When Monique cries, even her tears smell like rotting fish. She's only 23, but is unable to work or socialize like others her age due to suffering from a rare genetic condition known as trimethylaminuria for the past three years. "I stay in. I don't go anywhere. I don't have any friends. I'm even afraid to go to college because of it."

Body odour is the main symptom of trimethylaminuria (also known as TMAU, or 'fish odor syndrome'). The smell is likened to fish, feces, and garbage, and excreted through the pores, sweat, urine, saliva, and even vaginal fluids of those affected. It's estimated that 1 percent of the UK population are affected, and as of 2011, less than 200,000 people in the US. There is no cure.

Elizabeth Shephard, a professorial research associate for the Structural & Molecular Biology at University College London, is a leading expert in the area of TMAU. She's worked with other scientists since the 80s to reach a better understanding of the condition. She receives one to two emails a week from those in the UK and around the world that have either been diagnosed with TMAU, or are concerned they might have it.

"The condition is one caused by a bad gene and not bad hygiene. A bad FMO3 gene causes an ineffective protein to be produced," Shephard explains. The noxious compound trimethylamine (TMA) builds up in the bodies of sufferers over time. The ineffective protein can't break it down into harmless trimethylamine N-oxide (TMAO) in the liver, causing that distinctive fishy smell. The severity of the odor depends on how severe the gene mutation is.

There are two forms of trimethylaminuria: primary and secondary. Primary is caused by the faulty FMO3 gene, while secondary is not. "We still do not understand how this [secondary] form arises but it causes the same body odor problems. Possibly due to a change in the gut microflora that allows bacteria or microorganisms that produce TMA to flourish more than is usual," Shephard continues.

During my research I'd read that TMAU was found more commonly in women. "I do not think there is a sex bias in the condition. However, the condition is exacerbated in women at the time of menstruation. This is because the available FMO3 is diminished by hormonal changes at this time. " This means the contraceptive pill can worsen things too. (It's worth mentioning, however, that if it's only your vagina that smells of fish, it could be a sign of bacterial vaginosis.)

A 2014 study found that more than a third of women aged 18 to 24 already felt uncomfortable talking to their doctor about intimate issues, so imagine working up the courage to do so if you're already worried that you smell of decomposing fish.

To others, TMAU sufferers may smell of fish, feces, and garbage. Photo by Ilya via Stocksy

It's not just the embarrassing nature of the condition that is leading many to go undiagnosed, but also a lack of awareness amongst medics. "Doctors don't know much about it," said Monique. "I tried to get tested once, but I was given the runaround... I first realised [it was TMAU] when I exhausted all my options and went to the internet to do some research."

Testing for TMAU involves providing a urine sample after taking choline tablets to detect the presence of TMA and TMAO, but this is something doctors are hesitant to do, especially if the patient has a history of mental health issues. Instead, their symptoms are often labelled as paranoia.

"Patients tell me that they do struggle to convince their doctor that they have (or might have) the condition," Shepherd says.

While the rareness of a condition makes doctors' dismissiveness understandable, it's extremely frustrating for those wanting medical attention. Sufferers' distress was evident from their contributions to a popular forum for the condition. After being refused an official test, Mary* commented, "I realize that with a diagnosis; it wouldn't change how I feel but, at least I'd know that it's not just a case of me going mad."

I don't think anyone wants a girl that smells this bad.

The more I looked into it all, the more I realized how lonely and confusing TMAU must be; becoming socially isolated by a smell you can't control, yet unable to find any answers or a clear diagnosis without being told it's all in your head. Perhaps this was why so many of those I'd messaged were hesitant to talk to me.

When I asked Monique about how she managed relationships, she responded with: "I don't think anyone wants a girl that smells this bad." Her experiences at work had only fuelled the fears of being around others. "I was teased at work. I got dirty looks and would take my lunch break to shower and not eat lunch."

It's the social rejection that causes many sufferers to develop depression and anxiety; in extreme cases, some even become suicidal. One lady wrote on a TMAU forum, "I'm exhausted with the negativity, rejection, and isolation. Constantly being undermined and judged, and the habitual humiliation has worn my soul down..." Monique told me: "Honestly, I'm losing it. I'm constantly depressed, seeing everyone enjoying life except me."

There is still no cure and very little information on treatment, leaving sufferers feeling hopeless. "No matter what I take to control it it's still here... I get reactions like sneezing, covering nose, coughing. Nothing I've tried works," Monique explains.

Read more: How Eating Pussy Could Be Good for Your Health

I asked Shepherd what the future holds for trimethylaminuria. "There are research groups working on potential treatments, but like all treatments these have to be rigorously tested before agencies will approve them for use." Until then, the main thing you can do is watch what you eat. "Avoid foodstuffs that can be metabolised by the gut bacteria and in the process produce TMA." This includes foods such as eggs, Brussels sprouts, peas, and soy products.

Accordingly, TMAU sufferers have built an online community for themselves. For those with conditions that are still unheard of, being able to share their frustrations with others in the same situation seems to be an effective balm of sorts, allowing them to feel less alone. In lieu of a medical cure, friendship has sprung up in its place.

"There are still sufferers out there feeling lonely and alienated because they don't know what on earth is wrong with them. Let's raise awareness to help them, lead them to diagnosis and/or the support of our network," writes one forum contributor. "Our community is great and can be even greater..."