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==Overview==
==Overview==
Rocky Mountain spotted fever, like all rickettsial infections, is classified as a [[zoonosis]]. Zoonoses are diseases of animals that can be transmitted to humans.  Many zoonotic diseases require a [[vector (biology)|vector]] (e.g., a mosquito, tick, or mite) in order to be transmitted from the animal host to the human host. In the case of Rocky Mountain spotted fever, ticks are the natural hosts, serving as both reservoirs and vectors of ''R. rickettsii''. Ticks transmit the organism to [[vertebrate|vertebrates]] primarily by their bite. Less commonly, infections may occur following exposure to crushed tick tissues, fluids, or tick feces.
If left untreated patients with Rocky Mountain spotted fever will undergo three developmental stages of infection. The early stages of infection begin within 2-14 days of inoculation by an infected tick and present themselves as a fever, nausea, vomiting, and a severe headache. Late stage progression of symptoms will result in a maculopapular rash, abdominal and joint pain. Further progression of the disease, if left untreated, will result in the following complications; gangrene, pulmonary complications, ARDS, cerebral edema as well as other long term complications. Ultimately, if Rocky Mountain spotted fever progresses entirely untreated, it will conclude in the patient's death. With a fatality rate as high as 87%, without antibiotic intervention. <ref name="“Austin">Mills, Jackie. Rocky Mountain Spotted Fever. Austin CC. Derived: Masters, E. J., G. S. Olson, S. J. Weiner, and C. D. Paddock. 2003. Rocky Mountain spotted fever: a clinician’s dilemma. Archive of Internal Medicine 163:769–774. http://archinte.ama-assn.org/cgi/content/full/163/7/769 Accessed January 11, 2016</ref> <ref name="RMSF DeptImmuno”">Dantas-Torres, Filipe. Lancet Infect Disease 2007;7:724-32. Department of Immunology, Center of Research Aggeu Magalhaes, Oswaldo Cruz Foundation. Recife Pernambuco, Brazil. Volume 7, November 2007. Accessed on January 11, 2016</ref>


A female tick can transmit ''R. rickettsii'' to her eggs in a process called [[transovarial transmission]]. Ticks can also become infected with ''R. rickettsii'' while feeding on blood from the host in either the larval or nymphal stage. After the tick develops into the next stage, the ''R. rickettsii'' may be transmitted to the second host during the feeding process. Male ticks may transfer ''R. rickettsii'' to female ticks through body fluids or [[spermatozoa]] during the mating process. These types of transmission represent how generations or life stages of infected ticks are maintained. Once infected, the tick can carry the pathogen for life.
==Natural history==
 
Rocky Mountain spotted fever patients will progress from early symptoms to late symptoms and possible chronic conditions, as well as death, if left untreated. The infection begins with inoculation of the disease from an infected tick. Once inoculated, the organism ''Rickettsia rickettsii'' will incubate for 2- 14 days. As the incubation period concludes early onset symptoms will begin, these symptoms are listed below.  
 
=====Early onset symptoms=====
*[[Fever]]
*[[Vomiting]]
*[[Nausea]]
*Severe headache
*Muscular soreness and pain
*[[Anorexia]]
*[[Rash]] (within may appear within 2-5 days of fever onset.)<ref name="“Austin">Mills, Jackie. Rocky Mountain Spotted Fever. Austin CC. Derived: Masters, E. J., G. S. Olson, S. J. Weiner, and C. D. Paddock. 2003. Rocky Mountain spotted fever: a clinician’s dilemma. Archive of Internal Medicine 163:769–774. http://archinte.ama-assn.org/cgi/content/full/163/7/769 Accessed January 11, 2016</ref>
 
Treatment is most effective if an antibiotic therapy is administered at this point. As the disease progresses, treatment loses effectiveness, thus it is of utmost importance to diagnose and begin treatment early on. Most individuals who begin treatment will usually clear the infection.  


