Rocky Mountain Spotted Fever

Rocky Mountain spotted fever is a potentially fatal disease caused by the gram-negative bacteria Rickettsia rickettsii. Upon infection with the R. rickettsii parasite, common symptoms that develop include: fever, nausea, headache, vomiting, muscle pain, abdominal pain, red eyes, lack of appetite and a characteristic rash. The bacteria are transmitted to humans via the infected tick vector after attachment to a human host for a feeding period that can range largely from 10 minutes to 10 hours (Saraiva et al. 2014).  Some genera of common tick vectors for Rocky Mountain spotted fever are Dermacentor, Rhipicephalus, and Amblyomma. The exact vector of the disease changes according to region, but the primary vectors for Rocky Mountain spotted fever in the United States are the American dog tick (Dermacentor variabilis) and the Rocky Mountain wood tick (Dermacentor andersoni).

Figure 1: Prototypical rash of Rocky Mountain spotted fever.

After R. rickettsii enters the blood through infected tick bite, the bacteria attempts to enter target endothelial cells, The bacteria are able to enter the cells through binding of the bacterial outer-membrane protein B (OmpB) to host cell receptor Ku70 (Walker and Ismail 2008). However, other studies have been done in an attempt to uncover other surface proteins that work to mediate bacterial interaction with host cells (Gong et al. 2014). Upon entering the endothelial cells of the host, R. rickettsii are able to multiply through binary fission in the cytoplasm of the cells.

Although Rocky Mountain spotted fever is relatively rare disease with fewer than 20,000 cases a year in the United States, treatment and prevention still remains crucial as a result of its potentially fatal consequences. While there is no vaccine available to prevent the disease, some antibiotics are now available to limit the symptoms. Although it was unsuccessful, one recent study has even been conducted in an attempt to create a vaccine that affects the binding of surface proteins in the host (Riley et al. 2015). Additionally, further studies have been done to compare the genome R. Rickettsia with the genome of the non-virulent form of it (R. peackockii) in order to determine the mutations at this level that would cause the bacteria to become infectious (Felsheim et al. 2009). Each year new studies continue to get published in an attempt to further protect humans from the potentially fatal effects of Rocky Mountain spotted fever.

Figure 2: Life cycle of Rickettsia rickettsii.
Figure 2: Life cycle of Rickettsia Rickettsii.

Other Pages:

History and Metabolic Context

Molecular Basis of the Disease state

Treatments and Disease Management

Conclusions and Proposals for Future Work

Annotated Bibliography

10 Replies to “Rocky Mountain Spotted Fever”

  1. Man makes you not want to go outside. Scary. Informative as well. I clicked the hyperlinks for some of the words which brought me to the bio-chemistry primer but several of your hyperlinked words did not appear ( for example vector). Other than that great job.

    1. Hey Rick, thank you for the kind words and even more so for bringing that to my attention. I have fixed that problem and now all the hyperlinked words are shown on the page and hyperlinked via the biochemistry primer to another outlet for more information.

  2. The article presented a clear, concise description of how exposure to bacteria enters the body. Citations supporting key aspects of the disease process are presented allowing the reader to follow up for more information. A non-scientist reading the article is provided a good overview of how Rocky Mountain Spotted Fever causes disease.

    1. Hi Perry, thank you very much for all the supportive comments on my page. I am very glad you were able to understand everything in a clear and concise manner.

  3. Very understandable well written article. Some parts like the symptoms were very easy to comprehend. However you discuss the bacteria targeting endothelial cells but I’m not sure what those are.

    1. Hi Meg I am sorry that I did not define what the endothelial cells were exactly to help with your reading. I have now linked the word to the biochemistry primer and provided a definition as to make it less confusing!

  4. I typically read things such as this with a ‘who, what, where, when, why, how’ mentality and this answered those very well. However, in the first paragraph, I was confused by the lack of clarity in the first paragraph between ‘some genera…..’ and ‘the primary vector…in the American Dog tick.’ The explanation of vector origination felt contradictory with both of these sentences. Otherwise, well done.

    1. Hi Lise, thank you for bringing that to my attention I can definitely see how that sounded contradictory as I transitioned between ways of naming the vectors. The confusion most likely stemmed from the fact that I changed from naming vectors in terms of genus and species to just the common name. I will be sure to reword that passage in an attempt to make my point much clearer.

  5. Well written article. First paragraph had terms I did not understand, i.e. gram-negative and vector. But was able to click on the link for vector. The article explained the topic well for a non-scientist, but also provided additional information that other surface proteins may possibly work to mediate bacterial interaction with host cells. Was glad to see the article included a picture of the characteristic rash.

    1. Hi Maryanne, thank you for your helpful comments. I hope you were able to click on the hyperlink for those more confusing terms to get better definitions when reading. If you still have more problems with the specific words, the link on the biochemistry primer page will bring you to a specific cite for each word that provides more definitions and information about them. I am glad you enjoyed the picture of the rash because I think it is definitely useful for recognizing one of the major symptoms of the disease.

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