Impact of sexually transmitted infections on women health

Manisha Yadav, Neha Verma, Rakesh Singh Dhanda•View original
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A woman walks into a prenatal clinic. She feels fine, with no unusual discharge, no pain, and no reason for concern. She is there for a routine check. The screen comes back positive for chlamydia. She had no idea. That gap — between infection and awareness — is where much of the damage from sexually transmitted infections actually occurs. Manisha Yadav, Neha Verma, and Rakesh Singh Dhanda set out to map that damage in their review of sexually transmitted infections and their impact on women's health. What they found is a global problem that is both enormous and undercounted, falling harder on women by nearly every measure that matters. Start with the scale. The World Health Organization estimated that in 2005, there were 448 million new cases of curable sexually transmitted infections in adults every single year. That number covers only the curable bacterial and parasitic infections and excludes HIV and other viral sexually transmitted infections entirely. The review identifies more than 20 distinct types, grouped into three causative categories: bacteria, parasites, and viruses. The headline seven that the authors return to repeatedly are chlamydia, gonorrhea, syphilis, trichomoniasis, genital herpes, human papillomavirus, and HIV and AIDS. Trichomoniasis alone — caused by the parasite Trichomonas vaginalis — infects an estimated 170 million people each year worldwide, with 154 million of them in resource-limited settings. Yadav and colleagues state that the incidence of T. vaginalis exceeds the combined incidence of chlamydia and gonorrhea, making it the most common non-viral sexually transmitted infection on the planet. Yet, it is routinely missed. The standard diagnostic tool, wet-mount microscopy, has a sensitivity of only 35 to 82 percent compared with the more accurate culture or polymerase chain reaction methods. This means a substantial fraction of cases are invisible to routine testing. One study cited from South Africa found that 20 percent of otherwise healthy asymptomatic women attending a family-planning clinic tested positive. In an obstetrics and gynecology clinic in India, the figure was 47 percent. Across different populations in India — clinic attendees, commercial sex workers, and community samples — T. vaginalis prevalence ranged from 1.2 to 28.5 percent. This is the first pattern worth noting: the numbers are large, and the diagnostics routinely undercount them. The gap between actual infection and detected infection is not a minor technical footnote; it is a public health crisis in slow motion. Now let’s go deeper into what these pathogens actually do, starting with the bacteria. Chlamydia trachomatis infects an estimated 90 million people worldwide annually. It causes mucopurulent cervicitis — inflammation of the cervix — and can ascend into the fallopian tubes, producing salpingitis, an inflammation that often leaves no obvious symptoms. The review reports that roughly two-thirds of women with salpingitis are asymptomatic, while only one-third experience symptoms. That silent inflammation causes real damage: tubal scarring, which can lead to infertility. Tubal factors account for 14 to 38 percent of all female infertility in studies cited by the paper. More than 50 percent of women with cervical chlamydial infection have no symptoms at all. Additionally, women with chlamydial infection are reported to be up to five times more susceptible to acquiring HIV if subsequently exposed. Gonorrhea follows a similar pattern. Neisseria gonorrhoeae is highly adapted to the female genital tract, and the paper reports that women face a 60 to 80 percent risk of acquiring gonorrhea from a single act of vaginal intercourse with an infected man. Yet, it frequently produces no symptoms. When untreated, the infection ascends; endocervical gonorrhea leads to acute salpingitis in an estimated 8 to 16 percent of women. After a single episode of acute salpingitis, almost 10 percent of women may become infertile due to complete tubal occlusion. The risk of ectopic pregnancy following salpingitis is six to ten times higher than in unaffected women. Syphilis introduces a different dimension of harm: the impact on the next generation. When a pregnant woman carries untreated Treponema pallidum, vertical transmission — meaning transmission from mother to fetus — approaches 100 percent in some of the studies cited. Approximately 66 percent of congenitally infected infants are asymptomatic at birth and are identified only through routine screening. Fetal or perinatal death occurs in around 40 percent of affected infants. The mechanism is direct: the spirochete damages both the placenta and the umbilical cord, compromising fetal growth and viability. The