==Natural history==
After the first three days of early onset symptoms, other symptoms will progress. These symptoms are described as late stage symptoms and will include the characteristic rash that is commonly associated with Rocky Mountain spotted fever. Not all patients will have the same clinical presentation of the disease. Particularly, the rash is present within the majority of infected patients, yet 10-15% of patients may never develop the characteristic spotted rash. If the infection progresses in severity, patients will be hospitalized at this point. Late stage symptoms may be observed below.
[[Image:Life cycle of ticks family ixodidae.PNG|left|thumb|330px|The life cycle of ''Dermacentor variabilis'' and ''Dermacentor andersoni'' ticks (Family [[Ixodidae]])]]


*Rickettsiae are transmitted to a [[vertebrate]] host through saliva while a tick is feeding. 
=====Late stage=====
*It usually takes several hours of attachment and feeding before the rickettsiae are transmitted to the host. 
*[[Maculopapular rash]]  
*The risk of exposure to a tick carrying ''R. rickettsii'' is low.  In general, about 1%-3% of the tick population carries ''R. rickettsii'', even in areas where the majority of human cases are reported.
*[[Diarrhea]]
*There are 2 major vectors of ''R. rickettsii'' in the United States, the [[American dog tick]] and the [[Rocky Mountain wood tick]]. 
*[[Abdominal pain]]
*American dog ticks (''Dermacentor variabilis'') are widely distributed east of the Rocky Mountains and also occurs in limited areas on the Pacific Coast. 
*[[Joint issues and pain|Joint pain]]
*Dogs and medium-sized mammals are the preferred hosts of adult ''D. variabilis'', although it feeds readily on other large mammals, including humans. 
*This tick is the most commonly identified species responsible for transmitting ''R. rickettsii'' to humans. 
*Rocky Mountain wood ticks (''Dermacentor andersoni'') are found in the Rocky Mountain states and in southwestern Canada.
*The life cycle of this tick may require up to 2 to 3 years for completion: Adult ticks feed primarily on large mammals and larvae and nymphs feed on small rodents.


''Other tick species have been shown to be naturally infected with ''R. rickettsii'' or serve as experimental vectors in the laboratory. However, these species are likely to play only a minor role in the ecology of ''R. rickettsii''.**''
With proper treatment and antibiotic therapy, most patients will have cleared the infection. However, if left untreated or improperly diagnosed, Rocky Mountain spotted fever will progress further and may involve chronic complications or severe tissue damage as well as death. Complications and chronic conditions associated with untreated development of Rocky Mountain spotted fever are found below.
=====Untreated or improperly diagnosed=====
*[[Gangrene]]
*[[ARDS]]
*[[Myocarditis]]
*[[Acute renal failure]]
*[[Meningoencephalitis]]
*[[Pulmonary hemorrhaging]]
*[[Pulmonary edema]]
*[[Cerebral edema]]
*[[Death]] <ref name="“Austin">Mills, Jackie. Rocky Mountain Spotted Fever. Austin CC. Derived: Masters, E. J., G. S. Olson, S. J. Weiner, and C. D. Paddock. 2003. Rocky Mountain spotted fever: a clinician’s dilemma. Archive of Internal Medicine 163:769–774. http://archinte.ama-assn.org/cgi/content/full/163/7/769 Accessed January 11, 2016</ref>


