Pelvic Inflammatory Disease (PID), in which one or more sexually transmitted organisms invade the uterus, tubes, ovaries, pelvis or all of these, is diagnosed in more than one million women in the United States each year. More than 75 percent of the infections occur in women younger than 25, and at least one in five cases involves an adolescent - and the rate at which teenagers are affected continues to rise.

At least 10 to 12 percent of women become infertile after a single significant episode of PID, usually because of scarring of the fallopian tubes. Repeated infections increase this risk dramatically.

In Bombay, HIV prevalence has reached 50% in sex workers, 36% in STD patients, and 2.5% in women seen in antenatal clinics. The infection affects both urban and rural areas. In Bombay, seroprevalence rose from 2-3% in patients seen in STD clinics in 1990 to 36% in 1994 and in rural areas 3-4% of some populations have an STD.

Adolescent girls are particularly susceptible to STDs. A 15-year-old is 10 times more likely to develop PID than a 24-year-old involved in the same type of sexual behavior. This vulnerability is the result of two physiologic realities. First, the cervix (opening of the uterus) in a teenager is covered by a lining of cells that is more fragile, produces more mucus, and is more easily invaded by organisms that cause STDs than is the lining in an older woman. After a woman has had a baby or reaches her twenties, these cells are replaced by a tougher lining that is more resistant to infection.

Second, during the first several months after the onset of menses, many menstrual cycles occur without ovulation. This causes the mucus in the cervix to be thinner and thus a friendlier environment for STD organisms.

In addition to the physiological reasons, adolescent girls are particularly susceptible to STDs for other reasons. They often have multiple sexual partners, they choose partners who are at risk for STDs themselves, and they do not consistently insist that their sexual partners use condoms.

When STDs are discussed in health-education classes and public-service messages geared to teenagers, the emphasis is on preventing the transmission of HIV/AIDS. As serious as this epidemic is, a number of others should not be ignored.

Syphilis is caused by a spiral-shaped organism known as a spirochete. It is usually curable with penicillin, but resistant strains are now emerging. The initial sign of infection is a single painless ulcer, or chancre, which appears in the genital area (or wherever the initial point of contact was made). The chancre heals in two to six weeks without treatment and may even go unnoticed by the infected individual.

A secondary phase occurs in six weeks to six months, producing a mild rash or more serious changes in various parts of the body. If untreated, a third stage may develop years later, with life-threatening heart disease and central nervous system disturbances.
Syphilis can be detected by a blood test. If the initial screen is positive, additional tests will be necessary to confirm the diagnosis and determine the proper course of treatment.

Gonorrhea is a bacterial infection that affects millions of people around the world each year. Symptoms in males tend to be dramatic: a thick discharge from the penis accompanied by significant pain during the passage of urine. Many infected women have no symptoms, while others experience problems ranging in severity from mild discharge to abscesses in the pelvis requiring surgical treatment. In some cases extensive scarring of a woman's tubes may occur. Depending upon the extent of damage, infertility may result.

Once uniformly responsive to penicillin, gonorrhea strains resistant to penicillin are now common in many places.

Chlamydia infection has risen from obscurity in the 1970s to become the most common bacterial STD in the United States. One in 10 sexually active adolescent girls age 15 to19 years is infected with chlamydia. Girls under the age of 25 represent 79 percent of all chlamydia infections.18 Assuming it is detected (which may not always occur because symptoms may be subtle or nonexistent), a chlamydia infection normally responds to antibiotics.

In men chlamydia often causes a discharge from the penis that tends to be more watery and less profuse than with gonorrhea. Pain with the passage of urine is also less severe. In women chlamydia may produce vague pelvic discomfort, pain with urination or no symptoms. Whether or not symptoms are present, chlamydia can infect and damage a woman's reproductive organs and create a significant risk of infertility later in life. A single teenage sexual encounter that transmits chlamydia may cause untold emotional pain and major medical bills years later if a woman is unable to bear children.

Herpes simplex virus (HSV) The first outbreak of genital herpes is usually the worst, with an irritating, sometimes painful, cluster of blisters that gradually crust and fade over 10 to 14 days. Men usually see an eruption on the penis, although they may not realize its significance because it resolves without treatment. Women are frequently unaware of the infection, but some suffer extreme discomfort in the genital area. The virus is sometimes transmitted through the skin or mucous membranes even when no blisters are present. This undoubtedly contributes to its high prevalence. Up to 70-80 percent of men and women are asymptomatic with herpes recurrences, another reason why the disease is transmitted so readily.

At least 70 percent of those infected will have recurrent outbreaks for months or years. Stress, intercourse or other local irritation of the genital area (even from tight clothing) may trigger an outbreak, although these normally are not as severe as the first episode. Recurrences may occur several years after the initial contact, often causing concern and consternation in a subsequent relationship. For many the primary discomfort from a herpes infection is psychological, arising from the knowledge that this virus can never be eradicated and that any future sexual partner will probably become infected as well.

