AIDS overview

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

Overview

Acquired immune deficiency syndrome (AIDS) is a collection of symptoms and infections resulting from the specific damage to the immune system caused by the human immunodeficiency virus (HIV) in humans, and similar viruses in other species (SIV, FIV, etc.). The late stage of the condition leaves individuals susceptible to opportunistic infections and tumors. Although treatments for AIDS and HIV exist to decelerate the virus's progression, there is currently no known cure. HIV is transmitted through direct contact of a mucous membrane or the bloodstream with a bodily fluid containing HIV, such as blood, semen, vaginal fluid, preseminal fluid, and breast milk. This transmission can come in the form of anal, vaginal or oral sex, blood transfusion, contaminated hypodermic needles, exchange between mother and baby during pregnancy, childbirth, or breastfeeding, or other exposure to one of the above bodily fluids.

Classification

Since June 5, 1981, many definitions have been developed for epidemiological surveillance such as the Bangui definition and the 1994 expanded World Health Organization AIDS case definition. However, clinical staging of patients was not an intended use for these systems as they are neither sensitive, nor specific. In developing countries, the World Health Organization staging system for HIV infection and disease, using clinical and laboratory data, is used and in developed countries, the Centers for Disease Control (CDC) Classification System is used.

Pathophysiology

Human Immunodeficiency virus causes AIDS by depleting CD4+ T helper lymphocytes. T lymphocytes are essential to the immune response and without them, the body cannot fight infections or kill cancerous cells. Thus the weakened immune system allows opportunistic infections and neoplastic processes. The mechanism of CD4+ T cell depletion differs in the acute and chronic phases, to sum it all AIDS has a complex pathophysiology.

Differentiating AIDS from other Diseases

AIDS is an immunodeficiency disease. It should be considered in patient presenting with symptoms of immunodeficiency. AIDS should be distinguished from congenital disorders and considered in the differential diagnosis of childhood immunodeficiency.

The possibility of HIV infection should be considered on a case-by-case basis and other causes of immune suppression must be considered.

Various medical conditions that cause immunosuppression are chemotherapy, immune disorders, severe combined immune deficiency [SCID], severe malnutrition.

Epidemiology and Demographics

Most researchers believe that HIV originated in sub-Saharan Africa during the twentieth century. It is now a pandemic. In 2007, an estimated 33.2 million people lived with the disease worldwide, and it claimed the lives of an estimated 2.1 million people, including 330,000 children. Over three-fourths of these deaths occurred in sub-Saharan Africa, retarding economic growth and destroying human capital Antiretroviral treatment reduces both the mortality and the morbidity of HIV infection, but routine access to antiretroviral medication is not available in all countries.. HIV/AIDS stigma is more severe than that associated with some other life-threatening conditions and extends beyond the disease itself to providers and even volunteers involved with the care of people living with HIV.. In 2010, an estimated 34 million people were living with HIV, of whom more than 30 million were living in low- and middle-income countries.

Screening

At the end of 2006, an estimated 1,106,400 persons (range: 1,056,400 – 1,156,400) in the United States were living with HIV. CDC estimates that 56,300 new HIV infections occurred in the United States in 2006. About 1 million Americans have HIV — to a surprise, an estimated 25 percent do not know they have the infection. Therefore, HIV screening is important to both extend their lives and prevent further spreading of the disease.

Natural history, complications, and prognosis

Currently there is no cure for AIDS but taking treatment dramatically increased the amount of time people with HIV remain alive. Research continues in the areas of drug treatments and vaccine development. Unfortunately, HIV medications are not always available in the developing world, where the bulk of cases now occur. Opportunistic infections and other coinfections that might be common in HIV-infected persons, such as sexually transmitted infections, can also have adverse effects on the natural history of HIV infection.

Opportunistic infections

It is important to recognize that the relationship between opportunistic infections (OIs) and HIV infection is bi-directional. HIV causes the immunosuppression that allows opportunistic pathogens to cause disease in HIV-infected persons. OIs, as well as other co-infections that may be common in HIV-infected persons, such as sexually transmitted infections (STIs), can adversely affect the natural history of HIV infection by causing reversible increases in circulating viral load that could accelerate HIV progression and increase transmission of HIV. The widespread use of ART starting in the mid-1990s has had the most profound influence on reducing OI-related mortality in HIV-infected persons in those countries in which these therapies are accessible and affordable.

