ATrain Education

 

Continuing Education for Health Professionals

WA: HIV/AIDS, 4 units

Module 1

Part I: Etiology and Epidemiology of HIV/AIDS

 

Your client, Mr. Glover, has been diagnosed with HIV. You don’t know much about HIV and are concerned whether you can “catch” HIV by working with him or even shaking hands. You recognize your need to be better educated so you can give appropriate care without bias or fear. You know that quality care can be given when you have a sound understanding of the disease, risk factors, diagnostics, clinical symptoms, and treatments. Becoming culturally sensitive to the unique needs of your patients requires you to better understand your patient’s values, definitions of health and illness, and preferences for care.

 

Definition of HIV and AIDS

[Material in this course is from CDC unless otherwise cited.]

The human immunodeficiency virus (HIV) has infected tens of millions of people around the globe in the past three decades, with devastating results. In its advanced stage—acquired immunodeficiency syndrome (AIDS)—the infected individual has no protection from diseases that may not even threaten people who have healthy immune systems. While medical treatment can delay the onset of AIDS, no cure is available for HIV or AIDS.

The human immunodeficiency virus (HIV) kills or impairs the cells of the immune system and progressively destroys the body’s ability to protect itself. Over time, a person with a deficient immune system (immunodeficiency) may become vulnerable to common and even simple infections by disease-causing organisms such as bacteria or viruses. These infections can become life-threatening.

The term AIDS comes from “acquired immunodeficiency syndrome.” AIDS refers to the most advanced stage of HIV infection. Medical treatment can delay the onset of AIDS, but HIV infection eventually results in a syndrome of symptoms, diseases, and infections. The diagnosis of AIDS requires evidence of HIV infection and the appearance of specific conditions or diseases beyond just the HIV infection. Only a licensed medical provider can make an AIDS diagnosis. A key concept is that all people diagnosed with AIDS have HIV, but an individual may be infected with HIV and not yet have AIDS.

How HIV Infects the Body

HIV enters the bloodstream and seeks out T-helper lymphocytes, which are specialized white blood cells essential to the functioning of the immune system. One of the functions of these cells is to regulate the immune response in the event of attack from disease-causing organisms such as bacteria or viruses. When the virus infects the T-helper lymphocyte, the cell sends signals to other cells, which produce antibodies. This T-helper lymphocyte cell is also known as the T4 or the CD4 cell.

Antibodies are produced by the immune system to tag the specific foreign invaders that can cause disease and signal to phagocytic white blood cells where to destroy the pathogens. Producing antibodies is an essential function of our immune system. The body makes a specific antibody for each disease. For example, if we are exposed to the measles virus, the immune system will develop antibodies specifically designed to attack the measles virus. Polio antibodies identify the poliovirus and signal to other white blood cells where they are in the bloodstream so they can be destroyed.

When our immune system is working correctly, it protects against these foreign invaders. HIV infects and destroys the T-helper lymphocytes and damages their ability to signal for antibody production. When this happens, the immune system eventually becomes ineffective against any invading pathogen or antigen.

There are five stages of HIV/AIDS infection:

  1. Primary or acute infection
  2. The window period ending with seroconversion
  3. The asymptomatic period
  4. The symptomatic period
  5. Full-blown AIDS

Primary or Acute HIV Infection

Primary or acute HIV infection is the first stage of HIV disease—typically lasting only a week or two—when the virus first establishes itself in the body. This is the period of time between first infection and when the body begins to produce antibodies. The virus is highly infectious but unfortunately not detectable by any tests. During this primary infection, patients have no symptoms.

 

Answer: C

Test Your Learning

Acute primary HIV infection is:

  1. The period just preceding full-blown AIDS.
  2. Referred to as the window period.
  3. The first week or two after infection when the firus is still undetectable.
  4. The time when antibodies are first detected.

 

Online Resources

Video: How HIV Kills So Many CD4 T Cells

https://www.youtube.com/watch?v=8gnpnUFNloo

 

(Video) HIV: What’s Going on Inside Your Body
https://www.youtube.com/watch?v=_x13XDNr39o

 

Video: How HIV Causes Disease
https://www.youtube.com/watch?v=_x13XDNr39o

 

Video: HIV—The Goals of Undetectable
https://www.youtube.com/watch?v=mZ1bIphjxbw

Window Period

The window period is the period of time between initial infection with HIV and the point when the body produces detectable antibodies, which can vary from 2 to 12 weeks. During the window period a person is infectious, with a high viral load, but still presents with a negative HIV antibody test. This means the infected person might get a negative test result while actually having HIV. The point when the HIV antibody test becomes positive is called seroconversion. Patients also may remain asymptomatic during the window period with no clinical manifestations, which decreases patient motivation for testing.

