There has been an enormous increase in STIs in recent years, reaching 19 million cases in 2006 in the USA according to the Centers for Disease Control (CDC) [15]. This included 1,030,911 cases of Chlamydia, a record high, with the actual number estimated as 2.8 million [15]. There were 358,366 reported cases of gonorrhoea, the actual number being twice this, and 9,756 cases of syphilis in the USA in 2006 [15]. Genital herpes, papillomavirus (HPV) account for the vast majority of STI cases, although doctors are not required to report them nationally [15].
Ulcerative STIs (particularly chancroid and syphilis) are associated with lack of circumcision.
This section deals with all STIs apart from human immunodeficiency virus (HIV) and human papillomavirus (HPV), which are dealt with in separate sections to follow.
STIs have an enormous adverse impact on global public health [340]. For example, HPV accounts for 3.3 million disability adjusted life years (DALYs) from cervical cancer caused by high risk HPV types [340]. Syphilis, which is associated with fatalities, stillbirth in pregnant women, prematurity and congenital infection, is responsible for 4.2 million DALYs [340].
Chlamydia and gonorrhoea, which account for 7 million DALYs, cause infertility by blocking fallopian tubes in women and the vas deferens in men, as well as being responsible for ectopic pregnancy, which can lead to death of the mother [340]. A commitment to control all STIs needs dispassionate public health action to replace ‘moral prophylaxis’ [340]. Condoms, while helpful, are not completely effective even when consistently used [340]
The link between circumcision and protection from STIs has a history going back to over 150 years. So let’s walk through the research findings over time.
In 1855 syphilis was discovered to be associated with lack of circumcision [259]. Then in 1891 Romondino confirmed this finding and also noted the possible protection afforded by circumcision against genital herpes and urethritis [462].
In 1947, a study involving 1,300 consecutive patients in a Canadian Army unit, showed that being uncircumcised was associated with a 9-fold higher risk of syphilis and 3-times higher gonorrhea [628]. A report in 1949 found higher syphilis, chancroid and gonorrhoea [233]. Higher chancroid was also reported in 1952 [33]
In 1967 higher HSV-2 was found in men who were not circumcised [427]. Then, in the mid-70s work by the London Hospital showed higher chancroid, syphilis, papillomavirus and herpes in uncircumcised men [566]. Higher chancroid was also seen in a 1980 report [231]. Subsequent to this, a study in 1983 at the University of Western Australia, showed twice as much herpes and gonorrhea, 5-times more candidiasis and 5-fold greater incidence of syphilis [428]. In South Australia, a study in 1992 showed that uncircumcised men had more chlamydia (odds ratio 1.3) and gonoccocal infections (odds ratio 2.1) [238]. Others have reported higher rates of non-gonococcal urethritis in uncircumcised men [536].
In 1988 a study in Seattle of 2,776 heterosexual men reported higher syphilis and gonorrhoea in uncircumcised men, but no difference in herpes, chlamydia and non-specific urethritis (NSU) [127]. Like this report, a study in 1994 in the USA, found higher gonorrhoea and syphilis, but no difference in other common STIs. An earlier (1987) study of 9,514 sexually transmitted infection patients from a US military base found higher non-gonococcal, but not gonococcal, urethritis in those who were circumcised [536].
In 1994, Donovan and associates reported the results of a study of 300 consecutive heterosexual male patients attending Sydney STI Centre at Sydney Hospital [154]. They found no difference in NSU, genital herpes (24% having a history of this [64]) or seropositivity for HSV-2 (65% [64]) and genital warts (i.e., the benign, so-called 'low-risk' human papillomavirus types 6 and 11, which are visible on physical examination, unlike the 'high-risk' types 16 and 18, which are not). As mentioned earlier, 62% were circumcised and the two groups had a similar age, number of partners and education. Gonorrhoea, syphilis and hepatitis B were too uncommon in this Sydney study for them to conclude anything about these other STIs.
Similar findings were obtained in the National Health and Social Life Survey in the USA, which asked about gonorrhoea, syphilis, chlamydia, non-gonococcal urethritis, herpes and HIV (a virus more often acquired intravenously in heterosexual i.v. drug-using men in the USA) [326], although some under-reporting by uncircumcised men was likely as they tended to be less educated. Also, circumcision at birth was assumed, so that the number who sought circumcision later in life for problems, such as STIs and/or other infections, and therefore had switched group, was not taken into account.
In a cross-sectional and cohort study from a multicenter controlled trial involving 2021 men in the USA from 1993 to 1996, and using multiple logistic regression to compare STI risk among circumcised and uncircumcised men adjusted for potential confounding factors, uncircumcised men were significantly more likely to have gonorrhoea in the multivariate analysis adjusted for age, race and site (odds ratio 1.3 and 1.6 for each respective study) [150]. This was also the case for syphilis (odds ratios 1.4 and 1.5), but not chlamydia.
The warm moist environment under the prepuce favours bacterial replication. The delicate inner lining’s mucosal nature and risk of tearing it and the frenulum during intercourse are other factors. Chancroid is more likely to present on the inner and outer prepuce, whereas syphilis and herpes simplex type 2 (HSV-2) tend to infect the genitalia more widely.
Non-ulcerative STIs tended to be more prevalent in uncircumcised men in earlier studies, especially in developing nations. However, more recent studies tend to show little or no difference. For genital herpes a 1998 review of 11 studies [380] noted 2 studies that showed an association with lack of circumcision [428, 566] and 4 that found no association [64, 127, 154, 327].
