Can the  microbiome aid research into sexual assault?

Neen is neen

Almost 13 rape reports per day were registered in Belgium in 2019. Jups, you read that right, more than a dozen !! Or simply 4,664 rapes in just 1 year! Even worse, this is just the tip of the iceberg. As experts agree, we are dealing with a so-called dark number. This means that the number of reports is only 10% of the total number of actual incidents. And suppose you think it is something far from your own life. You must know that according to the international human rights organization Amnesty in Belgium, 1 in 5 women have been raped. That makes me silent for a moment…

Break the silence around sexual assault

We are experiencing a 25% increase in reported incidents over the last 10 years. Does this mean there are more rapes? Or that they are more reported? Experts say it is a combination of better policies and a decreasing stigma from the # MeToo movement. 

We must send a message across the world that there is no disgrace in being a survivor of sexual violence.
The shame is on the aggressor.

Angelina Jolie

Another aspect that has contributed to this is the setting up of three Care Centers after Sexual Violence in Ghent, Liège, and Brussels. These centers have received and helped more than 2,514 victims since 2017. Victims can always go here at all times for medical, psychological, and social care. Victims are also free to have a forensic investigation carried out and file a complaint. Three additional care centers are currently being set up in Antwerp, Leuven, and Charleroi.  In June 2020, the expansion to 10 centers was approved by the ministers’ council!  

But to really suppress the dark number above, a multidisciplinary approach is essential. These centers’ goal is to provide quick and comprehensive relief for victims. In this way, the victims receive the best possible help, increasing the chance of catching the perpetrator. Forensic investigation is crucial for the latter. And Isala (link to research) wants to contribute to this.  

How can the microbiome help with a sexual assault case?  

Despite the diminishing stigma and number of victims emerging, sexual assault remains extremely difficult to prosecute. From a social point of view, the movement that we observe has not taken place at the criminal level. The laws on sexual assault are still very outdated, not uniform, and highly dependent on the country (read more about it here). Amnesty International declares that more than half of the rapes (53%) between 2010 and 2017 have not been prosecuted. This means that less than 5% of the rape cases result in an effective conviction… very poor results and demotivating for the victims.  

One major reason for this is the lack of evidence. For example, in a case where physical contact has or has not taken place, or when the suspect admits to having been in contact but claims to have had consent, a ‘my word against yours’ situation may arise. Even in cases where there is ample physical evidence, many victims do not immediately come forward due to the trauma and persistent stigma surrounding sexual assault. For example, the option to use the (physical) evidence often decreases by the time they make the choice to file a (late) declaration.  

While still in its infancy, microbiome analyzes may supplement the existing evidence of a sexual assault. Just as we leave a unique fingerprint of human DNA, we also leave a trail of characteristic microorganisms – a microbial fingerprint – on everything and everyone we come into contact with. So, in an assault, the rapist could potentially leave a unique microbial fingerprint on the victim and at the crime scene. This can then tell researchers more about what may have happened. Furthermore, it can also assist in testimonials from the victim or suspect.  

In a sub-project of Isala, named ’GeneDoe, ‘ we investigate different body locations’ microbial fingerprints. What are the differences and the similarities? The more samples we can study, the better we can match samples to the correct body location. Because there is variation between individuals and circumstances anyway. Indeed, in cases of rape, it can be beneficial to first identify the origin of the sample in question (vaginal, salivary skin, etc.). For example, suppose we have a sample with a microbial composition that is very similar to our Isala reference samples for saliva or the oral cavity. In that case, this is a strong indication that the sample in question is saliva. The same applies to vaginal and skin samples.  

A significant advantage is that microbial DNA is relatively stable and robust. It can resist conditions  (time, temperature,…) better than human DNA. This gives the victim, traumatized by the sexual violence, the advantage that late reports still have a chance of successful evidence. More studies into the microbiome, the techniques’ specificity, and their application in forensic research are needed. We are working on it!