The acquired immunodeficiency syndrome (AIDS), caused by the diabolically unique human immunodeficiency virus (HIV-1), has profoundly changed contemporary society and medical practice. The chapters in this part enable the physician to understand the virus and its effects on humans. In addition, there is an extensive discussion of involvement of various organ systems, both by the virus itself and by opportunistic infections. The management of patients with HIV infection is presented in detail.

In 1981, the first cluster of cases of what we now call AIDS was recognized and reported. Nearly all of the early identified cases were in young homosexual men, but it was quickly learned that HIV infection could be transmitted by heterosexual contact and by blood transfer from infected to noninfected individuals.

After an initial flurry of fearful reactions by health care workers who believed that they were at a very significant risk for acquiring HIV infection, the facts are somewhat reassuring and protective procedures have been established. It is clear that the greatest risk to health care workers is needle stick (or other sharp) transmittal of blood from infected patients to health care workers, with an infection rate of about 3 per 1000: Universal precautions were established on the premise that blood and body fluids from all patients should be considered potentially infectious.

Recent data indicate that antiretroviral therapy reduces the risk of infection after accidental inoculation with HIV. Medical students and house officers training in many of our large medical centers are now just as likely to see patients with Pneumocystis carinii pneumonia as patients with pneumococcal pneumonia. The possibility of HIV infection must be considered in patients with a broad array of presenting symptoms because of the protean manifestations of this disease and its accompanying opportunistic infections and malignancies.

In the United States and other countries, governmental agencies have reacted to the HIV infection pandemic. New civil rights and public health legislation has been passed. The potential penalty for acquiring a sexually transmitted disease has now escalated to death. Despite this, countries around the world have been relatively slow to realize that the rules of the game for sexual contact have changed. We cannot wait for a vaccine to wipe out HIV infection. Educational efforts to reduce the spread of this disease have been supported by nearly all medical and public health groups, but have been opposed by other factions on religious or moral grounds. The process for drug testing, development, and approval has been altered. Activist groups have caused re-examination of some of the processes and regulations regarding approval of new therapies. This has resulted in “fast tracks” for certain agents. The concept of “surrogate markers” for disease progression has emerged. In a disease where time from infection to death is about 10 years, the use of survival measurements to determine efficacy of therapy would be impossibly slow. Therefore, surrogate markers such as CD4 counts and viral load are widely considered appropriate.

Despite more than a decade of significant progress related to understanding the molecular biology of the virus and details of pathogenesis of the disease, neither a cure nor an effective vaccine is in sight. However, modern therapy is very effective in those patients who are compliant and who can tolerate multiple drug regimens.

Study of patients who have resisted acquiring infection despite multiple exposures, and those who have had slow or no progression of their HIV infections, has uncovered the importance of chemokine receptors for viral entrance into cells. There is exciting potential to exploit this knowledge for new strategies of treatment and prevention.

All practicing physicians must know the basics of AIDS pathogenesis, disease presentation, and principles of management in order to effectively care for patients in the present era.