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).
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.