The human immunodeficiency virus (HIV) is a retrovirus that causes AIDS (acquired immune deficiency syndrome). The retrovirus primarily attacks the immune defense system, making the body extremely vulnerable to opportunistic infections.
HIV is transmitted from person to person via bodily fluids. It can be spread by sexual contact with an infected person, by sharing needles/syringes with someone who is infected, or, less commonly (and rare in countries where blood is screened for HIV antibodies), through transfusions with infected blood. HIV has been found in saliva and tears in very low quantities and concentrations in some AIDS patients. However, contact with saliva, tears or sweat has never been shown to result in HIV transmission.
Currently, there is no cure for HIV/AIDS. Patients receive antiretroviral drugs, which suppress the virus. These drugs do not reduce the risk of transmitting the disease to someone else.
Since 1981, when the first case of AIDS was reported in the United States, the disease has become a global pandemic, causing an estimated 65 million infections and 25 million deaths worldwide.
According to the U.S. Centers for Disease Control and Prevention (CDC), an estimated 2.8 million patients died from AIDS, 4.1 million people became infected with HIV and 38.6 million were living with HIV worldwide in 2005. According to the Joint United Nations Programme on HIV/AIDS (UNAIDS) and World Health Organization (WHO) 2006 AIDS Epidemic Update, an estimated 39.5 million people are currently living with HIV worldwide. It is also estimated that 4.3 million people became newly infected in 2006, with 2.8 million (65%) of these cases occurring in Sub-Saharan Africa. In 2006, 2.9 million people died from AIDS-related illnesses.
Certain geographic regions, such as Sub-Saharan Africa and the Caribbean, have much higher rates of infection than others. Subpopulations, such as women in Sub-Saharan Africa, men who have sex with men (MSM), prostitutes and injection-drug users, are also affected disproportionately when compared to the general population.
Effective prevention (like condoms) and antiretroviral therapy (ART) are now available in many developing countries that have limited resources. However, educational programs are still needed to help individuals who need treatment and to prevent further transmission of the disease.
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About 10% of the world population lives in Sub-Saharan Africa, but the region is home to about 64% of the global population living with HIV. In this region the disease is primarily transmitted through heterosexual contact, and more women are infected with HIV than men.
All countries in southern Africa, except Angola have an estimated adult (individuals ages 15-49) prevalence of HIV/AIDS greater than 10%. In fact, more than 20% of adults in Botswana, Lesotho, Zimbabwe and Swaziland have HIV/AIDS. Researchers estimate that 18.8% (5.5 million people) are living with HIV in South Africa.
In general, more women than men in Sub-Saharan Africa are infected with HIV. Researchers estimate that there are 13 women living with HIV for every 10 men who are HIV-positive in the region. In addition, women are typically infected at an earlier age than men. The difference between male and female infection rates is most apparent in people between the ages of 15-24 years old. In this age group, it is estimated that there are 36 females living with HIV for every 10 males. One of the most significant causes of the high HIV infection rate among females is their subordinate role in society. Married women must be subservient to their husbands, which makes it difficult for them to negotiate safe sex. In addition, women's economic dependence on men contributes to their vulnerability to HIV/AIDS infection.
Kenya, Uganda, Zimbabwe and urban areas of Burkina Faso have experienced declines in adult HIV prevalence in the last few years. Even though these countries have experienced a decline in risky sexual behaviors, and less people are diagnosed with HIV each year, the AIDS rates are still on the rise.
In general, the widespread prevalence of HIV and AIDS in Sub-Saharan Africa may be attributed to poor hygiene and economic conditions, as well as unprotected sex and blood transfusions. The WHO estimated that 25% of the blood transfused in Africa was not tested for HIV in 2000. Consequently, about 5-10% of HIV infections in Africa in 2000 were transmitted by blood transfusions. Poor economic conditions, which often lead to unsanitary conditions in healthcare clinics, contribute to the high infection rate. Unsanitary healthcare clinics may not be able to properly sanitize medical and surgical equipment, or may not have access to blood barriers like gloves. Prostitution also contributes to the spread of the disease. Many females are forced into prostitution because they lack economic power and job opportunities.
In 2000, South African President Thabo Mbeki publicly questioned the efficacy of HIV medications and doubted that HIV causes AIDS. While South Africa has created preventative programs to address the HIV epidemic, critics claim that the South African government has been slow to create antiretroviral programs. In Sub-Saharan Africa, about 17% of the estimated people in need of ART received the treatment in 2005.
The prevalence of adult HIV is lower in Asian countries than in Sub-Saharan African countries. According to the CDC, the epidemic in most Asian countries is attributed to high-risk behaviors, such as unprotected sex and injection-drug use. An estimated 16% of people who required ART in Asia received treatment in 2005.
