10 Sexually Transmitted Diseases

Transcription

1 Chapter 10 Sexually Transmitted Diseases Overview -Sexually transmitted diseases (STDs), also known as sexually transmitted infections (STIs), are diseases that are transmitted by sexual contact with another person. -Arthropods, bacteria, and viruses can cause a variety of STDs. - Consequently, there are 3 major categories of STDs: arthropodal STDs, bacterial STDs, and viral STDs. 139 Categories of STDs arthropodal STDs bacterial STDs viral STDs pubic lice (crabs) gonorrhea herpes scabies chlamydia genital warts syphilis viral hepatitis HIV/AIDS Arthropodal STDs -There are 2 major arthropodal STDs: pubic lice and scabies. 1. pubic lice - Pubic lice, which are technically called Phthirus pubis, attach to pubic hair in the genital area of the body (Figure 15.6, Crooks). -These organisms are parasites that periodically bite into the skin and feed on blood from nearby blood vessels. -Pubic lice are visible to the naked eye: they are tiny and resemble miniature crabs. -Consequently, pubic lice are also known as crabs. -The color of pubic lice ranges from yellow to white to gray. -Transmission sexual contact -Pubic lice can move from the pubic hair of one person to the pubic hair of another as two people engage in sexual intercourse. -It is important to realize that once a person is infected, he or she may inadvertently transfer some of the pubic lice to hair on other

2 140 parts of the body (like the scalp, eyebrows, mustache, armpits, etc.) by touching the pubic hair region and then touching these areas. wearing the same clothing or using the same towels or bedding that an infected individual has used -Pubic lice can live outside the body for about 1 day on clothing (especially underclothes), towels, and bedding (sheets, comforters, sleeping bags, etc.). -In addition, eggs that have been deposited by pubic lice on these items can survive for several days and then hatch. -Signs and Symptoms itching visible confirmation of the pubic lice - In other words, the person sees pubic lice crawling on his or her pubic hair. -Treatment topical lotions, creams, or shampoos that kill pubic lice. -The individual should also wash any clothing, towels, or bedding that may have been used before treatment in order to prevent reinfection. 2. scabies -Scabies is caused by mites known as Sarcoptes scabiei. -In contrast to pubic lice, the mites that cause scabies are microscopic and, therefore, cannot be seen with the naked eye. -Scabies mites are parasites that burrow (dig tunnels) into the skin to feed on surrounding tissue and to lay eggs, which hatch soon thereafter. -Transmission prolonged skin-to-skin contact -Scabies can be transmitted via sexual activity if there is prolonged skin-to-skin contact. - This can occur when people lay naked on top of one another while having sex. -Scabies can also be transmitted by prolonged skin-to-skin contact that is nonsexual. -This can be the case when children are playing, when a medical procedure is being performed, or when taking care of the elderly. -Consequently, precautions have to be taken to prevent scabies outbreaks in daycare centers, hospitals, and nursing homes.

3 141 -Shaking someone s hand or giving somebody a hug does not usually transmit scabies because the duration of the skin-to-skin contact is not long enough. wearing the same clothing or using the same towels or bedding that an infected individual has used -Scabies mites can live outside the body for about 2 days on clothing, towels, and bedding. -Signs and Symptoms itching red rashes -caused by skin irritation to the scabies mites burrow marks -the sites where scabies mites have burrowed into the skin -resemble thin lines that a pencil typically makes -Treatment topical lotions that kill scabies mites - The individual should also wash any clothing, towels, or bedding that may have been used before treatment in order to prevent reinfection. Bacterial STDs -There are 3 major bacterial STDs: gonorrhea, chlamydia, and syphilis. 1. gonorrhea -also known as the clap or the drip -caused by the bacterium Neisseria gonorrhoeae, which is also referred to as gonococcus -Transmission sexual contact -Gonococcus grow wells in the mucosa that lines the vagina, urethra of the penis, anus, and oral cavity. -Consequently, gonorrhea can be transmitted via sexual contact (penile-vaginal sex, anal sex, oral sex, etc.). -Once a person is infected, he or she may unknowingly spread the gonorrheal infection to other areas of the body (such as the eyes) by touching the infected genitals and then touching these areas. mother to baby at birth -The baby can pick up gonorrhea from the vaginal mucosa as it passes through the vagina during birth.

