What you need to know about HIV/AIDs

AIDS- the result of infection with the human immunodeficiency virus (HIV), is an incurable and deadly STD.
AIDS- attacks the body’s immune system, leaving victims unable to fight off even the mildest infections.
While HIV can be transmitted by other means, sexual contact is the most common means of transmission.
Women who are infected with HIV can pass the virus to their infants during pregnancy, childbirth or, less frequently, in breast milk.
Treatment options -for people infected with HIV include protease inhibitors, which can markedly increase survival.

Becky Kuhn, M.D.,
co-founder of Global Lifeworks

What is Human immunodeficiency Virus?

(HIV/AIDs)

Infectious agent that causes acquired immunodeficiency syndrome (AIDS), a disease that leaves a person vulnerable to life-threatening infections. Scientists have identified two types of this virus.

HIV-1 Is the primary cause of AIDS worldwide.

HIV-2 is found mostly in West Africa.

HIV belongs to the retrovirus family of viruses.

HIV transmission

Occurs when a person is exposed to body fluids infected with the virus;

a.) blood

b.) semen

c.) vaginal secretions

d.) breast milk

The primary modes of HIV transmission are;

(1) sexual relations with an infected person

(2) sharing hypodermic needles or accidental pricking by a needle contaminated with infected blood.

(3) transfer of the virus from an infected mother to her baby during pregnancy, childbirth, or through breast-feeding.

When HIV enters the bodyIt infects lymphocytes, white blood cells of the immune system.

The virus commandeers the genetic material of the host cell, instructing the cell to replicate more viruses.

The newly formed viruses break free from the host, destroying the cell in the process.

The new viruses go on to infect and destroy other lymphocytes.

Over a period that may last from a few months to up to 15 years.

HIV may destroy enough lymphocytes that the immune system becomes unable to function properly.

An infected person develops multiple life-threatening illnesses from infections that normally do not cause illnesses in people with a healthy immune system.

Some people who have HIV infection may not develop any of the clinical illnesses that define the full-blown disease of AIDS for ten years or more.

Doctors prefer to use the term AIDS for cases where a person has reached the final, life-threatening stage of HIV infection.

What are the Immune system components?

THE IMMUNE SYSTEMThe ability of the immune system to mount a response to disease is dependent on many complex interactions between the components of the immune system and the antigens on the invading pathogens, or disease-causing agents.

A Macrophages
White blood cells are the mainstay of the immune system.
Some white blood cells, known as macrophages.
play a function in innate immunity by surrounding.
ingesting.
and destroying invading bacteria and other foreign organisms in a process called phagocytosis (literally, “cell eating”).
which is part of the inflammatory reaction.

Macrophages also play an important role in adaptive immunity in that they attach to invading antigens and deliver them to be destroyed by other components of the adaptive immune system.

B Lymphocytes
Lymphocytes are specialized white blood cells whose function is to identify and destroy invading antigens.
All lymphocytes begin as “stem cells” in the bone marrow, the soft tissue that fills most bone cavities, but they mature in two different places.
Some lymphocytes mature in the bone marrow and are called B lymphocytes. B lymphocytes, or B cells, make antibodies, which circulate through the blood and other body fluids, binding to antigens and helping to destroy them in humoral immune responses.
Other lymphocytes, called T lymphocytes, or T cells, mature in the thymus, a small glandular organ located behind the breastbone.
Some T lymphocytes, called cytotoxic (cell-poisoning) or killer T lymphocytes, generate cell-mediated immune responses, directly destroying cells that have specific antigens on their surface that are recognized by the killer T cells.
Helper T lymphocytes, a second kind of T lymphocyte, regulate the immune system by controlling the strength and quality of all immune responses.
Most contact between antigens and lymphocytes occurs in the lymphoid organs—the lymph nodes, spleen, and tonsils, as well as specialized areas of the intestine and lungs.
Mature lymphocytes constantly travel through the blood to the lymphoid organs and then back to the blood again.
This recirculation ensures that the body is continuously monitored for invading substances.

C Antigen Receptors
One of the characteristics of adaptive immunity is that it is specific:Each response is tailored to a specific type of invading antigen. Each lymphocyte, as it matures, makes an antigen receptor—that is, a specific structure on its surface that can bind with a matching structure on the antigen like a lock and key.
Although lymphocytes can make billions of different kinds of antigen receptors, each individual lymphocyte makes only one kind.
When an antigen enters the body, it activates only the lymphocytes whose receptors match up with it.

D Antigen-Presenting Cells
When an antigen enters a body cell, certain transport molecules within the cell attach themselves to the antigen and transport it to the surface of the cell, where they “present” the antigen to T lymphocytes.
These transport molecules are made by a group of genes called the major histocompatibility complex (MHC) and are therefore known as MHC molecules.
Some MHC molecules, called class I MHC molecules, present antigens to killer T cells; other MHC molecules, called class II MHC molecules, present antigens to helper T cells.

Retrovirus structure

Retrovirus StructureOn average, retroviruses are about 90 nanometers (nm, about 0.000004 in) across, which means they are so small that they can only be seen with an electron microscope.

Retroviruses consist of a flexible outer membrane called the envelope that surrounds a protein case known as the capsid.The envelope is studded with glycoproteins, chemical receptors that enable the virus to lock on to target cells.The capsid’s hollow interior contains two identical strands of RNA.

