Researchers have discovered that herpes can travel from the nose to the nervous system, causing long-term health issues – and could be spread between sexual partners just by kissing
Scientists have issued an urgent warning over the risks posed by the herpes virus which can potentially cause inflammation to the brain and lead to complications including dementia.
Researchers have discovered that herpes simplex virus type 1 (HSV-1) can travel from the nose to the nervous system, causing long-term health issues. The study, carried out by University of Illinois Chicago researchers, is the first to show that by exploiting a cellular enzyme, the virus can produce behavioural symptoms.
Professor Deepak Shukla, who led the research, said there is a risk of contracting the virus in the bedroom. According to the scientist, any position that allows someone’s nose to come into contact with virus particles from a person who carries HSV-1 could put them at risk of contracting it.
HSV-1 is a common virus – and the World Health Organisation estimates that nearly two-thirds of the global population carry it. Most HSV infections are asymptomatic or unrecognised, but symptoms of herpes include painful blisters or ulcers that can recur over time.
The virus is mainly transmitted via contact in sores, saliva or skin surfaces in or around the mouth. Less commonly, it can also be transmitted to the genital area through oral-genital contact to cause genital herpes. HSV-2, which is part of the same family of viruses, is mainly transmitted during sex through contact with genital or anal surfaces, skin, sores or fluids of someone infected with it.
Speaking to the Daily Mail, Dr Shukla explained that someone with oral herpes, which can cause blisters around the lips, can pass on the virus when kissing someone. There is also cases of HSV-1 causing genital herpes, meaning that an infected carrier passed on the virus during oral sex.
This happens because someone could inhale infectious particles when their face is pressed up against skin or sores shedding HSV-1. In the first study of its kind, which has been published in the journal mBio, scientists have now found that there is an enzyme called heparanase (HPSE) which could amplify inflammation after the virus gets into the brain through the nose. In the long-term, this could cause issues including brain damage and dementia.
Dr Shukla’s laboratory previously studied how the virus spreads to the eye and brain and can lead to blindness, encephalitis and other conditions. But the new research looked at intranasal infection, when the viral particles have a more direct access to the nervous system through the nose.
“If an infected individual is shedding virus via tears, it could reach the nasal cavity, where it could go more directly to the brain,” Shukla said. “I think it’s underdiagnosed and understudied, but the neurological consequences, we believe, are much more severe than you would normally see with fever blisters or ocular infection.”
While carrying out animal experiments, researchers noticed high levels of inflammation and neuronal damage just days after HSV-1 infection. Then over the next few months, which are equivalent to decades of life in humans, infected animals performed more poorly on tests of motor coordination and memory – and also showed more anxious behaviour when compared to non-infected animals.
“There is definitely nerve damage if you take the intranasal route, and the effects are long-term, which is alarming,” Dr Shukla said. Chandrashekhar Patil, research assistant professor in the College of Medicine and co-author of the paper, said: “The virus reactivates throughout life; it’s a lifelong infection. So, I think this awareness will be really important among the large population which is carrying this virus.”
Hemant Borase, a UIC postdoctoral researcher and first author of the study, added: “These insights open the door to potential therapeutic approaches to mitigate the effects of neuroinflammation and prevent long-term brain injury caused by viral infections.”
