Whether uncircumcised males face a higher risk of infection depends heavily on the specific type of pathogen, the individual’s age, and environmental factors. Circumcision status is one variable among many that influence susceptibility. A review of the evidence reveals distinct patterns of risk across different stages of life and against various infectious agents.
Infections Specific to the Foreskin and Glans
The presence of the foreskin creates a unique microenvironment that can predispose some individuals to localized inflammatory conditions. These conditions, such as balanitis (inflammation of the glans penis) and balanoposthitis (involving both the glans and the foreskin), are almost exclusively observed in uncircumcised males. Balanoposthitis is relatively common, with a prevalence reported to be as high as 20% in some populations.
These issues arise from the accumulation of microorganisms, shed skin cells, and secretions beneath the foreskin, creating an ideal breeding ground for bacteria and yeast. Inadequate hygiene or a tight foreskin (phimosis) can exacerbate the problem, leading to inflammation and secondary infection. Studies suggest that circumcision decreases the prevalence of these inflammatory conditions by approximately 68%.
Urinary Tract Infection Risk in Infants
The relationship between circumcision status and the risk of urinary tract infection (UTI) is most pronounced in the first year of life. Medical literature demonstrates a strong association between the lack of circumcision and an elevated risk of UTIs in male infants. The foreskin can trap uropathogenic bacteria near the urethral opening, allowing these microorganisms to ascend the short urethra and cause an infection in the bladder or kidneys.
A meta-analysis found that uncircumcised male infants aged 0 to 1 year had a relative risk of UTI nearly 10 times higher than that of circumcised infants. Although the absolute incidence of UTIs in male infants is generally low, an infection in this age group can be serious, potentially leading to long-term kidney damage. Some experts note that the number needed to treat is high because the baseline incidence is low overall. The risk differential persists beyond infancy; uncircumcised males aged 1 to 16 years have a relative risk of UTI approximately 6.5 times higher.
Sexually Transmitted Infection Risk in Adults
The impact of circumcision on the acquisition of sexually transmitted infections (STIs) in adults has been extensively studied, particularly concerning viral pathogens. Randomized controlled trials, primarily conducted in sub-Saharan Africa, demonstrated that male circumcision significantly reduces the risk of heterosexually acquired Human Immunodeficiency Virus (HIV) infection by approximately 60%. This reduction is a major public health finding that led the World Health Organization and UNAIDS to recommend the procedure as an additional component of comprehensive HIV prevention strategies in high-prevalence settings.
Circumcision also offers a measurable protective effect against certain other viral STIs. Studies show that circumcised men are 25% to 28% less likely to acquire Herpes Simplex Virus type 2 (HSV-2), which causes genital herpes. Similarly, the prevalence of Human Papillomavirus (HPV), a virus linked to genital warts and certain cancers, is reduced by about 35% in circumcised men. This protective effect is attributed to the removal of susceptible mucosal tissue.
This protective effect does not extend equally to all STIs. The evidence for bacterial STIs, such as Syphilis and Chancroid, is less consistent or non-existent. Studies have found no significant difference in the incidence of Syphilis between circumcised and uncircumcised men. The variation in protection highlights the importance of the specific biological interaction between the pathogen and the penile tissue.
How Circumcision Status Affects Microbial Environment
The protective effects of circumcision are largely explained by changes to the local biological and physical environment of the penis. The foreskin creates a perpetually warm, moist, and low-oxygen space, known as an anaerobic microenvironment. This environment supports the growth of specific microbial communities, particularly anaerobic bacteria.
Studies show that circumcision causes a dramatic shift in the penile microbiome, the collection of microorganisms living on the skin. Following the procedure, there is a significant decrease in the abundance of anaerobic bacteria. Concurrently, there is an increase in oxygen-tolerant bacteria, known as facultative anaerobes. This change from an anaerobic to a more aerobic environment results in a decrease in total bacterial load and microbial diversity.
The inner surface of the foreskin is mucosal tissue, which is not fully keratinized, making it less robust and more susceptible to abrasions during friction. This mucosal tissue contains a high concentration of immune cells, including Langerhans cells and CD4+ T-cells, which are primary targets for the HIV virus. Removing the foreskin eliminates this vulnerable tissue and exposes the glans to air, causing the skin to dry and become more resilient. This reduces the surface area through which viruses can enter the body. The reduction in anaerobic bacteria may also decrease local inflammation, which is thought to make the tissue less vulnerable to infection.