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This article was published in 1982
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Lice Control in Sheep - the Departmental View
B.P. Healy, Director, Animal Disease Control, NSW Department of Agriculture, SYDNEY NSW
HISTORY
The sheep louse, Damalinia ovis, was possibly introduced with early settlement together with ked and sheep scab. Concerted efforts, which were successful in eradicating scab by 1869, may well have reduced lice to insignificant levels but it may be difficult to explain why 'itch' was often encountered but lice not mentioned in reports until about 1889 - twenty years later, when it was described as a problem in many flocks. 'Itch' appears to have been due to itch-mite but may be it was due to lice unrecognised as such or the local vernacular for lice.
The text 'Parasites of Sheep, 1892' discusses scab, ked and itch but not lice: Were lice regarded as unimportant or did they not exist then?
In 1920-1930 lice were apparently widespread but with defined distributions in each State, i.e. only the wheat belt of N.S.W. Western areas were regarded as too hot and dry for lice survival.
Sulphur dips were used at this time and Cramsie ('Management and Diseases of Sheep, 1920') made the interesting statement - 'A thorough dipping with sulphur dip rids the sheep of this pest but a sulphur and tonic lick will have the same effect. The latter treatment will also strengthen and enrich the blood ensuring the sheep against further attacks. Tests, with successful results during recent years, have been made and this can be safely recommended.'
Perhaps an opportunity was lost during the 1950's to eradicate lice as the availability of chlorinated hydrocarbons at that time enabled easier control with efficient chemicals with considerable residual activity. These attributes overcame some of the present reasons for failure or eradication.
The banning of these compounds in 1962 accentuated the problems of lice control and consensus is that lice now cannot be eradicated. An appropriate level of control should be our aim.
POLICIES IN OTHER STATES
TASMANIA
Tasmania pursues the most restrictive policy and maintains an aim at eradication. Dipping is compulsory, lice is notifiable and quarantinable and release is only possible after two dippings. Certified free flocks can be exempted from dipping. Prosecutions are rarely undertaken but all saleyards and problem flocks are regularly inspected. The aim is to inspect all flocks routinely every 2-3 years.
SOUTH AUSTRALIA
Because of problems of the pastoral areas, as in other states, the aim is control only as eradication is impossible at the present time. Dipping is compulsory. Lice is notifiable and release from quarantine occurs after a satisfactory inspection. Prosecutions for failure to notify, travelling, straying or attempted sale are undertaken together with routine inspection of saleyards, neighbouring and suspicious flocks. The situation remains fairly static with fifty odd flocks in permanent quarantine.
VICTORIA
Similar to South Australia but dipping is not compulsory. Warnings are issued before prosecutions launched. More intensive inspections are carried out in western areas and generally the levels of infestation maintained are very low.
WESTERN AUSTRALIA
As for South Australia, but compulsory dipping is not enforced. Release from quarantine occurs only after 100 days post dipping as a minimum. There is an emphasis on inspection standards but many breakdowns occur. Good opportunities exist for saleyard and lairage monitoring of infection. Levels of infestation and degree of notification appear similar to N.S.W. Major problems occur in the pastoral zone.
QUEENSLAND
Lice is not notifiable or quarantinable. The policy aims only to prevent spread. No dipping requirement except for infested flocks and prosecutions are not conducted. Inspection only of travelling stock, Lice are not considered a problem in the hot inland.
NEW ZEALAND
No notification, quarantine or compulsory dipping but saleyards are inspected and infested sheep shorn and dipped. Owners are warned then prosecuted for exposing sheep for sale. In lieu of no treatment, New Zealand permits spray races and shower dusting but these are not allowed in any Australian state because of inefficiency.
N.S.W. POLICY
N.S.W. has maintained a control policy involving notification and quarantine with release after post dipping inspection. Breaches of notification requirements, travelling, straying or attempting to sell have resulted in warnings then prosecutions for repeat or blatant offenders.
The methods of post dipping inspection, legal enforcement and routine inspection practices vary widely between districts and between inspectors. The apparent level of infestation recorded for any district is, therefore, largely a reflection of the activity and ability of individual inspectors.
The policy, or its implementation, until recently, served to penalise those owners in whose flocks infestations were notified or detected. It gave little encouragement or stimulus to owners to understand the epidemiology or economics of lice infestation. A casual or superficial approach by inspectors does not allow the sheep owner to realise that legislative control is probably responsible for maintaining the status quo.
