Infectolab - tick-borne diseases

Is Rocky Mountain Spotted Fever The Same As Rickettsia?

Lice, ticks, fleas, and mites carry numerous strains of bacteria. Not all of those are capable of infecting humans, but many can – so many, in fact, that it’s impossible for the average person to keep track. Vector-borne diseases are transmitted through the bites of these tiny creatures. Once they’re in the bloodstream, many of the initial symptoms are generalized and similar, as the body works to fight the infection with its natural immune defenses. This complicates matters and can make accurate diagnosis problematic.

Lyme disease is probably the most prominent vector-borne disease in the world, but there are plenty of others capable of doing just as much damage. One such disease is called Rocky Mountain Spotted Fever (RMSF). Another is a group of diseases known collectively as rickettsia. But are Rocky Mountain Spotted Fever and rickettsia the same thing? And if not, how can you tell these disorders apart?

Infectolab - rash
Image by Hans on Pixabay: One of the predominant symptoms of RMSF is a rash.

What is Rocky Mountain Spotted Fever?

First, let’s look at these two prominent vector-borne disorders individually. RMSF is a very dangerous disease carried predominantly in North America by the American Dog Tick. Before antibiotics were routinely used to treat infections, the mortality rate of RMSF was as high as 25–30%. Even today, when antibiotics are commonplace, the rate remains at 3–5%, which is considered very high. It places RMSF as one of the most dangerous vector-borne diseases out there. A large part of the danger is due to the generalized initial symptoms. These early symptoms are not specific to RMSF; they include headaches, fever, aches, and nausea. However, the infection can rapidly progress to a serious, life-threatening condition if not treated promptly.

Evidence of the disease has been found in every state on the mainland U.S. except Alaska. It is far more prominent in Central and Eastern states, however, with Tennessee, Kentucky, Kansas, Oklahoma, Missouri, and Arkansas being some of the worst affected. The Rocky Mountain wood tick and the brown dog tick also carry the disease.

What is Rickettsia?

Rickettsia isn’t considered a disease in and of itself. Instead, it is the name for a genus of bacteria, many of which cause infections in humans. Rickettsia are unique among microorganisms in that they require a host cell for growth (like viruses), but use oxygen and are susceptible to antibiotics (like bacteria). Despite this overlap, they are classified as bacteria. Species of rickettsia are classified under two antigenically distinct groups: the typhus group and the spotted fever group. The former contains only two strains that are capable of infecting humans, while the latter contains at least 32.

Is Rocky Mountain Spotted Fever the Same as Rickettsia?

This is a common question. The short answer is yes, but the longer answer is slightly more complicated. RMSF is a rickettsial infection, classified under the spotted fever group. While it’s fair to say that RMSF is equal to rickettsia, it is incorrect to say that rickettsia is equivalent to RMSF. Rickettsia isn’t a distinct disease. It’s an umbrella term for diseases caused by the same genus of bacteria. The bacteria that causes Rocky Mountain Spotted Fever is called R. Rickettsii. It is the most common and most serious rickettsial infection in the United States. However, it is not the only one, and indeed all diseases caused by the rickettsial strain could be broadly classified as “rickettsia”.

Is Rickettsial Infection Contagious?

Rickettsial infections do not spread directly between people. They require direct assimilation with the bloodstream, which is achieved via tick bite. So while Rocky Mountain Spotted Fever can be extremely debilitating and even fatal, it is not contagious.

Is Rickettsia the Same as Lyme Disease?

This is another common question, and the answer is a lot simpler. Lyme disease is caused by the Borrelia strain of bacteria, specifically Borrelia burgdorferi. It is not a rickettsial infection. In fact, B. burgdorferi is carried primarily by deer ticks (or black-legged ticks). These ticks do not carry any strain of rickettsia, although other co-infections, such as babesiosis and bartonelliosis are surprisingly common.

Infectolab - blood testing
Image by PublicDomainPictures on Pixabay: RMSF is traditionally diagnosed with a blood test, based on Immunoglobulin M (IgM) and IgG serologic responses to the causative bacteria.

How is Rocky Mountain Spotted Fever Diagnosed?

RMSF is traditionally diagnosed with a blood test, based on Immunoglobulin M (IgM) and IgG serologic responses to the causative bacteria. Because the disease presents with generalized symptoms during its initial stages, a large degree of clinical suspicion is also a factor. Because RMSF can be fatal, medical professionals will usually begin treatment immediately, rather than waiting on lab results.

At the beginning of 2020, Infectolab and BCA-clinic will release a new rickettsia ELISpot test that aims to increase diagnostic accuracy. This test builds on their new Lyme ELISpot, which is able to provide doctors and analysts with more accurate information. The new procedure doesn’t just test for the presence of infection, but can also ascertain the stage infection is at. It achieves this by testing for two distinct types of antigen molecules, the IFN-gamma and IL-2. The former are IFN-gamma molecules, which are produced by the attacking antigen-specific T-cells traveling through the blood, while IL-2 molecules are produced by the antigen-specific effector memory cells. The result is a much more accurate picture of the stage of the disease a patient is at. It also allows doctors to test for any kind of rickettsial infection.

How to Protect Yourself from Rocky Mountain Spotted Fever

The only way to contract RMSF is to be bitten by an infected tick. Therefore, good education about tick habitats and behavior will help you avoid getting bitten and to know what to do if you are. Quick action is the key to successfully treating any vector-borne infection; the odds for complete recovery are very high if the disease is caught in the early stages, and routine antibiotics will take care of the large majority of cases. If that window is missed, however, symptoms can become more severe, and treatment more complex.

Featured Image by francok35 on Pixabay

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