==Complications==
==Complications==
Possible complications include:
====Possible complications include:====
*[[Meningitis]]
*[[Brain damage]]
*[[Brain damage]]
*[[Clotting]] problems
*[[Clotting]] problems
Line 30: Line 49:
*[[Kidney failure]]
*[[Kidney failure]]
*[[Lung failure]]
*[[Lung failure]]
*[[Meningitis]]
*[[Adult respiratory distress syndrome]]
*[[Pneumonitis]] (lung inflammation)
*[[Pneumonitis]] (lung inflammation)
*[[Shock]]
*[[Encephalitis]]
==Prognosis==
*Noncardiogenic [[pulmonary edema]]
*Treatment usually cures the [[infection]].
*Cardiac arrythmia
*Complications are rare but can include [[paralysis]], hearing loss, [[nerve]] damage, and, rarely, death.
*Impaired [[blood clotting]]
*Rocky Mountain spotted fever can be a severe illness, and the majority of patients are hospitalized.
*Skin [[necrosis]]
*Infection with R. rickettsii is thought to provide long lasting [[immunity]] against re-infection.   
*Gastrointestinal bleeding
*Prior illness with Rocky Mountain spotted fever should not deter persons from practicing good tick-preventive measures or visiting a [[physician]] if signs and symptoms consistent with Rocky Mountain spotted fever occur, especially following a tick bite, as other diseases may also be transmitted by ticks.
*[[Shock]]<ref name="RMSF ALDF”">Rocky Mountain Spotted Fever general information.  American Lyme Disease Foundation (2016).  Accessed on January 11, 2016</ref><ref name="RMSF Treatment CDC”">Rocky Mountain Spotted Fever Symptoms. Centers for Disease Control and Prevention (2015).  http://www.cdc.gov/rmsf/symptoms/index.html Accessed on December 30, 2015</ref>


*Before [[antibiotics]] were readily available to fight off Rocky mountain spotted fever, the [[mortality rate]] was as high as 30%. Now, with drugs such as [[doxycycline]] available, the mortality rate is approximately 1.4%.
=====Long term complications=====
*Paralysis of lower extremities
*Impaired bladder function
*Impaired bowel function
*[[Gangrene]] and amputation
*Hearing impairment
*Movement and speech disorders<ref name="RMSF ALDF”">Rocky Mountain Spotted Fever general information.  American Lyme Disease Foundation (2016).  Accessed on January 11, 2016</ref>
*These complications are most frequent in persons recovering from severe, life-threatening disease, often following lengthy hospitalizations. <ref name="RMSF Symptoms CDC”">Rocky Mountain Spotted Fever Symptoms. Centers for Disease Control and Prevention (2015).  http://www.cdc.gov/rmsf/symptoms/index.html Accessed on December 30, 2015</ref>


==Illness Severity==
==Prognosis==
[[Image:RMSF incidence.jpg|left|300px|Epidemiology Graph 3 - Comparison between RMSF cases and their fatality.]]
*The prognosis is usually good for patients suffering from a Rocky Mountain spotted fever infection.
*Factors that might contribute to a poor prognosis are infections within children 0-9, especially 5-9, and adults over 60 years of age. With a higher rate of fatality within these groups.
*Other host factors associated with severe or fatal Rocky Mountain spotted fever include advanced age, male sex, African-American race, chronic alcohol abuse, and
[[glucose-6-phosphate dehydrogenase]] (G6PD) deficiency.
*It should be noted that although the prognosis is usually good, RMSF is a severe illness and many infected patients will be hospitalized.
*The mortality rate is approximately 20% if untreated and 5% if treated properly. <ref name="RMSF DeptImmuno”">Dantas-Torres, Filipe. Lancet Infect Disease 2007;7:724-32. Department of Immunology, Center of Research Aggeu Magalhaes, Oswaldo Cruz Foundation. Recife Pernambuco, Brazil. Volume 7, November 2007. Accessed on January 11, 2016</ref>
*Infection with ''R. rickettsii'' may provide long lasting [[immunity]] against re-infection.  
*Previous infection with Rocky Mountain spotted fever should not deter persons from practicing good tick-preventive measures or visiting a [[physician]] if signs and symptoms consistent with Rocky Mountain spotted fever occur, especially following a tick bite, as other diseases may also be transmitted by ticks. <ref name="RMSF ID”">Rocky Moutnain Spotted Fever. Department of Health. Idaho Health District 4. http://www.cdhd.idaho.gov/CD/public/factsheets/rockymtnspottedfever.htm Accessed on January 11, 2016</ref>


