NSW Police Force (Western Region) v Smith - [2011] NSWWCCPD 8

WORKERS COMPENSATION COMMISSION
DETERMINATION OF APPEAL AGAINST A DECISION OF THE COMMISSION CONSTITUTED BY AN ARBITRATOR
CITATION:		NSW Police Force (Western Region) v Smith [2011] NSWWCCPD 8
APPELLANT:		NSW Police Force (Western Region)
RESPONDENT:		John Andrew Smith
INSURER:		Allianz
FILE NUMBER:		A1-4445/10
ARBITRATOR:	Mr Robert Caddies
DATE OF ARBITRATOR’S DECISION:		9 November 2010
DATE OF APPEAL DECISION:		22 February 2011
SUBJECT MATTER OF DECISION:		Section 4 of the Workers Compensation Act 1987; injury; proof of causation; circumstantial evidence
PRESIDENTIAL MEMBER:		Deputy President Kevin O’Grady
HEARING:		On the papers
REPRESENTATION:		Appellant:	Turks Legal
Respondent:	Whitelaw McDonald Solicitors
ORDERS MADE ON APPEAL:		The Arbitrator’s finding and orders as found in Certificate of Determination dated 9 November 2010 are confirmed. The appellant is to pay Mr Smith’s costs of this Appeal.

BACKGROUND TO THE APPEAL

Mr John Andrew Smith, who is 41 years of age, served as a police officer with the NSW Police Force (the appellant) until his retirement on medical grounds in 2010. In 2008 he held the rank of Senior Constable and was stationed at Inverell, New South Wales. In March 2008 he sought treatment for symptoms of fever following which he was diagnosed as suffering acute Ross River Virus infection (RRV). It is alleged by Mr Smith that the condition RRV was caused by his exposure to infected mosquitoes in the course of his work with the appellant. He became incapacitated for work by reason of medical complications following his infection which included fatigue and pains in his joints.
A claim for compensation benefits was made by Mr Smith and he received weekly compensation and medical expenses until 4 August 2010 at which time liability for such payments was declined on behalf of the appellant by its insurer.
In February 2010 a claim was made on behalf of Mr Smith by his solicitors against the appellant in respect of lump sums pursuant to s 66 and s 67 of the Workers Compensation Act 1987. That claim was denied. An Application to Resolve a Dispute was filed on behalf of Mr Smith with the Commission on 3 June 2010. The matter came before an arbitrator for conciliation/arbitration on 12 August 2010. The matter proceeded to hearing following which the Arbitrator reserved his decision. A determination was made on 9 November 2010 at which time a Certificate of Determination, accompanied by a Statement of Reasons (Reasons) for that decision, was issued by the Arbitrator.

THE DECISION UNDER REVIEW

The Certificate of Determination dated 9 November 2010 records the Arbitrator’s finding and orders as follows:
“1.     Finding that on or about 28 and 29 February 2008, the Applicant suffered injury by mosquito bites in the course of his employment with the Respondent which resulted in him acquiring Ross River Fever and the post-infective fatigue syndrome following the Ross River virus infection.
2.     There being no other issue in the proceedings, remit the matter to the Registrar for referral to an Approved Medical Specialist on the following basis:-
(a) Date of Injury: on or about 28 and 29 February 2008
(b) Matters for assessment: Haemapoietetic System
(c) Method of Assessment: WPI
(d) Evidence:
(a) Application to Resolve a Dispute and attached document;
(b) Report of Professor Andrew Lloyd dated 19 July 2010;
(c) Reply and attached documents;
(d) The Applicant’s general practitioner’s records
(e) Report of Associate Professor Damon Eisen dated 20 July 2010;
(f) Curriculum vitae of Associate Professor Damon Eisen.
3.     Order that the Respondent pay the Applicant’s costs as agreed or assessed.
4.     I certify on the application of the Applicant that this matter is complex and grant an uplift of 25%.
5.     Reasons for uplift
This is a matter of complexity and importance requiring a careful review of the mechanism of the injury, consideration of the incubation period necessary, consideration of the facts which could give rise to an inference of injury in the course of employment of the Applicant with the Respondent and as to the nature of the determination to be made by the approved medical specialist. I have no hesitation in granting an uplift. I determine the uplift as being 25% (both parties).
A brief statement is attached to this determination setting out the Commission’s reasons for the determination.”
An application seeking leave to appeal against the Arbitrator’s decision was filed with the Commission on 7 December 2010.

