As you get to know Lyme disease, you come to appreciate that the illness is much more complicated than an infection with bacteria known as Borrelia burgdorferi. Since 1981, many other species of Borrelia bacteria have been discovered worldwide, many of which have the potential to cause Lyme-disease-like syndromes.
This has led to the terms Borrelia burgdorferi sensu stricto and Borrelia burgdorferi sensu lato. The former refers to microbes that are similar enough genetically and structurally to the microbes discovered by Dr. Burgdorfer in 1981 to be called the same species. The latter are species of Borrelia that cause Lyme-like syndromes, but are not similar enough to be defined as the same species.[12]
As of 2015, there are over 20 known species of Borrelia worldwide and an uncountable number of different strains of each species. At least a dozen of them can cause Lyme-disease-like syndromes. (Current medical textbooks still only provide an outdated discussion of three species, and most doctors have received little education about Lyme disease.)
And this may just be scratching the surface; the more researchers look, the more they find. New species are popping up all over the world.
If you consider the nature of the microbe, this shouldn’t be surprising. Borrelia is an extremely adaptable microbe. It has been adapting to a wide range of different hosts and different environments over millions of years. With each adaptation, it changes ever so slightly. The potential for new variations is almost infinite.
If one group of Borrelia is only slightly different than another group, then the two are considered different strains of the same species. If differences are more significant, they are considered different species.[13]
Note that “newly discovered” does not necessarily imply that any of them are just emerging (coming onto the scene and rapidly expanding). The species present today have likely been present for a long time; it’s simply that researchers are looking harder and getting better at looking.
Before 1981, researchers were hardly aware of any of them. Gradually, as other species were identified worldwide, and it became apparent that Borrelia is much more widespread in tick populations than originally thought.
Now, 35 years later, it is well accepted that Borrelia is widely distributed worldwide (WHO). And that’s just the Borrelia species that we know about. With every year that goes by, new species of Borrelia are identified.
Despite all the species and all the variations, however, the method of operation for all Borrelia microbes causing Lyme disease is the same: transmit to a susceptible host via a tick bite, adapt to that host, fool the host’s immune system enough to persist in low concentrations, wait for another tick to come along, spread to new host…and then do it all over again.
In other words, Lyme disease is Lyme disease, but because Lyme disease can be caused by different species and strains of Borrelia, it can vary in presentation. Some people with chronic Lyme disease have more pronounced neurological symptoms, and some people have more arthritis…or possibly a different presentation altogether.
Lyme disease also can vary geographically. Contracting Borrelia in Europe can be slightly different than contracting it in Australia or the United States. And Lyme disease in California may be slightly different than Lyme disease in Wisconsin or the Southeast.
ESSENTIAL LYME DISEASE FACTS
Other Borrelia-Associated Illnesses
Borrelia infections are not limited to Lyme disease. Certain species of Borrelia are associated with illnesses that share many symptoms with Lyme disease, but also have unique features.
Even so, the basic mode of operation is still the same: infect by way of an insect bite, reproduce inside a susceptible host, and spread to other hosts via an insect. The twist is in how the unique species of Borrelia fools the host’s immune system, resulting in odd symptoms.
STARI, standing for Southern tick-associated rash illness, is a Lyme-disease-like syndrome presently limited to the southeastern and south central United States (it may be spreading, but no one knows for sure). It is specifically associated with bites from the lone star tick (Amblyomma americanum).
The illness commonly presents with a bull’s-eye rash (erythema migrans) and a flu-like syndrome that is like, but typically milder than classic Lyme disease. Though an absolute causative agent has not been defined, a species of Borrelia (no surprises here), called Borrelia lonestari has been isolated from some cases.
Relapsing fever is a form of Borrelia infection defined by abrupt onset of shaking chills, high fever, severe muscle aches, and headache. Associated enlargement of the spleen and liver is common. The acute phase resolves after 3 to 7 days, only to recur about a week later. Multiple recurrences are possible (varies with the species of Borrelia).
There are two types of relapsing fever, one transmitted by soft ticks[14] (tick-borne relapsing fever) and the other by lice[15] (louse-borne relapsing fever). Each is associated with different species of Borrelia, which are also different than those that cause Lyme disease.
Morgellons disease is a peculiar illness that is getting a lot of attention lately (though it is relatively rare). The illness is characterized by skin lesions containing filaments of varying colors (white, black, red, blue, purple, and green) and sensations of things crawling under the skin. Analysis of the filaments has shown that they are composed of abnormal keratin and collagen. Other symptoms include fatigue, neurological symptoms, and joint pain. Recently, an association has been made with spirochetes identified as Borrelia species (Middelveen 2015), though other tick-borne microbes may also be part of the syndrome.
