The following quotation from Goodman among others (1990) on the nature of field epidemiology is highly relevant:
There is a perception in the public health community that field investigation represent quick and dirty epidemiology. This perception may reflect the inherent nature of circumstances for which rapid responses are required. However, these requirements for action do not provide a rationalization for taking epidemiological shortcuts. Rather, they underscore for the practising epidemiologist the importance of combining good science with prudent judgement. A better descriptor of a good epidemiologic field investigation would be quick and appropriate.Participatory and rapid rural appraisal techniques were developed within the context of international development to address the need for fast and low cost qualitative data collection. Increasingly, participatory exercises are being adapted to generate semi-quantitative output, which can be analysed statistically. However, the real strength of participatory rural appraisal is its flexibility. The close interaction between beneficiaries and researchers in the absence of rigid frameworks promotes a more direct understanding of the significance of information. Most importantly, participants are able to express their information within the context of their own conceptual framework and knowledge systems, where it is most meaningful. Regardless of the availability of time and money, participatory appraisal is and will remain an invaluable tool in its own right.
Participatory epidemiology, as an emerging methodology, should seek to build upon the strengths of participatory appraisal and to complement existing epidemiological methods. The real strength of participatory veterinary epidemiology is its ability to collect the fresh and novel perspectives of the livestock owning communities. These perspectives offer insights into the patterns of disease and suggest paradigm shifts that can serve to focus future research, disease investigation and disease control activities. Participatory epidemiology has a contribution to make to quantitative analytical epidemiology through the design of more appropriate questionnaires and studies. Participatory appraisals could be used to identify and refine epidemiological hypothesis as well as to tailor statistical studies to the needs of the beneficiaries.
In a limited number of cases, participatory appraisal has been applied to issues in the developed world. At least one application to human primary health care in the developed world has been published (Murray among others, 1994), however the potential in the veterinary sphere is probably greater. Modern farmers are increasingly called upon to make complex and highly technical management decisions regarding health issues. Further, the economics of production and animal health care require that farmers make diagnosis and perform treatments on a day to day basis, albeit with periodic professional consultation. Thus, first world farmers have animal health knowledge and information based in their own unique perspective - that of the producer.
The results of a recent quantitative survey on Johnes disease in the United States conducted by the USDA found that farmers could apparently identify Johnes affected cattle (NAHMS, 1997). The study found a strong association between Johnes affected herds as detected by culture and farms that reported culling cattle with Johnes disease symptoms (p<0.001). In fact, the study concluded that the best estimate of Johnes disease prevalence at the herd level was derived from a combination of biological test results and farmer-provided clinical data on cull animals.
Although currently underestimated, the need for qualitative epidemiology or ecologic epidemiology remains strong. In recent years, quantitative analytical epidemiology has received a lot of emphasis. This may be linked to the current technology drive and the increasing ease with which complex analysis can be performed. However, in diseases with complex etiological, sociological and ecological interactions, special insights will always be needed to design effective research capable of elucidating causal networks. Modern farms are still ecosystems, granted highly artificial ones, and it is increasingly being recognised that modern production diseases are more the result of mans manipulation of that system than simply which microbes are present. Participatory epidemiology is designed to rapidly and reliably generate epidemiological intelligence on complex issues and will enrich modern epidemiologic models.