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Acquired Immune Deficiency Syndrome: The Facts

By Steven Parker | Aids HIV | Rating:

Introduction

The first cases of acquired immune deficiency syndrome (AIDS) were reported in the U.S. in June of 1981. The occurrence of the syndrome among homosexual men, intravenous (IV) drug abusers and, later, blood transfusion recipients and persons with hemophilia suggested a transmissible agent as the cause. In 1984, scientists identified a retrovirus, human immune deficiency virus (HIV), also known as human T-Iymphotropic virus type III/lymphoadenopathy, associated virus (HTLV-III/LAV), as the primary cause of AIDS. In 1985, screening tests to detect antibodies to HIV were licensed, allowing identification of infected individuals and the screening of the blood supply. Researchers have been able to map the genetic structure of HIV and to demonstrate the nature of the immune defect. Ongoing research is aimed at identifying risk factors and preventive strategies, evaluating antiviral drugs, developing drugs to augment the immune system, and developing a vaccine.

An estimated 1,000,000 Americans have been infected by the HIV virus. The virus has been isolated from various bodily fluids including blood, semen, saliva, tears, urine, breast milk and cerebrospinal fluid. Transmission of HIV occurs primarily through four major routes: sexual contact, intravenous drug use, blood transfusions and perinatal contact with an infected mother. The screening of donated blood since 1985 for HIV antibodies has virtually eliminated blood transfusion as a risk for acquiring AIDS in the U.S. 95% of the cases of AIDS reported in the U.S. have belonged to the following high risk groups: homosexual and bisexual men, 73%; IV drug abusers, 17% (11% of homosexual and bisexual men also inject drugs); blood transfusion recipients, 2%; persons with blood clotting disorders or hemophilia, 1%; heterosexual contacts of persons in the above groups, 1%; and infants born to mothers with AIDS or HIV infection, 1%.

All persons with AIDS or with antibodies to HIV are considered carriers of the virus and capable of transmitting it to others. It is believed that most people with antibodies to HIV will remain free of AIDS symptoms. The ratio of persons infected with HIV to those with AIDS is estimated currently at between 100:1 to 50:1. The three-year incidence of AIDS among persons with the HIV infection ranges from 8% to 34.2% in selected municipal studies. Estimates are that 10% to 30% of infected persons will develop AIDS within 5 years. For persons who develop AIDS, the overall fatality rate in April of 1986 was 54%. At the end of two years following diagnosis of AIDS, however, the fatality rate was over 75%. At five years, the fatality rate was about 90%.

90% of AIDS patients are between 20-49 years of age. The loss of years of potential life before age 65 due to AIDS is nearly the same as for cancer in single men 25-44 years of age. The economic costs of AIDS are considerable, totalling an estimated $4.1 billion in 1985. Data cited here are changing rapidly and represent the situation only as of 1986.

Prevalence

Prevalence of HIV Infection

As of 1987, an estimated 1.5 million Americans were infected with the HIV virus.

In 1984-1985, the prevalence of the HIV antibody in populations of homosexual men ranged from a low of 44% in Washington, D.C. to 65% in New York City to a high of 68% in San Francisco.

In 1984, the prevalence of the HIV antibody in population of IV drug users ranged from a low of 9% in San Francisco to a high of 68% in New York City.

In 1983-1985, the prevalence of the HIV antibody in populations of hemophilia patients ranged from 46% to 75%.

The period of time between known exposure to the HIV virus and seroconversion ranges from 19 days to 12 weeks.

AIDS in adults usually develops more than two years after HIV infection and may appear more than five years after seroconversion.

The three-year incidence of AIDS among all HIV seropositive subjects in a study of five cohorts (three groups of homosexual men, one group of IV drug users and one group of hemophilia patients) ranged from 8.0% to 34.2%.

Prevalence of AIDS

A total of 21,517 cases of AIDS were reported in the United States by June 9, 1986.

AIDS cases have been reported from all 50 states, the District of Columbia and 3 U.S. territories.

Although the number of new AIDS cases continues to increase each year, the rate of increase has diminished, as shown below.

The length of time required for a doubling of the cumulative number of AIDS cases in the U.S. has increased from 5 months in 1982 to 11 months in January, 1986.

The annual incidence rate of AIDS in the U.S. has increased from 0.11 cases per 100,00 persons in 1981 to 1.43 cases per 100,000 persons for the year ending May 31, 1984.

The prevalence of AIDS in the U.S. as of June 9, 1986, was 94.5 cases per million population. Broad geographical variation exists, with the highest prevalence rates recorded in New York City (722.0 cases per million) and San Francisco (684.8 cases per million). Those two cities accounted for 41% of all 21,517 AIDS cases reported in the U.S. by June 9, 1986.