good news here is concrete — penicillin given to pregnant women with syphilis significantly reduces the risk of stillbirth and preterm delivery. Trichomonas vaginalis in pregnancy carries its own set of risks: preterm rupture of membranes, preterm labor, fetal loss in the third trimester, neonatal death, and low birth weight. Like chlamydia, it can also increase the risk of acquiring HIV. The paper notes that trichomoniasis is associated with cervical erosion and a predisposition to cervical neoplasia. An organism that most people think of as causing minor irritation turns out to have implications for cancer biology. That connection leads directly to the viral sexually transmitted infections, where the stakes shift fundamentally. Bacterial and parasitic infections are, in principle, curable. Viral infections are not. As Yadav and colleagues put it, viral sexually transmitted infections “may not virtually have any cure, though the medicines may keep the disease under control.” That distinction — management versus elimination — defines everything that follows. Human papillomavirus, or HPV, is the clearest example of what that distinction costs. More than 120 HPV types have been identified. About a dozen, including types 16, 18, 31, and 45, are classified as high-risk because they drive cancer. High-risk oncogenic types 16 and 18 are associated with 99.7 percent of all cervical cancers. The Centers for Disease Control and Prevention estimates roughly six million new sexually transmitted HPV infections are reported in the United States each year, and the paper states that at least 20 million people in India are already infected. India carries approximately one quarter of the global cervical cancer burden, with about 130,000 new cases annually and 75,000 to 80,000 deaths. Here is the insidious part of HPV's natural history. About 70 percent of infections clear within one year, and 90 percent within two years. Most infected people never know they had it. However, in 5 to 10 percent of infected women, the infection persists — and persistent infection carries a high risk of progressing to precancerous lesions. The progression from persistent infection to detectable cancer can take 10 to 15 years. That long window between infection and consequence is why HPV is so challenging to communicate about. The harm is real, but it is delayed, and the connection between a sexual exposure years earlier and a cancer diagnosis today is not obvious. Two vaccines exist: Cervarix and Gardasil, both of which protect against types 16 and 18. Gardasil additionally covers types 6 and 11, which cause 90 percent of genital warts. Vaccination works best before sexual debut because protection depends on the immune system encountering the vaccine before the virus. Genital herpes, caused by herpes simplex virus type 1 and type 2, is extraordinarily prevalent. Globally, combined rates of HSV-1 and HSV-2 in adults fall between 60 and 95 percent. HSV-2 specifically infects approximately 535 million people between the ages of 15 and 50 — about 16 percent of that global population. Most infected people have only mild symptoms and remain unaware they are infected. That unknowing carriage is a transmission engine. People pass herpes to sexual partners and to newborns without knowing they are contagious. Acquisition of genital herpes during pregnancy has been associated with multiple spontaneous abortions, preterm labor, and congenital herpes. Antiviral drugs, including aciclovir, famciclovir, and valaciclovir, can suppress recurrences and reduce transmission but do not eliminate the virus. In late pregnancy, these antivirals are described as equally beneficial in reducing viral shedding, lesion healing time, and the risk of neonatal transmission. Daily valaciclovir in recurrent disease reduces the risk of transmitting HSV-2 to an uninfected sexual partner. HIV sits at the intersection of all of these. The virus causes acquired immunodeficiency syndrome through progressive immune failure. Transmission routes include genital fluids, blood transfusion, and breast milk. The paper describes a direct biological link between other sexually transmitted infections and HIV acquisition: ulcerative infections such as genital herpes, syphilis, and chlamydia increase heterosexual HIV transmission by creating portals of entry through genital lesions. Chlamydia raises a woman's susceptibility to HIV by up to five times. Infection with HSV-2 is itself independently associated with increased HIV transmission and acquisition. These are not coincidental co-occurrences; they are mechanistically connected. Untreated or undiagnosed sexually transmitted infections actively increase a woman's vulnerability to the one infection with the highest long-term mortality. For maternal transmission of HIV, the concentration of the virus in the mother's blood at delivery determines