The limited epidemiological investigation in this case shows that the patient could have developed AIDS in as little as 2 months, but that it might have taken as long as 10, Dr. Frieden said. On average, it takes 10 years from the time a person is first infected with H.I.V. for AIDS to develop. But it can take only months for some people, and 20 years for others.
At the news conference in Lower Manhattan, Dr. Frieden was joined by nearly a dozen AIDS experts and community leaders. Several participants said they were experiencing the same worried feeling they had more than two decades ago, when AIDS first appeared and there was no treatment.
Health officials cautioned that the emergence of the rare strain did not mean that people who are currently responding well to H.I.V./AIDS treatment needed further testing, unless ordered by a physician. They did warn, however, that people with H.I.V./AIDS could be re-infected with a different and more dangerous strain if they practiced unprotected sex.
More tests need to be completed before it is clear if any combination of drugs can effectively treat this strain of the virus, but Dr. Frieden said that therapy now appeared to be extremely difficult.
The man is currently receiving a cocktail of drugs, including one, Enfuvirtide, that is believed to be effective. Doctors cautioned, however, that single-drug therapy was rarely effective against AIDS in the long term.
From the moment the Health Department learned about this case on Jan. 22, its scientists have been studying complex laboratory tests to decipher the patterns of resistance, and epidemiologists have tried to trace the man's sexual partners and notify them of the potential risk.
In May 2003, the man tested negative for H.I.V., health officials said. Investigators believe he contracted H.I.V. in October 2004, when he engaged in unprotected anal sex with multiple partners while using crystal methamphetamine. The man found some of his partners on an Internet Web site, officials said, though they would not identify the site. Health officials said they were working with those who used the Web site to reach as many people as possible who might have been infected or are worried that they could have been.
Ilustración estilizada de una sección del Virus de Inmunodeficiencia Humana (SIDA).''Fuente: NIH''
 Una mutación resistente y de acción rápida del VIH, virus causante del sida, se detectó en Nueva York el pasado viernes.

Esta cepa, llamada 3-DCR HIV, progresa más rápido que otras formas del virus. En el caso del hombre infectado, cuya identidad se mantiene en reserva, el virus fue diagnosticado a mediados de octubre y se había desarrollado completamente a mediados de enero, tres meses después, cuando normalmente la infección con VIH puede tardar hasta 10 años para convertirse en sida. El enfermo habría confesado haber tenido relaciones sexuales sin protección con varios compañeros.

El Dr. Ronald O. Valdiserri, director del programa de prevención del sida en el Centro para Control y Prevención de Enfermedades (CDC), dijo al ''New York Times'' que esta nueva forma del virus es única por el rápido avance de la enfermedad y su resistencia a los tratamientos farmacéuticos actuales. A pesar de ser un caso aislado, el CDC ya envió una alerta nacional a los departamentos de salud de todos los estados de la Unión Americana.

Las opiniones se encuentran divididas. Para Robert Gallo, uno de los precursores del tratamiento contra el sida y director del Departamento de Virología de la Universidad de Maryland, "es probable que algunos pacientes desarrollen más rápido la infección porque son altamente susceptibles y no porque su cepa del virus sea más agresiva". Otros se preguntaban si este aviso fue, hasta cierto punto, imprudente.