4 142 -Signs and Symptoms -A person may exhibit one or more of the following signs and symptoms depending on where the gonorrheal infection occurs and how far it spreads: painful and frequent urination -caused by gonorrheal infection of the urethra -There may also be a burning sensation that occurs during urination. vagina discharge -typically yellow in color -caused by gonorrheal infection of the vagina and/or uterus penile discharge -typically white to yellow in color (Figure 15.1, Crooks) -caused by gonorrheal infection of the penile urethra pelvic inflammatory disease -In women, gonorrheal infection can spread from the vagina to the other organs of the female reproductive tract (uterus, fallopian tubes, and ovaries) and into the pelvic cavity. These areas become inflamed, which leads to pelvic inflammatory disease. -A consequence of pelvic inflammatory disease is the formation of scar tissue in the fallopian tubes, which increases the woman s risk of infertility or having an ectopic pregnancy later on in life. inflammation of the genitourinary tract -In men, gonorrheal infection can spread from the urethra to the kidneys, prostate gland, vas deferens, epididymis, and testes, which causes these areas to become inflamed. -Once the inflammation reaches the epididymis and testes, sperm maturation and production may be reduced, which can lead to infertility. oral and throat infections -caused by the presence of gonorrhea in the oral cavity and pharynx rectal bleeding and pain -caused by gonorrheal infection of the anus -These symptoms may occur within a few days to a few months after gonorrheal infection. -In some cases, however, the person may have no symptoms at all or the symptoms may even go away without treatment. -In any of these situations, the person is still infectious and, consequently, can transmit gonorrhea to another person. -Treatment antibiotics -Antibiotics are chemicals that kill bacteria.

5 chlamydia -caused by the bacterium Chlamydia trachomatis, which is a type of coccus. -Transmission sexual contact - Chlamydia can be transmitted via sexual contact (penile-vaginal sex, anal sex, oral sex, etc.). -Once a person is infected, he or she may inadvertently spread chlamydia to other areas of the body (such as the eyes) by touching the infected genitals and then touching these areas. mother to baby at birth -The baby can pick up chlamydia from the vaginal mucosa as it passes through the vagina during birth. -Signs and Symptoms -The types of signs and symptoms depend on where the chlamydia infection occurs and how far it spreads. -The signs and symptoms of chlamydia are very similar to those of gonorrhea: painful and frequent urination -caused by chlamydial infection of the urethra -There may also be a burning sensation that occurs during urination. vagina discharge -typically yellow in color -caused by chlamydial infection of the vagina and/or uterus penile discharge -typically clear to white in appearance -caused by the chlamydial infection of the penile urethra pelvic inflammatory disease -In women, chlamydial infection can spread from the vagina to the other organs of the female reproductive tract and into the pelvic cavity, thereby causing pelvic inflammatory disease. -As mentioned earlier, pelvic inflammatory disease can lead to infertility and ectopic pregnancy in women. inflammation of the genitourinary tract -In men, chlamydial infection can spread to the organs of the genitourinary tract, which become inflamed. -Recall that this can lead to infertility if the infection is severe in the epididymis and testes. oral and throat infections -caused by the presence of chlamydia in the oral cavity and pharynx rectal bleeding and pain -caused by chlamydial infection of the anus

6 144 trachoma -a severe form of conjunctivitis -caused by chlamydial infection of the eye -can lead to blindness if not treated -These symptoms typically occur within 1 to 3 weeks after chlamydial infection. -In many cases, however, the person may have no symptoms at all or the symptoms may even go away without treatment. -In any of these situations, the person is still infectious and, consequently, can transmit chlamydia to another person. -Treatment antibiotics 3. syphilis -caused by the bacterium Treponema pallidum, which is a type of spirochete. -Transmission sexual contact -Syphilis can be transmitted from open lesions of an infected person to the mucosa that lines the vagina, urethra of the penis, mouth, and anus. -Therefore, a person can get syphilis from sexual contact (penile-vaginal sex, anal sex, oral sex, etc.). mother to baby at birth -The baby can pick up syphilis from the vaginal mucosa as it passes through the vagina during birth. -Signs and Symptoms -There are 4 major stages of syphilis: primary, secondary, latent, and tertiary; the signs and symptoms of syphilis vary with each of these stages. primary syphilis associated with the formation of a chancre. chancre -A chancre (SHANG-kur) is a red, painless lesion that forms at a site of syphilis infection (Figure 15.2, Crooks) -appears about 3 weeks after infection -eventually disappears without treatment, but the person still has syphilis and is contagious