ISSUE IN DISPUTE

The issue in dispute in the appeal is whether the Arbitrator erred in finding that Mr Smith received injury, being infection with RRV, arising out of or in the course of his employment with the appellant.

ON THE PAPERS REVIEW

Section 354(6) of the Workplace Injury Management and Workers Compensation Act 1998 (the 1998 Act) provides:
“(6) If the Commission is satisfied that sufficient information has been supplied to it in connection with proceedings, the Commission may exercise functions under this Act without holding any conference or formal hearing.”
Having regard to Practice Directions Nos 1 and 6, the documents that are before me, and the submissions by the parties that the appeal can proceed to be determined on the basis of these documents, I am satisfied that I have sufficient information to proceed ‘on the papers’, without holding any conference or formal hearing, and that this is the appropriate course in the circumstances.

LEAVE

There is no dispute between the parties concerning the threshold requirements as prescribed by s 352 of the 1998 Act.
In the circumstances, and having regard to the matters raised on submissions, I conclude that it is appropriate that leave be granted to proceed with the appeal and I so order.

THE ARBITRAL PROCEEDINGS

The proceedings before the Arbitrator were recorded and a Transcript (T) has been produced and made available to each of the parties. That transcript records submissions put on behalf of each party. Also recorded is short evidence given, by leave, by Mr Smith. That evidence is addressed below. No other oral evidence was adduced before the Arbitrator.
The documentary evidence which was before the Arbitrator was summarised by him at [18] of Reasons.

