Leptospirosis

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INITIATIVES TAKEN SINCE THE PUBLICATION OF THE GUIDELINES

In the period since the publication of the Guidelines there have been at least 10 meetings of industry groups and stakeholders additional to the regular (4 monthly) meetings of the Meat Industry Association's Health & Safety Forum.

Department of Labour Paper: Towards a National Strategy of the Control of Leptospirosis

In October 2002 Frank Darby circulated this paper to a wide group of stakeholders requesting comment and feedback on a range of issues. Some significant points from that paper were that people who had contracted the disease, who had been surveyed, painted a picture of confusion and ignorance over recognition of leptospirosis, its suitable treatment, ACC entitlements, and the social acceptance of the disease (Aftermath 2002).

Having presented a number of datasets the conclusion is drawn that taken overall the data suggests that leptospirosis is an important occupational health problem and that efforts to prevent it, to address the early identification of the disease, and to advise GPs of its preferred manner of treatment - need to be ongoing.

This is supported by Baker, writing in "Family Practice News (Baker 1999) who claimed that leptospirosis was very common but often misdiagnosed and because the prevalence of it is under appreciated by GPs, probably 60% to 70% of patients with leptospirosis are initially misdiagnosed.

In the "National Strategy" paper vaccination is suggested as a viable option for all stock - dairy herds, beef herds, deer, and sheep and the costs of vaccination programmes for the different species are presented. However it is noted that more information is required on the source of the disease in humans and while vaccination of dairy herds is regarded as a "practicable step", and it would appear to be transferable to beef cattle and deer, questions remain as to whether vaccination for sheep is effective and a practical step.

A total of 13 possible steps for the control of leptospirosis were presented for comment:

The vaccination of all stock (or certain types of stock) passing into meat processing plants.
Meat processing plants refuse to accept non-vaccinated stock (or certain types of stock).
The refusal by herd testers and other non-farm employees to work with unvaccinated stock.
Dairy companies accept milk from vaccinated herds only.
Improved work practices - on farms and in meat processing plants including the use of splash containment devices and appropriate face protection - (See DOL Guideline)
The continued use and monitoring of the effectiveness of appropriate personal protective equipment (PPE) - on farms and in meat processing plants.
The initiation and/or maintenance of the practice of giving information to employees about leptospirosis during induction training and at regular intervals.
The maintenance of training given to employees about preventing leptospirosis (i.e. the safe work methods required to prevent infection).
A unified approach to the diagnosis and treatment of leptospirosis is adopted by doctors, government agencies (DOL, MoH, MAF, and ACC), employers, and employees.
The development of advice about the medical treatment of leptospirosis, its relation to ACC criteria and its communication to GPs.
Employees continuing to have available a card to take to a GP consultation for flu like symptoms - saying "I am at risk from leptospirosis".
Improve notification to the DOL NODS system.
Clarification of the ACC claims acceptance criteria and procedures.

Some of the challenges with respect to completeness of data sets are highlighted by the comments from ESR when it is stated:

"A total of 105 cases of leptospirosis were notified in 2001. Of these, 76 were recorded on EpiSurv as being confirmed cases. In comparison, 113 cases were laboratory-reported in 2001. Matching of laboratory-reported and notified cases indicated that 82 cases were both notified and laboratory-reported during 2001; suggesting that 23 cases were notified but not laboratory-reported, and controversially, 31 cases were laboratory reported but not notified."

Information on prosecutions involving leptospirosis is presented with one conviction being obtained in June 1995 with the farmer being fined $15,000 and a second conviction, obtained in November 1999 resulting in a meat processing plant being fined $3000.

Summary of responses to "National Strategy" paper

A summary of responses to the points made in that paper is contained in a memorandum by Dougall McNeill dated 28 January 2003.

The central focus of comments received was the option of vaccinating all stock, or certain types of stock prior to their entry to meat processing plants, and meat processing plant refusing to accept non-vaccinated stock. Two thirds of the submissions opposed the proposal because either it could not be considered a practicable step, or there was insufficient research which demonstrated its efficacy.