7 145 secondary syphilis associated with the presence of a skin rash skin rash -lesions that develops on the body, especially on the palms of the hands and the soles of the feet (Figure 15.3, Crooks) -usually appears within a month to a year after infection -eventually disappears without treatment, but the person still has syphilis and is contagious latent syphilis -This stage occurs several years after infection. -No major signs and symptoms occur during this stage. -After 1 year of the latent stage, the person is no longer contagious. tertiary syphilis -This stage follows the latent stage of syphilis. -During tertiary syphilis, the syphilis infection spreads to many organs of the body, resulting in one or more of the following. brain damage mental disorder paralysis blindness heart failure liver damage -If not treated, the tertiary stage of syphilis can lead to death. -Treatment antibiotics -A person should get treated for syphilis as early as possible. -If a person delays treatment, the infection will progress through the various stage of syphilis with death being a possible result. Viral STDs -Viral STDs are problematic because most of them do not ever leave the body once the person is infected. -Instead, most of these viruses cycle through periods of activity and periods of latency. -During the active stage of infection, the virus makes numerous copies of itself, which causes the person to become symptomatic. -During the latent stage of infection, the virus becomes dormant (inactive) as it integrates into the DNA of its host cell, which causes the person to become asymptomatic. -Regardless of whether the virus is active or latent, the person is still contagious and, therefore, can transmit the virus to someone else.

8 146 -There are 4 major viral STDs: herpes, genital warts, viral hepatitis, and HIV. 1. herpes -Types -There are several types of herpes viruses: herpes simplex virus type 1 (HSV-1) -causes oral herpes herpes simplex virus type 2 (HSV-2) -causes genital herpes varicella-zoster virus (VZV) -causes chicken pox in children and shingles in adults Epstein-Barr virus (EBV) -causes infectious mononucleosis -Of these herpes viruses, HSV-1 and HSV-2 are the ones that are transmitted sexually and, therefore, are considered to be STDs. -Transmission sexual contact -HSV-1 is usually transmitted by kissing, while HSV-2 is usually transmitted via penile-vaginal sex or anal sex. -Either one of these viruses, however, can also be transmitted by oral sex. mother to baby at birth -The baby can pick up herpes from the vaginal mucosa as it passes through the vagina during birth. -Signs and Symptoms -The signs and symptoms of HSV-1 or HSV-2 infections may include one or more of the following: lesions -The lesions associated with oral or genital herpes look the same, regardless of whether they are caused by HSV-1 or HSV-2 (Figure 15.4, Crooks). Initially, the lesions begin as red, painful bumps. Subsequently, the lesions turn into blisters filled with a clear fluid containing viable herpes viruses.

9 147 Eventually, the blisters heal and then disappear. -HSV-1 infection typically causes the lesions to develop in or around the mouth. In such cases, the lesions are called cold sores or fever blisters. HSV-2 infection typically causes the lesions to develop around the genitalia or anus. Oral sex, however, can cause HSV-1-induced lesions or HSV-2-induced lesion to develop in atypical places. Examples: - HSV-1-induced lesions may develop on the genitalia of an individual who receives oral sex from a person with oral herpes. -HSV-2-induced lesions may develop in or around the mouth of an individual who performs oral sex on a person with genital herpes. -It is possible for a person to spread oral or genital herpes to other areas of the body (such as the eyes) by touching these lesions and then transferring herpes viruses to other body parts. Therefore, to avoid spreading herpes infection, an infected person should avoid touching the lesions or should thoroughly wash his or her hands if these lesions are touched. malaise swollen lymph nodes headache fever herpes keratitis -also called ocular herpes -eye infection caused by the presence of HSV-1 or HSV-2 in the eye -The symptoms of oral or genital herpes typically occur within a a few days after infection and usually last for several weeks. -In many cases, however, the person may have no symptoms at all. -Nevertheless, the person is still infectious and, consequently, can transmit oral or genital herpes to another person. -Recurrence -Because HSV-1 and HSV-2 can cycle between active and latent stages, the herpes lesions can appear, disappear, and then reappear at a later time.