===Initial health problems===
==References==
{{Reflist|2}}


*Rocky Mountain spotted fever can be a very severe illness and patients often require hospitalization. Because ''R. rickettsii'' infects the cells lining [[blood vessel]]s throughout the body, severe manifestations of this disease may involve the [[respiratory system]], [[central nervous system]], [[gastrointestinal system]], or [[renal system]].
[[Category:Bacterial diseases]]
*Host factors associated with severe or fatal Rocky Mountain spotted fever include advanced age, male sex, African-American race, chronic alcohol abuse, and
[[Category:Rickettsiales]]
[[glucose-6-phosphate dehydrogenase]] (G6PD) deficiency.
[[Category:Zoonoses]]
*Deficiency of G6PD is a sex-linked genetic condition affecting approximately 12% of the U.S.
*African-American male population; deficiency of this enzyme is associated with a high proportion of severe cases of Rocky Mountain spotted fever. This is a rare clinical course that is often fatal within 5 days of onset of illness. <ref name="RMSF Symptoms CDC”>  Rocky Mountain Spotted Fever Symptoms. Centers for Disease Control and Prevention (2015).  http://www.cdc.gov/rmsf/symptoms/index.html Accessed on December 30, 2015</ref>


*Long-term health problems following acute Rocky Mountain spotted fever infection include partial [[paralysis]] of the lower extremities, [[gangrene]] requiring amputation of fingers, toes, or arms or legs, hearing loss, loss of bowel or bladder control, movement disorders, and language disorders.
[[Category:Dermatology]]
*These complications are most frequent in persons recovering from severe, life-threatening disease, often following lengthy hospitalizations. <ref name="RMSF Symptoms CDC”>  Rocky Mountain Spotted Fever Symptoms. Centers for Disease Control and Prevention (2015).  http://www.cdc.gov/rmsf/symptoms/index.html Accessed on December 30, 2015</ref>
 
===Long term health problems===
*Patients who had a particularly severe infection requiring prolonged hospitalization may have long-term health problems caused by this disease.
*Rickettsia rickettsii infects the [[endothelial cells]] that line the [[blood vessels]].
*The damage that occurs in the [[blood vessels]] results in a [[disease]] process called a "[[vasculitis]]", and [[bleeding]] or [[clotting]] in the [[brain]] or other [[vital organs]] may occur. *Loss of [[fluid]] from damaged [[vessels]] can result in loss of [[circulation]] to the [[extremities]] and damaged [[fingers]], [[toes]] or even limbs may ultimately need to be [[amputated]]. *Patients who suffer this kind of severe [[vasculitis]] in the first two weeks of [[illness]] may also be left with permanent long-term health problems such as profound [[neurological]] deficits, or damage to [[internal organs]].
*Those who do not have this kind of [[vascular]] damage in the initial stages of the [[disease]] typically recover fully within several days to months. <ref name="RMSF Symptoms CDC”>  Rocky Mountain Spotted Fever Symptoms. Centers for Disease Control and Prevention (2015).  http://www.cdc.gov/rmsf/symptoms/index.html Accessed on December 30, 2015</ref>
 
==References==
{{Reflist|2}}

Latest revision as of 18:39, 18 September 2017

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Ilan Dock, B.S.

Overview

If left untreated patients with Rocky Mountain spotted fever will undergo three developmental stages of infection. The early stages of infection begin within 2-14 days of inoculation by an infected tick and present themselves as a fever, nausea, vomiting, and a severe headache. Late stage progression of symptoms will result in a maculopapular rash, abdominal and joint pain. Further progression of the disease, if left untreated, will result in the following complications; gangrene, pulmonary complications, ARDS, cerebral edema as well as other long term complications. Ultimately, if Rocky Mountain spotted fever progresses entirely untreated, it will conclude in the patient's death. With a fatality rate as high as 87%, without antibiotic intervention. [1] [2]

Natural history

Rocky Mountain spotted fever patients will progress from early symptoms to late symptoms and possible chronic conditions, as well as death, if left untreated. The infection begins with inoculation of the disease from an infected tick. Once inoculated, the organism Rickettsia rickettsii will incubate for 2- 14 days. As the incubation period concludes early onset symptoms will begin, these symptoms are listed below.

