July 2011 Page 1 of 4

What Is HIV/AIDS and 

How Is It Spread?

The human immunodeficiency virus (HIV), 

which causes acquired immunodeficiency 

syndrome (AIDS), is a virus that lives in 

and can severely deplete white blood cells 

(CD4+ lymphocytes), which are part of the 

immune system. HIV can be transmitted by 

contact with the blood or other body fluids 

of an infected person. In addition, infected 

women can pass HIV to their infants during 

pregnancy, delivery, and breastfeeding.

An HIV-infected person may look and feel 

fine for many years and may therefore be 

unaware of the infection. However, as the 

immune system weakens, the individual 

becomes more vulnerable to illnesses and 

common infections. Over time, a person 

with untreated HIV is likely to develop 

AIDS and succumb to multiple, concurrent 

illnesses. Because HIV/AIDS is a condition 

characterized by a defect in the body’s 

natural immunity to diseases, infected 

individuals are at risk for severe illnesses 

that would not normally pose a threat. 

Although no vaccines or medications yet 

exist to prevent a person from acquiring 

HIV, and AIDS still has no cure, effective 

medications are available to treat HIV 

infection and help prevent the progression 

to AIDS. 

What Is the Extent and 

Impact of HIV/AIDS?

Approximately 1.1 million adults and 

adolescents are living with HIV infection 

in the United States, with an estimated 

56,300 more becoming infected each 

year, according to the Centers for Disease 

Control and Prevention (CDC). 

A number of complex and interacting 

biological, social, and economic factors place 

some populations at increased risk for HIV/

AIDS. For example:

•	 Although African Americans make up about

12 percent of the U.S. population, they 

accounted for nearly half of all people living 

with HIV/AIDS at the end of 2007. At some 

point in their lives, 1 in 16 African American 

men will be diagnosed with HIV infection, as 

will 1 in 30 African American women. 

o In 2006, HIV/AIDS infection was the 

third leading cause of death for both 

African American men and women 

aged 35–44 and the ninth leading 

cause of death for African Americans 

of all ages.

o The rate of new HIV infections for

African American men was about 

6 times that of White men and 

3 times that of Hispanic American

men. The HIV prevalence rate for

African American women was nearly

15 times that of White women and

nearly 4 times that of Hispanic 

American women. 

• 	Hispanic Americans make up about

15 percent of the population, yet they 

accounted for 17 percent of people living 

with HIV in the United States in 2006. In 

2007, HIV/AIDS was the fifth leading cause 

of death among Hispanic American men 

and women aged 35–44. 

• 	Men having sex with men remains the

primary avenue for HIV transmission in the 

United States, accounting for over half of 

all new HIV infections each year, as well as 

Drug Abuse and the Link to HIV/AIDS 

and Other Infectious Diseases
July 2011 Page 2 of 4

studies have shown that stimulants can 

increase HIV viral replication, and in a 

human study, HIV caused greater neuronal 

injury and cognitive impairment in drug 

users than in nondrug users. 

Is AIDS Treatable?

Since the mid-1990s, the lives of people 

with HIV/AIDS have been prolonged and 

symptoms decreased through the use 

of HAART (highly active antiretroviral 

therapy). HAART is a customized 

combination of different classes of 

medications prescribed for individual 

patients based on such factors as their 

viral load, CD4+ lymphocyte count, and 

clinical symptoms. 

Interventions aimed at increasing 

adherence to HIV treatment are crucial 

to treatment success, but they usually 

require dramatic and often difficult lifestyle 

changes to counter the irregular lifestyle 

created by drug abuse and addiction. 

However, relatively easy measures can 

also be effective. For example, one study 

found that simply helping HIV-infected 

inmates complete the paperwork required 

to get their prescriptions filled upon 

release significantly diminished treatment 

interruption. Adequate medical care for 

HIV/AIDS and related illnesses is also 

critical to reducing and preventing the 

spread of new infections.

Is HIV/AIDS Preventable?

Yes. Cumulative research has shown 

that comprehensive HIV prevention—

drug abuse treatment, community-based 

outreach, testing, counseling for HIV 

and other infections, and early initiation 

of HAART—is the most effective way to 

reduce the risk of blood-borne infections. 

nearly half of all those living with HIV. Men

who have sex with men (MSM) constitute the

only risk group for which new HIV infections 

are increasing. 

•	 Individuals infected through heterosexual

contact account for about 30 percent of new 

HIV infections and more than a quarter of 

persons living with HIV. 

Furthermore, CDC estimates that in 2006 

about one in five HIV-infected persons in the 

United States were unaware of their infection, 

down from an estimated one in four who were 

unaware in 2003. Not only are these infected 

individuals at high risk for transmitting HIV to 

others but they are also not taking advantage 

of effective medical treatments for HIV that 

can slow disease progression and reduce 

AIDS-related illnesses.

How Are HIV/AIDS and Drug 

Abuse Linked? 

Drug abuse and addiction have been 

inextricably linked with HIV/AIDS since the 

beginning of the pandemic. HIV transmission 

can occur by sharing needles and other 

injection paraphernalia. In fact, about onefourth of AIDS cases in the United States have 

resulted from injection drug use. However, any 

drug and alcohol use can put people at risk for 

HIV by interfering with their judgment, leading 

to risky sexual behaviors:

•	 According to combined data from 2005

to 2009, 64 percent of those living with 

HIV/AIDS had used an illicit drug, but not 

intravenously; only 19 percent had never 

used an illicit drug. 

