This colorized scanning electron micrograph shows Giardia lamblia reproducing asexually. Image: Stan Erlandsen, CDC’s Public Health Image Library.
Most sexually transmitted infections are caused by bacteria or viruses, but some are caused by organisms that are classified as completely different lifeforms. Trichomoniasis, for example, is caused by a protozoan organism; protozoa occupy their own kingdom, separate from plants, animals, and bacteria. Intestinal parasites are often protozoan organisms, but can also include parasitic worms (which are members of the animal kingdom). They are spread through contact with fecal matter – and as such, they can be transmitted sexually as well as nonsexually. Intestinal parasites are usually transmitted by fecal contamination of food or water, and are most common in areas with insufficient sewage treatment and untreated water in the wilderness. Some pathogens, however, have low infectious doses, making their sexual transmission more likely.
What has eight flagella and can live in your intestines?
Oral contact with the anus, also called anilingus or rimming, is the primary means of the sexual transmission of these pathogens. Putting fingers or hands in your mouth after they have had contact with the anus is also risky. Other modes of transmission include oral sex, as genitals can be contaminated with feces, as well as sharing sex toys and other equipment. For these reasons, it is very important to use dental dams or latex gloves during contact with the anus; to clean the anus before engaging in rimming; to clean or use condoms on shared sex toys; and to use condoms or dental dams during oral sex. Continue reading
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Most sexually transmitted infections (STIs) are caused by microorganisms – lifeforms that are too small to be seen without a microscope. Many STIs, however, are caused by viruses, which technically aren’t even alive. Rather, viruses are pieces of genetic information that are stored in protein capsules. When these capsules come into contact with a host cell, the genetic information is able to enter the cell and hijack its machinery so that the host cell manufactures copies of the virus, as well as potentially harmful viral proteins. Many well-known STIs, such as herpes and HIV/AIDS, are caused by viruses, but this month we will focus on two lesser-known viral STIs, cytomegalovirus and molluscum contagiosum. Your local Planned Parenthood health center, as well as other clinics, health departments, and private health-care providers, can help you get a diagnosis and treatment for these STIs.
Cytomegalovirus leaves granules inside its host cells called inclusion bodies, pictured here. Image: Public Health Image Library, CDC
The bad news is that most people are infected with cytomegalovirus (CMV) at some point in their lives. About 80 percent of the U.S. population is estimated to be carriers, about 4 in 10 Americans are infected with CMV before puberty (usually through contact with saliva), and adults can be reinfected through sexual activity. The good news is that among healthy adults, a CMV infection usually does not have any symptoms, though if they do they could seem like a mild case of mono. Being reinfected with the virus later in life also carries with it only a small risk for symptoms in healthy adults.
And back to the bad news: While an infection with cytomegalovirus usually does not have symptoms, if someone is infected while pregnant it can harm the fetus. About 1 in 100 U.S. babies is infected with CMV, but usually doesn’t show symptoms. Every year in the United States, around 5,500 babies are born with symptomatic cytomegalic inclusion disease (CID). Symptoms of CID vary, but the most severe include mental retardation and hearing loss. If the mother was already infected before conception, there is a 2 percent chance the virus will be transmitted to the fetus; however, if the infection occurs during pregnancy, this risk jumps into the 40 to 50 percent range. Continue reading
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Tagged CID, CMV, condom, condoms, cytomegalic inclusion disease, cytomegalovirus, cytomegalovirus retinitis, dental dam, dental dams, fetus, HCMV, Herpesviridae, herpesvirus, herpesviruses, HHV-5, HIV/AIDS, human cytomegalovirus, human herpesvirus-5, immune system, inclusion bodies, latex barriers, lesion, lesions, molluscum contagiousum virus, Poxviridae, pregnancy, sexually transmitted disease, sexually transmitted diseases, sexually transmitted infection, sexually transmitted infections, STD, STDs, STI, STIs, virus, wart, warts
Treponema pallidum, the causative agent of syphilis, is seen in this electron micrograph adhering to a surface with the end of its structure. Image: Public Health Image Library, CDC
When syphilis first descended upon Europe, it was seen as a new plague, and anxiety and blame coalesced around this mysterious scourge. Was it a punishment from God? Was it introduced by a hated Other? Was it caused by the stars’ alignment or the presence of “bad air”? The panic it provoked foreshadowed the hysteria that surrounded the emergence of HIV in the 1980s, as syphilitics were discriminated against, feared, or thought to have received punishment for their “unbridled lust.”
