Sexually transmitted disease pathophysiology
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Sexually transmitted disease Microchapters |
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Pathophysiology
Many STIs are (more easily) transmitted through the mucous membranes of the penis, vulva, and (less often) the mouth. The visible membrane covering the head of the penis is a mucous membrane, though it produces no mucus (similar to the lips of the mouth). Mucous membranes differ from skin in that they allow certain pathogens into the body.
This is one reason that the probability of transmitting many infections is far higher from sex than by more casual means of transmission, such as non-sexual contact—touching, hugging, shaking hands—but it is not the only reason. Although mucous membranes exist in the mouth as in the genitals, many STIs seem to be easier to transmit through oral sex than through deep kissing. According to this chart, many infections that are easily transmitted from the mouth to the genitals or from the genitals to the mouth, are much harder to transmit from one mouth to another. With HIV, genital fluids happen to contain much more of the pathogen than saliva. Some infections labeled as STIs can be transmitted by direct skin contact. Herpes simplex and HPV are both examples. KSHV, on the other hand, may be transmitted by deep-kissing but also when saliva is used as a sexual lubricant, which is common among gay men engaging in anal intercourse.
Depending on the STD, a person may still be able to spread the infection if no signs of disease are present. For example, a person is much more likely to spread herpes infection when blisters are present (STD) than when they are absent (STI). However, a person can spread HIV infection (STI) at any time, even if he/she has not developed symptoms of AIDS (STD).
All sexual behaviors that involve contact with another person or the bodily fluids of another person should be considered to contain some risk of transmission of sexually transmitted diseases. Most attention has focused on controlling HIV, which causes AIDS, but each STD presents a different situation.
As may be noted from the name, sexually transmitted diseases are transmitted from one person to another by certain sexual activities rather than being actually caused by those sexual activities. Bacteria, fungi, protozoa or viruses are still the causative agents. It is not possible to catch any sexually transmitted disease from a sexual activity with a person who is not carrying a disease; conversely, a person who has an STD got it from contact (sexual or otherwise) with someone who had it, or his/her bodily fluids. Some STDs such as HIV can be transmitted from mother to child either during pregnancy or breastfeeding.
Although the likelihood of transmitting various diseases by various sexual activities varies a great deal, in general, all sexual activities between two (or more) people should be considered as being a two-way route for the transmission of STDs, i.e., "giving" or "receiving" are both risky.
Healthcare professionals suggest safer sex, such as the use of condoms, as the most reliable way of decreasing the risk of contracting sexually transmitted diseases during sexual activity, but safer sex should by no means be considered an absolute safeguard. The transfer of and exposure to bodily fluids, such as blood transfusions and other blood products, sharing injection needles, needle-stick injuries (when medical staff are inadvertently jabbed or pricked with needles during medical procedures), sharing tattoo needles, and childbirth are other avenues of transmission. These different means put certain groups, such as doctors, haemophiliacs and drug users, particularly at risk.
Recent epidemiological studies have investigated the networks that are defined by sexual relationships between individuals, and discovered that the properties of sexual networks are crucial to the spread of sexually transmitted diseases. In particular, assortative mixing between people with large numbers of sexual partners seems to be an important factor.
It is possible to be an asymptomatic carrier of sexually transmitted diseases. In particular, sexually transmitted diseases in women often cause the serious condition of pelvic inflammatory disease.
Transmission Probabilities
The risks and transmission probabilities of sexually transmitted diseases are summarized by act in the table below.[1][2][3][4][5][6][7] [8] [9] [10] [11]
| Odds of transmission per unprotected sexual act with an infected person | |||
|---|---|---|---|
| Known risks | Possible or unknown risks | ||
| Performing oral sex on a man |
With anal to oral practices: |
| |
| Performing oral sex on a woman | |||
| Receiving oral sex—man | |||
| Receiving oral sex—woman | |||
| Vaginal sex—man | |||
| Vaginal sex—woman | |||
| Anal sex—insertive | |||
| Anal sex—receptive | |||
| Anilingus |
|
| |
References
- ↑ Department of Public Health, City & County of San Francisco (2011). STD Risks Chart
- ↑ 2.0 2.1 2.2 2.3 Varghese B, Maher JE, Peterman TA, Branson BM,Steketee RW (2002). "Reducing the risk of sexual HIV transmission: quantifying the per-act risk for HIV on the basis of choice of partner, sex act, and condom use". Sex. Transm. Dis. 29 (1): 38–43. doi:10.1097/00007435-200201000-00007. PMID 11773877.
- ↑ 3.0 3.1 3.2 Jin F; et al. (2010). "Per-contact probability of HIV transmission in homosexual men in Sydney in the era of HAART". AIDS. 24 (6): 907–913. doi:10.1097/QAD.0b013e3283372d90. PMC 2852627. PMID 20139750. Unknown parameter
|month=ignored (help) - ↑ 4.0 4.1 4.2 4.3 4.4 Hoare A (2010). models of HIV epidemics in Australia and Southeast Asia
- ↑ 5.0 5.1 5.2 Burchell A; et al. (2006). "Modeling the Sexual Transmissibility of Human Papillomavirus Infection using Stochastic Computer Simulation and Empirical Data from a Cohort Study of Young Women in Montreal, Canada". American Journal of Epidemology. 169 (3): 534–543. doi:10.1093/aje/kwj077. PMID 16421235. Unknown parameter
|month=ignored (help) - ↑ 6.0 6.1 6.2 6.3 6.4 Australasian contact tracing manual. Specific infections where contact tracing is generally recommended
- ↑ Bryan C (2011)INFECTIOUS DISEASE CHAPTER EIGHT SEXUALLY TRANSMITTED DISEASES
- ↑ 8.0 8.1 8.2 Mahiane, Séverin-Guy; et al. (2009). "Transmission probabilities of HIV and herpes simplex virus type 2, effect of male circumcision and interaction: a longitudinal study in a township of South Africa". 23 (3): 377–383. doi:10.1097/QAD.0b013e32831c5497. Unknown parameter
|month=ignored (help) - ↑ 9.0 9.1 Holmes, King; et al. (1970). "An estimate of the risk of men acquiring gonorrhea by sexual contact with infected females". 91 (2): 170–174.
- ↑ 10.0 10.1 Platt, Richard; et al. (1983). "Risk of Acquiring Gonorrhea and Prevalence of Abnormal Adnexal Findings Among Women Recently Exposed to Gonorrhea". JAMA. 250 (23): 3205–3209.
- ↑ 11.00 11.01 11.02 11.03 11.04 11.05 11.06 11.07 11.08 11.09 11.10 Sarah Edwards, Chris Carn (1998). "Oral sex and the transmission of non-viral STIs". Sex Transm In. 74 (1): 95–100.