Sexually Transmitted Diseases

Infectious diseases that pass from a person to another during sexual contact are called sexually transmitted diseases ( STDs)

Human immunodeficiency virus (HIV) can exists in blood. this virus can hide in body cells, sometimes for years. In fact, you can become infected with HIV by having sex with an HIV infected person or through an injection by an infected needle. However, a freshly unwrapped sterile needle cannot transmit the infection. Also,the risk of getting HIV through blood transfusion is small because all donated blood is tested for the presence of HIV.

HIV cannot multiply outside the body, and it does not survive for long time in the environment. It's important to recognize that this virus cannot be transmitted by touching an infected person, by handling objects used by the person unless they are contaminated with body fluids, or from contact with a toilet seat.

An HIV infection can lead to Acquired Immune Deficiency Syndrome (AIDS), which is a disease that attacks the body's immune system. HIV attacks T helper cells in the immune system. the virus enters T cells and multiply, so as when the bursts cells open, it releases more HIV. with time, so many T cells are destroyed and not enough B cells are stimulated to produce antibodies. As a result, the body has no longer an effective way to fight invading antigens nor to fight HIV. For this reason, people with HIV die from other diseases such as tuberculosis, cancer, etc..

A person can be infected with HIV and not show any symptoms of the infection for several years. Why does this characteristic make the spread of AIDS more likely ??

source of image : Shanise Welch (shanisewelch.blogspot.com/)

source of image: AIDS(www.nlm.nih.gov/.../ency/imagepages/17015.htm)

source of image : HIV (www.answers.com/topic/hiv)

source of image : Primary HIV infection:(www.nlm.nih.gov/.../ency/imagepages/17268.htm)

Fighting Disease

- washing a small wound with soap and water is the first step in preventing an infection

- cleaning the wound with an antiseptic and covering it with a bandage are other steps

- it is important to wash your body in order to prevent diseases, and also to destroy some surface microorganisms and to reduce your body odor.

- using dental floss and routine tooth brushing keep the organisms present your mouth under control.

- exercise and good nutrition help the circulatory and respiratory systems work more effectively.

Why is it important to clean a wound????

source of images : Personal Hygiene, Health, Grooming & Body Care Films (1928-1953) (www.qualityinformationpublishers.com/personal...)

How Diseases are Spread

A disease that is caused by a virus or a bacterium is called infectious disease. Infectious diseases are spread by a direct contact with the infected organism, through water and air, on food, by contact with contaminated objects, and by disease carrying organisms called biological vectors ( such as birds, cats,dogs,fleas..)

- people can also be carriers of disease: when you have influenza and sneeze, you expel thousands of viruses into the air.

- cold and many other diseases are spread through contact.

P.S: - A virus is a minute piece of genetic material surrounded by a protein coating that infects and multiplies in hos cells. The host cells die when the viruses break out of them. These new viruses infect other cells, leading to the destruction of tissues or the interruption of vital body activities.

- to avoid the spread of disease and ill-health, take a better care of the body, keep water supplies clean, exercise and eat a healthy diet

What are three ways that pathogens are reduced in today's operating room????

source of image : Personal Hygiene, Health, Grooming & Body Care Films (1928-1953) (www.qualityinformationpublishers.com/personal...)

source of image : 1957 Gr 5 Health note How Communicable Diseases Spread (timetraces.com/.../Odds_and_Ends/image025.htm)

Active and Passive Immunity

Active Immunity: the body makes its own antibodies in response to a certain antigen. it can be naturally acquired or achieved through vaccination.

Vaccination: it is an attenuated form of a disease; it is a form of an antigen that gives you immunity against a certain disease and it prevents the disease but not cure it. Vaccination is the fact of giving a vaccine by injection or inhalation. In fact, when a specific vaccine is injected into your body, your body forms antibodies against the pathogen, so that if you later encounter the same antigen, your bloodstream already has antibodies that are needed to fight and destroy it.

Vaccines have helped reduce cases of childhood diseases such as: Measles, Tetanus, Rubella,etc...

Passive Immunity: it doesn't last for too long as active immunity. Well, you were born with all the antibodies that your mother had in her blood. However, these antibodies stayed with you for only few months. Also, nowadays, passive immunity can be achieved by injecting a patient with a serum containing antibodies directly used against a specific disease.

Source of image: 25. Immunity: Active and Passive (www.web-books.com/eLibrary/ON/B0/B8/25MB8.html)

Several diseases have symptoms similar to those of measles.Why doesn't the measles vaccine protect you from all of these diseases???

Introduction

knowing how diseases are spread will help you to understand how your body fights a specific disease.

The body defends himself against pathogens and microorganisms by a series of mechanisms that can be achieved through three lines of defense:

1 - Non-specific Immunity ( includes first lines of defense and second lines of defense)
2- Specific Immunity

The defense of your body can be enhanced through active and passive immunity, which we will learn about later on.

Finally, we will be studying how diseases are spread and we will focus mainly about Sexually Transmitted Disease ( HIV)

Source of image : The Massachusetts Workers’ Compensation Act (www.workrightspress.com/workerscompch1.html)

Second lines of Defense

If microbes get past your first line of defence, it is up to the second line of defence, your immune system, to keep you from getting sick. It is made up of lots of different cells that are always patrolling your body and fighting any bad microbes they find :

• Phagocytes - cells which "eat" foreign material to destroy them :
• Nutrinophils - phagocytize bacteria
• Eosinophyls - secrete enzymes to kill parasitic worms
• Basophils - secrete histamine to enhance inflammation
• Macrophages - "big eaters" phagocytize just about anything

These highly specialized white blood cells surround, engulf and destroy antigens that could compromise your body’s health.

Your body is exposed to many different types of microbes everyday, so your immune system is always hard at work, keeping you healthy!

image's source : The Immune System : (http://www.uic.edu/classes/bios/bios100/summer2002/lect18.htm)

Response's Steps of Immune System

1- Recognition : White blood cell surrounds pathogen and signals T cells. More T cells are produced and helper T cells signal B cells

2- Mobilization: B cells produce antibodies

3- Disposal: antibodies destroy pathogens

4- Immunity : some antibodies remain for future use

How diseases are spread ??

Image source : Science aid.co.uk ( scienceaid.co.uk/biology/micro/immune.html)