We now know that syphilis is not caused by supernatural forces, foreigners, or “bad air,” but rather by a species of spiral-shaped bacteria called Treponema pallidum, which can cause infections in the vagina, anus, urethra, or penis, as well as the lips and mouth. It is mostly spread by sexual contact – vaginal or anal intercourse, as well as oral sex – in which one person comes into contact with a syphilis sore. These sores can be hidden on the cervix or in the vagina, urethra, rectum, or mouth, making it not immediately apparent that one is infected with syphilis. Syphilis can also spread to a fetus during pregnancy. Sexually active people can reduce their risk of contracting syphilis by using latex barrier methods such as condoms or dental dams. Continue reading
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Tagged antibiotic, antibiotics, antigenic variation, arsenic, bacteria, chancre, Great Pox, gummatous syphilis, latent syphilis, lesion, lesions, malaria, malaria therapy, mercury, Neosalvarsan, Paul Ehrlich, penicillin, primary syphilis, Salvarsan, secondary syphilis, sexually transmitted disease, sexually transmitted diseases, sexually transmitted infection, sexually transmitted infections, spirochete, STD, STDs, STI, STIs, syphilis, T. pallidum, tertiary syphilis, Treponema pallidum, ulcer
Sexually transmitted infections can be caused by viruses, bacteria, protozoans, and even animals. Bacterial vaginosis and chancroid are both infections caused by bacteria, which means that they can be treated with antibiotics. While bacterial vaginosis only affects people with vaginas, chancroid disproportionately affects people with penises. You can seek diagnosis and treatment for bacterial vaginosis and chancroid at a Planned Parenthood health center, as well as health clinics, private health-care providers, and health departments.
Bacterial vaginosis is caused by an imbalance of bacteria species in the vagina. Image: renjith krishnan / FreeDigitalPhotos.net
Bacterial vaginosis seems to be most commonly caused by the bacteria species Gardnerella vaginalis. Scientists aren’t quite sure how this infection is caused, but risk seems to correlate with a change in sexual partners, having multiple sexual partners, douching, or using an intrauterine device; it can also occur in females who have never been sexually active. It is more common in pregnant women. There is no counterpart to this infection in males, although G. vaginalis can be found in their urethras; this raises the possibility that bacterial vaginosis can be sexually transmitted, in which case it could be directly transmitted between two females or indirectly transmitted from one female to another via a male.
Bacterial vaginosis seems to result from an imbalance in the vaginal flora (“flora” is a somewhat fanciful term for the bacteria that live in your body; under normal circumstances they are harmless and even beneficial). Vaginas usually are habitat to a population of bacteria called Lactobacillus, which produce hydrogen peroxide as a byproduct. When the number of Lactobacillus declines, G. vaginalis is able to move in on Lactobacillus’ old territory. The decrease in Lactobacillus and increase in G. vaginalis leads to a rise in the vagina’s pH. The new vaginal environment is less acidic and more alkaline; a vaginal pH of more than 4.5 is one criterion for the diagnosis of bacterial vaginosis. Another symptom includes a vaginal discharge that may smell somewhat fishy. There might also be genital itching or pain during urination. It is also possible not to have symptoms. Continue reading
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Tagged antibiotic, antibiotics, bacteria, bacterial vaginosis, chancroid, circumcision, discharge, douche, douching, erythromycin, G. vaginalis, Gardnerella vaginalis, H. ducreyi, Haemophilus ducreyi, intrauterine device, IUD, Lactobacillus, lesion, lymph node, lymph nodes, metronidazole, pelvic inflammatory disease, PID, pregnancy, pus, sexually transmitted disease, sexually transmitted diseases, sexually transmitted infection, sexually transmitted infections, sore, STD, STDs, STI, STIs, ulcer, uncircumcised, vagina, vaginal bacteria, vaginal discharge, vaginal flora, yogurt