10 148 -The recurrence of these lesions varies from individual to individual. -The person is most contagious when the herpes lesions are present because large numbers of viable herpes viruses are found within the lesions. -However, even though the lesions disappear and the skin looks normal, herpes viruses can still travel to the skin surface without forming new lesions. -This phenomenon is known as asymptomatic viral shedding. -Since there are herpes viruses present on the skin during asymptomatic viral shedding, it is possible to transmit herpes to someone even though there are no visible herpes lesions. -Fortunately, the risk of transmission is usually low because only a small number of herpes viruses are typically on the skin surface during asymptomatic viral shedding the majority of the herpes viruses at this time are latent. -Treatment -There is no cure for HSV-1 or HSV-2 infection. -Instead, treatment focuses on helping the person live with the herpes infection: antiviral drugs -Examples acyclovir (Zovirax) valacyclovir (Valtrex) 2. genital warts -caused by the human papillomavirus (HPV) -Types of HPV -About 100 types of human papillomaviruses exist; about half of these types of HPV can be transmitted sexually, leading to the formation of genital warts. -In addition, it is possible for a person to get different types of HPV from different sexual encounters. -Transmission sexual contact -Genital warts can be transmitted via penile-vaginal sex, anal sex, oral sex, and anilingus. mother to baby at birth -The baby can pick up genital warts from the vaginal mucosa as it passes through the vagina during birth.

11 149 -Signs and Symptoms -The main sign of HPV infection is the presence of one or more genital warts. genital warts -range from white to pink to gray in color and may have a circular or cauliflower shape (Figure 15.5, Crooks). -usually found on the surface or inside lining of the genitals -However, oral sex or anilingus may cause genital warts to form in the mouth or anus, respectively. -usually appear within several weeks to several months after HPV infection. -In many cases, a person with HPV infection may not have any visible genital warts. -Nevertheless, the person is still infectious and, consequently, can transmit genital warts to another person. -Recurrence -Because HPV can cycle between active and latent stages, genital warts can appear, disappear, and then reappear at a later time. -The recurrence of these warts varies from individual to individual. -The person is most contagious when genital warts are present because large numbers of HPV are present in the warts. -However, HPV infection can also be transmitted when there are no warts present because HPV can undergo asymptomatic viral shedding. - The risk, though, is usually lower during asymptomatic viral shedding compared to when the individual is symptomatic of HPV infection. -Treatment -There is no cure for HPV infection. -Instead, treatment focuses on helping the person live with HPV infection: antiviral drugs -Example: interferon removal of warts -This can be done in several possible ways: cryotherapy -involves the use of a cryoprobe that freezes off the genital warts

12 150 cauterization -involves the use of a laser that burns off the genital warts surgery application of topical agents Even though the warts are removed, new ones may reappear in the same places at some point in the future. -Genital Warts and Cancer -HPV infection increases a person s risk of developing cancer of the vulva, penis, anus, and cervix. This is due to the fact that HPV can damage or alter DNA as it integrates into the chromosomes of its host cell. If HPV affects genes involved in cell division, the result is that the host cell may divide out of control and, therefore, become cancerous. 3. viral hepatitis -Hepatitis refers to liver inflammation. -There are 2 major forms of hepatitis: non-viral hepatitis and viral hepatitis. non-viral hepatitis -caused by alcohol, drugs, and other chemicals viral hepatitis -caused by viruses -All major forms of viral hepatitis have the potential to be transmitted sexually. -When this happens, viral hepatitis is considered to be an STD. -Types of Viral Hepatitis -There are 5 major types of viral hepatitis: hepatitis A hepatitis B hepatitis C hepatitis D hepatitis E -Each type of viral hepatitis is caused by a different virus.