neonatal risk. In HIV-infected pregnant women, in-utero transmission is approximately 20 percent, with additional transmission possible at delivery and through breastfeeding. So why do all of these infections affect women more severely? Yadav and colleagues argue the answer is partly biological and partly structural, with the two reinforcing each other. Biologically, a large mucosal surface area creates greater exposure risk during intercourse. Structurally, the high rate of asymptomatic infection in women means fewer infections are caught and treated. According to their data, more than half of women with gonococcal, chlamydial, trichomonal, and other infections experience no symptoms. When an infection is silent, there is no prompt to seek care. The infection persists, ascends, scars, and transmits — to partners, fetuses, and newborns. Screening exists precisely because of that silence. The US Preventive Services Task Force recommends sexually transmitted infection screening for women who engage in high-risk sexual behavior. Syphilis screening during pregnancy is specifically highlighted because of the near-complete vertical transmission rate and the 40 percent fetal and perinatal death rate in untreated cases. Systematic reviews on improving syphilis screening in pregnancy, cited in the paper, demonstrate that antenatal screening identifies infected infants or enables treatment before severe outcomes occur. The screening is not a formality; it is the mechanism that catches what symptoms would have missed. Given that these infections are common, often silent, and sometimes incurable, what actually works in prevention and treatment? On prevention, condoms are the most effective non-abstinence tool available. They are described as "very effective" against HIV, gonorrhea, chlamydia, trichomoniasis, and hepatitis B. For men infected with genital herpes, using condoms in more than 25 percent of sexual acts reduces the transmission of HSV-2 to uninfected partners. However, condoms have real limits: the review notes they "fail to provide effectiveness to a large extent" for infections spread through skin-to-skin contact across surfaces that a condom does not cover — syphilis, HPV, and genital herpes among them. The paper is clear: correct preventive measures "greatly reduce but do not completely eliminate the risk." On treatment, the division between curable and incurable neatly maps onto bacterial and parasitic versus viral. Chlamydia is treated with azithromycin, which has favorable oral absorption and tissue penetration, or with doxycycline, erythromycin, or ofloxacin. Gonorrhea responds to cephalosporins, which include cefixime, ceftriaxone, and cefpodoxime. Trichomoniasis is treated with metronidazole. Syphilis in pregnancy is treated with penicillin. These treatments work. The problem is not the drugs; it is that asymptomatic infections are never brought to a clinician in the first place. For viral infections, management replaces cure. Antivirals suppress herpes but do not eliminate it. Vaccines against hepatitis B and HPV prevent infection if given before exposure. There is no cure for HIV, genital herpes, or HPV once an infection is established. This brings the argument to its final point. The tools exist: condoms, antibiotics, antivirals, vaccines, and screening programs. However, Yadav and colleagues are candid that managing sexually transmitted infections "is difficult and complicated." Long asymptomatic periods mean infections circulate undetected. Declining condom use within established relationships removes the primary prevention barrier. Diagnostic tests with limited sensitivity — the wet-mount microscopy that misses up to 65 percent of trichomoniasis cases — leave infections invisible. The burden of consequences falls most heavily on the population least likely to exhibit symptoms: women. The paper closes with a specific recommendation: public health prevention messages should focus on encouraging individuals to adopt safer sexual practices, and women specifically must be educated about the difference between ulcerative and non-ulcerative sexually transmitted infections and the different HIV acquisition risks each carries. Vaccination before sexual debut is emphasized — not as an afterthought, but as the window of maximum protection. Once the virus is present, the vaccine is too late. The woman who walked into that prenatal clinic, feeling fine and unaware of her infection, is not an outlier. She is the norm. The entire architecture of sexually transmitted infection prevention and treatment, as Yadav and colleagues outline, is built around the hard reality that the most common presentation of these infections is no presentation at all. This lecture was created by ennepō. Go to https://ennepo.ai to Discover, Create and Follow the latest research in your field. Read when you can. Listen when you want to.

