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WHAT IS THE EXTENT OF HARM?

Accurate assessment of the extent of harm is particularly difficult based on the records available and because of the potential degree of under reporting, the inherent variability of symptoms, and variability also in the severity of the condition. Reports contained in case studies and included in publications such as "Aftermath" make sobering reading. Workers in the field report that in many cases the effects of leptospirosis can persist for periods well beyond the initial "recovery phase" of 3 - 6 months.

The differences of views between, on the one hand ACC, and on the other hand those who are affected by the condition need to be explored and resolved. ACC maintains that, especially since 1998 when leptospirosis was added to the Corporation's Schedule 2 that the acceptance and coverage of claims is much more straightforward. The ACC statistics show that covered claims, expressed as a percentage of lodged claims, is lower in the period since 2000-2001 than it was in the period 1991-1992 through 1999 - 2000. (See The Report's Table 3)

Other important factors in assessing the extent of the hazard are the challenges in testing for leptospirosis. One testing regime is that a specimen is referred for serological testing using the microscopic agglutination test (MAT) and that a second test is undertaken some 4 - 6 weeks later. A 4 fold increase in titre is required to provide confirmation of a positive diagnosis. The increase does not always happen within this time period but may take place several months later. Many patients, for a variety of reasons, do not return for the "convalescence" (i.e. second) test and therefore are not considered for being confirmed as having the condition.

Alternatively the individual's sample can be analysed using the polymerase chain reaction test offered by Canterbury Health Laboratories. The analysis of one sample provides a definitive diagnosis of the presence, or absence, of leptospirosis, however it is not able to provide information on the serovar causing the infection.

There are numerous accounts of delays by both GPs and hospital clinicians in ordering tests, and also in employers being reluctant to meet the cost of either the MAT or the PCR tests.

A significantly better estimate could be made of the extent of harm if there was good data on the number of people affected by leptospirosis and comprehensive details collected from all the 200 or so who are affected over a 2 year period. It has been suggested that maybe there are only 1000 workers in New Zealand that are really exposed and that it would be better to work extensively with these people.

It would be useful to know "how large is the number of workers in these groups?" and "are workers rotating around various tasks or are they staying in the same (high risk) job?"

Updating of the "Guidelines"

It is acknowledged that the "Guidelines" are readable and very good from a scientific point of view - but do people carry out what is recommended? It would be better to go for a limited number of things and get more people to do them well - especially those who are in the "really exposed" category. There is a need to find what workers think; what the key issues are, and what happens to people in the situations in which they are particularly at risk.

What is the cost of the harm?

At this stage some reasonable guestimates can be made of the cost of the 42% of those contracting leptospirosis who are employees in the meat industry. Reasonable data is available for their time off work, the medical and hospital costs incurred, and the need to employ additional staff to provide cover while affected employees are recovering. That would appear to be some $405,000 per annum for employees in the meat industry.

However virtually no comparable details are currently available for the other 37% engaged in various kinds of "farming" and certainly not for the remainder in the "other" and "unknown" occupational groupings.

How can the risk be minimised?

For the meat industry one case of leptospirosis occurs for every 4 million carcasses processed hence there would be real advantages if there were tests developed to indicate when lines of stock that were actively shedding leptospires were being presented for slaughter. Lines so identified could be put through at the end of a shift and staff on the chain encouraged to take particular care and ensure that the maximum PPE was worn. In the meantime, for their own protection, workers must treat all stock as infected unless it is known otherwise.

Researchers at Massey University have liaised with workers in Thailand who reported that they had an antigen-detecting dipstick which can be used to detect leptospira in the urine of cattle. The test is not instantaneous, taking some 3 hours to give a result and does require the use of a centrifuge and other laboratory equipment. (A. Midwinter and J Collins-Emerson pers. comm.)

Workers associated with the International Leptospirosis Society indicate that they use a dipstick test as a screening tool for human serum and therefore the possibility of having an animal IgM dipstick made with species specific conjugate could be explored. A contact would be Rudy Hartskeeri contactable through the International Leptospirosis Society webpage. Issues relating to the dilution factor with composite samples and the possibility of cross contamination will need to be addressed and overcome.

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