Rather than proposing a very costly ($6m p.a. for beef cattle, and $9m p.a. for sheep) national program for a regional disease it was considered that more attention should be focused on work practices, personal protective equipment, and training. The Department of Labour's current position on vaccination of different species is as follows:

Dairy cattle:	Vaccination is definitely a practicable step for all Dairy Herds. This is supported by Court decisions, the extent of contact of dairy farmers and their employees with urine and the efficacy of the vaccine
Beef cattle:	Vaccination would be effective - but exposure of farmers to urine is much less than for dairy farmers and the cost effectiveness would therefore be less owing to an increased requirement for stock movements
Deer:	Recent work suggests that vaccination may be a practicable step, may afford production benefits (increased fawning rate and growth rate). This question needs careful assessment by an Industry group.
Sheep:	Definitely not viable at present for reasons of cost and efficacy.
Pigs:	The Industry requires vaccination for leptospirosis before pigs will be accepted for slaughter

While most respondents support a greater unity of approach to the diagnosis and treatment by doctors it is interesting to note that ACC considered the option of a unified approach confused. It argued that the issue of medical treatment of leptospirosis has no relationship to the question of cover criteria and that its acceptance of cover did not need any clarification as there was no difficulty if diagnosis had been made and it was clear that the infection was occupationally acquired.

There was significant difference of view on this point between the Alliance Group which agreed with ACC and the Meat Workers Union which argued there were "huge problems in this area and that the problems were worse with employers who were part of the ACC partnership programme". The writer notes that given the figures set out in Table 4 it would appear that there is still difference of view on this issue.

It was suggested that because of the interest and disagreement between the parties consulted on the topic of vaccination, that the issues of testing, practicable steps, and effective prevention of leptospirosis require careful study if agreement is to be reached and progress made.

Meeting of stakeholder Discussion Group on "Leptospirosis in Sheep" at Massey University 1 April 2003

This meeting was attended by representatives from Massey University, the Meat Workers Unions, DOL, ESR, and animal vaccine manufacturers. The purpose was to exchange information about leptospirosis occurring in meat workers exposed to sheep (and other species) and of current knowledge of the epidemiology of leptospirosis in sheep. A major focus was the proposal by DOL that vaccination of animals going to slaughter was a practical option for preventing disease in the workers. The key objective was to identify gaps in knowledge about leptospirosis in both the human and animal arenas and determine priority areas for research.

It was acknowledged that information on the incidence of leptospirosis in "sheep only" meat works, and the serovars involved, was very limited. Obtaining good systematic data from human cases was essential.

Current measures to prevent infection in meat works were only partially effective and cases have occurred in people working in areas of the works that would have been considered low risk. Exposure to leptospirosis, in most cases, will not lead to recognised disease incidence. Specific objectives could include a cross-sectional study of blood samples from meat workers to determine seroprevalence for all six serovars endemic in New Zealand, a longitudinal study of seronegative workers to determine incidence of seroconversion (and disease) by serovar and work location, and an estimate of the cost of the disease to the industry based on lost work days.

It was noted that the available information on leptospiral infection of sheep was both sparse and dated. Specific objectives for study would include:

A national seroprevalence study of slaughtered sheep to determine seroprevalence by serovar, region, and class of stock (lambs, hoggets, and mature stock).
Epidemiology of leptospirosis on farms, including age of infection, enterprise types, and interspecies transmission.
Risk and duration of shedding by infected sheep and their role as potential maintenance hosts.
Vaccine efficacy related to reduction of renal infection and urinary shedding for relevant serovars.
Studies addressing the design of appropriate vaccination strategies and other interventions.

It was noted that it would be necessary to identify researchers to pursue these studies in the human and animal arenas. Massey University had appropriate facilities and expertise to undertake the work on animals. Efforts would need to be taken to pursue potential collaborators in the human work. No specific follow-up steps or actions appear to have been determined.

Mel Tyson's paper "Where are the Opportunities for DOL with Leptospirosis Prevention?"

This paper, dated 5 May 2003 which was presented to the Agricultural Industry Focus Group explored, among other strategies, the opinion that vaccination of affected species (beyond the dairy herd) maybe a new "practicable step" for sheep, cattle, dear and goats. But it was suggested that before this could be done convincing answers needed to be found to all of the following:

What are the demographics for human cases?
What was the likely host animal for each case and is there information on demographics (and degrees of infection and serovars) in these species?
What are the demographics of vaccinated domestic species and what are the serovars in humans in these areas?
Would the definition of "practicable" differ from one region to the next depending on the above?
What are the serovars in each of the notified cases?
What is the likely role of rodents and feral species and is there any data on rodent control?
What the advances in testing livestock and other means of targeted information of infected/carrier animals?
Could the imminent new system of animal identification ear tags identify risks for meat workers?
Information about economic and social impact of infection.
Information about time taken to reach diagnosis and treatment for sufferers.
Is there data on the effectiveness of vaccines in all farmed species?
Have there been field trials of vaccines by universities or animal remedies suppliers?