Mr Smith’s Evidence

The evidence of Mr Smith is to be found in a written statement made by him dated 28 May 2010 and in the oral evidence, given by him before the Arbitrator. It is important to note that certain dates which appear in the written statement were corrected by Mr Smith in the course of his oral evidence. Those corrections were made following tender by the appellant of late documents at the hearing which included copies of Mr Smith’s duty roster at the relevant time. It is clear that Mr Smith had been on leave for a period in February 2008 and that following his return to duty in late February he was engaged on three consecutive days being 28 and 29 February and 1 March 2008 on a cannabis related operation. The nature of Mr Smith’s duties on those days is addressed below.
At relevant times Mr Smith resided with his family on a rural property some distance from Inverell. The property, being some 130 acres, is mostly cultivated or open grazing land together with approximately 20 acres of lightly timbered grazing country. The property is utilised to fatten cattle and sheep. Mr Smith and his family reside in a cottage on the property which is situated approximately 400 metres from a dam. The cottage is equipped with fly screens on all windows. The house yard is mainly lawn with a few trees. There are no low points in the cottage yard which would hold surface water. Water storage tanks supplying the cottage are equipped with mesh fitters on inlets and overflows. Mr Smith states that since moving to the property in 2006 mosquitoes have not been a problem. He states that occasionally in summer there may have been “the odd small black mosquito”.
Mr Smith’s evidence, as corrected, concerning his duties is that on 28 February, during the cannabis operation, he attended areas around Armidale, Gyra, Tingha, Bundarra and Inverell. During that day’s duty he did not notice any mosquitoes at the various locations which he attended.
On 29 February 2008 Mr Smith’s shift commenced at 6:00 am and concluded at 6:30 pm. He attended Wytaliba which is approximately 60 kilometres east of Glen Innes. Mr Smith states that, in the past, police have located large amounts of cannabis which had been cultivated in that vicinity. On that day cannabis was located and Mr Smith and others were engaged in removal of the plants. That work continued throughout the day during which large amounts of cannabis plants were removed from the bushland. Where cannabis is found there is generally a watering system in place. Those systems are improvised drip watering systems utilising drums and plastic sheeting. The ground around the plants was moist and at times swampy. During that day Mr Smith noticed there were a lot of mosquitoes both in the air, in the cannabis plants and also on his body. He was bitten by mosquitoes on numerous occasions and at times the bites were irritating causing him to scratch his skin.
The following day, 1 March 2008, Mr Smith returned to the vicinity of Wytaliba. On this occasion the authorities had a search warrant which was executed at a property. Cannabis plants were again located and Mr Smith was required to remove them. The conditions on this day were similar to the conditions encountered the day before. Mr Smith states that the weather during those days was “very humid if not tropical”. The ground was quite wet and at times he was working in swampy conditions with large numbers of mosquitoes present. The mosquitoes he observed were “not the normal small black household mosquitoes but large striped mosquitoes”. His shift, again, extended from 6:00 am to 6:30 pm.
On 2 March 2008 Mr Smith commenced a three consecutive day rest period. When he awoke on that day he was “quite sore”, felt tired and noticed a mild rash on his stomach. He felt as though he was experiencing the early stages of a cold or flu. Those symptoms continued and worsened over the next two weeks. He began to suffer extreme fever and sweats especially at night. He was prevented, by reason of those symptoms, from continuing work and consulted a general practitioner, Dr Boates. His usual medical officer was not available.
Mr Smith states that a blood test was arranged by Dr Boates which confirmed that he was suffering from RRV. By that time he was experiencing difficulty moving by reason of muscle pain. Mr Smith remained absent from work until 7 April 2008 following which he returned, it seems, to part-time work on a return to work program instituted by the appellant. Upon return to work Mr Smith experienced difficulty completing his shift by reason of fatigue. That fatigue has remained with him. He was referred to Professor Andrew Lloyd at the Prince of Wales Hospital in Sydney and then to the Fatigue Clinic at Randwick.
Mr Smith stated in his oral evidence that he made a claim for compensation benefits in March 2008 and that he had been paid such benefits until early August 2010. The benefits which he received included weekly payments and medical expenses. He also stated that, when he received notice of cessation of payments, he had been advised that the denial of liability had been based upon the opinions of Associate Professor Eisen and Dr Whittaker. When cross-examined he accepted a proposition put to him by counsel that “you could have been bitten by a mosquito in your home and you wouldn’t have known”(T8).
There were in evidence three reports from Professor Andrew Lloyd, Professor of Medicine, Consultant Infectious Diseases Physician dated 23 November 2009, 7 December 2009 and 19 July 2010 tendered by Mr Smith. Mr Smith first consulted Professor Lloyd in September 2008. Professor Lloyd’s reports record a history consistent with the time-frame which is summarised above concerning exposure to mosquito bites in the course of performance of his duties, although on dates which varied by one day to that which is summarised above. It is common ground that exposure to mosquito bite may cause transmission of RRV. When Professor Lloyd first assessed Mr Smith he concluded that his condition was “a well characterised acute Ross River Virus infection confirmed by serology, which had been followed by a subsequent post – infective fatigue syndrome of typical pattern.” Professor Lloyd also recorded that the fatigue syndrome had been complicated to some degree by sleep disorder and also by intercurrent anxiety disorder.
Professor Lloyd expressed the opinion in the second of his reports that:
“It is evident that Mr Smith has a well established post infective fatigue syndrome following from initial Ross River Virus infection, which I believe most likely to have been acquired in the course of his policing duties (in particular clearing of the cannabis crop at Wytaliba)”.
A further report from Professor Lloyd dated 19 July 2010 was admitted as a late document by the Arbitrator at the hearing. This report addresses the subject of the incubation period for RRV infection as is found in the medical evidence which is relied upon by the appellant. This evidence is considered below.
Mr Smith relied upon a number of further documents which were attached to his application which are not directly relevant to the issue raised on this appeal.