13 151 -Transmission of Viral Hepatitis hepatitis A -found in feces (stool) of an infected individual or in food or water that is contaminated with infected fecal material -Consequently, hepatitis A can be transmitted in the following ways: fecal-oral route -This may occur, for example, when an infected food service worker uses the bathroom (defecates), does not wash his or her hands, and then prepares your food. Infected fecal material is then transferred from the fingers of the food service worker to the food that you eventually eat. -This is why it is mandatory that food service workers thoroughly wash their hands after using the bathroom. sexual contact (mainly anilingus) hepatitis B -found in many body fluids of an infected individual: blood, semen, vaginal fluid, and saliva. -In addition, hepatitis B may also be present on contaminated needles. -Thus, hepatitis B can be transmitted in the following ways: sexual contact (mainly penile-vaginal sex, anal sex, and oral sex) -This is due to the fact that any hepatitis B in blood, semen, vaginal fluid, or saliva can enter a person s bloodstream through cuts or abrasions in the penis or in the mucosa lining the vagina, anus, or mouth. injection drug use -Spread of hepatitis B can occur if an infected individual shares a contaminated needle with another person. mother to baby during birth

14 152 hepatitis C -found in infected blood -transmitted in a similar way as hepatitis B: sexual contact (mainly penile-vaginal sex, anal sex, and oral sex) injection drug use mother to baby during birth hepatitis D -found in infected blood -transmitted in a similar way as hepatitis B: sexual contact (mainly penile-vaginal sex, anal sex, and oral sex) injection drug use mother to baby during birth -Hepatitis D only infects a person if the person has already been infected with hepatitis B. -This is due to the fact that the hepatitis D virus requires the hepatitis B virus to replicate. hepatitis E -found in feces (stool) of an infected individual or in food or water that is contaminated with infected fecal material -transmitted in a similar way as hepatitis A: fecal-oral route sexual contact (mainly anilingus) -Signs and Symptoms of Viral Hepatitis -Once a person contracts viral hepatitis, the virus infects cells in the liver and other organs of the body. This causes a variety of signs and symptoms that can range from mild to severe. -These signs and symptoms are similar for the various types of viral hepatitis and may include one or more of the following: jaundice malaise fever loss of appetite fatigue nausea vomiting diarrhea chills abdominal pain headache

15 153 -These signs and symptoms usually last for several weeks as the hepatitis virus runs its course. In some cases the person may be asymptomatic; nevertheless, the person is still contagious and, consequently, can transmit viral hepatitis to someone else. -Treatment rest -Mild forms of viral hepatitis resolve on their own with no specific treatment besides rest and adequate intake of fluids to prevent dehydration. antiviral drugs -Example: interferon -Long Term Effects -Hepatitis A and E typically do not cause any long term effects on the body. -After a few weeks of infection, the body s immune system can destroy the hepatitis A or hepatitis E virus and the person makes a complete recovery. -There is no latent state to hepatitis A and E infections. -In contrast, hepatitis B, C, and D infections do have long term effects on the body. -These viruses periodically become latent and then active again throughout the person s lifetime. -In addition, these viruses can cause liver cancer, cirrhosis, liver failure, and even death. -Vaccinations -Vaccines for hepatitis A and for hepatitis B are available as a precautionary measure. -Who should get vaccinated? health care workers food service workers people who have many sex partners homosexual and bisexual men

16 HIV infection -caused by the human immunodeficiency virus (HIV) -Structure of HIV membrane envelope -HIV is surrounded by a membrane envelope, which consists of a lipid bilayer. -HIV obtains this membrane envelope by taking part of the plasma membrane of its host cell as it buds off from this cell. glycoproteins -viral proteins that stick out of the membrane envelope -allow HIV to bind to its host cell capsid -a protein coat located deep to the membrane envelope RNA -2 separate strands of RNA serve as the genetic material of HIV and are located within its capsid. enzymes -3 major enzymes are also found within the capsid of HIV: a. reverse transcriptase -an enzyme that is used by HIV to convert its RNA into a DNA copy -HIV is classified as a retrovirus because of reverse transcriptase s ability to convert RNA into DNA, which is the reverse (hence the term retro ) of how genetic material is normally copied within cells. b. integrase -an enzyme that inserts the DNA copy of the HIV RNA into the DNA of HIV s host cell c. protease -an enzyme that is used by HIV to assemble its capsid -HIV Life Cycle -The typical host cell of HIV is the helper T cell, which is also called a CD4 cell because it contains CD4 (cluster designation 4) proteins in its cell membrane. -Helper T cells are types of leukocytes (white blood cells) that are vital to the normal functioning of the immune system. -HIV invades a helper T cell in the following way: HIV uses its glycoproteins to bind to the CD4 proteins in the cell membrane of the helper T cell.

