.

Common sense should prevail: when starting at a new property, shearer’s should wear clean laundered clothing and a pair of moccasins or shoes that were NOT worn at the previous property.

Clean clothes are an easy solution, but footwear may present a problem if shearers are moving to new properties each day or so for small jobs.

Dr James found that microwaving the moccasins for 5 minutes or leaving the moccasins in a freezer overnight killed all of the lice. But take care when microwaving!

• Do not microwave footwear with metal buckles or eyelets!
• Monitor closely for smouldering or fire, which can occur if footwear is microwaved for too long or at a higher power (the study used a 700 watt microwave).
• The smell is quite unpleasant. It may be wise to use a microwave out of the house.

If freezing or microwaving is not feasible, and ambient temperatures are hot, place the footwear in a black plastic bag, or on the dashboard of the closed vehicle, in the sun for some hours. But this relies on hot enough temperatures being achieved, which may not occur during winter or in cooler regions.

While transfer on shearer’s clothing is possible, it is still a low risk compared to introduction of lice through purchased or straying sheep.

URGENTLY WANTED: SHEEP LICE

Dr Peter James, University of Queensland, is conducting new research that requires lice from various locations.

What’s involved?
Dr James will come to your property and will use a small vacuum to suck lice from a number of sheep. No sheep need to be taken away. Collection likely in January 2018.

During the process Dr James, who is Australia’s most experienced lice research scientist, will be able to answer your lice management questions.

If you have obviously lousy sheep contact Dr James directly to see whether your situation meets the criteria for a collection. If your sheep don’t have lice, but your neighbour’s do, please pass on this notice.

Dr Peter James, email: p.james1@uq.edu.au, phone: 0408 148 511