India: In 2006, India surpassed South Africa as having the world's largest HIV population. Out of the estimated 8.3 million people living with HIV in Asia, about 5.7 million live in India. About 80% of HIV infections are acquired heterosexually. However, recent data show a decline in HIV prevalence in four Indian states among pregnant women ages 15-24. In 2000 an estimated 1.7% of pregnant women were infected, and in 2004 an estimated 1.1% of pregnant women were infected.
China: In China, an estimated 650,000 people are living with HIV. According to the CDC, about 50% of infected people acquired the disease from injection-drug use. However, the exact number is difficult to estimate because the Chinese government is reluctant to report the information. In addition, it is common for individuals to hide their HIV status because they are afraid of being discriminated against, according to the Chinese Department of Disease Control. There have been reports of some patients in China who were refused admission to hospitals because of their HIV-positive status.
and Cambodia: The HIV/AIDS epidemic in Thailand and Cambodia is attributed to commercial sex, which is legal in both of these countries.
In 2003 there was a decline in HIV prevalence among pregnant women. In 1995 2.4% of pregnant women were infected, and in 2003, 1.2% of pregnant women were infected. However, HIV incidence among men who have sex with men increased in Bangkok from 17% in 2003 to 25% in 2005.
According to the CDC, most HIV infections in the Americas are among men who have sex with men, injection-drug users and prostitutes. In general, about 68% of people in South and Central America and the Caribbean who needed ART received it in 2005. In the United States, about 55% of people who needed ART received it in 2005. High medical costs and lack of healthcare insurance significantly affect the availability of treatment.
United States: In 2006, more than one million people were living with HIV/AIDS in the United States. An estimated 252,000-312,000 HIV-infected people in the United States are unaware that they are HIV-positive, making them at high risk for transmitting HIV to others, according to the CDC.
Widespread availability of diagnostic tests for HIV infection has helped prevent HIV infections. About 50% of people ages 15-44 have reportedly taken an HIV test in the last year. Since the mid-1980s, blood donor screening methods and testing technology have continually improved. Today nucleic acid tests are used to screen blood products for infectious diseases like hepatitis and HIV. Therefore, the risk of HIV transmission is estimated to be as low as one per two million blood donations.
Prevention interventions, such as drug treatment programs, risk reduction education and peer outreach, have contributed to a steady decline in new HIV/AIDS diagnoses among injection-drug users. In 2001, an estimated 8,048 injection-drug users were diagnosed with HIV, compared to 5,962 in 2004.
Certain subpopulations are more likely to develop HIV. For instance, men who have sex with men (MSM) account for about 45% of newly reported HIV/AIDS diagnoses and nearly 54% of cumulative AIDS diagnoses. MSM made up about two-thirds of all men living with HIV in 2004, even though only about 5% to 7% of men in the United States reported having sex with other men. According to one national study, about 25% of male homosexuals surveyed in large U.S. cities are infected with HIV, and nearly 50% of those infected are unaware of their HIV status.
Racial and ethnic minority communities also are disproportionately affected by HIV/AIDS in the United States. Recent data show that during 2001-2004, African Americans and Hispanics together accounted for 69% of all reported HIV/AIDS cases in the United States. African Americans, who only make up about 13% of the U.S. population, accounted for 51% of all new HIV/AIDS diagnoses in the United States.
Currently, women account for about one quarter of all new HIV/AIDS diagnoses, and in 2002 HIV infection was the leading cause of death for black women who were 25-34 years old.
Brazil: Brazil has an adult HIV prevalence of about 0.5%. Brazil accounts for more than one-third of all HIV infections in Latin America. The virus is primarily transmitted during commercial sex, sex between men and injection-drug use.
Many Brazilians, ages 15-24, engage in high-risk behavior that could lead to the development of HIV. For instance, one of out three Brazilians, ages 15-24, reported that they engaged in sexual activity before the age of 15, and one in five reported that they had more than 10 sexual partners, according to the CDC.
Brazil provides free ART to everyone who needs treatment. An estimated 83% of HIV-infected people receive the treatment.
Caribbean: At the end of 2005, an estimated 330,000 people were living with HIV and AIDS in the Caribbean. About 37,000 people were newly infected during 2005, and about 27,000 died from AIDS. Researchers estimate that the adult prevalence rate is between 1.1% and 2.7%, making it the second-most affected region in the world.
HIV transmission is primarily heterosexual. However, sex between men is also a significant route of transmission.
HIV prevalence has declined in the urban areas of Haiti, but has remained relatively constant throughout other areas of the Caribbean.