17 155 The membrane envelope of HIV then fuses with the plasma membrane of the helper T cell. The HIV capsid enters the cytoplasm of the helper T cell and is subsequently shed. Reverse transcriptase then makes a DNA copy of the HIV RNA, and integrase inserts the DNA copy into the DNA of the helper T cell. The integrated HIV DNA is now referred to as a provirus. At this point, the provirus can become either active or latent. active phase of HIV infection -In the active phase of HIV infection, the provirus immediately undergoes transcription to form new HIV RNA, which is then translated into new viral proteins. -Subsequently, new copies of HIV bud from the helper T cell. -During the budding process, each virus uses protease to assemble its capsid and takes a piece of the helper T cell plasma membrane to form its membrane envelope. -Millions of copies of HIV can be formed in each helper T cell when HIV is active. -Consequently, the helper T cell dies because it loses so much of its plasma membrane as all of these viruses bud from it. latent phase of HIV infection -In the latent phase of HIV infection, the provirus remains dormant and no new virus is produced. -This latent phase of HIV infection does not last forever; at some point, the integrated HIV DNA will become activated and the active phase of HIV infection will occur. -It is important to realize that the phase of HIV infection can vary within the population of helper T cells of an individual. -HIV may be active in all helper T cells, latent in all helper T cells, or active in some of the helper T cells and latent in others. -This is why is there so much variability from one person

18 156 to another in terms of when the person is infected with HIV and when the signs and symptoms of AIDS occur. -Transmission -HIV is found in many body fluids of an infected individual: blood, semen, vaginal fluid, breast milk, saliva, and urine. -In addition, HIV may also be present on contaminated needles. -Thus, HIV can be transmitted in the following ways: sexual contact -This includes penile-vaginal sex, anal sex, oral sex, and possibly deep kissing and urophilia. -This is due to the fact that any HIV in blood, semen, vaginal fluid, saliva, and urine can enter a person s bloodstream through cuts or abrasions in the penis or in the mucosa lining the vagina, anus, or mouth. -Having lesions from another STD (such as herpes, syphilis, etc.) increases the risk of HIV infection because the lesions allow the virus entry into the bloodstream. injection drug use -Spread of HIV can occur if an infected individual shares a contaminated needle with another person. mother to baby during birth or via breastfeeding contaminated blood transfusions -The risk of getting HIV from blood transfusions in the United States is extremely low due to the fact that blood is screened very meticulously for the virus. - Any blood containing HIV is discarded. -Outside the United States, however, the risk of getting HIV from a blood transfusion may be greater, depending on how or if blood is screened in that particular country.

19 157 -Myths About HIV Infection and AIDS Myth Only homosexual men contract HIV. A person can get HIV from casual contact (shaking hands, hugging, or kissing with a closed mouth) Reality Anyone can get HIV: heterosexuals, homosexuals, young people, the elderly, men, women, Caucasians, Asians, African-Americans, and Latinos. A person will not get HIV from casual contact with an HIV-infected individual because there is no exchange of body fluids (blood, semen, vaginal fluid, etc.). A person can get HIV from an insect bite. HIV cannot survive or replicate within an insect. Therefore, insects are unable to transmit the virus from person to person. -Incidence -As of 2005, over 40 million people worldwide have been infected with HIV. The majority of these individuals live in Africa and Asia and transmission occurs primarily from sexual contact between heterosexuals. To date, there have been about 1 million cases of HIV infection in the United States. Most of these individuals are men who have sex with men. -However, the number of heterosexuals infected with HIV is growing.