The Appellant’s Evidence

The appellant relied upon the expert medical evidence of Dr Ross D Whittaker, Consultant Rheumatologist, as found in two reports dated 19 March 2010 and 18 May 2010. Reliance was also placed upon the evidence of Associate Professor Damon Eisen, Infectious Diseases Specialist, as found in his reports dated 16 June 2010 and 20 July 2010. That expert evidence is addressed below.
The appellant relied upon a number of other documents including a copy of the curriculum vitae of Associate Professor Eisen, the clinical notes produced by Mr Smith’s general practitioner and copies of Mr Smith’s duty roster relating to 28 and 29 February and 1 March 2008. Reference, where relevant, is made to those documents below.

The Appellant’s Submissions

The appellant, in the course of submissions before the Arbitrator, identified the issue for determination in the following terms:
“…the real question is whether on the balance of probabilities [Mr Smith] was injured in the course of his employment”.
Counsel for the appellant acknowledged that the evidence contained inconsistent histories concerning relevant dates of activities undertaken by Mr Smith. It was put that the evidence, as corrected at the hearing, established that Mr Smith was exposed to mosquito bites in the course of employment on two consecutive days. Symptoms, which had been accepted by the parties at the hearing as demonstrating RRV infection, were noted on the morning of the third day. Reliance was placed upon the expert medical evidence concerning the incubation period for RRV and it was put that the period of no more than 48 hours between the time of first possible infection in the course of employment and presentation of the symptoms was less than the accepted incubation period. Reference was made to evidence concerning Mr Smith’s activities during leave at his home prior to the cannabis eradication. It was argued that the area in which Mr Smith lived “is also a known area for Ross River virus mosquitoes” and it was put that the Commission should not be satisfied that RRV was caused by the work “more likely than it could have been occurred [sic] when [Mr Smith] was at home in the days before”.

Mr Smith’s Submissions

Counsel appearing on behalf of Mr Smith noted that the evidence, following correction, established that Mr Smith worked between 28 February 2008 and 1 March 2008 inclusive. On the first of those days, Mr Smith makes no allegation of exposure to possible infection by mosquito bite. Such exposure occurred on the second and third days namely 29 February and 1 March. Counsel noted the evidence that Mr Smith had been “bitten on numerous occasions”, that those bites caused irritation and that he was compelled to scratch his skin. Counsel emphasised the evidence of Mr Smith that he had no recollection of being bitten by a mosquito whilst on leave and residing at his home before the cannabis eradication work. Reliance was placed upon the evidence of Professor Lloyd “in relation to the likelihood of a mosquito bite in the course of [Mr Smith’s] employment being the cause of his condition as opposed to the bite of a mosquito away from his employment”.
Counsel made reference to the evidence of Associate Professor Eisen that “it is impossible to rule out an incubation period shorter than [78 hours]”. Counsel proceeded to make reference to relevant authority and argued that the “possibility” of an incubation period of less than 78 hours as established on the evidence may be taken into account with other factual matters to permit satisfaction, upon the basis of probability, that the infection occurred in the course of employment. It was acknowledged by counsel that the facts were unusual however all other relevant matters of fact “point to the work” as being the probable occasion of infection.