Early onset symptoms

Treatment is most effective if an antibiotic therapy is administered at this point. As the disease progresses, treatment loses effectiveness, thus it is of utmost importance to diagnose and begin treatment early on. Most individuals who begin treatment will usually clear the infection.

After the first three days of early onset symptoms, other symptoms will progress. These symptoms are described as late stage symptoms and will include the characteristic rash that is commonly associated with Rocky Mountain spotted fever. Not all patients will have the same clinical presentation of the disease. Particularly, the rash is present within the majority of infected patients, yet 10-15% of patients may never develop the characteristic spotted rash. If the infection progresses in severity, patients will be hospitalized at this point. Late stage symptoms may be observed below.

Late stage

With proper treatment and antibiotic therapy, most patients will have cleared the infection. However, if left untreated or improperly diagnosed, Rocky Mountain spotted fever will progress further and may involve chronic complications or severe tissue damage as well as death. Complications and chronic conditions associated with untreated development of Rocky Mountain spotted fever are found below.

Untreated or improperly diagnosed

Complications

Possible complications include:

Long term complications
  • Paralysis of lower extremities
  • Impaired bladder function
  • Impaired bowel function
  • Gangrene and amputation
  • Hearing impairment
  • Movement and speech disorders[3]
  • These complications are most frequent in persons recovering from severe, life-threatening disease, often following lengthy hospitalizations. [5]

Prognosis

  • The prognosis is usually good for patients suffering from a Rocky Mountain spotted fever infection.
  • Factors that might contribute to a poor prognosis are infections within children 0-9, especially 5-9, and adults over 60 years of age. With a higher rate of fatality within these groups.
  • Other host factors associated with severe or fatal Rocky Mountain spotted fever include advanced age, male sex, African-American race, chronic alcohol abuse, and

glucose-6-phosphate dehydrogenase (G6PD) deficiency.

  • It should be noted that although the prognosis is usually good, RMSF is a severe illness and many infected patients will be hospitalized.
  • The mortality rate is approximately 20% if untreated and 5% if treated properly. [2]
  • Infection with R. rickettsii may provide long lasting immunity against re-infection.
  • Previous infection with Rocky Mountain spotted fever should not deter persons from practicing good tick-preventive measures or visiting a physician if signs and symptoms consistent with Rocky Mountain spotted fever occur, especially following a tick bite, as other diseases may also be transmitted by ticks. [6]

References

  1. ↑ 1.0 1.1 1.2 Mills, Jackie. Rocky Mountain Spotted Fever. Austin CC. Derived: Masters, E. J., G. S. Olson, S. J. Weiner, and C. D. Paddock. 2003. Rocky Mountain spotted fever: a clinician’s dilemma. Archive of Internal Medicine 163:769–774. http://archinte.ama-assn.org/cgi/content/full/163/7/769 Accessed January 11, 2016
  2. ↑ 2.0 2.1 Dantas-Torres, Filipe. Lancet Infect Disease 2007;7:724-32. Department of Immunology, Center of Research Aggeu Magalhaes, Oswaldo Cruz Foundation. Recife Pernambuco, Brazil. Volume 7, November 2007. Accessed on January 11, 2016
  3. ↑ 3.0 3.1 Rocky Mountain Spotted Fever general information. American Lyme Disease Foundation (2016). Accessed on January 11, 2016
  4. ↑ Rocky Mountain Spotted Fever Symptoms. Centers for Disease Control and Prevention (2015). http://www.cdc.gov/rmsf/symptoms/index.html Accessed on December 30, 2015
  5. ↑ Rocky Mountain Spotted Fever Symptoms. Centers for Disease Control and Prevention (2015). http://www.cdc.gov/rmsf/symptoms/index.html Accessed on December 30, 2015
  6. ↑ Rocky Moutnain Spotted Fever. Department of Health. Idaho Health District 4. http://www.cdhd.idaho.gov/CD/public/factsheets/rockymtnspottedfever.htm Accessed on January 11, 2016
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