RICKETTSIAL DISEASES

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RICKETTSIAL DISEASES

• Dr Sajan Christopher
• Assistant Professor of Medicine
• Medical College ,Thiruvananthapuram

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RICKETTSIAE

• Rickettsiae are obligate intracellular gram
  negative parasites.
• Most are zoonoses spread to humans by arthropods.
  (except Q fever).

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• Rickettsiae replicate within the cytoplasm of
  endothelial cells and smooth muscle cells of
  capillaries, arterioles and small arteries
  causing necrotizing vasculitis.
• Most are febrile infections with a characteristic
  rash.
• An ESCHAR, a black ulcerated lesion may develop
  at the site of inoculation

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• Rickettsial diseases may be grouped on the basis
  of Clinical features and Epidemiological aspects
  as follows

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• Among the major group of rickettsioses, the
  commonly reported diseases in India are
• Scrub typhus
• Murine flea borne typhus
• Indian tick typhus
• Q fever

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Scrub typhus is considered in some detail Why?

• To be aware of this condition during the
  outbreaks of many fevers like DF,CKG Fever,
  Leptospirosis other viral fevers with secondary
  infections.
• Suspicion of the condition initiation of
  specific therapy cures the condition rapidly
  otherwise may lead to serious complications.

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SCRUB TYPHUS

• Highly endemic in Thiruvananthapuram urban,
  sub-urban rural areas.
• Most of the cases come from Nedumangadu
• taluk Chirayinkil taluk (Mamam near
• Attingal).
• Most of the Scrub typhus are regularly seen
  during the period November to March.

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• Causative agent is Rickettsiae tsutsugamushi.
  Found in areas where they harbour the infected
  chiggers particularly areas of heavy scrub
  vegetations.

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• RESERVOIR Trombiculid mite which feeds on small
  mammals.
• MODE OF TRANSMISSION By bite of infected larval
  mites.
• Infection occurs during wet season when the
  mites lay their eggs. It is the larva (chigger)
  that feeds on vertebrate hosts.
• TRANSMISSION CYCLE
• MITE------RATS AND MICE-----MITE----RATS AND
  MICE
• 
  
• 
  
  MAN

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CLINICAL FEATURES

• Fever, Chills, Generalised Lymph-adenopathy
• ESCHAR A punched out ulcer covered with a
  blackened scab which indicates the location of
  the mite bite.

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• Eschar is found only in around 50 of patients.
• Eschar is painless and patient wont complain of
  it.
• Often the patient wont notice it because of its
  presence in concealed sites.

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COMPLICATIONS

• Occurs mainly in untreated cases
• Myocarditis
• Anicteric Hepatitis
• Encephalitis
• Interstitial pneumonitis

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INVESTIGATIONS

• PCR Amplification of O tsutsugamushi DNA from
  the blood of febrile patients.
• SEROLOGICAL TESTS such as
• Indirect Flourescent antibody test (IFA) test (
  Titer 1 200 ),
• the Complement Fixation Test.
• The Weil Felix Test
• Scrub IgM ELISA Test Highly specific test

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WEIL-FELIX TEST

• Agglutination test in which sera are tested for
  agglutinins to the O antigens of certain non
  motile Proteus strains OX19, OX2 and OXK. The
  basis of the test is the sharing of an Alkali
  stable carbohydrate antigen by rickettsiae and by
  certain strains of Proteus.

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WEIL-FELIX TEST (contd)

• Sera from Epidemic and Endemic typhus agglutinate
  OX19 and sometimes OX2.
• In tick borne spotted fever, both OX19 and Ox2
  are agglutinated.
• OXK agglutinins are found only in scrub typhus.
  The test is negative in Rickettsial pox, Trench
  fever, and Q fever.

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WEIL-FELIX TEST (contd)

• False positive reaction may occur in some cases
  of urinary or other infections by Proteus and at
  times in liver diseases and Typhoid fever.
• Hence it is desirable to demonstrate a rise in
  titer of antibodies for the diagnosis of
  rickettsial infections. A 4 fold rise in
  agglutinin titres in paired titres is diagnostic.