The Arbitrator’s Reasons

The Arbitrator, following a summary of the evidence concerning Mr Smith’s activities in the course of his employment on 28 and 29 February 2008 and on 1 March 2008, noted the evidence that when he awoke on 2 March 2008 “[Mr Smith] was quite sore and tired and had a mild rash on his stomach. He says it felt like the early stages of a cold or flu”. It was also noted by the Arbitrator that it was agreed between the parties that RRV is caused by mosquito bites; that Mr Smith was incapacitated by reason of that viral infection; suffered a post infective fatigue syndrome; and that he was medically retired from the Police Service.
The Arbitrator at [14] of Reasons, characterised the issue as to injury as being “a medical one as to the incubation period for [RRV]”.
The Arbitrator proceeded to summarise the medical evidence concerning the incubation period relevant to RRV and expressed a preference for the evidence of Professor Lloyd. A finding was made (at [25] of Reasons) that “it seems more likely than not that [Mr Smith] was bitten by the relevant mosquito or mosquitoes during the period of his work with the [appellant] when participating in the cannabis eradication program on 29 February and 1 March 2008”. The Arbitrator proceeded to make appropriate orders remitting the matter to the Registrar for the purpose of referral to an Approved Medical Specialist for assessment of any entitlement Mr Smith may have in respect of whole person impairment resulting from the subject injury.

SUBMISSIONS, DISCUSSION AND FINDINGS

The appellant’s challenge to the Arbitrator’s finding of injury in the course of employment is founded upon the uncontroverted evidence that Mr Smith manifested symptoms of RRV infection within a period of no more than 48 hours of first exposure to possible infection in the course of that employment. The presentation of those symptoms as noted by Mr Smith when he awoke on 2 March 2008 has been accepted by the parties as being the first evidence of symptoms of RRV. The appellant’s argument is that the appearance of symptoms on that day, having regard to the evidence of Dr Whittaker and Associate Professor Eisen, indicates that the initial infection more likely occurred at a time earlier than the dates upon which Mr Smith was engaged in the cannabis eradication operation.
The views of Dr Whittaker concerning the incubation period relevant to RRV appear in his report of 15 March 2010 where it is stated (at p8):
“The literature suggests that the normal incubation period for Ross River Virus is 5-7 days, with some reports suggesting that the incubation period can be as short as three days. The incubation period is the period from the time of infection until the onset of symptoms”.