In the U.S., 95% of AIDS cases have occurred to persons belonging to one or more groups known to be at high risk for AIDS, including homosexual or bisexual males, intravenous drug abusers, hemophilia or coagulation disorder patients, blood transfusion recipients or heterosexual contacts of persons with AIDS or at risk of AIDS.

Of the 6% of AIDS cases initially reported without identifying risk factors, about 33% are persons from countries where heterosexual transmission accounts for many AIDS cases. Further interviewing of available members of the remaining group identified risk factors for all but 33%. Thus, less than 2% of all AIDS cases ultimately remained without identifiable risk factors.

Opportunistic infections occur in all AIDS patients. To date in the U.S., 58% of AIDS patients have had Pneumocystis carinii pneumonia (PCP), 17% have had Kaposi's sarcoma (KS), 5% have had both PCP and KS and 19% have had other opportunistic infections.

Kaposi's sarcoma has been reported in over 34% of homosexual men with AIDS, but in only 6% of AIDS patients in all other groups.

Mortality from AIDS

As of June 9, 1986, 11,713 people died in the U.S. from AIDS, representing 54% of all known cases.

The case fatality rate is over 75% for persons diagnosed with AIDS for two years or more.

In a follow-up of approximately 3,600 cases of AIDS in New York City and State, the median survival time for gay men was 10 months and for IV drug abusers 7 months.

The median survival of those AIDS patients with Kaposi's sarcoma was 14 months, those with Pneumocystis carinii pneumonia was 7 months and those with other opportunistic infections was 6 months.

Since about 90% of AIDS patients are between 20-49 years old, AIDS results in a disproportionate number of years of potential life lost (YPLL) before age 65. In single men ages 25-44 years in the U.S., AIDS caused nearly as many YPLL in 1984 (32,300) as did cancer (39,500) in 1980. In Manhattan and San Francisco in 1984, AIDS was the leading cause of YPLL among 25-44 year-old men with more YPLL than for accidents, homicide, suicide, and cancer combined.

Modes of Transmission

All persons with AIDS or with antibodies to HIV are considered carriers of the virus, capable of transmitting the infection to others.

Although HIV has been isolated from the blood, semen, saliva, tears, urine and breast milk of infected individuals, the only known transmission has been via blood and semen. Studies of nonsexual household contacts of AIDS patients indicate that casual contact with saliva and tears does not result in transmission of infection.

HIV infection can persist even in asymptomatic individuals for at least several years. Retrovirus infections in animals persist for life. The presence of HIV antibody is presumptive evidence of current infection and infectibility.

In most cases, HIV appears to have been transmitted through one or more of four routes: sexual contact, intravenous drug administration with contaminated needles, administration of blood and blood products, and passage of the virus from infected mothers to their unborn babies.

After four years of close observation of AIDS in the U.S., no evidence exists showing the transmission of HIV infection or AIDS through food, by arthropods, or from casual contact. Similarly, no cases of AIDS or HIV transmission have been attributed to the use of immunoglobulins or the hepatitis B vaccine.

The risk of HIV transmission through blood or blood products transfusion has been virtually eliminated by current practices, which include screening of donated blood for HIV antibodies and heat treatment of clotting factor concentrates.

The risk of perinatal transmission of HIV by infected mothers is not known precisely, but was observed in one study to be as high as 65%.

No known transmission of HIV infection to household contacts of infected persons has been detected when the household contacts have not been sex partners or infants of infected mothers.

No known transmission of HIV infection has occurred from the preparation or serving of food or beverages. No known risk of transmission to coworkers, clients, or consumers exists from HIV-infected workers in other worksites (e.g., offices, schools, factories, construction sites).

The risk of acquiring HIV infection from a needlestick exposure to a source patient is much less than 1%. For comparison, the risk of hepatitis B infection following a needlestick from a hepatitis B carrier ranges from 6%-30%.

AIDS Outside the United States

In Europe, a cumulative total of 1,573 cases of AIDS have been diagnosed through September 1985. The highest prevalence rates were recorded in Belgium (11.9 per million), Switzerland (11.8 per million) and Denmark (11.2 per million), but were far below the estimated prevalence of AIDS in the U.S. in September 1985 of 60.0 per million.

In Europe, 92% of the AIDS patients as of September 1985 were males and 88% were between 20-49 years of age. Of the total European AIDS cases, 69% were homosexual or bisexual men, 6% were IV drug abusers, 2% were both of the above, 3% were hemophilia patients, 2% were transfusion recipients without other risk factors, 2% were unknown, and 11% had no known risk factors. Of those without identifiable risk factors, up to 72% were from countries where heterosexual transmission of HIV occurs commonly.