Consider what would be the short and long term consequences of decriminalising lice. If sheep lice were given the same status as cattle lice, what would be the reaction of sheep stud breeders, of dealers, of wool or lamb producers or of the organisations (L.G.P.A., Pastures Protection Boards) representing them? What would happen to the incidence of lice infested flocks and to the levels of infestation within flocks? What economic losses would be sustained or what prevention, control or eradication steps would be adopted by industry? What would happen to field staff? - alternative occupation or termination?
There are many different points of view by staff both in the field and in Head Office and above, but the glaring lack of base line information prevents a factual assessment. As a result, the policy is one presenting a workable balance between what the sheep owner wants and what is practically, economically, legally and technically possible. The policy is under continuous appraisal. Changes have occurred and no doubt more will follow.
OWNER ATTITUDE SURVEY
This survey involved 292 owners or 1% of the State's sheep owners in 1980. It indicated that:
1. Lice infestation is much more widespread than official records indicate. Notification and detection combined represent only a small proportion of those infected.
2. Sheep owners (76% for and 24% against) regard lice as a significant problem for the industry but most (40% for and 60% against) consider that it is not a problem for themselves. 75% regarded lice as causing substantial economic loss but a lesser problem than footrot, worms or flystrike.
3. They regard neighbours and straying sheep (44%), bad mustering (24%) and purchased sheep (21%) as the main sources of infestation.
4. The majority (89%) of owners routinely dipped, regardless of infestation and 75% admitted to having lice at some time.
5. Most owners (72%) finding infestation in their flock failed to notify.
6. The majority of owners wanted no change to the policy regarding notification (69%) and advice to neighbours (88%). Actually, 95% said that they did not object to neighbours being told if their sheep were lousy.
7. The majority of owners wanted changes to the policy to make dipping compulsory (68%) and to permit sale for slaughter without treatment (63%).
8. Owners were equally divided on compulsory notification of shearing throughout the State.
WOOL STORE SURVEY 1981
This involved 700 properties and revealed that 23.5% of properties had lice infestation. Therefore, 90% of infestations are not detected by usual methods.
Wool store surveying could be a very effective method of traceback of infestations but there are some problems to be resolved before they could be employed. It would have to involve all selling centres.
Expansion of the survey is planned with the aim to obtain more prevalence information and to assess the economic loss caused by lice by comparing productivity and control costs of clean flocks with badly infested flocks.
Wool store inspections are used in Tasmania and advice of detection provided to regional veterinary officers for action at property level.
HYDATID SURVEY
This survey conducted in the Goulburn area in 1979 included an assessment of farmer attitudes to lice amongst other things. The findings were generally similar to the 1980 owner attitude survey but some relevant items were:
* 80 - 90% of sheep owners agree with Government control and want more Government involvement.
* 70% consider that the Department is ineffective in its policy through lack of public relations.
THE CURRENT POLICY
The current policy has attempted to respond to criticisms of the old policy to improve lice control.
Regionalisation has enabled some change and it is expected that more effective publicity will be provided to reduce our poor public relations image. We should aim to overcome our present images of officious saleyard inspectors, 'couldn't care less' attitudes and impersonal decisions from someone in his cosy office at some remote centre.
Relaxation of controls to meet industry requests without materially sacrificing overall control has been possible by permitting infested sheep to be sold for slaughter without treatment from either saleyards or quarantined properties.
As a consequence, owners should be more encouraged to notify as quarantine is less restrictive. Release of quarantine is also facilitated if owners notify. Provided saleyard inspectors adopt a reasonable attitude, fewer owners will attempt to run the gauntlet of consigning known lice infested sheep to saleyards in the hope of escaping detection.
PROSECUTIONS
Generally, owners should not be prosecuted for failure to notify although this is usually the easiest charge to achieve. Having lice is not an offence but to act in total disregard for others is offensive. Therefore, it is intended in the new policy to take a more serious view towards those who expose others to the risk of infestation by allowing lice infested sheep to stray or by attempting to sell lice infested sheep at saleyards.
It is expected that a much greater proportion of prosecutions recommended will be for the latter type of offence rather than for failure to notify as in the past.
The implementation of the new policy should facilitate notification but the levels of lice infestations at saleyards will remain as a barometer of the attitude of the inspector responsible.
A casual or 'couldn't care less' attitude will result in the saleyard obtaining or maintaining an adverse reputation for lice.