A woman walks into a prenatal clinic. She feels fine, with no unusual discharge, no pain, and no reason for concern. She is there for a routine check. The screen comes back positive for chlamydia. She had no idea. That gap — between infection and awareness — is where much of the damage from sexually transmitted infections actually occurs. Manisha Yadav, Neha Verma, and Rakesh Singh Dhanda set out to map that damage in their review of sexually transmitted infections and their impact on women's health. What they found is a global problem that is both enormous and undercounted, falling harder on women by nearly every measure that matters. Start with the scale. The World Health Organization estimated that in 2005, there were 448 million new cases of curable sexually transmitted infections in adults every single year. That number covers only the curable bacterial and parasitic infections and excludes HIV and other viral sexually transmitted infections entirely. The review identifies more than 20 distinct types, grouped into three causative categories: bacteria, parasites, and viruses. The headline seven that the authors return to repeatedly are chlamydia, gonorrhea, syphilis, trichomoniasis, genital herpes, human papillomavirus, and HIV and AIDS.

Trichomoniasis alone — caused by the parasite Trichomonas vaginalis — infects an estimated 170 million people each year worldwide, with 154 million of them in resource-limited settings. Yadav and colleagues state that the incidence of T. vaginalis exceeds the combined incidence of chlamydia and gonorrhea, making it the most common non-viral sexually transmitted infection on the planet. Yet, it is routinely missed. The standard diagnostic tool, wet-mount microscopy, has a sensitivity of only 35 to 82 percent compared with the more accurate culture or polymerase chain reaction methods. This means a substantial fraction of cases are invisible to routine testing. One study cited from South Africa found that 20 percent of otherwise healthy asymptomatic women attending a family-planning clinic tested positive. In an obstetrics and gynecology clinic in India, the figure was 47 percent. Across different populations in India — clinic attendees, commercial sex workers, and community samples — T. vaginalis prevalence ranged from 1.2 to 28.5 percent. This is the first pattern worth noting: the numbers are large, and the diagnostics routinely undercount them. The gap between actual infection and detected infection is not a minor technical footnote; it is a public health crisis in slow motion.

Now let’s go deeper into what these pathogens actually do, starting with the bacteria. Chlamydia trachomatis infects an estimated 90 million people worldwide annually. It causes mucopurulent cervicitis — inflammation of the cervix — and can ascend into the fallopian tubes, producing salpingitis, an inflammation that often leaves no obvious symptoms. The review reports that roughly two-thirds of women with salpingitis are asymptomatic, while only one-third experience symptoms. That silent inflammation causes real damage: tubal scarring, which can lead to infertility. Tubal factors account for 14 to 38 percent of all female infertility in studies cited by the paper. More than 50 percent of women with cervical chlamydial infection have no symptoms at all. Additionally, women with chlamydial infection are reported to be up to five times more susceptible to acquiring HIV if subsequently exposed. Gonorrhea follows a similar pattern. Neisseria gonorrhoeae is highly adapted to the female genital tract, and the paper reports that women face a 60 to 80 percent risk of acquiring gonorrhea from a single act of vaginal intercourse with an infected man. Yet, it frequently produces no symptoms.

When untreated, the infection ascends; endocervical gonorrhea leads to acute salpingitis in an estimated 8 to 16 percent of women. After a single episode of acute salpingitis, almost 10 percent of women may become infertile due to complete tubal occlusion. The risk of ectopic pregnancy following salpingitis is six to ten times higher than in unaffected women. Syphilis introduces a different dimension of harm: the impact on the next generation. When a pregnant woman carries untreated Treponema pallidum, vertical transmission — meaning transmission from mother to fetus — approaches 100 percent in some of the studies cited. Approximately 66 percent of congenitally infected infants are asymptomatic at birth and are identified only through routine screening. Fetal or perinatal death occurs in around 40 percent of affected infants. The mechanism is direct: the spirochete damages both the placenta and the umbilical cord, compromising fetal growth and viability. The good news here is concrete — penicillin given to pregnant women with syphilis significantly reduces the risk of stillbirth and preterm delivery. Trichomonas vaginalis in pregnancy carries its own set of risks: preterm rupture of membranes, preterm labor, fetal loss in the third trimester, neonatal death, and low birth weight. Like chlamydia, it can also increase the risk of acquiring HIV. The paper notes that trichomoniasis is associated with cervical erosion and a predisposition to cervical neoplasia.

