Rickettsia Infections

Rickettsia Infections: 

Rickettsia Infections DR. A Essop DERMATOLOGY DEPARTMENT

HISTORY: 

24–year–old male with Down’s Syndrome Known diabetic, admitted for DKA Presented with widespread erythematous macular rash, including palms and soles ? Duration HISTORY

CLINICAL PRESENTATION: 

CLINICAL PRESENTATION

DIFFERENTIAL DIAGNOSIS: 

Rickettsia /Tick bite fever Leukocytoclastic vasculitis DIFFERENTIAL DIAGNOSIS

INVESTIGATIONS: 

Bloods FBC : Hb – 12.9, Platelets – 184 LFT : ALT – 43, AST – 78 UEC : Na + – 131 Ca 2+ – 1.8 Alb – 23 CRP – 97.7 Blood cultures – Staph aureus Skin biopsy INVESTIGATIONS

FINAL DIAGNOSIS: 

FINAL DIAGNOSIS RICKETTSIA

TREATMENT: 

TREATMENT Doxycycline 100mg bd – 14 days Infectious Disease Control Unit Internal Medicine Department

RICKETTSIA: 

RICKETTSIA Rickettsia – named after American pathologist Howard Ricketts Order – Rickettsiales Family – Rickettsiaceae Genus – Rickettsia Spotted fever Typhus fever Scrub typhus (1871 – 1910)

PATHOGENS: 

PATHOGENS Obligate, intracellular parasites Gram (-) pleomorphic coccobacilli ( coccal - 0.3 µm; bacilli 0.3 by 1-2 µm) Multiplies by binary fission, contains both RNA and DNA Stains red on Giemsa or Gimenez stain

PATHOGENS : 

PATHOGENS Transmitted to humans by arthropods (ticks, mites, louse and fleas) Spread by hematogeneous or lymphatic systems

PowerPoint Presentation: 

Group Disease Rickettsia Vector Distribution Typhus Epidemic typhus and Brill-Zinsser’s disease R. prowazecki Louse Wordwide Endemic murine typhus R. typhi Rat flea Central and South America, Malaya Spotted fever Rocky Mountain spotted fever Tick typhus R. rickettsi Tick North and South America - African R. conori Tick Mediterranean , Africa - Siberian R. siberica Tick Russia, Central Asia - Queensland R. australis Tick Australia Rickettsialpox R. akari Mouse mite North America, Russia, Africa Scrub typhus Tropical typhus or Japanese river typhus R. tsutsugamushi Mite South-East Asia Q fever - Coxiella burnetti - Worldwide (except Scandanavia ) Trench fever Rochalimaea quintana Body louse Europe, Africa, North America EPIDEMIOLOGY

EPIDEMIOLOGY: 

EPIDEMIOLOGY RSA – tick bite fever (TBF) is most common rickettsial disease R. conorii – dog tick: Boutonneuse TBF R. africae – cattle or game ticks: African TBF Rocky Mountain spotted fever is the most virulent of the rickettsial infections

CLASSIFICATIONS: 

CLASSIFICATIONS Spotted fever group Typhus group Scrub typhus group Rickettsia rickettsii Rocky Mountain spotted fever Rickettsia akari Rickettsialpox Rickettsia conorii Boutonneuse fever Rickettsia sibirica Siberian tick typhus Rickettsia australis Australian tick typhus Rickettsia felis Flea-borne spotted fever Rickettsia japonica Oriental spotted fever Rickettsia africae African tick bite fever Rickettsia prowazekii Epidemic typhus, recrudescent typhus and sporadic typhus Rickettsia typhi Murine typhus (endemic typhus) Rickettsia tsutsugamushi has been reclassified into the genus Orientia .

PATHOGENESIS: 

PATHOGENESIS

PATHOGENESIS: 

PATHOGENESIS

CLINICAL MANIFESTATIONS : 

CLINICAL MANIFESTATIONS Triad – fever, headache, rash Rash – wrist and ankles, spread centripetally (few days later) sparing the face Lesions – initially red macules – papules –evidence of petechiae or purpura Eschar (“ tache noir”) appears in patients with spotted fever other than RMSF Periorbital edema , abdominal pains (mimicking appendicitis), conjunctival injection, palatal petechial , edema of dorsal hands and calf pain, necrosis on the digits (rarely)

CLINICAL MANIFESTATIONS: 

CLINICAL MANIFESTATIONS

PATHOLOGY: 

PATHOLOGY Early course – perivascular lymphohistiocytic infiltrate and extravasated erythrocytes and dermal edema Advanced lesion – shows dermal and epidermal necrosis Immunohistochemical – positive staining for R. rickettsie

DIAGNOSIS: 

DIAGNOSIS Clinical diagnosis Serology Weil Felix agglutination test Immunoflourescence essay (IFA) Enzyme-linked immunosorbent assay (ELISA) Western blot immonoassay Immunologic detection of rickettsia in tissue Skin biopsy PCR-based detection of rickettsial DNA

DIFFERENTIAL DIAGNOSIS: 

DIFFERENTIAL DIAGNOSIS Differentials Dengue Kawasaki Disease Leptospirosis Malaria Measles Meningococcal Infections Rubella Streptococcal Infection, Group A Syphilis Toxic Shock Syndrome Vasculitis and Thrombophlebitis

TREATMENT: 

TREATMENT Adults Doxycycline , 100mg q12h for 5-10 days; OR Chloramphenicol , 50-75mg/kg/day q6h Children Doxycycline , 2.2mg/kg q12h for 5-10 days; OR Clarithromycin , 15mg/kg/day q12h for 7 days; OR Azithromycin , 10mg/kg/day daily for 3 days Pregnancy Doxycycline , 100mg q12h for 5-10 days; OR Chloramphenicol , 50-75mg/kg/day q6h

PREVENTION: 

PREVENTION Avoid tick exposure Wear protective clothing Perform tick checks when in tick infested area Proper tick extraction to lower risk of infection Use chemical repellents – diethyltoluamide (DEET) (35%) – safe in adults and children

PowerPoint Presentation: 

REFERENCES Bolognia JL, Jorizzo JL, Rapini RP. Volume1: Dermatology 2nd Edition. 2008. Mosby. Burns DA, Breathnach SM, Cox N, Griffiths CE. Volume 2 : Rook's Textbook of Dermatology. 7 edition.2004. Wiley-Blackwell Lever WF, Schaumburg-Lever G. Histopathology of the Skin. 7th Edition. 1990. J.B. Lippincott Company. Mandell GL, Bennett JE, Dolin R . Mandell , Douglas, and Bennett's Principles & Practice of Infectious Diseases.5 edition.2000 . Churchill Livingstone Rathore MH, Rickettsial Infection. Medscape Reference (Online). Accessed on 2011/05/24 . http://emedicine.medscape.com/article/968385-overview Wolff K, Goldsmith LA, Katz SI, Gilchrest BA, Paller AS, Leffell DJ. Volume1: Fitzpatrick’s Dermatology in General Medicine. 7th Edition. 2008. McGraw-Hill.