These RNA strands make up the virus’s genetic program and store all the instructions needed to replicate the virus once it has infected a host cell.Retroviruses also contain molecules of an enzyme called reverse transcriptase.When a virus infects a cell, reverse transcriptase copies the genetic instructions in the virus’s RNA and uses it to build complementary strands of DNA.

In common with most viruses, retroviruses are highly selective about the hosts that they infect. For instance, HIV only causes disease in human cells, not the cells of other types of animals.Also like most viruses, retroviruses show no signs of life when they are isolated from living cells. Many retroviruses, including HIV, are relatively fragile.

Their ability to infect cells lessens after prolonged exposure to the environment outside a host cell.When retroviruses do infect a host cell, their mode of replication leads to frequent mutations—changes in the genetic makeup of viral offspring.These mutations enable viruses to evolve at a rapid rate.

Genetic mutation is one of many reasons why retroviral infections are difficult to treat—medicines developed to combat one retrovirus with a specific genetic makeup are not effective against mutated offspring of that retrovirus.

History of Vaccine Safety

Perhaps the greatest success story in public health is the reduction of infectious diseases resulting from the use of vaccines. Routine immunization has eradicated smallpox from the globe and led to the near elimination of wild polio virus.

Vaccines have reduced some preventable infectious diseases to an all-time low, and now few people experience the devastating effects of measles, pertussis, and other illnesses. Prior to approval by the Food and Drug Administration (FDA), vaccines are tested extensively by scientists to ensure they are effective and safe.

Vaccines are the best defense we have against infectious diseases; however, no vaccine is 100% safe or effective. Differences in the way individual immune systems react to a vaccine account for rare occasions when people are not protected following immunization or when they experience side effects.

As the incidence of infectious diseases continues to decline, some people have become less interested in the consequences of preventable illnesses like diphtheria and tetanus. Instead, they have become increasingly concerned about the risks associated with vaccines. After all, vaccines are given to healthy individuals, many of whom are children, and therefore a high standard of safety is required.

Since vaccination is such a common and memorable event, any illness following immunization may be attributed to the vaccine. While some of these reactions may be caused by the vaccine, many of them are unrelated events that occur after vaccination by coincidence. Therefore, the scientific research that attempts to distinguish true vaccine side effects from unrelated, chance occurrences is crucial. This knowledge is necessary to maintain public confidence in immunization programs.

As science continues to advance, we strive to develop safer vaccines and improve delivery to protect ourselves against disease more effectively. This overview focuses on vaccine research, how vaccines are licensed, how safety is monitored, and how risks are communicated to the public

Why It’s Important to Monitor Vaccine Safety

John Iskander, MD, MPH, acting director, Immunization Safety Office, and Robert T. Chen, MD, MA, blood safety specialist, Epidemiology Branch, NCHHSTP,
wrote a chapter in the new book

Infectious Disease Surveillance to explain why it is important to monitor vaccine safety.

Rare Reactions.
The most important reason is to detect rare reactions. Although vaccines are tested extensively before they are licensed for use in the United States, not enough people are included in the tests to detect reactions that happen only rarely. If serious reactions are found when the vaccine is in widespread use, the vaccine may be withdrawn.

Higher Risk Groups.
Vaccine safety monitoring also makes sure new vaccines are safe for groups such as the elderly, those with chronic medical conditions, and pregnant women. Vaccine trials may deliberately exclude members of these groups.

Public Confidence in Vaccines.
Monitoring vaccine safety also helps to maintain public confidence needed to keep enough people vaccinated to prevent disease outbreaks.

How We Know If Vaccines Are Safe
Vaccine safety cannot be measured directly. Instead, it is estimated by the number of "adverse events" reported. An adverse event is "... a medical incident that takes place after an immunization ... and is believed to be caused by the immunization." Adverse events include—

True reactions to the vaccine.
Events that would have occurred even if the person had not been vaccinated (unrelated coincidences).
Reactions related to mistakes in vaccine preparation, handling, or administration.
Events that cannot be related directly to the vaccine; their cause is unknown.

A formal scientific study usually is required to distinguish between coincidences and true reactions. It is rarely possible to say for sure whether a vaccine caused a specific adverse event.

Vaccine Safety Information for Parents

Vaccines are held to the highest standard of safety. The United States currently has the safest, most effective vaccine supply in history. Years of testing are required by law before a vaccine can be licensed. Once in use, vaccines are continually monitored for safety and efficacy.
Immunizations, like any medication, can cause adverse events.

However, a decision not to immunize a child also involves risk.

It is a decision to put the child and others who come into contact with him or her at risk of contracting a disease that could be dangerous or deadly. Consider measles. One out of 30 children with measles develops pneumonia. For every 1,000 children who get the disease, one or two will die from it.

Thanks to vaccines, we have few cases of measles in the U.S. today. However, the disease is extremely contagious, and each year dozens of cases are imported from abroad into the U.S., threatening the health of people who have not been vaccinated and those for whom the vaccine was not effective.

The Centers for Disease Control and Prevention (CDC) and the Food and Drug Administration (FDA) continually work to make already safe vaccines even safer. In the rare event that a child is injured by a vaccine, he or she may be compensated through the National Vaccine Injury

Compensation Program (VICP) or call 1-800-338-2382.