It is acknowledged that while there are numerous sources for these items of information they are both variable and in many different formats. It is a considerable exercise for a coordinator, with knowledge of the sources, to draw together compatible data for each case notified.

A central coordinator, preferably someone who is independent of the stakeholders should be found as this concept of independence was very important for the development of the Guidelines. Understandably there will be the requirement to find a source of funding for such a project and the paper suggests that it is an ideal time for DOL to re-gather momentum and a profile for leptospirosis in the industries. An eight step project plan is proposed.

Leptospirosis Update for Agricultural Workshop (dated 8 August 2003) and Leptospirosis Update (dated 1 September 2003)

This paper highlights a number of current issues and suggests a way forward because funds are not available to engage a sufficiently respected and knowledgeable contractor as recommended in the Mel Tyson paper (Tyson 2003) reported above.

Consequently it was proposed that DOL would engage the lead Government Agencies, specifically the Ministry of Health and ACC, to develop a better understanding of leptospirosis. It was noted that a project was a possibility but that preparatory work would need to be done prior to any meetings to address:

Shared understanding and agreement about the leptospirosis procedures
Opportunities for commonality in investigation procedures
Identifying and removing barriers to more complete reporting
Appropriate roles for DOL and PHU staff
Resolution of privacy issues

Information is presented on what might be the impact of vaccination of sheep on meat workers and it is noted that research is needed to assess the efficacy of the vaccination of sheep as a practical step for preventing leptospirosis.

Leptospirosis Meeting - held on October 2003

The three purposes of the meeting were:

To discuss a draft DOL audit sheet about the practicable steps for preventing leptospirosis in the meat processing plants.
To discuss the worthwhileness of conducting the research necessary to establish the efficacy of vaccination against leptospirosis in sheep and in other animals.
To prepare for an industry gathering (e.g. a workshop or a conference) with the affected stakeholders that will provide a forum to share experiences about the prevention of leptospirosis and review general issues.

One proposed agenda item was to discuss the information needed to progress 4 current issues:

Any existing cost-benefit information on the vaccination of sheep and other farm animals.
Policies on glove use.
Evidence on the effectiveness of personal protective equipment.
Other current research.

However these questions were not addressed. It was resolved that:

Participants would comment on the draft Audit for Meat Processing Plants and a second draft would then be circulated for final comment before being made available for use by meat processing companies.
The MIA Health and Safety Forum would call a meeting of a subcommittee, with co-opted representatives of organisations not represented on the Forum, to develop an Action Plan for leptospirosis.

Key points seen for an Action Plan, as a result of the meeting on 21 October and subsequently, were:

A "whole of industry" approach is advocated.
There is strong anecdotal evidence that infection in sheep is increasing.
The action plan should cover the role of the GP and medical laboratories.
Could meat processing plants become more familiar with the expectations about prompt GP consultations, biological monitoring, and treatment?
The reporting of leptospirosis to ESR and DOL needs to be improved.
Look at recent improvements in the design of PPE.
Practicable steps are not static - experience in one plant informs what may be reasonably practicable nationally.
What is a practicable step in one plant may not be in another - but plants must make a fair trial of the step - and provide good evidence of why it has not been adopted.
Accredited employers may not appreciate issues of cover for leptospirosis.
The Leptosure programme exists and takes the comprehensive risk assessment approach.
A pilot programme to extend Leptosure to beef cattle is underway in the Taupo area.
Skin integrity is an important issue.
There may be methods to assess the risk posed by stock that arrive at a meat processing plant - perhaps by use of the animal health declaration form.
Meat processing plants are not dissimilar to operating theatres. An appreciation of hygiene practices (hand washing) similar to that of health care personnel does not exist in the industry. Such an appreciation plus equivalent practices is advised.

Some additional points discovered after the meeting:

Industry wide communication of leptospirosis strategies, issues, results, and research should occur - the infrastructure to do this exists now.
More information could be written on the card taken to GPs - and reference could be made to a web site.
Trial of prophylactic doxycycline.
Meat works liaison with GPs.
Animal status declaration.
Leptospirosis DNA analysis by Canterbury laboratories - prompt turnaround time.
Involve families of affected persons.

Leptospirosis Meeting - held on 11 February 2004

The Meat Industry Association representative stated that the Association's preference was that attention be given to musculo-skeletal injury and that there was not enough funding to support further work on leptospirosis.