The evidence of Associate Professor Eisen concerning the subject of incubation period is found in his report of 16 June 2010 where it is stated (at p4):
“The available literature regarding incubation periods of Ross River fever states that the incubation is typically 5 to 15 days. The briefest recorded incubation period is 3 days. This minimum period of incubation for Ross River fever comes from a description of an outbreak of Ross River fever on the Cook Islands in 1980. This described 100 serologically proven cases of Ross River infection. One of these patients had onset of arthritic symptoms 78 hours after arrival on the Cook Islands during the epidemic”.
The views expressed by Associate Professor Eisen as noted above were confirmed in a supplementary report provided by him dated 16 June 2010. That second report included a statement “it is not possible to conclude that it is more likely than not that Mr Smith was infected whilst involved in the cannabis removal operation…”. I note in passing that the dates of work exposure to mosquitoes noted by Dr Eisen and other witnesses do not correspond to the corrected history noted at [15] above. That fact is of no significance given that it is common ground that the relevant symptoms first presented the morning after two consecutive days work during which Mr Smith was engaged in cannabis eradication.
There is no issue that, as stated by Associate Professor Eisen, Mr Smith resided and worked in a rural region of New South Wales which, during 2007 and 2008, was an area in which there was a high rate of Ross River infection reported. The evidence establishes that during Mr Smith’s period of leave during February 2008, before commencing the cannabis eradication operation, he had remained at his residence. As earlier noted, Mr Smith acknowledged when cross-examined that it was possible that he may have been bitten by a mosquito at his property and that he may not have been aware of such a bite.
The question of causation of the infection is addressed by Professor Lloyd in his report dated 7 December 2009 as noted at [22] above. Professor Lloyd recorded in that report a history concerning a two day cannabis operation and the presentation of symptoms the day following that operation. The dates are incorrect, but that fact is of no consequence. It is apparent that Professor Lloyd was later requested by Mr Smith’s solicitors to address the question of the relevance of the incubation period for RRV and those matters stated in the reports of Dr Whittaker and Associate Professor Eisen. In his report of 19 July 2010 Professor Lloyd states concerning causation of infection:
“My conclusion that it is more likely than not that Mr Smith was infected with Ross River virus infection via mosquito bites which occurred during the cannabis eradication operation on the 28^th and 29^th February 2008 [sic], arises not only from the fact (as stated in the report by Professor Eisen) that the incubation period for Ross River virus infection may be as short as three days, but also from the fact that he reported that his property is appropriately fly-wire screened and that although there is a dam approximately 400 metres away from home, he did not recall having been bitten by mosquitoes in the period of weeks leading up to the onset of illness on March 1[sic]. By contrast, he did recall wearing work shorts and being frequently bitten by mosquitoes in the visit to Wytaliba. Unfortunately, no further information is available to impact on this assessment.”
The evidence of Professor Lloyd is challenged by the appellant upon the basis that he had made an assumption that Mr Smith was not exposed to mosquitoes whilst he was on leave and at his home. That assumption is said to be incorrect given Mr Smith’s “concession” noted at [20] above. It is argued that such assumption “went to the weight that should be given to Dr [sic] Lloyd’s opinion”. At [22] of submissions the appellant, following a summary of the evidence, asserts that “the more likely scenario, on the balance of probabilities, was that the respondent contracted the virus whilst at home at his property at Inverell”.
The burden is upon Mr Smith to establish, on the probabilities, that the infection from which he undoubtedly suffered was caused in circumstances arising out of or in the course of his employment. His case was that:
(a)     such infection was caused by mosquito bites;
(b)     he was bitten by mosquitoes on numerous occasions on 29 February and 1 March 2008 in the course of his employment, and
(c)     there is no direct evidence of any other relevant exposure to possible infection.
The appellant, on this appeal, argues that the evidence of Dr Whittaker and Associate Professor Eisen concerning the probable incubation period of the infection makes it “more likely” that Mr Smith was infected at home during leave “as that period of time was within the accepted incubation period” ([14] of submissions).
The appellant’s argument raises a competing hypothesis as to causation. The law, in the present circumstances, does not require that the appellant establish a “more likely” cause of infection than exposure in the course of employment. The onus remains upon Mr Smith. The nature of the requirements as to proof in civil proceedings such as the present are as stated by the High Court in Bradshaw v McEwans Pty Ltd (1951) 217 ALR 1 (per the Court at 5):
