Violence is clearly among the most menacing threats to human welfare around the world, yet it has not generally been thought of as a public health matter. Traditionally violence has been viewed primarily as a law enforcement issue, with a focus on punishment and deterrence. There may always be a need for these remedies, but as our cover story shows, violence is largely a preventable problem, and therefore the tools and perspectives of public health have much to offer in dealing with it. Public health methods of measuring the problem, investigating its causes, designing and implementing interventions and evaluating their success provide a promising approach to finding a solution.

Our second article is a photo essay featuring the stunning and poignant photographs of Brazilian photojournalist Sebastião Salgado. A modern-day philanthropist, Salgado has lent his considerable talent and energy to the noble cause of global polio eradication. The Americas eliminated polio and were declared free of the disease in 1994. But through Salgado's powerful images we see how polio still affects boys and girls, men and women in the countries where it has remained endemic. We also see that there is an end in sight to this totally preventable disease. Following health workers as they carry out a multi-country immunization campaign, Salgado documents what should soon become one of the finest successes of global public health.

"Battling over Biotechnology" tackles an issue that has emerged as much more controversial than was foreseen in the exciting early days of this field. Much to the consternation of scientists and companies working in this area, adamant objections have been raised to genetically modified (GM) foods, due to doubts about their potentially adverse effects on health and the environment. While the evidence supporting these objections remains sparse, the concerns cannot be ignored. Public health can play a critical role in addressing them by applying science-based criteria to the evaluation of new GM products. As our article reports, the Pan American Health Organization (PAHO) is actively working with its Member States to incorporate GM food and crops into their existing food safety systems.

This issue also features an article on PAHO's Pan American Foot-and-Mouth Disease Center (PANAFTOSA), showing how veterinary public health is integral to human public health. While foot-and-mouth disease is not directly dangerous to humans, PANAFTOSA's efforts to control it have been essential to ensuring food safety and security in our region while protecting meat production and trade.

This issue closes with two articles on communicable diseases, each with a very different focus. In a review of several recent books, "Purple Death: the Great Flu of 1918" treats us to a brief but absorbing history of the deadly Spanish flu. It reminds us of our vulnerability to such pandemics and is particularly sobering in the aftermath of the severe acute respiratory syndrome (SARS) epidemic earlier this year.

As a final note, our "Last Word" column broaches the enduring issue of stigma and discrimination against people living with HIV/AIDS. It calls attention to the regrettable fact that such discrimination can be found where it is least acceptable: in the health sector, where everyone is by training and vocation purportedly committed to promoting patients' mental and physical well-being. The column is based on a recent PAHO study of this issue and coincides with the launching of a regional campaign designed to eliminate stigma and discrimination from the health sector.

From the cover story to the "Last Word," the articles in this issue of Perspectives in Health illustrate the many faces and many strengths of public health. They provide evidence once again that our tried-and-true methods and our unique perspective—which sees all problems as at least partially preventable—can be applied fruitfully to virtually any threat to human health.

Mirta Roses Periago
Director