An organism that most people think of as causing minor irritation turns out to have implications for cancer biology. That connection leads directly to the viral sexually transmitted infections, where the stakes shift fundamentally. Bacterial and parasitic infections are, in principle, curable. Viral infections are not. As Yadav and colleagues put it, viral sexually transmitted infections “may not virtually have any cure, though the medicines may keep the disease under control.” That distinction — management versus elimination — defines everything that follows. Human papillomavirus, or HPV, is the clearest example of what that distinction costs. More than 120 HPV types have been identified. About a dozen, including types 16, 18, 31, and 45, are classified as high-risk because they drive cancer. High-risk oncogenic types 16 and 18 are associated with 99.7 percent of all cervical cancers. The Centers for Disease Control and Prevention estimates roughly six million new sexually transmitted HPV infections are reported in the United States each year, and the paper states that at least 20 million people in India are already infected. India carries approximately one quarter of the global cervical cancer burden, with about 130,000 new cases annually and 75,000 to 80,000 deaths. Here is the insidious part of HPV's natural history. About 70 percent of infections clear within one year, and 90 percent within two years. Most infected people never know they had it.

However, in 5 to 10 percent of infected women, the infection persists — and persistent infection carries a high risk of progressing to precancerous lesions. The progression from persistent infection to detectable cancer can take 10 to 15 years. That long window between infection and consequence is why HPV is so challenging to communicate about. The harm is real, but it is delayed, and the connection between a sexual exposure years earlier and a cancer diagnosis today is not obvious. Two vaccines exist: Cervarix and Gardasil, both of which protect against types 16 and 18. Gardasil additionally covers types 6 and 11, which cause 90 percent of genital warts. Vaccination works best before sexual debut because protection depends on the immune system encountering the vaccine before the virus. Genital herpes, caused by herpes simplex virus type 1 and type 2, is extraordinarily prevalent. Globally, combined rates of HSV-1 and HSV-2 in adults fall between 60 and 95 percent. HSV-2 specifically infects approximately 535 million people between the ages of 15 and 50 — about 16 percent of that global population. Most infected people have only mild symptoms and remain unaware they are infected. That unknowing carriage is a transmission engine. People pass herpes to sexual partners and to newborns without knowing they are contagious.

Acquisition of genital herpes during pregnancy has been associated with multiple spontaneous abortions, preterm labor, and congenital herpes. Antiviral drugs, including aciclovir, famciclovir, and valaciclovir, can suppress recurrences and reduce transmission but do not eliminate the virus. In late pregnancy, these antivirals are described as equally beneficial in reducing viral shedding, lesion healing time, and the risk of neonatal transmission. Daily valaciclovir in recurrent disease reduces the risk of transmitting HSV-2 to an uninfected sexual partner. HIV sits at the intersection of all of these. The virus causes acquired immunodeficiency syndrome through progressive immune failure. Transmission routes include genital fluids, blood transfusion, and breast milk. The paper describes a direct biological link between other sexually transmitted infections and HIV acquisition: ulcerative infections such as genital herpes, syphilis, and chlamydia increase heterosexual HIV transmission by creating portals of entry through genital lesions. Chlamydia raises a woman's susceptibility to HIV by up to five times. Infection with HSV-2 is itself independently associated with increased HIV transmission and acquisition. These are not coincidental co-occurrences; they are mechanistically connected. Untreated or undiagnosed sexually transmitted infections actively increase a woman's vulnerability to the one infection with the highest long-term mortality.

