By 1983, the US Center for Disease Control (CDC) knew enough about AIDS to declare that it was caused by a previously unknown infectious agent, and was transmitted only in specific ways. To Jonathan Mann this suggested a largely preventable disease, but one that, given human nature, still posed a grave epidemic threat to humankind. However, in most Americans, the preponderance of AIDS cases among gay men incited irrational reactions: stony silence from political and 'spiritual' leaders; instances of panicky fear among some of the populace; self-righteous indifference buttressed by thunderous admonitions from some clergy about "God's punishment for sin." Thus, in 1983 a terrible stigma had already been attached to AIDS in this country.

That same year, reports came from Europe of African immigrants seeking medical attention for a disease that seemed similar to AIDS, which was afflicting men and women in equal numbers. James Curran, director of the CDC AIDS Program, paid attention, and in 1984 he recruited Mann (then the chief epidemiologist and assistant director of the Health Department of the State of New Mexico), to take on directorship of an international AIDS research group that would work in Zaire (now the Republic of Congo). Mann accepted, and established "Projet SIDA," a highly productive Zairian, American and Belgian AIDS collaborative research effort.

Mann's team uncovered an already-vast epidemic of AIDS in sub-Saharan Africa. Consequently, in 1986, he was offered the position of first director of the World Health Organization's (WHO) Global Programme on AIDS (GPA). Within four years, Mann had created a global AIDS strategy and a WHO department that grew to more than 200 staff members with a $70 million annual budget. The GPA provided motivational, technical and financial support to 160 countries.

What made this achievement remarkable was the unique philosophy that propelled it. Mann's knowledge of the misguided early response to AIDS in the US and much of Europe, and his confrontations with government officials in many countries, made him realize that it is impossible to control an epidemic rationally when human lives are not valued equally. If certain groups are considered dispensable, certain ubiquitous human behaviors condemned, and the right to respect and dignity denied, disease—particularly an epidemic disease—not only continues, but is helped. His mantra became one of respect for human dignity and social justice as fundamental not only to economic development, but also to the protection of any population's health.

His triumph was that one person of unassuming appearance and mild voice but dogged moral conviction was able to effectively counter many governments' denial of the existence of AIDS among their people, and to denounce inhumane policies inflicted on those living with HIV or at risk of this infection. Mann gave a voice to countless suffering people who, for so long, had had no friend. The Global Programme on AIDS was the first UN agency to devote so much time and effort to working directly with non-governmental community-based organizations, and the GPA ultimately succeeded in uniting many countries against a common enemy and encouraging them to adopt policies based on sound public health and ethical principles.

But Mann's passion and zeal did not always sit well with Hiroshi Nakajima, then Director General of the WHO, and Mann resigned his position at the WHO in 1990. He joined the Harvard School of Public Health and became the first director of the Francois-Xavier Bagnoud Center for Health and Human Rights. He founded the Health and Human Rights Journal and organized the world's first conferences on this subject at Harvard University in 1994 and 1996.

In 1995 Mann met Mary Lou Clements at a scientific conference. They married in 1996. Clements' classic scientific and medical education at the University of Texas, the London School of Hygiene and Tropical Medicine, and Johns Hopkins University, underlay her technological pragmatism in the fight against AIDS. Her most recent goal was to bring about large-scale clinical trials of HIV vaccines. She was closely associated with the development of VaxGen's gp120 vaccine, and lived to see it enter phase III trials this summer ( Nature Med. 4, 753; 1998). At the time of her death, she was a tenured professor in the department of International Health at Johns Hopkins University School of Hygiene and Public Health, and without doubt a revered researcher, teacher and lecturer.

The couple's intellectual and emotional closeness translated in recent months into an adoption of each other's professional passions: Clements shared her husband's dedication to human rights, and he had begun to champion her views that conducting clinical trials with currently available vaccine candidates was the best strategy for the rapid development of an anti-HIV vaccine—a highly controversial subject in the field of HIV research ( Nature Med. 4, 648; 1998). Speaking recently before the President's Advisory Council on AIDS, he provocatively suggested that the NIH violated human rights by not proceeding to large-scale clinical trials with currently available AIDS vaccines. Perhaps passion for justice and hope had, this time, carried him too far—he was sharply rebuked for his comments. In January this year, Mann moved to be near his wife and accepted the directorship of the newly formed School of Public Health at Allegheny University in Philadelphia.

Jonathan Mann (51) and Mary Lou Clements-Mann (51) died September 3rd aboard the Swissair flight that crashed off the coast of Nova Scotia, Canada. Although each was renowned for a variety of accomplishments since the early days of their careers, both had chosen to dedicate their professional life to fighting the global scourge of HIV/AIDS. They did so to the last: the plane that crashed was to have taken them to Geneva for an HIV vaccine summit at the World Health Organization.