An inspector who is not prepared to carry out his duties effectively, not prepared to initiate prosecutions for serious offences, by being too lenient, inconsistent or Mr. Nice Guy will face an increasing problem in his saleyard. A firm stand, with fair and consistent decisions aimed to protect the majority against the indiscriminate minority and supported by adequate publicity and senior staff, will enhance the inspector's standing and respect in the district and the reputation of the saleyards.
LEGISLATION
No momentous changes in legislature are proposed but clarification of some matters has been achieved.
Our responsibility to notify neighbours of both the imposition and release of quarantine has been spelt out as has been the risk of defamatory action if advice of quarantined properties is given to other than the immediate neighbours.
Most, if not all, districts have now had the benefit of one or two day schools conducted by the Director of Legal Services. These schools have endeavoured to dispel the mystic or fear that some staff still feel about court action. It is unfortunate that some inspectors in the field have not yet seen the inside of a courtroom in action except on T.V.
Legal action is often the last resort to get some persons to co-operate in disease control and the success of any legal action, in the eyes of the defendant or of the community, depends much on the attitude and actions of the inspector.
Prosecutions based on fair and consistent decisions, more often than not, result in a marked change of attitude in the person prosecuted, regardless of the court's decision. This has been a frequent personal experience where the person prosecuted has become a significant advocate of the Department's policy and a regular recipient of animal health advice.
Inspectors have important roles to play in publicity, in general, before legal action is taken, and afterwards in publicising the particular offence as an example to others. In addition, convincing magistrates of the seriousness of the matter is important so that more appropriate penalties are considered as now provided for under the Act. The creation of judiciary awareness is no doubt due to the advice of local staff and this becomes an important deterrent to other would be offenders.
Inspectors should also be aware that appropriate costs (salary, travelling, etc.) for all staff involved in the prosecution are to be requested of the magistrate regardless of the DPA.
FUTURE CONSIDERATION
1. Decriminalisation of lice - whilst some case exists for this, current strong objection from industry precludes early adoption. In the owner attitude and hydatid surveys, 80 to 90% of owners indicated that they wanted Government control with at least notification and quarantine.
However, in W.A. the requirement for compulsory dipping has been dropped despite strong support from sheep owners. The change has been accepted by industry and the percentage of owners routinely dipping has risen rather than fallen since the requirement was removed.
2. Publicity - a more effective campaign is indicated to highlight the epidemiology and economic aspects and regulatory control of sheep lice. Motivation for such publicity is probably hampered by the lack of base information on economic losses due to lice.
Costs of Government control can be obtained and probably involve less than 0.5ยข per sheep. Dipping costs and losses from dipping (acute deaths, mycotic dermatitis, post dipping lameness and mortalities) can be extrapolated from F. Wilkinson's work in W.A. with cognisance of the higher incidence of mycotic dermatitis in W.A. and the development of pour on insecticides for sheep.
It is the cold hard statistics of loss of wool (or meat) production per sheep or per hectare and the loss of fleece weight quality and price which results from the various levels and durations of lice infestation in different classes of sheep under different environmental or pastoral conditions that are not readily obtainable.
The proposed extension of the wool store survey may enable the provision of answers to some aspects. In the interim, figures quoted by other workers will have to suffice.
Wilkinson in W.A. estimated that heavy lice infestation caused a reduction of 0.5 kg wool per sheep with additional losses in processing due to decreased fibre lengths and increased card and soil losses. He estimated that these losses represented 0.5% of the State's wool clip which was worth $150 million in 1976.
Tony Parsons in 'Country Magazine', September 1979, based on a S.A. survey some years before, stated that sheep with heavy lice infestations produced 0.8 kg less wool than similar clean sheep and that losses (productivity, quality and control costs) averaged $3.77 per head.
Parsons' quotation of the remark by Trevor Picker, renowned fine wool breeder from Bigga in the Central Tablelands, 'What's the use of saving a few cents by missing dipping if you end up with lousy wool', probably reflects the attitude of most sheep owners.
3. Staff motivation - The challenge faced by each inspector to provide an appropriate service to his district. A challenge also to his VI, DVO, RDVS to ensure that this motivation is developed and maintained. Direction, encouragement and support for such staff is vital to maintain this correct attitude to what is often an arduous duty.
4. Post dipping inspections - for release from quarantine. This is obviously an area requiring training and standardisation. Light lice infestation can easily be overlooked.
In W.A. inspections are not carried out until at least 100 days post dipping and a standard procedure (5 animals, 20 openings each) is followed. 15% of flocks fail this inspection and have to re-dip.
In S.A. where the post dipping interval and inspection standards are not stated, 5% of properties fail.
