We Finally Know How Deadly Fungal Meningitis Spreads in The Brain, And It's Brutal

Disease-causing pathogens have evolved many tricks to disrupt the body's immune system. They can sneak into the nervous system and even the brain.

A new study from researchers in the UK, Australia, and Singapore shows how a fungus that causes a rare type of meningoencephalitis spreads out of the bloodstream and into the brain in lab-grown zebrafish.

It seems that one of the diseases that can be caused by Crypt is the same one that can be caused by squeezing between the tightly packed cells of the blood-brain barrier and hitching a ride inside immune cells bound for the brain.

The brain has very complex and effective defenses against microbes, says senior author Simon Johnston, an infectious disease researcher at the University ofSheffield, UK.

We have found a simple and effective way for microbes to escape the blood and enter the brain.

Meningitis is a life-threatening disease caused by infections of the brain and spine that lead to swelling and inflammation of the meninges, the protective barrier to the central nervous system.

Meningitis can be fatal if not recognized and treated quickly, a problem made worse by the growing threat of antimicrobial-resistant infections, which are now the third leading cause of death worldwide.

Organ transplant recipients, people with HIV / AIDS, and other people with weakened immune systems are most at risk of contracting the disease, which can only be picked up from the environment.

The most common form of the disease that can be prevented with a vaccine is C. neoformans, which can be found in bug-filled soils. The pathogen can damage blood vessels.

We started this research because we knew there was unexplained blood vessel damage in some of the patients.

The image below shows how C. neoformans behaves in blood vessels, which are stained purple. The C. neoformans is depicted in fluorescent yellow.

The researchers visualized the blood-borne invaders over several days using high-resolution, live-cell images. As the infectious microbes grew, the blood vessels stretched and broke, releasing C. neoformans into the brain tissue.

C. neoformans bursting out of blood vessels. The University of Sheffield.

The blood vessels that C. neoformans cells could wedge in looked similar to the blood vessels found next to the brain of people who had died of the disease.

As blood flow backed up, thefungal obstruction increased the tension of the walls of nearby blood vessels, making them more prone to rupturing.

The research has focused on how microbes can break down the defenses of the brain or use immune cells as a route into the brain.

The team found that C. neoformans mass build up on average two days before blood vessels burst, a tight window in which doctors might possibly intervene to stop an infection before the damage is done.

Infections that cause meningitis can be treated with antibiotics, but patients are often very ill and a lot of damage can be done before treatment is effective.

New therapies that help limit damage to the brain's blood vessels will hopefully be developed as a result of understanding how the brain is affected by the disease.

The images were done in tiny zebrafish, which is not a big deal at this stage.

The researchers think their findings might be relevant to other types of infections that damage or rupture blood vessels.

The study was published in a journal.