Comments were made on the draft Audit of Plant Procedures and with respect to research issues there was a need, on the one hand to focus on protection against possible exposure, and on the other hand, the efficacy of vaccination of the animal. This necessitates knowing where the animal's exposure comes from. Once the quantity of exposure and the source of exposure had been established it would be easy to come up with a preventative focus. Consideration was given to developing a plan for the research, possible sources of funding, the needs for government agencies to retain control, and the desire to maintain momentum.

Meeting of Stakeholders at the Wellington School of Medicine

The aim of this meeting on 4 August 2004 was to identify high priority research questions relating to the epidemiology, prevention and control of leptospirosis in New Zealand, and those which have a reasonable chance of proceeding in the medium-term (based on practicality, funding, motivated end users, and interested researchers).

It was noted that there are currently up to five streams of incidence reporting of the infection (i.e. notifications, laboratory data, NODS, ACC, and Meat Industry databases) which are not fully integrated. The comment was made that this data was "opportunistic information" rather than "organised surveillance".

The group identified and prioritised important research questions:

What is the incidence and distribution of human leptospirosis in New Zealand?
What are the sources of human infection, notably the risk from sheep?
What are the pathways to exposure?
What control measures are effective?
What is the impact of leptospirosis on production and economics?
What is the optimal treatment for leptospirosis?

Possible funding sources were discussed briefly.

The Health Research Council had just advertised a DOL joint research partnership with the Department of Labour and ACC.
The possibility of potential funding from the Zoonosis Steering Committee convened by the Interagency Zoonotic Disease Research Coordination Programme; and
Various parties in the meat industry.

A national industry workshop was proposed for the wider sharing of information and this idea was well-received.

In the afternoon a meeting of researchers developed the ideas presented in the morning with the view to identifying research projects that justified further development, and mapping out a plan for proceeding with them. Important short-term research priorities identified were:

What is the "true" incidence of the infection, based on the linking of data from multiple sources?
What are the sources of human infection? What proportion of human leptospirosis is due to sheep and other livestock? Who is exposed? Which meat handling practices contribute?
What is the impact of leptospirosis on individuals and society? Can this be partly ameliorated by improved recognition and early treatment of cases?

The suggested title for a research project was

"Identifying the sources and reducing the impact of human leptospirosis in New Zealand"

and the aims would be:

To identify the sources of human leptospirosis in New Zealand and assess their relative importance notably
1. Animal contact in the workplace, including the types of animals (in particularly sheep), precise forms of contact, and impact of PPE and behaviours.
2. Environmental sources, including occupational and recreational
To assess the impact of leptospirosis on those infected, notably the severity and duration of illness, and the timing and extent of antibiotic treatment.

Meeting of health and animal researchers

This meeting was held on the afternoon of 4 August 2004 to refine the aims of this study which are listed as:

To evaluate risk factors for seroconversion of L. hardjo or L. pomona in abattoir workers.
To investigate the severity of leptospirosis and occupational and life style risk factors among patients.
To study the distribution of available denominator information among leptospirosis patients and non-patients among abattoir workers.
To compare genotypes of L. hardjo and L. pomona from sheep at slaughter with genotypes from human leptospirosis patients.

The particular focus is the investigation of humans suffering leptospirosis and comparison with comparable persons who are free from the disease (but may be seropositive). The study will compare the two groups with regard to previous exposure patterns related to lifestyle and occupation. Any isolates of leptospira obtained from patients will be compared with sheep isolates to determine the degree of genetic homology between the strains. The purpose is to demonstrate evidence of the transmission of leptospira from sheep to humans.

In the seroconversion study approximately 160 available sera from healthy abattoir workers will be tested and related to age, place, and position on the carcass processing line. This will provide a basis for further sampling. A cohort of 400 high risk abattoir workers will be identified and followed up at quarterly intervals for two years. Blood samples from each worker will be tested for L. hardjo and L. pomona every three months. The risk factors and exposure histories of each worker will be updated by questionnaire at the time of sampling.

It is hoped also to undertake a descriptor study in which cases of leptospirosis will be investigated in detail using a standard questionnaire covering exposures during the incubation period and the duration and severity of the symptoms. It is proposed that the study will investigate all cases occurring in New Zealand over a two-year period.

It is also hoped to undertake an abattoir survey in which cases of leptospirosis among abattoir workers will be compared to non-cases with respect to available denominator information. This process will include a detailed survey of all abattoirs in New Zealand to establish the size of the workforce and the numbers working in each distinct exposure category.

A feature of these studies will be that the leptospira strains collected from cases will be genotyped by pulsed field gel electrophoresis (PFGE). This process will include an education programme aimed at abattoir health care services encouraging them to forward suitable specimens for culture. These strains will be compared to strains obtained from sheep in the other components of this project, and strains collected opportunistically from other animals.