20 158 -HIV Test -Whether HIV become active or latent, the body responds to HIV infection by making antibodies against the virus. These antibodies attempt to destroy HIV. -However, the viral load (amount of virus in the blood) of HIV increases so quickly with time that at some point the HIV population outnumbers the amount of antibodies, which consequently become ineffective. -These HIV antibodies are formed within 2 weeks to 6 months after HIV infection. Most HIV tests screen for the presence of HIV antibodies in the blood. A person is said to be HIV positive if the HIV antibodies are in the blood. A person is said to be HIV negative if there are no HIV antibodies in the body. -Signs and Symptoms of HIV Infection -Within a few weeks of HIV infection, a person may exhibit one or more of the following signs and symptoms: enlarged lymph nodes night sweats severe diarrhea headache fatigue weight loss fever oral candidiasis -also called thrush -a type of yeast (fungal) infection that occurs in the mouth and throat -These signs and symptoms may fade and then reappear from time to time.

21 159 -Progression to AIDS -During the course of HIV infection, the helper T cell count of an HIVinfected individual becomes so low that specific immune responses against pathogens can no longer occur, which makes the immune system nonfunctional. -At this point, the HIV-infected individual is said to have AIDS, which stands for acquired immunodeficiency syndrome. -The time from HIV infection to the development of AIDS varies from person to person. - It can happen within months after HIV infection or take as long as 10 years or more. -Signs and Symptoms -A person with AIDS typically has the following signs and symptoms: low helper T cell count -The term AIDS is formally used when a person s helper T cell count drops below 200 cells per microliter of blood. The normal helper T cell count is around 1000 cells per microliter of blood. opportunistic infections -disorders that have the opportunity to develop within a person because of a debilitated and deficient immune system -Examples: Kaposi s sarcoma -a type of cancer that can develop within cutaneous blood vessels -causes purple lesions to form on the skin pneumocystis carinii pneumonia -a type of fungal infection of the lungs tuberculosis encephalitis meningitis lymphoma -A person who has AIDS usually dies from one or more of these opportunistic infections.

22 160 -Treatment -There is no cure for HIV infection and AIDS. -Instead, treatment focuses on helping the person to live with HIV as long as possible: antiviral drugs -Specifically, the drugs used by HIV/AIDS patients prevent the formation of new HIV by blocking certain stages of the HIV life cycle. -Types: reverse transcriptase inhibitors -block the action of reverse transcriptase, thereby preventing HIV from making a DNA copy of its RNA -Examples: a. zidovudine (AZT) b. didanosine c. stavudine protease inhibitors -block the action of protease, thereby preventing HIV from making its capsid -Examples: a. saquinavir b. ritonavir c. indinavir -Typically, reverse transcriptase inhibitors and the protease inhibitors are taken in combination as a part of a drug therapy known as HAART: HAART -highly active antiretroviral therapy -also known as triple therapy or the AIDS cocktail -involves taking 2 reverse transcriptase inhibitors and 1 protease inhibitor -Patients who receive HAART typically experience one or more of the following: a decrease in the viral load of HIV an increase in the number of viable helper T cells a delay in the progression of HIV infection to AIDS remission of opportunistic infections -Therefore, HAART is allowing HIV/AIDS patients to live longer lives.

23 161 -However, there are several drawbacks to HAART: HAART is expensive: the cost may be as much as $10,000 a year or more. The drugs typically cause harsh side effects. The patient has to continue HAART for the duration of his or her life. Ways To Prevent STD Transmission -The following is a list of possible ways to reduce the risk of STD transmission: Be abstinent. Use a condom. -When used properly, a condom significantly reduces the risk of STD transmission. Realize, however, that condom usage does not completely eliminate the risk of getting an STD. -Thus, even when using a condom, a person should still be cautious about engaging in sexual activity with a partner whose STD status is unknown. -Not all condoms provide the same amount of protection against STDs. -A latex or polyurethane condom consists of material that significantly reduces the transmission of most STDs. A natural membrane (lambskin) condom, however, contains natural pores. -These pores are too small to allow sperm cells to pass through them, but are large enough to allow passage to many STD-causing pathogens (including HIV). -Therefore, a lambskin condom is an effective contraceptive barrier, but it does not provide significant protection against STDs. Inspect the sex partner s body (especially the genitals) for signs and symptoms that may be associated with STDs (such as the presence of genital warts, a chancre, lesions, etc.) -The risk of STD transmission is higher when the person is symptomatic than when a person is asymptomatic. Reduce the number of sex partners: be monogamous. -The more sex partners a person has, the greater the risk of STD transmission. Do not share needles, razors, or any other items that may contain contaminated blood.