Pestilence, Plague and Pandemics: A Troubled History.

Humankind has lived with the danger of endemic, epidemic and pandemic disease for thousands of years. The effects of these outbreaks have often devastated human populations. Sixteen pandemic events causing an estimated 147 million deaths have occurred since the eighth century, The Black Death and the influenza pandemic of 1918-1920 probably having the greatest impact. Animal populations, both wild and domestic, have similarly suffered devastating outbreaks of disease which, on occasions, have translated into serious effects on human health. The deliberate or accidental introduction of animals into virgin areas has given rise to unforeseen disease events occasionally leading to extinction. Similarly, human intent or negligence and the vagaries of nature itself has resulted in ill health and loss of life. This paper describes the history of pandemics, epidemics and disasters, and the attempts to bring them under control.

The usefulness of tyrosinase in the immunohistochemical assessment of melanocytic lesions: a comparison of the novel T311 antibody (anti-tyrosinase) with S-100, HMB45, and A103 (anti-melan-A).

AIM: To compare the sensitivity and staining pattern of the new immunohistochemical antibody to tyrosinase (T311) with S-100, HMB45, and the recently evaluated antibody to melan-A (A103) in a range of melanocytic lesions. METHOD: Archival, formalin fixed, paraffin wax embedded sections from 50 benign and malignant melanocytic lesions were stained immunohistochemically with anti-tyrosinase, A103, S-100, and HMB45. They were scored semiquantitatively for the distribution and intensity of staining. RESULTS: All melanomas, with the exception of desmoplastic melanoma, showed some staining with all four antibodies. Overall, T311 and A103 showed an intermediate sensitivity compared with that of S-100 and HMB45. T311 stained most benign and malignant lesions strongly and diffusely with minimal background staining. Immunoreactivity was found to be patchy in some naevi, with weak or absent staining of the mature melanocytes. A103 showed strong and diffuse staining of all benign lesions and most melanomas with minimal background staining. S-100 was the most sensitive, with diffuse staining of most lesions, including desmoplastic and metastatic melanoma, but lacked specificity. HMB45 was the least sensitive antibody, frequently demonstrating patchy staining with absent staining in some benign naevi. CONCLUSIONS: S-100 remains the most sensitive marker of melanocytes. However, because of its lack of specificity, it should be used with at least one other more specific antibody. HMB45 is more specific, but lacks sensitivity; T311 is a reliable marker of melanocytes in paraffin wax embedded sections and is worth consideration for use in a staining panel, although it shows no additional benefit over A103.