The Pan-American Health Organization reports 1,685 cases of AIDS in the Americas outside the U.S. through December 31, 1985. The majority of those cases were from Brazil (540), Canada (435) and Haiti (377).

Cases of AIDS have been reported in residents of nearly 20 African countries, but studies of AIDS have been conducted primarily in Zaire and Rwanda. In Zaire, the male-to-female ratio was approximately 1:1 and the annual incidence was estimated at 17-40 per 100,000 population. In the U.S., the male-to-female ratio among adults is currently 14.2:1. In 1984, the annual incidence of AIDS in the U.S. among single males was 14.3 per 100,000, and among the general population, 1.4 per 100,000.

HIV and AIDS in Homosexual and Bisexual Men

In a cohort of 6,875 homosexual and bisexual men in San Francisco, the prevalence of HIV antibodies had reached 73.1% by August, 1985.

In the San Francisco cohort, 3.8% of the entire group and 5.2% of those with HIV antibodies had developed AIDS by August, 1985.

Two-thirds of the men in the San Francisco cohort study who had HIV infections for over five years had not developed AIDS or AIDS-related illness.

The seroprevalence of HIV antibody among a group of homosexual males in New York City was 65% in a 1985 study.

The three year incidence of AIDS was 34.2% in a, cohort of HIV seropositive homosexuals in Manhattan.

Intervention Data

Changes in Sexual Behavior Among High Risk Groups

Surveys of risk factors for HIV infections among gay and bisexual men in San Francisco revealed that the percentage of persons with more than one sexual partner during the 30 days prior to the survey decreased from 49% in August, 1984, to 26% in April, 1985. The percentage of persons who were monogamous, celibate or had no unsafe sexual activity outside a primary relationship increased from 69% in August, 1984, to 81% in April, 1985. (In this study, an unsafe sexual practice included anal intercourse without a condom and oral sex with exchange of semen.)

Cases of rectal gonorrhea in men attending the San Francisco City Health Department clinics declined 73% between 1980-1984.

Between 1980-1983, rates of rectal and pharyngeal gonorrhea in men in Manhattan decreased 59%.

Use of Health Services

The initial hospitalization of AIDS patients entails a mean length of stay of 31 days. Rehospitalization for new or recurrent opportunistic infections is frequent.

A New York City study found that 14% of AIDS patients died during the initial hospitalization, 35% spent less than 30% of the time in the hospital after the initial hospitalization, 16% spent between 30%-50% of the time hospitalized and the remaining 35% spent more than 50% of the time in the hospital.

It is estimated that the first 10,000 patients with AIDS will spend a total of 1,677,900 days in the hospital.

A California study reported that AIDS patients had an average of 6.4 hospitalizations at an average length of stay of 14 days over an 18-month average lifespan.

Economic Impact

An estimated $147,000 is spent on the entire hospital care of each AIDS patient.

A study of the economic costs of AIDS estimated that in 1984 each AIDS patient was admitted to a hospital an average of 1.7 times for an average length of hospitalization of 13.0 days. The average charge per hospital day was $740. The average outpatient charge was estimated at $2,015 for each AIDS case in 1984.

The total economic impact of the first 10,000 cases of AIDS in the U.S. has been estimated at $6.3 billion, including $1.4 billion on direct hospitalization expenses, $189 million in lost wages due to disability and $4.6 billion in lost earnings from premature death.

The direct economic costs of AIDS in 1985 have been estimated at a total of $836.5 million, including $517.4 million in personal medical care costs and $319.1 million in non-personal costs (research, blood screening, education and prevention services).

The indirect economic costs of AIDS in 1985 were estimated at $3,285.6 million, including $205.7 million in morbidity costs (value of productivity losses due to illness and disability) and $3,079.0 million in mortality costs (value of earnings lost due of premature death).

According to these estimates, the total direct and indirect costs of AIDS in 1985 were $4,122.1 million.

In 1984, total personal health care expenditures in the U.S. were estimated at $387.4 billion, and total indirect costs of morbidity and mortality of all illness and death were estimated at $304.7 billion, for a total of $692.1 billion in direct and indirect costs. Estimates of the direct and indirect costs of AIDS for 1984 total $1.9 billion, a fraction of 1% of the total economic costs for all diseases that year.

Expenditures for Research on AIDS

Research expenditures on AIDS have increased from $60 million in 1984 to $113.6 million in 1985 to $233.7 million in 1986.

The expenditures for AIDS health education, information and support services by the Centers for Disease Control, State and local governments and community-based volunteer organizations have been estimated at $19.3$23.3 million for 1985 and $27.6$31.6 million for 1986.





Steven Parker

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