 

Answer: A

Test Your Learning

The window period:

  1. Is the time between infection with HIV and the body’s production of detectable antibodies.
  2. Typically lasts only a week or two.
  3. Refers to the stage of disease when the newly infected person is not yet contagious.
  4. Is the first stage of HIV disease.

 

Online Resources

Video: Understanding HIV Window Periods

https://www.youtube.com/watch?v=Ej6-91wY1fo

 

Video: Diagnosing HIV—Concepts and Tests
https://www.youtube.com/watch?v=3CjCAeGhtHA

Asymptomatic Stage

After the acute stage of HIV infection, people infected with HIV continue to look and feel completely well for long periods, sometimes for many years. During this time, the virus is replicating and slowly destroying the immune system. This asymptomatic stage is sometimes referred to as clinical latency. This means that, although a person looks and feels healthy, they can infect other people through any body fluid contact such as unprotected anal, vaginal, or oral sex or through needle sharing.

The virus can also be passed from an infected woman to her baby during pregnancy, birth, or breastfeeding when she is unaware of being HIV positive. Unless the infected person is given antiretroviral therapy, the onset of AIDS occurs an average of 10 years after being infected with HIV.

 

Answer: D

Apply Your Learning

Q: If a person has been infected with HIV but is not symptomatic, how would you explain this to a patient with HIV?

A: Although there may be no clinical symptoms, the HIV is replicating and slowly attacking the immune system’s CD4 cells. An untreated person can look and feel healthy, sometimes for many years, however the virus is still present in the blood and can cause infection in others. Also, the virus can be passed through unprotected sex and from pregnant or lactating mother to child.

 

Test Your Learning

During the asymptomatic state of HIV infection:

  1. The virus can be passed through unprotected sex, but cannot be passed to a baby through breastfeeding.
  2. The virus is in the dormant stage and is not replicating.
  3. People infected with HIV experience frequent illnesses.
  4. An untreated person can look and feel healthy for an average of 10 years before the start of AIDS symptoms.

Symptomatic Stage

The symptomatic stage occurs when clinical manifestations appear, including nausea, vomiting, cold and flu-like symptoms, weight loss, malaise, and general infections. Because these symptoms occur with many other illnesses, patients don’t recognize them as unique to HIV infection and often do not get screened, tested, diagnosed, or treated. Clinical symptoms appear as the body’s immune system can no longer respond effectively to other pathogens because the HIV has taken over the CD4 lymphocytes.

Full-blown AIDS

Autoimmune deficiency syndrome (AIDS) is always caused by HIV, but HIV is not always in the full state of AIDS. Only after the HIV has completely infected the CD4 cells and used their metabolism and multiplication ability is the body’s immune system incapacitated. AIDS is diagnosed when the CD4 count is less than 200 compared with the normal range of 1,000 T cells in healthy people. Primary tests for diagnosing HIV and AIDS include a positive ELISA test, viral load test, or Western Blot Test.

The Origin of HIV

Since the human immunodeficiency virus was identified in 1983, researchers have worked to pinpoint the origin of the virus. In 1999 an international team of researchers reported that they discovered the origins of HIV-1, the predominant strain of HIV in the developed world. A subspecies of chimpanzees native to West Equatorial Africa was identified as the original source of the virus. Researchers believe that HIV-1 was introduced into the human population when hunters became exposed to infected blood. The transmission of HIV was driven from Africa by migration, housing, travel, sexual practices, drug use, war, and economics, which affect both Africa and the entire world.

HIV Strains and Subtypes

HIV has divided into two primary strains: HIV-1 and HIV-2. Worldwide, the predominant virus is HIV-1, and generally when people refer to HIV without specifying the type of virus they are referring to HIV-1. The relatively uncommon HIV-2 type is concentrated in West Africa and is rarely found elsewhere.

HIV is a highly variable virus that mutates very readily. This means there are many different strains of HIV, even within the body of a single infected person. Based on genetic similarities, the numerous virus strains may be classified into types, groups, and subtypes.