Antiviral medications such as acyclovir (Zovirax), valacyclovir (Valtrex) and famciclovir (Famvir) can limit the severity of the first or subsequent herpes outbreaks, assuming that they are started at the outset of the eruption. When taken on a daily basis, they can reduce the frequency of recurrences, although this treatment can become expensive on a long-term basis. Herpes outbreaks are rarely life threatening for adults. Unfortunately the same cannot be said for newborns. A baby born vaginally to a mother with HSV may be infected during delivery if there is a herpes outbreak on the mother's genital area, especially if it's her first HSV infection. Fifty percent of babies born vaginally to mothers with initial primary infection will be infected, whereas 5-6 percent of babies born to mothers with recurrent infection will be infected.

If the newborn is infected with HSV, the results can be disastrous. About 20 percent of infected infants will have surface (skin and mucous membrane) involvement only. In the other 80 percent, the virus spreads throughout the body and central nervous system, with a strong likelihood of major consequences including blindness, mental retardation and death.

Genital warts are caused by the human papilloma virus (HPV). This is one of the most common sexually transmitted diseases in the world. (One study of sexually active college females who visited the student health center showed an HPV infection rate of over 40 percent.) Like herpes and many other STDs, HPV can be transmitted by an individual who has no visible signs of the disease. Condoms offer little, if any, protection against HPV, a fact that has not been widely publicized.

Many who are infected with HPV never have any problem with it. However, the virus frequently causes soft, wartlike growth in the genital area. Small growths, which are usually the most common, respond to topical chemical treatment, but they can become quite large in size, requiring laser or other methods to remove them.

Of greater concern is that HPV has been clearly demonstrated to be the underlying cause of most cervical cancer and is implicated in cancers of the vulva, vagina and penis. While the male cancer is rare, cancer of the cervix causes thousands of deaths each year. This cancer risk is specifically increased by early onset of sexual activity and contact with multiple partners. The cancer is also more aggressive among teenagers than in older adults; a disturbing recent trend has been an increasing number of precancerous abnormalities of the cervix among adolescent women. The aggressiveness of HPV appears to be enhanced by nicotine - yet one more reason to avoid smoking. Any woman who has had genital warts (or for that matter, any woman who has been or is sexually active) should have regular Pap smears to detect early changes in the cervix, which can be treated before they develop into a cancerous growth.

Acquired immune deficiency syndrome (AIDS) is caused by the human immunodeficiency virus (HIV). The virus is transmitted through semen, vaginal secretions, blood and breast milk. Most HIV infections are transmitted during sexual contact (in all forms - heterosexual or homosexual, vaginal, oral or anal), through accidental injection of infected blood, contaminated needles or by transfer from infected mother to baby during pregnancy. A small number of cases in infants have been attributed to nursing from an infected mother. Some early cases of HIV resulted from transfusions of blood from infected donors. Revised blood-bank procedures and scrupulous screening of donors have reduced the likelihood of this happening to less than one in 1 in 100,000.

At highest risk for this disease are people who have many sexual partners (especially male homosexuals) and/or who are intravenous drug users. But HIV infections are not limited to those with high-risk lifestyles. The virus can be transmitted during a single sexual encounter, even to someone having sex for the first time. For a variety of reasons, the rate of new HIV infections has been steadily rising among heterosexuals, especially adolescents.

After causing an initial flu-like illness, HIV multiplies quietly within the immune system for years. The infected individual may feel perfectly well during this period but will be capable of transmitting the disease to others. Eventually the virus destroys the competence of the immune system, resulting in full-blown AIDS. Without adequate defenses, the body becomes vulnerable to a variety of devastating infections and some forms of cancer.

Typical screening tests for HIV detect a person's antibody response to the virus, not the virus itself. Once HIV enters the body, it will take a minimum of three weeks, and in some cases many months, to generate a detectable antibody response. An infected individual whose blood tests remain negative for HIV can still transmit the virus to others.

Hepatitis B is a viral infection of the liver transmitted through the same mechanisms as HIV. The majority of cases resolve completely following a flulike illness with fever, nausea and jaundice (a yellow discoloration of skin caused by a buildup of a compound called bilirubin, which an inflamed liver does not process normally). However, about 5 percent develop a chronic infection that can lead to cirrhosis (scarring) or even cancer of the liver. Chronic carriers can transmit the virus to sexual partners or from mother to baby during pregnancy or delivery. Most babies infected at birth become chronic carriers as well and risk developing long-term complications if not treated.

Hepatitis B is the only STD for which a reliable vaccine has been developed. Because efforts to vaccinate those at highest risk did not substantially reduce the number of new cases and because many cases of hepatitis B occur in people who do not have a history of risky behavior, current recommendations call for immunizing all infants, children and adolescents against the virus.