Trichomonas and Prostate Cancer: Link Questioned by New Study

Trichomoniasis is a sexually transmitted infection caused by the parasite Trichomonas vaginalis. It affects both women and men and because it can be symptomless, or present with symptoms similar to other STIs, it can be difficult to diagnose.

The good news is that trichomonas is relatively rare in the UK; in a study from the end of last year it was found that only 6,000 cases are reported per annum. The bad news is that this fairly innocuous STI is a risk factor for other serious diseases – although not, as previously thought, prostate cancer.

Back in 2006, a study found that that men infected with the T. vaginalis parasite had a 40% greater chance of developing prostate cancer. In 2012, another researcher claimed to have discovered the "molecular mechanism" causing the association between the two conditions.

For men around the world this was concerning news, trichomonas being a common STI in many countries, and not always easily detected. However, doubt has been cast upon these findings by more recent research, which has challenged the idea that trichomonas could lead to prostate cancer.

A study from last year looked specifically at African American men, amongst whom the prevalence of trichomonas and the risk of developing prostate cancer is higher than average. Ultimately, researchers found no strong evidence to suggest a causal link between trichomonas and prostate cancer in these men.

It’s not clear yet what has caused these contradictory results, but one theory is that the T. vaginalis parasite increases inflammation, and encourages the growth of both benign and cancerous cells. Trichomonas, therefore, may not actively cause the development of prostate cancer, but may contribute to more aggressive forms of it.

In other words, men who are particularly at risk of prostate cancer (whether because of age, lifestyle or family history) may do well to stay cautious about STIs such as trichomonas; however, there’s no need to be overly concerned if you receive a diagnosis. Trichomonas is one of the easier STIs to treat. Typically you take an antibiotic called metronidazole for five to seven days.

What is more concerning is that trichomonas is known to increase the risk of HIV transmission and acquisition in women. The T. vaginalis parasite is thought to increase vaginal shedding in women with HIV, which makes them more infectious.

Going forward, the safest thing to do is to continue to practise safe sex, to familiarise yourself with the symptoms of STIs and to get tested if you think you might be at risk of infection.

Trichomonas, STIs & Safe Sex

The symptoms of trichomonas are similar to chlamydia and gonorrhoea. It is thought that about half of all people infected do not suffer any symptoms, but those who do might experience the following:

• Abnormal discharge from the penis (thin, white) or vagina (thick, thin, or frothy, yellow or green, unpleasant smell)
• Pain when urinating
• Soreness and swelling around the vagina or the head of the penis
• Men may need to urinate more frequently, and women may experience pain during sex

If you are with a partner who is showing any of these symptoms, you should refrain from sex until they have been tested. If you develop these symptoms you should get tested for trichomonas as soon as possible. Click here to visit our clinic and order a home test kit.

Other STI symptoms to watch out for include:

• Blisters, bumps or sores around the genitals or anus
• Itching, tingling or burning around the genitals or anus
• In women, bleeding between periods or after sex
• In women, pain in the abdomen

To avoid contracting these kinds of unpleasant symptoms, you should always use condoms for penetrative sex if you aren’t sure your partner is free from STIs. You should also be aware that oral sex can transmit STIs; to stay safe when you aren’t sure about your partner’s STI status, use condoms or dental dams during oral sex.

Avoid sharing sex toys that haven’t been washed between uses, and be aware that condoms can’t provide full protection against diseases like genital herpes or warts, as these are spread by skin-to-skin contact.

If you’ve had unprotected sex recently, or if you have sex with multiple or casual partners frequently, it is a good idea to get tested.

If you’re a woman, you may be familiar with Gardnerella vaginalis, a type of bacteria that can invade the vaginal tract, altering the pH balance and causing unpleasant odours and discharge. Usually this condition is known as bacterial vaginosis, but it’s also sometimes referred to as gardnerella (after the bacteria that is commonly responsible).

