 "Photo: David J. Olender / Photo Editor")
Imagine strolling out to your mailbox one bright, sunny morning. You take out your usual mail - the coupons, the bills - and then you notice an interesting letter. As soon as you open the letter, you notice faint traces of a white powder blowing into the air. Days later, you're dead.
Anthrax-laced letters may be a remote threat, but the thought of actually receiving one is enough to cause fear. In 2001, five people died as a result of bio-terror attacks. But now, scientists are making discoveries that make the anthrax threat even more insignificant.
Researchers at San Diego State recently proved that anthrax is able to penetrate the blood-brain barrier, a barrier that keeps dangerous viruses and bacteria from entering the brain. This information will allow further investigation into ways to stop the spread of the bacteria and make the bio-terror threats less effective.
For the past 18 months, scientists from SDSU and UC San Diego collaborated to research anthrax.
"I am excited about our research as I believe that the more we understand the basic mechanisms by which Bacillus anthracis (anthrax) interacts with the human host to cause disease, the better equipped we will be in designing therapies and preventative treatments," Dr. Kelly Doran, SDSU lead researcher, microbiologist and professor, said.
Doran explained how genes are turned on to make proteins that eventually signal an immune response. White blood cells come to the site of the infection to fight bacteria from spreading into the brain.
"In this current study, we show that the anthrax bacterium blocks this signaling process; meaning the bacteria and specifically the toxins, turn off those same genes," Doran said. "Thus the immune response is impaired, which gives the bacteria free reign to continue spreading into the brain to cause disease."
With the immune system impaired, the bacteria can penetrate the blood-brain barrier and multiply rapidly, causing meningitis and CNS infection - both infections of the nervous system.
The symptoms of anthrax meningitis are stiffness and pain in the neck in addition to fever, fatigue, headache, nausea, vomiting and sometimes agitation, seizures and delirium. These symptoms could be followed by a rapid neurological degeneration and death. Bacterial infections, including those caused by anthrax, are fatal if not treated with antibiotics, Doran said.
"The human BBB (blood brain barrier), which is comprised principally of a single-layer of specialized brain microvascular endothelial cells serves as a critical barrier to maintain the protective environment of the central nervous system," Doran said. "It also serves as a barrier against microbial invasions."
Doran said that she and her colleagues created an in vitro model system of the BBB to examine bacteria-host interactions. The model was created out of the same matter that makes up the human BBB. The researchers also used micro array analysis, a technique that allowed them to look at all the genes that are turned on in response to any bacterial infections, including anthrax, Doran said.
She said that the origin of the deadly bacteria is actually found in soil, making cattle vulnerable to infection. Humans become infected because of contact with infected animals and products.
The anthrax bacteria can produce spores that may remain dormant for decades. Humans can become infected because of exposure to the spores either through a cut in the skin or by inhalation. Infection by inhalation is usually used in bio-terrorism attacks, Doran said.
Inhaling the spores is more dangerous because it leads to systemic disease. Anthrax contracted through a cut is usually more curable, although a small percentage of these infections turn into systemic disease, Doran said.
Systemic infection that occurs as a result of inhaling the spores has a mortality rate approaching 100 percent, Doran said. Death usually occurs a few days after the onset of symptoms.
However, the closer scientists come to understanding the process of the anthrax bacteria, the more likely they are to find measures to prevent fatal exposure.
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