Meeting of stakeholders on 17 August 2005

The meeting was attended by representatives of the meat industry, the Meat Workers Union, Massey University, the Wellington School of Medicine and the Department of Labour.

The agenda was to receive a briefing on results of the Massey University abattoir study, comment on the plan of action, and on the possibility of a national workshop on leptospirosis.

Massey University had obtained limited funding from a variety of sources which was enabling an abattoir study of sheep and deer to be conducted. Initial results to date showed that each worker (including meat inspectors) on a sheep/deer line was exposed to an average of 19/239 shedding carcasses each day respectively. Unfortunately the funding was insufficient to provide sufficient samples to allow comprehensive statistical analysis.

While there is awareness of the issue in the meat industry and animal vaccine marketers, which is acknowledged by the Agricultural Health and Safety Council, the view was expressed that the farming community does not believe there is a significant problem.

Reference was made to the "Plan of Action" developed by Frank Darby in November 2003. Some 50% of the 104 cases notified to medical officers of health the previous year, and of the 113 laboratory confirmed cases, had come from persons working on the meat industry.

Mention was made of be proposed study to take blood samples from 400 volunteers in abattoirs (including those working in different parts of the plant e.g. the slaughter floor, in yards and in small goods department) at quarterly intervals over a two-year period to follow the rate of seroconversion. A key feature of the study would be that it will report leptospirosis on the basis of antibodies in the blood rather than people being diagnosed as being "sick".

Key questions being addressed include:

What is the total leptospirosis infection in humans - both incidence and distribution?
What are the modes of transmission, and hence the best methods for their control?
What are the roots of transmission from sheep and deer to meat workers?
What practicable steps should the industry be taking?
Is the Department of Labour's treatment advice up-to-date?

It was suggested that a one-day workshop for the meat industry would be beneficial so that attendees from all levels in the industry could see:

The situation other parties are in.
What other parties are doing in the face of a difficult problem.
The need to take the reasonably practicable steps open to employers in relation to known and foreseeable risks
Where the balance lies of employers' and employees' responsibilities

Meeting of Stakeholders at Massey University on 14 June 2006

Participants discussed work recently completed, currently under way, and topics that needed to be researched in order to elucidate key questions. Conclusions reached were:

It is currently neither reasonable nor feasible to establish the distribution of leptospirosis-infected herds and flocks in the entire country.
Objective 1 (national survey) should therefore be limited to sheep and to 2-3 regions with contrasting climate/ecology, probably representing extremes for New Zealand. Such a reduced approach would save substantial funds.
Objective 2 (inter-species transmission) may be investigated experimentally by exposure of a sample of sero-negative animals (e.g. sheep) to an infected mob of another species (e.g. deer) on the same farm, and comparing sero-conversion of exposed with non-exposed animals (sheep).
Objective 3 (production response) will be included in vaccine efficacy studies at the animal level on non-vaccinated farms (Objective 4).
Objective 4 (vaccine efficacy) shall be limited to the comparison of vaccinated farms (all species) with non-vaccinated farms. It is understood that this approach requires a large number of farms, but that only a small number of animals will be followed on each farm. Thus a large portion of funding will be consumed by the cost of vaccine. To evaluate efficacy by the rate of shedding, the required sample will not be large given that initially non-infected animals are enrolled (because this would provide a high expected efficacy, thus a low sample size). Whether culture of kidneys at slaughter or dark-field microscopy combined with culture of urine is required probably depends on the species (renal culture for sheep and beef, urine samples from live animals for deer). Moreover, cultures need to be typed as efficacy should be evaluated for both serovars, provided dual infected farms will be available.
Objective 5 (wildlife) may be explored in a case-control approach, i.e. trapping and testing various wildlife species around infected and non-infected farms. A concurrently planned study on the distribution of Johne's disease in domestic species and wildlife could be exploited by testing wildlife for leptospirosis cultures and serovars. Thus funding would only have to cover extra testing.
Objective 6 (genotyping) will not be used for large field studies at this stage because of uncertainties about practical methods of sampling for cultures during a survey of live animals. Genotyping will initially be addressed by developing techniques at Massey University (Hopkirk Institute) using available isolates from sheep and deer. These isolates originate from slaughter stock and allow an analysis of within and between line distributions.

Comments have been requested from the attendees on these proposals by mid August 2006 with the view to drafting details (e.g. methods, sample sizes, budgets), obtaining confirmation by the end of September, and then seeking funding.