Typically, bacterial vaginosis is associated with foul, fishy smelling vaginal discharge – but it’s not a serious condition in any sense, and is not usually accompanied by any other symptoms. What is known, however, is that conditions that change the vaginal microflora can have implications for the transmission of sexually transmitted infections. Recently, we reported that, because gardnerella can disrupt the "good" bacteria in the vagina, this can lead to inflammation, which can in turn make HIV transmission easier. In the same article, we also noted that women with bacterial vaginosis may also be harder to treat with the anti-HIV pre-exposure treatment tenofovir. Now, further studies have come to light seeming to confirm this worrying research.

The Research

As reported here, Dr Sharon Hillier from the University of Pittsburgh School of Medicine has been looking into the HIV/gardnerella question for some time. In a recent study she looked at 41 HIV-negative women who were administered tenofovir vaginal gel or film for six days. Before the trial, vaginal swabs were collected to ascertain levels of bacterial vaginosis, and at the end, further tests were carried out to measure levels of tenofovir in the women’s systems.

Hillier and her team found that, overall, concentrations of tenofovir were lower in women with high levels of gardnerella bacteria. In simple terms, that means that gardnerella reduces the amount of tenofovir that can enter the genital tissues and blood.

This is significant because it could change the way that doctors administer pre-exposure prophylaxis, such as tenofovir, to HIV-negative women. Before PrEP of this kind can be administered, it may be that women will have to undergo a gardnerella test and, if their levels of these bacteria are too high, take a course of antibiotics.

Until more is known about the efficacy of PrEP treatments, people at risk of HIV transmission are advised to take certain precautions, which can be found below.

Preventing HIV Transmission

The best way to avoid contracting HIV is to practise safe sex. That means that you should always use condoms when you aren’t certain that your sexual partner is free from infection. You should never share needles or other injecting equipment, as HIV is carried in blood as well as seminal, anal and vaginal fluids.

During sex, using lubricants can help prevent condoms from breaking, and dental dams can be used for oral stimulation (HIV can be passed on through oral sex, although the risk is far greater with penetrative vaginal or anal sex).

If you already know that your sexual partner has HIV, there are some other things to be aware of; if your partner is being treated for their HIV and they have what is known as an undetectable viral load, for instance, it is extremely unlikely that they can pass on the infection during sex.

However, if you have had unprotected sex with an HIV-positive partner and you think you may have been exposed, you should seek out post-exposure prophylaxis. This is an emergency anti-HIV treatment that must be commenced within 72 hours of unprotected sex. It lasts for a month and is often accompanied with serious side effects; however, it’s the best option for people who have been exposed.

Unfortunately, pre-exposure prophylaxis such as tenofovir vaginal gel is not currently available on the NHS. However, it is going to be trialled in the UK over the next three years.

The last thing to bear in mind is that HIV is best managed when it is diagnosed early. If you think you might be at risk of HIV you should get regular tests.

Gardnerella Tests

Until pre-exposure prophylaxis such as tenofovir becomes available on the NHS, concerns over gardnerella and bacterial vaginosis needn’t be a priority. However, if you would like to get tested for gardnerella, you can do so easily at your local NHS centre or through The STI Clinic. We can safely supply a simple home test kit and a course of prescription antibiotics.

Can Gardnerella bacteria increase HIV risk?

The vagina is not a body part that many people feel comfortable talking about. But, as with many medical issues, the more we educate ourselves, the better equipped we are to stay healthy.

In the case of bacterial vaginosis, for instance, it’s important to understand that there’s a link between this common, but not life-altering, condition and the transmission of more serious infections – most critically HIV.

New studies have found that the microflora of a woman’s vagina has a direct effect upon how susceptible she is to the human immunodeficiency virus. To understand this connection, it’s important to elaborate a little on what we mean by vaginal microflora.

The first thing to know is that a healthy vagina is slightly acidic, as this keeps unwanted bacteria from multiplying. The second thing to know is that this acidity level is, strangely enough, maintained by a type of (good) bacteria called Lactobacillus.