“The difference between the criminal standard of proof in its application to circumstantial evidence and the civil is that in the former the facts must be such as to exclude reasonable hypotheses consistent with innocence while the latter you need only circumstances raising a more probable inference in favour of what is alleged. In questions of this sort where direct proof is not available it is enough in [sic, if] the circumstances appearing in the evidence give rise to a reasonable and definite inference: they must do more than give rise to conflicting inferences of equal degrees of probability so that the choice between them is mere matter of conjecture (see per Lord Robson, Richard Evans & Co Ltd v Astley [1911] AC 674 at 687). But if circumstances are proved in which it is reasonable to find a balance of probabilities in favour of the conclusion sought then though the conclusion may fall short of certainty it is not to be regarded as a mere conjecture or surmise: cf per Lord Loreburn, above, at 678.”
What is clear is that the appellant challenges the Arbitrator’s finding as to causation of the infection upon the basis that the evidence before him was not sufficient to establish, on the probabilities, that the infection occurred during the cannabis eradication operation. The time-frame, it is argued, strongly suggests that such infection would not have occurred within 48 hours of presentation of first symptoms.
The evidence relied upon by Mr Smith is entirely circumstantial, there being no direct evidence available as to the fact and timing of infection. It is accepted by Associate Professor Eisen that “it is impossible to rule out an incubation period shorter than [78 hours]”. Notwithstanding that concession, Associate Professor Eisen states that it remains unlikely that the RRV infection suffered by Mr Smith was associated with his police operation. Acceptance by Associate Professor Eisen of the possibility of there being an incubation period less than 78 hours permits an inference that it is possible that the infection occurred in the course of Mr Smith’s work. Such evidence of possibility is not, alone, sufficient to establish causation at law. As was stated by Spigelman CJ in Seltsam Pty Limited v McGuiness; James Hardie and Company Pty Limited v McGuiness [2000] NSWCA 29; 49 NSWLR 262 (McGuiness) (at [80]):
“The common law test of balance of probabilities is not satisfied by evidence which fails to do more than establish a possibility. See especially the unanimous joint judgment of the High Court in St George Club Ltd v Hines (1961-62) 35 ALJR 106 at 107 where the court referred to Bonnington Castings Ltd v Wardlaw [1956] UKHL 1; (1956) AC 613 as authority for the following proposition:
‘In an action at law a plaintiff does not prove his case merely by showing that it was possible that his injury was caused by the defendant’s default.’”
The evidence before the Commission relevant to the question of causation of the subject infection may be summarised as follows:
(a)     RRV infection is caused by mosquito bite;
(b)     there is no evidence of mosquito bite being received by Mr Smith in the month of February prior to his work eradicating cannabis;
(c)     when working on the cannabis operation he was bitten on numerous occasions by mosquitoes;
(d)     the relevant incubation period is typically between five and 12 days, the briefest recorded period is three days (Associate Professor Eisen);
(e)     the literature suggests that the normal incubation period for RRV is five to seven days, with some reports suggesting that period can be as short as three days. The source of the infection is not entirely clear. It may have occurred on his farm. It may have occurred during the cannabis eradication program (Dr Whittaker);
(f)      it is impossible to rule out an incubation period shorter than 78 hours as recorded following an outbreak of RRV on the Cook Islands in 1980 (Associate Professor Eisen);
(g)     the infection was most likely to have been acquired in the course of Mr Smith’s policing duties, in particular clearing of the cannabis crop (Professor Lloyd);
(h)     it is not possible to conclude that it is more probable than not that Mr Smith was infected while clearing the cannabis (Associate Professor Eisen);
(i)      on the available information concerning incubation period it seems unlikely that the infection was associated with the cannabis eradication operation (Associate Professor Eisen);
(j)      Mr Smith may have been bitten by mosquito, but not been aware of that occurrence, while at home on leave (Mr Smith’s response when cross-examined), and
(k)     the conclusion, as stated by Professor Lloyd, that it was more likely than not that infection occurred in the course of Mr Smith’s work, arises not only from the fact that the incubation period for RRV may be as short as three days, but also from the fact that, as reported by Mr Smith, his property is appropriately fly-wire secured and he has no recall of being bitten whilst on leave (Professor Lloyd).
The opinion expressed by Professor Lloyd may be the subject of some criticism given his failure to acknowledge the primary point made by Associate Professor Eisen. That point is that the time-frame between earliest possible infection in the course of work and the appearance of symptoms was less than the recorded minimum incubation period. That criticism has not been raised by the appellant in submissions. Notwithstanding Professor Lloyd’s failure to fully acknowledge Associate Professor Eisen’s reasoning, it is clear that he has read the latest reports and has responded to Mr Smith’s solicitor’s request seeking commentary. It is plain that, notwithstanding the matters raised by Associate Professor Eisen, Professor Lloyd does not resile from his earlier expression of opinion concerning causation.
