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Rickettsia

Updated : February 5, 2024





Background

Worldwide, a family of vector-transmitted pathogens known as rickettsiae causes febrile diseases. Although rickettsial infections have a consistent clinical appearance, the underlying epidemiology and species can differ regionally.

To accurately treat and diagnose these diseases quickly, it is crucial to understand both the clinical signs and the epidemiological of a specific area. This is because they can be linked to severe death and morbidity.

Epidemiology

The most common vectors used to spread rickettsiae are body lice, ticks, fleas, and mites. Humans are typically considered to be unintentional hosts. With the American dog ticks, Mountain wood ticks, and Lone Star ticks being linked to the majority of cases of Rocky Mountain spotty fever in the U.s, the transmitting ticks differ based on the organism and region.

Alternative names for Amblyomma cajennense include Amblyomma variegatum or Amblyomma hebraeum in South Africa and spotty sickness in Southern America. Illness with rickettsiae is more frequent during warmer months and in those exposed to outdoor recreation due to the interaction with ticks as well as other carriers.

Typhus epidemics, R. prowazekii, a body lice-transmitted illness linked to crowded areas and subpar hygiene. Flea stings are linked to murine typhoid (R. typhus), which is most frequently observed in subtropical and tropical regions.

Anatomy

Pathophysiology

Rickettsiae causes the widespread symptoms and increased mortality associated with these infections by preferentially infecting the capillary endothelial lining of the medium and small arteries all across the body. Endothelial infection results in increased capillary permeability, widespread inflammation, and loss of barrier function all across the body.

As a result, those who contract the infection experience disorientation, fever, rash, headache, cardiac instability, and myalgias. Infections that are severe enough to cause death can happen. To find novel treatment targets, researchers are examining the mechanisms underlying the organism’s quick entry into the cell and the reduced expression of immune systems that permits infection persistence.

Etiology

A range of obligate intracellular bacterium belonging to the genus Rickettsiae causes rickettsial infections, which are divided into the typhus class, spot fever group, ancestor group, and transition group. The most serious and quite well rickettsiae illness in America, Rocky Mountain spot fever, is caused by the bacterium Rickettsial rickettsiae.

It’s crucial to note that other species are widespread in all the other regions of the world, such as Rickettsiae conori, which affects Mediterranean spot fever in North Africa and Europe, and Rickettsiae Africa, which causes African tick attack fever in Africa.

Genetics

Prognostic Factors

The pathogenicity of the Rickettsiae genus, as well as host variables, for example, the level of immunocompetence, influence the severity of rickettsiae illnesses. If an infected person is not detected and managed for their infection quickly, R prowazekii and R rickettsii are among the deadliest species.

For instance, without quick diagnosis and antibiotic therapy, the fatality rate for individuals with Mountain spot fever might reach 30%. Starting the right antibiotics during the 1st week of the particular patient has a very positive impact and leads to outstanding results.

Clinical History

Physical Examination

Age group

Associated comorbidity

Associated activity

Acuity of presentation

Differential Diagnoses

Laboratory Studies

Imaging Studies

Procedures

Histologic Findings

Staging

Treatment Paradigm

by Stage

by Modality

Chemotherapy

Radiation Therapy

Surgical Interventions

Hormone Therapy

Immunotherapy

Hyperthermia

Photodynamic Therapy

Stem Cell Transplant

Targeted Therapy

Palliative Care

Medication

 

calcitriol 

Indicated for Vitamin D dependant rickets:


1mcg orally every day



doxycycline 

200

mg

each day orally or intravenously divided twice daily


Intravenous dose can be once daily

Maintenance Dose
100-200 mg each day orally or intravenously divided twice daily

Intravenous dose can be once daily



 
 

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References

https://www.ncbi.nlm.nih.gov/books/NBK431127/

Rickettsia

Updated : February 5, 2024




Worldwide, a family of vector-transmitted pathogens known as rickettsiae causes febrile diseases. Although rickettsial infections have a consistent clinical appearance, the underlying epidemiology and species can differ regionally.

To accurately treat and diagnose these diseases quickly, it is crucial to understand both the clinical signs and the epidemiological of a specific area. This is because they can be linked to severe death and morbidity.

The most common vectors used to spread rickettsiae are body lice, ticks, fleas, and mites. Humans are typically considered to be unintentional hosts. With the American dog ticks, Mountain wood ticks, and Lone Star ticks being linked to the majority of cases of Rocky Mountain spotty fever in the U.s, the transmitting ticks differ based on the organism and region.

Alternative names for Amblyomma cajennense include Amblyomma variegatum or Amblyomma hebraeum in South Africa and spotty sickness in Southern America. Illness with rickettsiae is more frequent during warmer months and in those exposed to outdoor recreation due to the interaction with ticks as well as other carriers.

Typhus epidemics, R. prowazekii, a body lice-transmitted illness linked to crowded areas and subpar hygiene. Flea stings are linked to murine typhoid (R. typhus), which is most frequently observed in subtropical and tropical regions.

Rickettsiae causes the widespread symptoms and increased mortality associated with these infections by preferentially infecting the capillary endothelial lining of the medium and small arteries all across the body. Endothelial infection results in increased capillary permeability, widespread inflammation, and loss of barrier function all across the body.

As a result, those who contract the infection experience disorientation, fever, rash, headache, cardiac instability, and myalgias. Infections that are severe enough to cause death can happen. To find novel treatment targets, researchers are examining the mechanisms underlying the organism’s quick entry into the cell and the reduced expression of immune systems that permits infection persistence.

A range of obligate intracellular bacterium belonging to the genus Rickettsiae causes rickettsial infections, which are divided into the typhus class, spot fever group, ancestor group, and transition group. The most serious and quite well rickettsiae illness in America, Rocky Mountain spot fever, is caused by the bacterium Rickettsial rickettsiae.

It’s crucial to note that other species are widespread in all the other regions of the world, such as Rickettsiae conori, which affects Mediterranean spot fever in North Africa and Europe, and Rickettsiae Africa, which causes African tick attack fever in Africa.

The pathogenicity of the Rickettsiae genus, as well as host variables, for example, the level of immunocompetence, influence the severity of rickettsiae illnesses. If an infected person is not detected and managed for their infection quickly, R prowazekii and R rickettsii are among the deadliest species.

For instance, without quick diagnosis and antibiotic therapy, the fatality rate for individuals with Mountain spot fever might reach 30%. Starting the right antibiotics during the 1st week of the particular patient has a very positive impact and leads to outstanding results.

calcitriol 

Indicated for Vitamin D dependant rickets:


1mcg orally every day



doxycycline 

200

mg

each day orally or intravenously divided twice daily


Intravenous dose can be once daily

Maintenance Dose
100-200 mg each day orally or intravenously divided twice daily

Intravenous dose can be once daily



https://www.ncbi.nlm.nih.gov/books/NBK431127/