3) Epidemiology/Transmission/Vaccines
Chair： Dr. P. Fine
The workshop attendees addressed the four major topic areas outlined and came to the following consensus opinion.
Leprosy today patterns and trends
Routine "Prevalence" data generated in recent years, in most countries of the world, have been greatly influenced by 'operational' factors (eg： changes in ascertainment, diagnostic and classification criteria, treatment duration etc.). As such they may not, and often do not, reflect the underlying epidemiological situation, and can only be interpreted in the context of clear explicit information on these underlying factors over the time period covered by the data.
We recommend that all tables, figures and reports which purport to represent leprosy "Prevalence" "Incidence" or "Case Detection" patterns or trends be accompanied with clear and explicit captions specifying the operational factors (ascertainment methods, case and classification definitions, treatment durations, etc.) employed during the entire period to which the data refer.
Leprosy frequency and patterns often differ greatly between various segments of populations. This heterogeneity at national, district and local level is not evident in crude summary statistics, which can thus lead to a distorted picture of the actual situation. Whenever possible, an effort should be made to separate high prevalence populations from other group data, or at least to point out how crude data are effected by their inclusion (eg： data from Asia, Africa and Latin America are heavily influenced by India, Ethiopia, Madagascar and Brazil, and national data for each of these areas are influenced by other area-specific operational/historical factors.
New insights into the natural history of leprosy
Evidence for zoonotic leprosy in armadillos of the southern United States is now overwhelming. It is no longer correct to claim there is "no extra-human reservoir" of M. leprae. The relevance of primates in leprosy's natural history remains anecdotal but deserves more rigorous study including surveys in the wild and studies of human risk associated with primate contact. Any realistic consideration of leprosy eradication must contend with this issue.
Recent PCR-based data on widespread presence of M. leprae in nasal cavities of individuals in endemic populations, and in environmental samples, are potentially very important for our understanding of the natural history of leprosy. Some of these studies have, or appear to have, been influenced by appreciable numbers of false positives. To ensure credibility such studies require rigorous controls to demonstrate high specificity of the assay used (preferably inclusion of large numbers of blind coded samples, from non-endemic populations, among the study samples). Presentation of such data by age, sex, contact status and area will enhance interpretability and credibility. Appropriate multivariate analysis should be carried out in order to ensure proper control of confounding factors.