The Arbitrator’s reasoning concerning the question of causation of the infection is to be found at [25] of Reasons where it was stated:
“I accept that Professor Lloyd and Associate Professor Eisen are both eminent experts in the field of Ross River Fever and its aetiology. Professor Lloyd, making the necessary assumptions as to his activities on holidays and thereafter during the course of his activities for the cannabis eradication programme had no difficulty, despite the shortness of time in accepting the possibility of the Applicant contracting Ross River Fever within the 78 hour period or a period shorter than the usual incubation period. I note the concession made in Associate Professor Eisen’s evidence that an incubation period shorter than 78 hours cannot be excluded. Given the history provided by the Applicant, which I find compelling, including the fact that it is significantly less likely that the Applicant was bitten by mosquitoes at his home for the reasons given by Professor Lloyd, it seems more likely than not that he was bitten by the relevant mosquito or mosquitoes during the period of his work with the Respondent when participating in the cannabis eradication programme on 29 February and 1 March 2008. I prefer the evidence of Professor Andrew Lloyd AM in the circumstances. I am therefore of the view that it was the mosquito bite or bites in the course of his employment on the balance of probabilities, despite the shortness of the incubation period, which have resulted in the Applicant acquiring Ross River Fever and the post-infective fatigue syndrome following the Ross River virus infection or, put alternatively, which have caused the Applicant to suffer injury in the course of his employment with the Respondent.”
The manner in which the Arbitrator expressed his reasons indicates, in my view, that he has taken into account all those evidentiary matters which I have attempted to summarise at [46] above.
It was open to the Arbitrator to accept the evidence of Associate Professor Eisen that an incubation period of less than 78 hours was impossible to rule out. Such acceptance establishes the possibility of a causal nexus between work and infection. The next question which required consideration by the Arbitrator was, adopting the words of Mahony JA in Fernandez v Tubemakers of Australia Ltd (1975) 2 NSWLR 190 (at 199), whether it was open to him “to infer that, in this case, [the work] was the actual cause …”.
It was also open to the Arbitrator to accept that evidence which is summarised by him at [25] of Reasons. That evidence is, in my view, sufficient to permit an inference, as was drawn by him, that on the balance of probabilities the subject infection was caused by mosquito bite occurring in the course of employment. As was stated by Spigelman CJ in McGuiness (at [90] and [91]):
“Proof on the balance of probabilities, indeed on the beyond reasonable doubt standard, may be established on the basis of circumstantial evidence. As Lord Cairns said in Belhaven and Stenton Peerage [1875] 1 AC 278 at 279:
‘My Lords, in dealing with circumstantial evidence, we have to consider the weight which is to be given to the united force of all the circumstances put together. You may have a ray of light so feeble that by itself it will do little to elucidate a dark corner. But on the other hand, you may have a number of rays, each of them insufficient, but all converging and brought to bear upon the same point, and, when united, producing a body of illumination which will clear away the darkness which you are endeavouring to dispel.’
Causation, like any other fact can be established by a process of inference which combines primary facts like ‘strands in a cable’ rather that ‘links in a chain’, to use Wigmore’s simile. (Wigmore on Evidence (3rd ed) para 2497, referred to in Shepherd v R [1990] HCA 56; (1990) 170 CLR 573 at 579).”
The appellant’s argument, that the weight of Professor Lloyd’s evidence must be diminished by reason of his reliance upon mosquito proofing as suggesting no earlier infection, must be rejected. The fact of mosquito proofing, and the absence of any report of earlier mosquito bite, have properly been taken into account by Professor Lloyd when addressing the probable cause of infection. The “concession” made by Mr Smith when cross-examined does not, in my view, undermine those assumptions and historical facts considered by Professor Lloyd when forming his opinion. The Arbitrator’s finding as to causation of the subject infection was one open to him on the evidence and is one which, following this review on the merits, I conclude is correct. In the circumstances the appeal must fail and the Arbitrator’s determination should be confirmed.

DECISION

The Arbitrator’s finding and orders as found in Certificate of Determination dated 9 November 2010 are confirmed.

COSTS

The appellant is to pay Mr Smith’s costs of this Appeal.

Kevin O’Grady

Deputy President
22 February 2011

I, PENELOPE FLEMING, CERTIFY THAT THIS IS A TRUE AND ACCURATE RECORD OF THE REASONS FOR DECISION OF KEVIN O’GRADY, DEPUTY PRESIDENT OF THE WORKERS COMPENSATION COMMISSION.

ASSOCIATE