HIV/AIDS: State of Washington Mandatory 2 Hour Training

Part 1. Etiology and Epidemiology of HIV and AIDS


Introduction

Part 1. Etiology and Epidemiology of HIV and AIDS

Part 2. HIV Transmission and Infection Control

Part 5. Ethical and Legal Issues

Conclusion

Glossary

Resources

References

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Definition of HIV and AIDS

HIV and AIDS are not the same. Everyone who has AIDS has been infected with HIV; but everyone with HIV infection does not have AIDS.

The Human Immunodeficiency Virus (HIV) is a virus that attacks the immune system, the body's natural ability to protect itself against infections and diseases, damaging the body's ability to fight diseases and infections. Without a healthy, functioning immune system, a person is at risk of infections by bacteria, other viruses and disease-causing organisms. Some of these infections can cause life-threatening illnesses.

This highly magnified transmission electron micrographic (TEM) image
revealed the presence of mature forms of the human immunodeficiency
virus (HIV) in a tissue sample under investigation.

Courtesy of US Public Health Image Library.

Acquired ImmunoDeficiency (sometimes Immune Deficiency) Syndrome (AIDS) is a complex of symptoms and infections caused by the HIV virus as it impacts the immune system. It is an acquired infection; it is not hereditary. A person must come in contact with the virus; it enters the body through blood and body fluids. As HIV damages the immune system, infected persons become vulnerable to infections or diseases known as opportunistic diseases. These opportunistic infections generally do not pose a threat to persons with healthy functioning immune systems. The term AIDS applies to the most advanced stages of an HIV infection. Medical treatments, particularly the antiretroviral medications, have delayed the onset of AIDS in persons who are infected with HIV.

How HIV Impacts the Human Body

When HIV enters the bloodstream, the virus starts seeking a particular form of white blood cell (lymphocyte) essential to the functioning of the immune system. This cell is called a T-Helper lymphocyte. One of its functions is to "orchestrate" the immune system in the event of attack from harmful foreign invaders, pathogens such as bacteria, viruses, and other disease-causing organisms. It is also referred to as the T4 or the CD4 cell.

When the HIV makes contact with the T-cell, the T-cell sends signals to other cells which produce antibodies. Antibodies are produced by the immune system to help get rid of specific foreign invaders that can cause infection.

Producing antibodies is an essential function of our immune systems. The body makes a specific antibody for each infection. For example, if we are exposed to measles virus, the immune system will develop antibodies specifically designed to attack the measles virus. Polio antibodies fight polio virus. When our immune system is working correctly, it protects against these harmful pathogens.

HIV infects and destroys the T-Helper lymphocytes and damages their ability to signal for antibody production. This results in the eventual decline of the immune system.

Progress of HIV Infection

Viral Transmission

This is the initial infection with HIV. When a person is infected with HIV, they will probably have virus circulating in their bloodstream, and may become infectious to others within five days. The person may be infectious before the onset of any symptoms. They will remain infectious for the rest of their lives.

Primary HIV Infection

During the first few weeks of HIV infection, an infected person has a very high amount of virus in their bloodstream. The high viral load means the individual may more easily pass the virus to others. Unfortunately, during primary infection, many people are unaware that they are infected.

The most common symptoms noticed by persons newly infected with HIV are fever, swollen glands in the neck, armpits and/or groin, rash, fatigue and a sore throat (also common with many other types of infections). This is sometimes called "seroconversion syndrome" or "seroconversion sickness." It resembles mononucleosis infection, with similar symptoms and length of illness.

These initial symptoms go away in a few weeks, but the individual continues to be infectious to others. It is extremely important that healthcare providers consider the diagnosis of HIV primary infection of an individual has behaviors which put him or her at risk for HIV and is presenting with the above symptoms. If individuals experience these symptoms after having unprotected sex or sharing needles, they should seek medical care and tell their provider why they are concerned about HIV infection. An HIV antibody test should be done, but it will only reflect the person's prior HIV status. To detect acute HIV infection, an HIV RNA test that tests directly for the HIV virus must be done.

There are many arguments for and against treatment in primary infection, and healthcare providers have different opinions regarding whether or not a newly HIV infected person should start drug therapies immediately.

Seroconversion

Seroconversion is the time period that it takes from infection to the production of antibodies, which would show positive on an HIV test. This may vary from person to person but HIV antibodies are detectable sometime within the first three to six months of infection, and in most cases will be detectable for life. This time frame is also known as the window period, in that the infected person will test negative for HIV antibodies, if tested prior to seroconversion, although they are already infected and are able to transmit the virus to others.

Asymptomatic HIV Infection

During this time period an HIV-infected person has no noticeable signs or symptoms. The person may look and feel healthy, but can still pass the virus to others. It is not unusual for an HIV-infected person to live 10 years or longer without any outward physical signs of progression to AIDS. Meanwhile, the person's blood and other systems are affected by HIV. This would be reflected in laboratory tests. Unless a person in this stage has been tested for HIV, they will probably not be aware they are infected.

Symptomatic HIV Infection

HIV Infection During the symptomatic stage of HIV infection, a person begins to have noticeable physical symptoms that are related to HIV infection. Although there are no symptoms that are specific ONLY to HIV infection, some common symptoms are:

  • A persistent low grade fever
  • Pronounced weight loss that is not due to dieting
  • Persistent headaches
  • Diarrhea that lasts more than one month
  • Difficulty recovering from colds and the flu
  • A person may become sicker than they normally would
  • Women may have recurrent vaginal yeast infections
  • Thrush (a yeast infection) coating the mouth or tongue

Anyone who has symptoms like these and has engaged in behaviors that transmit HIV should seek medical advice. The only way to know for sure if you are infected with HIV is to take an HIV antibody test.

AIDS

An AIDS diagnosis can only be made by a licensed healthcare provider. The diagnosis is based on the result of HIV-specific blood tests, and the person's physical condition. A diagnosis of AIDS is made because the person has an illness, one of the "AIDS-defining illnesses", and has white blood cell counts and other conditions that are specifically linked to making an AIDS diagnosis. Once a person is diagnosed with AIDS, even if they later feel better, they do not "go backwards" in the classification system for HIV infection. This means that they are always considered to have AIDS.

People who have an AIDS diagnosis may often appear to a casual observer to be quite healthy, but continue to be infectious and can pass the virus to others.

Over time, people with AIDS frequently have a reduced white blood cell count and develop poorer health. They may also have a significant amount of virus present in their blood, which is measured as viral load.

HIV Strains and Subtypes

HIV has divided into two primary strains: HIV-1 and HIV-2. HIV-1 is found throughout the world; generally when HIV is referred to without specifying a type of virus, it is the HIV-1 that is referred to. HIV-2 is found primarily in West Africa, where the virus may have been in circulation since the 1960s - 1970s. It is rarely found elsewhere. HIV is highly variable virus and mutates very easily. This means that 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 sub-types.

The Origin of HIV

Since HIV was discovered 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. The researchers believe that HIV-1 was introduced into the human population in the 1930s and 1940s when hunters became exposed to infected blood.

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