Beyond Borrelia
To complicate matters even more, chronic Lyme disease is rarely Borrelia alone.
Ticks are nature’s perfect vehicle for transmitting microbes (certainly as good as mosquitos, and possibly better because they feed longer), and many different types of microbes take advantage of this extraordinary opportunity.
A search on PubMed reveals citations for hundreds of different tick-borne microbes that have the potential to cause illness in humans and other animals. The list includes viruses, bacteria, protozoa, and even fungi.
In his 2015 book on Lyme disease, Stephen Buhner points out that “depth examination of Ixodes ticks has found they can carry up to 237 genera of microorganisms that are infectious to vertebrates” (and that’s just one type of tick). A genus is a group of organisms with similar characteristics. For microbes, a genus can include many species. Tallied up, the list of different species of tick-borne microbes adds up into the hundreds or even thousands.
This shouldn’t be surprising; all creatures harbor a wide variety of microbes. We humans are capable of harboring several thousand different microbe species. While we are a permanent host for these microbes, many microbes found in ticks are just using the tick as a vector to transfer from host to host.
Just like humans or any other creature, the spectrum of microbes present in different ticks is highly variable. Certain microbes are more prevalent in certain geographic regions. Certain microbes are also more prevalent in certain tick species or tick populations. But one thing is for sure: all ticks carry a variety of microbes (Moutailler 2016).
It is nature as intended. Microbes harbored by ticks are in the process of searching for a host. Every tick bite is an opportunity for tick-borne microbes to infect and colonize a new host. Microbes (usually more than one variety) always enter the host’s bloodstream when a tick bite occurs.
If you have ever been bitten by a tick, tick-borne microbes have entered your bloodstream.
Tick-Borne Microbe Sampler
The most commonly described tick-borne microbes associated with Lyme disease include Borrelia, Mycoplasma, Bartonella, Babesia, Ehrlichia, Anaplasma, Rickettsia, and more recently, Chlamydia. Just like Borrelia, however, each one of these groups (genera) of microbes consists of many species and an almost unlimited number of different strains. And these are just the ones we know something about — who knows how many tick-borne microbes are still yet to be identified. Beyond bacterial species, research is also turning up a wide variety of viruses that can be carried by ticks (Estrada-Peña 2014).
Next to Borrelia, Mycoplasma is thought to be the most common microbe associated with chronic Lyme disease (about 75% of cases, but possibly even more, as Mycoplasma is also very hard to diagnose). It is also widespread in the general population. Virtually everyone has been exposed to Mycoplasma, and somewhere between 30 and 70% of different populations of people studied harbor it chronically without having symptoms (Razin 1998).
Mycoplasma is the smallest of all bacteria. There have been over 200 species of Mycoplasma classified, and at least 23 of them can infect humans (some are considered normal flora, but many can cause illness). Mycoplasma can be spread by ticks, but it also commonly occurs as respiratory and genital infections. Acute infections generally resolve without consequence in healthy individuals, but, like Borrelia, chronic infections can occur. The symptoms of chronic infection are nonspecific and very different from those of the acute infection.
Like most tick-borne microbes, Mycoplasma lives inside cells. They commonly infect white blood cells, which allow them to hitch a ride to every part of the body. The microbes must scavenge everything they need to survive; favorite sites include collagen-rich areas (joints, skin, brain) and myelin-covered nerves. To do this, they manipulate the immune system to generate inflammation to break down tissues. (Is this story starting to sound familiar?)
Chlamydia is extremely small bacteria with characteristics like Mycoplasma. Presently, there are nine recognized species of Chlamydia, but others will likely be uncovered. Chlamydia can be spread by ticks, but it is more commonly spread by respiratory infections (C. pneumoniae) and intimate contact with other people (C. trachomatis). More than half of people have been exposed to the more common species of Chlamydia, and chronic subclinical infection (chronic infection without overt symptoms) is very common. How often it occurs with chronic Lyme disease is currently unknown (but possibly very commonly).
Bartonella, the next most common chronic Lyme disease player, occurs widely in nature. All mammal populations harbor Bartonella (including whales and dolphins), and more than a dozen species of Bartonella can infect and cause illness in humans. As a Lyme disease coinfection, it occurs in an estimated 25 to 50% of cases. Like the other microbes discussed so far, most people have been exposed to some form of Bartonella, and a third of people carry it without having symptoms.
Bartonella is spread by ticks, but also by other biting insects, especially fleas. The most well-known acute Bartonella infection is cat-scratch fever (Bartonella henselae), but there are many other variations. It infects and reproduces inside specialized white blood cells that line blood vessels (slight variation on the theme). Symptoms arise from damage to small blood vessels (small vessel disease). Typical organs that can be affected include the liver, spleen, bone marrow, eyes, skin, and the entire vascular system, including the heart. This is important to note when vascular symptoms are part of the chronic Lyme disease complex.