For maternal transmission of HIV, the concentration of the virus in the mother's blood at delivery determines neonatal risk. In HIV-infected pregnant women, in-utero transmission is approximately 20 percent, with additional transmission possible at delivery and through breastfeeding. So why do all of these infections affect women more severely? Yadav and colleagues argue the answer is partly biological and partly structural, with the two reinforcing each other. Biologically, a large mucosal surface area creates greater exposure risk during intercourse. Structurally, the high rate of asymptomatic infection in women means fewer infections are caught and treated. According to their data, more than half of women with gonococcal, chlamydial, trichomonal, and other infections experience no symptoms. When an infection is silent, there is no prompt to seek care. The infection persists, ascends, scars, and transmits — to partners, fetuses, and newborns. Screening exists precisely because of that silence. The US Preventive Services Task Force recommends sexually transmitted infection screening for women who engage in high-risk sexual behavior. Syphilis screening during pregnancy is specifically highlighted because of the near-complete vertical transmission rate and the 40 percent fetal and perinatal death rate in untreated cases.

Systematic reviews on improving syphilis screening in pregnancy, cited in the paper, demonstrate that antenatal screening identifies infected infants or enables treatment before severe outcomes occur. The screening is not a formality; it is the mechanism that catches what symptoms would have missed. Given that these infections are common, often silent, and sometimes incurable, what actually works in prevention and treatment? On prevention, condoms are the most effective non-abstinence tool available. They are described as "very effective" against HIV, gonorrhea, chlamydia, trichomoniasis, and hepatitis B. For men infected with genital herpes, using condoms in more than 25 percent of sexual acts reduces the transmission of HSV-2 to uninfected partners. However, condoms have real limits: the review notes they "fail to provide effectiveness to a large extent" for infections spread through skin-to-skin contact across surfaces that a condom does not cover — syphilis, HPV, and genital herpes among them. The paper is clear: correct preventive measures "greatly reduce but do not completely eliminate the risk." On treatment, the division between curable and incurable neatly maps onto bacterial and parasitic versus viral. Chlamydia is treated with azithromycin, which has favorable oral absorption and tissue penetration, or with doxycycline, erythromycin, or ofloxacin. Gonorrhea responds to cephalosporins, which include cefixime, ceftriaxone, and cefpodoxime.

Trichomoniasis is treated with metronidazole. Syphilis in pregnancy is treated with penicillin. These treatments work. The problem is not the drugs; it is that asymptomatic infections are never brought to a clinician in the first place. For viral infections, management replaces cure. Antivirals suppress herpes but do not eliminate it. Vaccines against hepatitis B and HPV prevent infection if given before exposure. There is no cure for HIV, genital herpes, or HPV once an infection is established. This brings the argument to its final point. The tools exist: condoms, antibiotics, antivirals, vaccines, and screening programs. However, Yadav and colleagues are candid that managing sexually transmitted infections "is difficult and complicated." Long asymptomatic periods mean infections circulate undetected. Declining condom use within established relationships removes the primary prevention barrier. Diagnostic tests with limited sensitivity — the wet-mount microscopy that misses up to 65 percent of trichomoniasis cases — leave infections invisible. The burden of consequences falls most heavily on the population least likely to exhibit symptoms: women.

The paper closes with a specific recommendation: public health prevention messages should focus on encouraging individuals to adopt safer sexual practices, and women specifically must be educated about the difference between ulcerative and non-ulcerative sexually transmitted infections and the different HIV acquisition risks each carries. Vaccination before sexual debut is emphasized — not as an afterthought, but as the window of maximum protection. Once the virus is present, the vaccine is too late. The woman who walked into that prenatal clinic, feeling fine and unaware of her infection, is not an outlier. She is the norm. The entire architecture of sexually transmitted infection prevention and treatment, as Yadav and colleagues outline, is built around the hard reality that the most common presentation of these infections is no presentation at all. This lecture was created by ennepō. Go to https://ennepo.ai to Discover, Create and Follow the latest research in your field. Read when you can. Listen when you want to.

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