For gonorrhoea 5 reported significant association [127, 238, 251, 428, 628] and 2 no association [327, 536]. For chlamydial, non-gonococcal or other types of urethritis 2 studies reported association with lack of circumcision [238, 584], 3 with circumcision [251, 327, 393] and 3 no association [127, 154, 536]. Similarly, no association was found in a 2005 report [147]. An Australia-wide telephone survey found no differences in genital warts, Chlamydia, genital herpes, gonorrhea, non-specific urethritis or public lice between circumcised and uncircumcised men [465].
Results of the first meta-analyses of ulcerative STIs were reported in 2006 by Weiss and co-workers in London. This was based on 26 research articles (from the USA, UK, Australia, Africa, India and Peru) [612] and are summarized in the Table below. The analyses established that circumcised men were at very much lower risk of chancroid and syphilis. The association with HSV-2 was weaker.
Table. Studies show circumcision reduces risk of ulcerative STIs.
|
STI
|
Studies
|
Relative risk (confidence interval)
|
|
|
|
|
Syphilis
|
14 of 14 studies
|
0.61 (0.54–0.83)
|
|
|
|
0.53 (0.34–0.83)*
|
|
Chancroid
|
6 of 7 studies
|
0.12–1.11†
|
|
HSV-2
|
6 of 10 studies
|
0.88 (0.77–1.01)
|
*When circumcision was done prior to first sexual intercourse.
†Individual study RR, since meta-analysis was not possible.
For the syphilis studies in this Table, adjusted odds ratios or prevalence ratios in each were: 0.54 [89], 0.69 [91], 0.25 [127], 0.52 [150], 1.01 [214], 0.64 [328], 0.60 [393], 0.19 [428], 0.63 [464], 0.78 [557], 0.70 [573], 0.95 [582], and 0.71 [589].
The risk ratios in the chancroid studies in the Table were: 0.13 [233], 1.11 [455], 0.40 [337], 0.04 [61], 0.66 [388], 0.62 [95], [237].
In the case of the HSV-2 studies, rate, prevalence or odds ratios were: 0.88 [208], 1.20 [42], 0.81 [214], 0.56 [285], 1.18 [328], 0.39 [405], 0.91 [464], 0.84 [553], 0.73 [611], and 1.04 [611]. Another meta-analysis, published in 2007, found uncircumcised men were 2.3 times more likely to have genital uncer disease [588a].
In a randomized controlled trial in Uganda the protective effect of circumcision against genital ulcer disease was 48% [216].
A New Zealand study saw no difference in frequency of serum antibodies to HSV2 (7%) between men aged 26 who had been circumcised prior to the age of 3 compared with those who were uncircumcised [147]. Similarly, the NHANES study by the CDC found no association between HSV-2 and circumcision status, seroprevalence being 13.7% in uncircumcised and 11.6% in circumcised [650]. In men aged 20-49 who had had sex, the dual biomedical factors that can lead to HSV-2 acquisition were only 0.8% in whites, but 8.5% in blacks and 7.5% in Hispanics [650].
Design aspects of a number of the studies have been criticized. As a result there is still no overwhelming agreement, as highlighted in the meta-analyses [612] referred to in the Table above. Nevertheless, on the bulk of evidence, it would seem that at least some STIs are more common in the uncircumcised. This association not as strong in Western settings, and the incidence may be influenced by factors such as the degree of genital hygiene, availability of running water and socioeconomic group being studied. In some more recent studies in developed nations, in which hygiene is good, little difference was apparent in several of the more common STIs such as gonorrhea and herpes
The randomized controlled trial (RCT) is the ‘gold standard’ for study design in epidemiology. This approach is, however, challenging and expensive, and no RCTs have been carried out for STIs and circumcision. Longitudinal studies, however, are regarded as superior to case-control association studies and one such has been carried out in New Zealand.
This involved a birth cohort born in the early 1970s. It found that to age 25 the uncircumcised had a 3.2-fold higher rate of STI when compared with those who were circumcised, after adjustment for the higher number of sexual partners and of rate of unprotected sex in the 30% who were circumcised [173] (The frequency of STIs amongst the participants were 52% Chlamydia, 31% genital warts 31%, 12% non-specific urethritis, 10% genital HSV-2 and 5%, gonorrhea). It was concluded that if all had been circumcised their rate of STI would have been reduced by 48%. For Chlamydia the OR was 2.5 (CI 0.73-8.5).
Promiscuous teenagers and early 20s are contributing to an epidemic of STIs such as Chlamydia, gonorrhoea and syphilis, with the number of new infections in Australia soaring to a record high [606]. In Australia Chlamydia infections have more than tripled between 1999 and 2006 [30, 282]. Chlamydia is 2.5 times higher in females than males [606]. Its rise coincides with an increase in the numbers of uncircumcised males in these sexually more promiscuous younger people.
In a global society risk of contracting an STI cannot be ascribed parochially. Travellers are particularly vulnerable to the different risk in a new country they may visit, particularly when holiday-making is associated with consumption of alcohol and other drugs, as well as an attitude of having a good time, which can lead to sexual relations with the locals, often with no condom [349].
THRUSH
Penile candidiasis (thrush) is also significantly less common in circumcised men (odds ratio 0.40) [465]. This yeast (fungal) infection can occur from contact with a female sexual partner who has it. Men with diabetes are at increased risk. Symptoms can be none, a transient rash or severe burning sensation after intercourse.