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WEIL-FELIX TEST (contd)

• However, with a single serum sample
• available, the test is suggestive of
• infection only at a high cut off titer (
• 1 320) at which the positive predictive
• value and the specificity is reliable.

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• The serological tests for Rickettsial diseases
  including the specific IgM antibody tests become
  positive only in the second week and a second
  sample is often required.
• Serological tests cannot provide early diagnosis
  and a specific diagnosis may not be available
  until after the patient has died or recovered.

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• A thorough knowledge of the clinical features of
  scrub typhus including its complications and its
  varied presentations is especially important to
  provide early empiric treatment in appropriate
  cases which may be life saving.

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TREATMENT

• Tetracycline is the DOC.
• Doxycycline 100mg Bid PO 7-15 days.
• Chloramphenicol 500mg qid PO7-15 days.
• IV Chloramphenicol 150 mg/ kg per day for 5 days.

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CONTROL

• Vector control. Clearing the vegetation where
  rats and mice live.
• Rodent control

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Presentation

• 45 year old male patient presented with
  complaints of
• Fever 10 days.
• Cough and mucoid sputum -5 days.
• Fever was high grade continuous nature with
  intermittent exacerbation.
• Head ache and myalgia
• No dyspnoea

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Contd

• Patient was from Aruvikkara
• He was on inpatient treatment for 6 days in a
  private hospital.
• Patient received Inj. Cefotaxim Azithromycin.
• Because of persistent fever cough.with
  radiological evidence of Rt basal pneumonitis.
• Patient was referred as a case of Rt LL Pneumonia.

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Physical examination

• Patient was febrile, BP- Normal.
• Muscle tenderness
• No jaundice, no rash.
• No generalized LN Enlargement.
• Respiratory system
• R.rate 36/mt, Bilateral basal crepitations
• More on Rt side.
• Other systems Normal

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Investigations on admission

• TLC 12,400 N -50, L- 45, E- 5, ESR- 32mm/Hr.
• X-ray Chest
• Bilateral LZ NH opacities Rtgt Lt.

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X-Ray chest taken before admission
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Inpatient course of patient

• Because of fever, myalgia with muscle tenderness,
• raised TLC with bilateral LZ interstitial
  shadows in Xray chest,
• A provisional diagnosis of Leptospirosis was
  made and admitted with advice to start
  InjCrystalline penicillin.
• Later General examination revealed an ulcer/
  eschar of lt 3mm size in the left inguinal region.
• There was B/L enlarged mildly tender Inguinal
  lymph nodes.
• A diagnosis of Scrub typhus was
  made.
• Inj CP was discontinued and patient was put on
  Doxycycline.

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Left inguinal eschar
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Other investigations results

• RFT Normal.
• LFT
• S.Bilirubin 1.7mg
• SGOT 166U/L
• SGPT 126U/L
• S. ALP 80U/L
• S.Na 138mEq/L
• S.K 3.4 mEq/L.
• ECG WNL

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Investigation results contd

• Leptospira antibody test Negative
• CRP 2.8mg ( N - lt 0.6mg)
• Weil Felix test was done
• Result came as
• Proteus OX K 1/80 lt 1/40 Dilution (
  Normal range)
• Proteus OX 2 1/20
  ,,
• Proteus OX19 1/20
  ,,

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Outcome of treatment

• Patient became afebrile within 2 days after
  starting doxycycline and other symptoms subsided.
• Patient discharged on 6th day.
• Repeat X-ray chest on follow up showed clearance
  of lung opacities.

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X-Ray chest on follow up
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Case is presented because of the following reasons

• Even though the disease is very frequently seen
  for the last few years many Doctors are unaware
  of this condition mismanage the patient.
• The eschar / ulcer the diagnostic sign detected
  was very small and may miss unless carefully
  looked for.
• There was no generalized LNE which is the most
  frequent sign

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Thank you