•	 One in four of those living with HIV in 2009

reported use of alcohol or drugs at a level 

that warranted treatment. 

Drug abuse and addiction can also worsen 

the progression of HIV and its consequences, 

especially in the brain. For example, animal 
July 2011 Page 3 of 4

known as “Seek, Test, Treat, and Retain,” 

seeks out high-risk individuals who have 

not recently been tested, initiates HAART 

therapy for those who test positive, and 

monitors their progress over time. 

And while innovative strategies to reduce 

HIV risk behaviors are making their 

mark, studies are also looking at ways 

to improve the long-term effectiveness 

of successful interventions. Randomized 

controlled trials that compare different 

strategic approaches (case management 

strategies, use of incentives, use of 

technology, co-location of drug abuse 

treatment with care for infectious disease 

and other comorbid conditions, etc.) will 

help ascertain the most effective ways to 

retain in care those who test positive to 

improve both individual and public health.

What Other Infectious 

Diseases Are Associated 

with Drug Abuse?

Besides increasing their risk of HIV 

infection, individuals who take drugs or 

engage in high-risk behaviors associated 

with drug use also put themselves and 

others at risk for contracting or transmitting 

hepatitis C (HCV), hepatitis B (HBV), and 

tuberculosis (TB), as well as a number of 

sexually transmitted diseases including 

syphilis, chlamydia, trichomoniasis, 

gonorrhea, and genital herpes. Injection 

drug users (IDUs) are susceptible to skin 

infections at the site of injection, which, 

if left untreated, can cause serious health 

problems. IDUs are also susceptible to 

bacterial and viral infections such as 

bacterial pneumonia and endocarditis.

Effective drug abuse treatments (both 

pharmacological and behavioral) have a 

demonstrated impact on reducing HIV risk 

behaviors and HIV transmission. For drug 

abusing populations, drug abuse treatment 

is HIV prevention, since the behaviors 

associated with drug abuse, such as sharing 

drug injection equipment and/or engaging 

in risky sexual behavior while under the 

influence of drugs or alcohol, can foster 

disease transmission. To illustrate:

•	 Recent research that combined methadone

treatment with behavioral therapy showed 

that about half of study participants 

reporting injection drug use at intake 

reported no such use at study exit. Over 

90 percent of all participants reported no 

needle sharing at study exit. 

•	 Reduction in cocaine use has also been

associated with large decreases in HIV risk, 

mainly as a result of fewer sexual partners 

and less unprotected sex. 

•	 Buprenorphine/naloxone treatment

administered in physicians’ offices for 

opioid abuse is associated with decreased 

injection drug use and other HIV risk 

behaviors.

Research has also demonstrated that broadbased HIV screening and early initiation 

of HAART can reduce viral load and HIV 

incidence at the population level. Moreover,

HIV screening has been shown to be costeffective—as cost-effective as screening for 

other conditions such as breast cancer and 

high blood pressure.

Research is therefore under way to develop 

and test strategies to expand HAART 

coverage. A promising new approach, 
July 2011 Page 4 of 4

People with latent TB infection do not 

have symptoms, may not develop active 

disease, and cannot spread TB. However, 

if such individuals do not receive 

preventive therapy, they may develop 

active TB, which is contagious. NIDA 

research has shown that IDUs have high 

rates of latent TB infection. Because HIV 

infection severely weakens the immune 

system, people infected with both HIV 

and latent TB are at increased risk of 

developing active TB and becoming highly 

infectious. Effective treatment for HIV and 

TB can reduce TB/HIV-associated disease 

and the risk of transmission to others. 

Other Information 

Sources

To learn more about the link between drug 

abuse and HIV/AIDS, visit www.nida.

nih.gov/DrugPages/HIV.html.

To learn more about resources for HIV/

AIDS, hepatitis, and TB, or for testing and 

referral in your geographic area, call 

1-800-CDC-INFO (1-800-232-4636), or 

visit www.cdc.gov/hiv, www.cdc.

gov/ncidod/diseases/hepatitis, or

www.cdc.gov/tb/.

To find publicly funded treatment services 

for drug abuse and addiction in your 

State, visit www.findtreatment.

samhsa.gov.

HCV, HBV, and HIV/AIDS

HCV and HBV are two of several viruses 

that cause inflammation of the liver. HCV, 

the leading cause of liver disease, is highly 

prevalent among IDUs and often co-occurs 

with HIV; HBV is also common among drug 

abusers. NIDA-funded studies have found 

that within 3 years of beginning injection 

drug use, most IDUs contract HCV. Up to 90 

percent of HIV-infected IDUs may also be 

infected with HCV. 

Chronic infection with HCV or HBV can 

result in cirrhosis (liver scarring) or primary 

liver cancer. How HCV infection and 

HIV/AIDS interact is not completely 

understood; however, the course of HCV 

infection is accelerated in dually infected 

individuals, with higher rates of progressive 

liver disease and death in those infected with 

both HIV and HCV than in those infected with 

HCV alone. Assessment of disease stage is 

important to the timing of therapy initiation 

for both infections, as is long-term medical 

followup in order to improve quality of life.

TB and HIV/AIDS

TB is a chronic and infectious lung disease. 

Through major public health detection and 

treatment initiatives, its prevalence declined 

in the United States for several years—in 

2005, 14,000 cases were reported, the 

lowest number since surveillance began in 

1953. However, the decline of TB prevalence 

has slowed by half in recent years, and TB 

infection remains intertwined with HIV/AIDS 

and drug abuse.