HIV Coinfections

HIV Coinfetions are the diseases that are most commonly occuring along with HIV infections and hence they must be screened for in a HIV infected individual. The most commonly found coinfections are tuberculosis, hepatitis B and hepatitis C.

HIV and pregnancy

About 120,000 to 160,000 women in the United States are infected with HIV. Nearly one out of four of these women are unaware of their disease, which puts them at high risk of passing the virus to their babies. Mother-to-child transmission is the most common way children become infected with HIV. Nearly all AIDS cases in U.S. children are because of mother-to-child transmission.

HIV infection in infants

The use of ART during pregnancy in HIV-infected women has resulted in a dramatic decrease in the transmission rate to infants, which is currently less than 2% in the United States, and the number of infants with AIDS in the United States continues to decline. Finally, children living with HIV infection are, as a group, growing older, bringing new challenges of adherence, drug resistance, reproductive health planning, management of multiple drugs, and long-term complications from HIV and its treatments.

Diagnosis

History and symptoms

AIDS is a multi organ disorder which presents with a wide array of symptoms depending upon the immune status of the patient. They can present pulmonary infections, neurological diseases and opportunistic infections.

Physical examination

The appearance of the patient depends on the stage of the disease. The patient may be completely asymptomatic or be ill-looking. The patient have fever, nightsweats, weight loss, sleep disturbance, adenopathy, frailty.

Laboratory Findings

A number of laboratory tests are important for initial evaluation of HIV-infected paients. Two surrogate markers (CD4 T-cell count (CD4 count), plasma HIV RNA) are routinely used to asses immune function and level of viral viremia.

Electrocardiogram

The pericardium is frequently involved in HIV infections. Also medications used in AIDS therapy can cause EKG changes. Since the cardiac complications in the initial phases are not very obvious, periodic electrocardiogram monitoring is indicated in HIV positive individuals.

Chest X Ray

Chest X-ray is an extremely common procedure done to evaluate the organs located in the chest area i.e. lungs, heart, and chest wall. It also helps in diagnosing the cause of various symptoms. (for example persistent cough, shortness of breath, chest pain or injury, and fever)

CT

CT scans of chest are important part of diagnosis in HIV patients having pulmonary symptoms. It has an advantage over X-Ray in being more sensitive in detection of early interstitial lung disease, lymphadenopathy, and nodules.

MRI

Magnetic resonance imaging or MRI is used in great deal for the care of HIV-positive patients. MRI is the first-choice among neuroimaging modality in the workup for AIDS dementia complex. An MRI is more sensitive than a head CT in determining if a lesion is truly solitary.

Echocardiography

Patients infected with the human immunodeficiency virus (HIV) have an increased risk of developing heart disease and they may need an echocardiogram.

Treatment

Medical Therapy

The primary goal of antiretroviral therapy (ART) is to reduce HIV-associated morbidity and mortality. This goal is best accomplished by using effective ART to maximally inhibit HIV replication, as defined by achieving and maintaining plasma HIV RNA (viral load) below levels detectable by commercially available assays. Durable viral suppression improves immune function and quality of life, lowers the risk of both AIDS-defining and non-AIDS-defining complications, and prolongs life. Based on emerging evidence, additional benefits of ART include a reduction in HIV-associated inflammation and possibly its associated complications.

Surgery

HIV infected patients may require surgery to treat infections and diseases associated with the condition. Childbirth and organ transplant are two of the many conditions that may require surgery in a HIV patient.

Primary Prevention

There is currently no vaccine or cure for HIV or AIDS. The only known methods of prevention are based on avoiding exposure to the virus or, failing that, an antiretroviral treatment directly after a highly significant exposure, called post-exposure prophylaxis (PEP).

Secondary Prevention

Secondary prevention emcompasses measures to reduce the complications of HIV as well as spread of the disease in the population.

Cost-Effectiveness of Therapy

HIV and AIDS retard economic growth by destroying human capital. Without proper nutrition, health care and medicine that is available in developed countries, large numbers of people are falling victim to AIDS. They will not only be unable to work, but will also require significant medical care. The forecast is that this will likely cause a collapse of economies and societies in the region. In some heavily infected areas, the epidemic has left behind many orphans cared for by elderly grandparents.

Future or Investigational Therapies

Research to improve current treatments includes decreasing side effects of current drugs, further simplifying drug regimens to improve adherence, and determining the best sequence of regimens to manage drug resistance.