Both HIV-1 and HIV-2 have several subtypes. It is virtually certain that more undiscovered subtypes are in existence now. It is also probable that more HIV subtypes will evolve in the future. As of 2001, blood testing in the United States can detect both strains and all known subtypes of HIV.

Epidemiology of HIV and AIDS

Epidemiology is the study of how disease is distributed in populations and the factors that influence the distribution. Epidemiologists try to discover why a disease develops in some people and not in others. Clinically, AIDS was first recognized in the United States, including the State of Washington, in 1981. In 1983 HIV was discovered to be the cause of AIDS. Since then, the number of AIDS cases has continued to increase, both in the United States and in other countries.

People who are infected with HIV come from all races, countries, sexual orientations, genders, and income levels. Globally, most of the people who are infected with HIV have not been tested, and are unaware that they are living with the virus. The Centers for Disease Control and Prevention (CDC) estimate that 1.2 million people aged 13 years and older are living with HIV infection, including 168,000 (14%) who are unaware of their infection. This is a decline from 25% in 2003 and 20% in 2012, and it is a positive sign because studies have shown that people with HIV who know that they are infected avoid behaviors that spread infection to others; also, they can get medical care and take antiviral medications that could reduce HIV spread by as much as 96% (CDC, 2016a).

CDC estimates that that there are only 4 transmissions per year for every 100 people living with HIV in the United States, which means that at least 95% of people living with HIV do not transmit the virus to anyone else. This represents an 89% decline in the transmission rate since the mid-1980s, reflecting the combined impact of testing, prevention counseling, and treatment efforts targeted to those living with HIV infection (CDC, 2013).

The estimated incidence of HIV has remained generally stable in recent years, at about 50,000 new HIV infections per year (CDC, 2014a). While this number is still too high, stabilization is in itself a sign of positive progress. With continued increases in the number of people living with HIV due to effective HIV medications, there are potentially more opportunities for HIV transmission than ever before. Yet, the annual number of new infections has not increased (CDC, 2013).

Worldwide, there were about 2.1 million new cases of HIV in 2013, and about 35 million people are living with HIV around the world. Of those, 3.2 million are children, 2.1 million are adolescents, and 4.2 million are people over age 50. In 2013 new HIV infections worldwide were 2.1 million, but new infections have fallen 38% since 2001 and new infections among children have fallen by 58% in the same period (CDC, 2014b; UNAIDS, 2014b).

Through 2011 the cumulative estimated number of deaths of people with diagnosed HIV infection ever classified as stage 3 (AIDS) in the United States was 648,000 (deaths may be due to any cause, which can make data interpretation complex). Nearly 39 million people with AIDS have died worldwide since the epidemic began (CDC, 2014b).

Globally, AIDS-related deaths, which peaked in 2005 at 2.4 million and have declined steadily ever since, were estimated at 1.5 million in 2013 (UNAIDS, 2014a). Even though Sub-Saharan Africa bears the biggest burden of HIV/AIDS, countries in South and Southeast Asia, Eastern Europe and Central Asia, and those in Latin America, are significantly affected by HIV and AIDS (CDC, 2014b; UNAIDS, 2014b).

The discovery of combination antiviral drug therapies in 1996 resulted in a dramatic decrease in the number of deaths due to AIDS among people given the drug therapies. On the down side, many people who have access to the therapies may not benefit from them or may not be able to tolerate the side effects. The medications are expensive and require strict dosing schedules. Furthermore, in developing countries many people with HIV have no access to the newer drug therapies.

 

Online Resource

U.S. Statistics (CDC)

 

WA state

The Washington State Department of Health collects surveillance data and publishes a report twice a year. In Washington State from 2011 to 2015 more than 20,000 people have been diagnosed with HIV and over 6,700 have died as a result. The number of new cases in the state has recently seen a small decrease. Between 2011 and 2015 new cases decreased from 570 to 470 persons per year. At the end of 2015 more than 12,500 people across the state were living with HIV, and the majority (44%) were black males with the highest incidence in King County (WDOH, 2016). These reports are available on the Department’s website.

HIV and AIDS Cases Are Reportable

HIV cases became reportable to the U.S. Department of Health in the fall of 1999. AIDS cases have been reportable (physicians must confidentially report any cases among their patients) to the CDC since 1984, when the existence of the syndrome that follows HIV infection was clearly established.

WA state

AIDS and symptomatic HIV infections have been reportable to the Washington State Department of Health (WDOH) since 1984 and 1993, respectively. HIV cases became reportable to the Washington State Department of Health in fall 1999.

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