How Do You Test For Rickettsia?

Positive, concrete diagnosis in the field of vector-borne diseases has been a recurring problem. One of the biggest issues with Lyme disease is the misdiagnosis rate. This is hard to estimate accurately, but with chronic Lyme mimicking the symptoms of other, more common chronic disorders, misdiagnosis numbers are believed to be in the hundreds of thousands globally. Testing for vector-borne diseases (those spread by ticks, mites, lice, and fleas) can be a complex procedure, especially if the initial bite that caused the infection was not noticed immediately. Without specific telltale signs on the site of the bite, many of the initial symptoms of Lyme and other infections are generalized and hard to pin down. Compounding matters is the fact that if the tests are conducted too early in the disease’s lifecycle, they can often return false negatives. This is a recurring problem with disorders initiated by the Rickettsia pathogens. 

What is Rickettsia?

Rickettsia is an umbrella term for a genus of bacteria that causes a number of infections in human hosts. There are three main groups of Rickettsia: typhus group, scrub typhus group, and spotted fever group. Of these three, the most common by a long shot is the spotted fever group. One of the prime illnesses associated with spotted fever Rickettsia is Rocky Mountain Spotted Fever (or RMSF for short). This disorder can range from mild to severe, but concerningly has some of the highest mortality rates for a vector-borne disease. Other rickettsial disorders include anaplasmosis, ehrlichiosis, and typhus.

Image by Belova59 on Pixabay: How do you test for Rickettsia? A new EliSpot method.

How Do You Contract Rickettsia?

So where is Rickettsia found? And how do you fall victim to it? The most common method of transmission is via tick bite. Inhaling bacteria may also result in infection. Although the highest incidences of Rickettsia-related diseases can be found in Africa and Asia, it is a global issue. Not every species of tick is capable of transmitting pathogens to humans, and of the species that can, not every tick is carrying this particular bacteria. If we isolate RMSF as an example, we find that the American dog tick, the brown dog tick, and the Rocky Mountain wood tick all have the potential to pass on the disease to humans if they’re infected with it.  

How is Rickettsia Diagnosed?

Rickettsia obviously covers a broad category of illnesses, so what is the name of the test used to detect rickettsial agents? Unfortunately, diagnosis of rickettsial infections often brings up a few issues. Being aware of the initial tick bite is often key, as the early stages of many spotted fever diseases often resemble many other illnesses, including the common flu. In the case of RMSF in particular, early diagnosis is crucial, as fatality rates reach as high as 25% without rapid antibiotic intervention. The traditional serological test (blood test) for RMSF diagnosis is the indirect immunofluorescence antibody assay for immunoglobulin G (IgG), utilising R. rickettsii antigen. However, antibodies are often found to be negative during the early stages of the illness, which can often compound both diagnosis and treatment. It’s also very hard for laboratories to differentiate one spotted fever from another using the serological method. 

Image by DarkoStojanovic on Pixabay: How is Rickettsia Diagnosed? By using the revised EliSpot to test for Rickettsial antigens.

A New Test for Rickettsia?

Lyme specialists Infectolab and BCA-clinic have recently supported the development of a new Rickettsia test for the spotted fever group, which they intend to make available in the New Year. They’ve used their successful pioneering Lyme diagnostic procedure as the foundation, and adapted it to the Rickettsia spectrum of diseases. So how does it work, exactly? While the scientific terms might be a little tricky to grasp at first, the actual mechanism is easy to understand once it’s put into context.

Our first line of defense against invading pathogens is white blood cells. They are part of our adapted immune system, and are the reason we become sick if a bacteria or virus manages to penetrate the epithelium (the outer layer of our skin). When the immune system detects a virus, specialist white blood cells called T-cells are dispatched through the blood to the site of the infection. These T-cells help stimulate the B-cells to create antibodies, also known as immunoglobulin. These Y-shaped proteins are used to neutralize the invading pathogen.

Once the pathogen is retreating, another set of T-cells is produced. Their task is to memorize the battle plan that successfully saw off the pathogen, and “memorize” it in case that pathogen ever re-enters the body. They reside in the lymph cells and wait to be called up to duty in the event of a recapitulation. These two T-cells are antigen-specific, meaning they can be tested for individually. Most tests only concern themselves with the attacking T-cells. The new test from Infectolab and BCA-clinic, however, tests for the presence of both antigens – in this case, specifically Rickettsia antigens. The result is a much clearer picture for both patient and doctor that can then help inform a detailed treatment plan.

How to Protect Yourself from Rickettsia

Unlike chronic Lyme, Rickettsia-related illnesses are easily treated via the antibiotic doxycycline. Diagnosis is the critical matter. With new pioneering tests like these, doctors will be able to pinpoint the stage of the patient’s infection, as well as test specifically for the presence of co-infections, which are diseases that may have been contracted simultaneously with either Rickettsia or Lyme disease. 

In the end, it all stems back to the tick. Protecting yourself from Rickettsia is as simple as protecting yourself from a tick bite. The critical thing to remember is to be aware of your surroundings. If you’ve been out and about in grassy areas, especially during the warmer months, check yourself thoroughly for tick bites when you come back indoors. Similarly, if you start to feel flu-like symptoms, check your body for bites or tell your doctor if you’ve spent recent time outdoors. Infections like Rickettsia can be easily treatable, but concrete, rapid diagnosis is key. 

Featured image by Belova59 on Pixabay

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