Semi-Precious Pathogens

Oct. 17, 2014

By Medical Discovery News

Bug in amber

Some diseases are older than others. AIDS, for instance, is a recent phenomenon, while malaria has plagued humans for millennia. Recently, scientists examining ticks fossilized in amber found they were infected with bacteria similar to those that cause Lyme disease, a spirochete named Borrelia burgdorferi. Lyme disease is a bacterial infection caused by the bite of an infected tick. The discovery of an ancient Borrelia-like bacterium, now named Palaeoborrelia dominicana, shows that tick-borne diseases have been around for millions of years.

Lyme disease was identified in the early 1970s when mysterious cases of rheumatoid arthritis struck children in Lyme, Conn., and two other nearby towns. The first symptom is a rash called erythema migrans, which begins with a small red spot where the tick bite occurred. Over the next few days or weeks, the rash gets larger, forming a circular or oval red rash much like a bull’s eye. This rash can stay small or can cover the entire back. But not everyone with Lyme disease gets this rash, and the other symptoms, including fever, headaches, stiff neck, body aches, and fatigue, are common to many other ailments. Some people develop symptoms of arthritis, nervous system problems, or even cardiac issues.

Lyme disease can be difficult to diagnose. Sometimes, people write off their initial symptoms as the flu or another common illness, and experience symptoms for months or even years before finding the true cause. To diagnose Lyme disease, doctors measure the levels of antibodies the body produces in response to Borrelia infection. Lyme patients are treated with antibiotics, but if the bacteria have been in the body for a long period of time, it can take a long time to cure. The sooner diagnosis and treatment begin, the more quickly and completely patients will recover. Even after treatment for Lyme disease, people can still experience muscle or joint aches and nervous system symptoms.

Scientists from Oregon State University have studied 15- to 20-million-year-old amber found in the Dominican Republic. Despite existing for millions of years, bacteria are rarely found in fossils. However, free-flowing tree resin traps and preserves material such as seeds, leaves, feathers, and insects in great detail. Amber is then formed from the fossilization of the resin over millions of years as it turns into a semi-precious stone. This is the oldest fossil evidence of ticks containing such bacteria.

Four ticks from the Dominican amber were examined and found to have large populations of spirochetes that resemble the Borrelia bacteria, such as those that cause Lyme disease today. The oldest reported case of Lyme disease was Oetzi, a well-preserved natural mummy who lived 5,000 years ago and was discovered by hikers in the Alps. In other studies, fossils have revealed bacteria such as Rickettsia, which cause modern diseases like Spotted Fevers and Typhus, found in ticks from about 100 million years ago. Evidence suggests that even dinosaurs may have been infected with Rickettsia, showing these microbes likely infected other creatures before humans were added to the mix. Millions of years of co-evolution resulted in highly adapted pathogens that scientists and physicians still struggle to understand and treat.

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Ticked Off Meateaters

August 2, 2013

By Medical Discovery News

Using bug spray is more important than ever – especially for those who particularly enjoy eating hamburgers. It might sound like those two things aren’t related, but a person bitten by a certain tick can develop a severe allergy to meat.

This type of food allergy only develops in people who have been bitten by the Lone Star Tick, which has previously been linked to a condition known as Southern Tick Associated Rash Illness (STARI). The tick bite that causes this illness results in a rash, fatigue, headache, fever, and muscle pains. It is often confused with Lyme disease, which is also spread by ticks.

After being bitten by the Lone Star Tick, a person develops antibodies, which are molecules of the immune system that normally target and destroy invaders like viruses and bacteria, against a complex sugar called galactose-alpha-1,3-galactose (alpha-gal). This sugar exists in all mammals except primates, including cows, pigs, and sheep. This specific allergy has a delayed response, so a person would experience symptoms like hives four to six hours after eating a meat such as bacon. Some people even suffer life-threatening anaphylactic shock.

It is unclear what in tick saliva triggers alpha-gal antibody production. When ticks latch on to people with their mouthparts they can remain attached for several days and introduce saliva into the skin at the bite site. Tick saliva contains molecules that keep the tick firmly attached to its host. It also keeps the blood at the site from clotting so the tick can continue its meal and can influence the immune response and angiogenesis, the development of new blood vessels. In addition, ticks can transmit a variety of viruses and bacteria through their saliva.

This allergy first came to light because some cancer patients were unusually sensitive to the cancer drug cetuximab, which includes the alpha-gal molecule. But only patients from the southeastern and eastern United States, where the Lone Star Tick lives, experienced this and they all had high levels of alpha-gal antibodies. Currently, more than 80 percent of the people with this meat allergy had tick bites before exhibiting symptoms.

But now that cases of this meat allergy have been reported outside the Lone Star Tick’s habitat, such as Hawaii, researchers are wondering whether this tick has spread further than they thought, or if other tick species can cause a similar reaction. The Lone Star Tick is very aggressive when it comes to biting people and animals, so to prevent tick bites use a bug spray with permethrin, avoid wooded areas, and frequently check for ticks when outside. Otherwise, a person may find themselves watching everyone else eat during a summer barbeque!

For a link to this story, visit http://www.medicaldiscoverynews.com/shows/350-ticked.html.