Even the failure rate is unknown in N.S.W. reflecting our lack of maintaining epidemiological data.
It is hoped that regional training schools can be conducted to overcome any deficiencies in procedures, to develop uniformity throughout the district and to instigate epidemiological data collection.
5. Division of State - Both S.A. and W.A. have distinct extensive (pastoral) and intensive zones similar to NSW where lice present different problems. In W.A. different policies apply to the two areas but in NSW the only difference is in regard to notification of shearing.
Flocks in western NSW were believed to be free of lice until about 1946 when extensive restocking occurred after a severe drought. This area is now generally infected and because of mustering and fencing problems, it will probably remain so for some time to come. Compulsory shearing notification applies in this area and industry has requested that this requirement be retained.
Consideration is being given to gazetting the western division as a quarantine area and invoke movement controls into central and eastern areas. Strict movement controls are enforced in W.A. for movement from the pastoral to the south west area and for movements within the south west area. In this latter area, a 30/30 day rule applies. This allows sheep that have been dipped within 30 days of shearing and held in isolation to be moved for sale at saleyards within 30 days of dipping. This rule could be adopted in our existing quarantine scheme.
Following its introduction in W.A., notifications increased from 29% to 40% of known infested flocks.
6. N.Z. Area Dipping Scheme - These are voluntary eradication schemes based on defined areas or organised groups of farms where all shearing and dipping is synchronised and all assist. These involve local farmer committees with good extension and help from staff. They do require energetic staff, informed cooperating owners and good base economic data.
IMPORTANT FACTS IN DRAFTING POLICY
A. A Practical Policy
I. No inspection technique will detect 100% of inspection. Therefore, one cannot certify freedom from infection in any situation.
II. Many owners are unable to recognise lice. Therefore, less notifications than actual infestations.
III. Sufficient staff to inspect all flocks is unobtainable. Therefore, some will remain infected to transmit infection.
B. An acceptable Policy
I. Based on owner co-operation rather than coercion. Aim to 'decriminalise' lice but accept that flagrant disregard for neighbours' welfare as a 'crime'.
II. Movement controls at an 'acceptable risk' level rather than a 'no risk' level.
III. Division of state into quarantine and eradication areas if benefits of control outweigh disadvantages of claims of confusion and discrimination.
IV. Increased publicity - identification of lice, economic effects, methods of control and prevention, dipping technique, etc.
V. Training of staff
(a) to understand the problem of lice;
(b) to direct a level of control appropriate to the area;
(c) to carry out an acceptable and effective method of surveillance of properties and saleyards; and
(d) inspection techniques at saleyards and for release of quarantine.
VI. Surveys to monitor infection and the effects of policy implementation.
VII. The collection and collation of full epidemiological data.
WHY ERADICATION OF LICE IS UNLIKELY IN N.S.W.
1. Incomplete musters particularly in some parts of western areas and in forest lease country on the highlands.
2. Continuous movement of infested sheep (usually off shears and with light infestation) from Western to inner areas.
3. Split shearing, e.g. rams often shorn at time far removed from main flock. Fat lambs not shorn.
4. Neighbours and purchased sheep often shorn at different times.
5. Inefficient shearing - too many cuts may delay dipping which may even be omitted.
6. Inefficient dipping in shower or plunge dips or use of spray dips which are reliably ineffective.
7. Modern insecticides have low residual value through conventional dips.
8. If neighbours are not informed - spread is possible.
9. Inadequate fencing - a worsening economic situation. Additional problems from fire, flood, pigs, kangaroos and other animals.
10. Traditionally, little co-operative effort between neighbours - Group control unlikely.
11. Poor management - a small proportion of owners mentally or physically incapable of controlling sheep let alone lice.
12. Straying sheep.
13. Hobby farmers - ignorance and economics of lice control.
14. Inefficiency or human error in well-meaning owners - unable to follow and carry out dipping instructions, mixing, topping up, diagnosis of lice and other technical problems. Publicity will help but not solve to enable eradication.
15. Inadequate motivation to report lice. Many producers regard the only disadvantage of a light infestation is the small risk of being reported or detected when selling sheep.
16. Stock agents deliberately or inadvertently give misleading advice for various reasons. Informed motivated stock agents can assist lice control substantially as they are an important advisory source to owners.
17. Inadequate motivation to look for lice and even then many owners would be unable to identify or even suspect lice an increasing problem as incidence of infestations diminish or as control measures impose a stigma on infected flocks.
18. Grossly inadequate official manpower to effect eradication.