While all of this sounds highly threatening, most people exposed to Bartonella do not get severely sick. After a brief flu-like illness, the person is back to full health; care from a doctor is rarely required, and a formal diagnosis of Bartonella is often never made. Antibiotic therapy is rarely prescribed for an acute Bartonella infection.
If immune function falters, however, chronic symptomatic infection can occur. Symptoms of chronic illness are nonspecific and very different than those of the acute illness. (This story should be sounding familiar by now — it is common to a wide variety of microbes, each microbe using a slightly different strategy for success).
Babesia, the next microbe on the list, is a protozoan. Protozoa are one-celled organisms with a nucleus surrounding their DNA (bacteria do not have a true nucleus). It is a distant cousin of malaria. Though it is much less threatening than malaria, it is more threatening than other tick-borne microbes. Fortunately, it is also less common than other tick-borne microbes and is associated with Lyme disease in only about 5 to 20% of cases.
There are more than a hundred-different species of Babesia, and at least a dozen are known to cause human illness. Babesia species, however, are more like groups of very similar organisms than distinct species; it has a near infinite ability to continually change its genotype (genetic presentation).
People bitten by a tick carrying Babesia may hardly get sick at all, or they may get very sick very suddenly. This may be a function of the strain or species of the microbe, the reaction of the person to the microbe, or both. In this way, it is very different than Borrelia and other tick-borne microbes. The one situation where infection with Babesia can be truly life-threatening is if the person has had a splenectomy. Anyone without a spleen suspected of having an infection with Babesia should be treated very aggressively with antimicrobial therapy.
Like malaria, it causes symptoms by infecting and destroying red blood cells (RBCs). It does this to scavenge essential nutrients from the cell. It can infect anything with RBCs (mammals, birds, reptiles, amphibians). It also infects white blood cells and can live inside different types of cells.
When people do get sick, they can get very sick. Common acute symptoms include high fever (105 °F), severe fatigue and malaise, shaking chills and sweats, severe headache, muscle aches, joint pain, abdominal pain, jaundice, and a range of other symptoms. Severe infection can last weeks to months.Also unlike Borrelia and previously mentioned tick-borne microbes, chronic illness with Babesia, when it occurs, is defined by relapses of acute symptoms (though some species may cause less severe recurrent symptoms).
The tick-borne microbes least commonly associated with Lyme disease include Ehrlichia, Anaplasma, and Rickettsia (5% or less of cases). The primary way these closely related microbes differ is by the cell type they infect. Ehrlichia and Anaplasma infect different types of white blood cells and are carried throughout the body (Ehrlichia causes more severe infections than Anaplasma). Rickettsia infects cells that line blood vessels.
Ehrlichia chaffeensis is the most common of seven known species of Ehrlichia. There are eight known species of Anaplasma with A. phagocytophilum being the most common. These microbes have been around for a long time, and as you might now expect, there are a huge number of possible strains of each species.
Like Babesia, infections with these microbes are either all or nothing: Two thirds of people will experience a mild illness that resolves without medical therapy, but some people will become very ill, very acutely. Acute symptoms include high fever, malaise, headache, confusion, joint pain, muscle aches, and a characteristic rash (more common with Ehrlichia and Rickettsia than Anaplasma).
Rickettsia rickettsii, the microbe causing Rocky Mountain spotted fever, differs from the other two in that it infects cells lining blood vessels (endothelial cells). This causes severe inflammation in blood vessels with obstruction. In addition to the symptoms above, it can cause loss of fingers and toes and organ failure. R. rickettsii is one of 26 known species of Rickettsia, most of which have potential to cause illness (Parola 2013).
These last three microbes are not ones to mess around with. When suspected, they should be treated aggressively with conventional antibiotics.
Diagnosis is based on clinical signs and symptoms and confirmed by labs after treatment is initiated. Labs are not helpful for the first 2 weeks when acute symptoms are most pronounced.
Chronic infection with these three microbes typically presents as recurrence of acute symptoms. Symptom-free phases can last months or even years.
Note that the above discussions are generalizations about the most well-understood species of tick-borne microbes; there are many different species and strains of each microbe. Each strain and species can have widely varying tendencies to cause illness. Milder species of Ehrlichia, Anaplasma, Rickettsia, and Babesia may be more commonly associated with chronic Lyme disease than once thought — making absolute conclusions about any microbe can be misleading.
ESSENTIAL LYME DISEASE FACTS