In women who have lower levels of Lactobacillus, the acidity of the vagina can become compromised, and unwanted bacteria can begin to develop. One common type of bacteria that develops under these circumstances is Gardnerella vaginalis. Its presence can lead to bacterial vaginosis, which causes unusual, unpleasant-smelling vaginal discharge.

The question is: what does this all have to do with HIV?

Well, as described here, HIV transmission is more likely when there is inflammation in the vagina. In turn, vaginal inflammation is closely associated with low levels of Lactobacillus. When researchers examined which types of bacteria were linked to decreasing levels of Lactobacillus and inflammation, one in particular was singled out: Prevotella bivia. Shockingly, women whose vaginal microflora contained more than 1% P. bivia showed the highest levels of inflammation; these women were 13 times more likely to contract HIV.

Gardnerella was also found to play a role in HIV transmission when it comes to pre-exposure prophylaxis (where medication is taken to prevent infection). In one study looking at tenofovir, an anti-HIV drug applied to the vagina in the form of a gel, it was found that the efficacy of the medication dropped by half when Gardnerella was introduced to the vagina.

This research could lead to much progress being made in the HIV/AIDS crisis, particularly in African countries. If bacterial infections in the vagina can be effectively treated with antibiotics, and if greater awareness can be spread about the importance of vaginal health, then we could start to see a decrease in HIV diagnoses.

Maintaining a Healthy Vagina

The first thing to know about vaginal health is that vaginal discharge is a completely natural feature of a healthy vagina. It is produced by the cervix to keep the vagina moist and free from infection. Normal vaginal discharge is clear or white, and thick and sticky for the majority of your menstrual cycle (it may become wetter around ovulation). Normal vaginal discharge should not smell strong or unpleasant.

Unusual vaginal discharge is characterised by any significant change in colour, consistency or smell. If it smells fishy, becomes lumpy, or turns green, yellow, or grey and watery, this is typically a sign of a sexually transmitted infection or a condition such as bacterial vaginosis.

Bearing this information in mind, it’s advised that you follow these guidelines to keep your vagina healthy:

• Keep the vagina, anus and perineum clean, particularly during your period

• Wash your hands before and after changing your sanitary towel, tampon or menstrual cup

• Avoid using vaginal douches, as these can disrupt your vaginal microflora

• Avoid using perfumed or antiseptic products on your vagina as these can also disrupt the microflora

• Use condoms and dental dams during sex when you aren’t sure that your partner is free from STIs

• Get tested for STIs if you might be at risk, even if you are not experiencing symptoms

• Get checked out if you experience any significant change in your discharge, or experience irregular bleeding or pelvic pain

• Attend a cervical screening every three years

The STI Clinic can supply safe home sampling kits for all kinds of STIs, including HIV and chlamydia. We can also supply a test for bacterial vaginosis. Click here to visit our clinic and find out more.

If there wasn’t already enough reason to practice safe sex consistently, we have recently been reminded that there is a natural weakness in female immunity as ovulation occurs, more than at any other time throughout the menstrual cycle. This is thought to occur in order to allow sperm to survive a potential immune response once inside the body of the female and go on to fertilise an egg. According to a recent study, this has the potential to make women more susceptible to a sexually transmitted infection while ovulating.

A study was carried out at the Laboratorio de Inmunobiologia Moleculare at the hospital Gregario Maranon and Complutense University, Madrid, and the team used mice for the purposes of the study. They found that estradiol, a sex hormone, which is mostly made in the ovaries and the placenta (in pregnancy) decreased the immune response in female mice leaving them more exposed to potential infections including yeast infections and sexually transmitted bacteria and viruses.

Since the mice were only tested using candida albicans (the cause of yeast infection), this is not enough proof to suggest that women would be more susceptible to all sexually transmitted infections during ovulation and so further investigations will be carried out in this area although the scientists behind the study are confident that their finding will translate to other infections.