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Plague

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Plague Powered By Docstoc
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                     Plague
 Background .
• The first pandemic was believed to have started
  in Africa and killed 100 million people over a
  span of 60 years. plague killed approximately
  one fourth of Europe's population.
• The pandemic that began in China in the 1860s
  spread to Hong Kong in the 1890s and was
  subsequently spread by rats transported on
  ships to Africa, Asia, California, and port cities of
  South America.

                     rabiezahran@gawab.com
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       Background
• In the early twentieth century, plague
  epidemics accounted for about 10 million
  deaths in India.
• Plague is worldwide in distribution, with
  most of the human cases reported from
  developing countries.




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               Epidemiology
• A vector is an organism that does not cause
  disease itself but that transmits infection by
  conveying pathogens from one host to another,[1]
  serving as a route of transmission.
• Natural reservoir, refers to the long-term host of
  the pathogen of an infectious disease. It is often the
  case that hosts do not get the disease carried by
  the pathogen or it is carried as a subclinical
  infection and so asymptomatic and non-lethal.


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            Causative organism.
Yersinia pestis :
• Non motile, non–spore-forming,
  pleomorphic, gram-negative
  cocco-bacillus.
• The bacteria elaborate a
  lipopolysaccharide endotoxin,
  coagulase, and a fibrinolysin,
  which are the principal factors in
  the pathogenesis of this disease.


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Yersinia pestis :
Yesinia is named in
honor of Alexander
Yersin, who
successfully isolated
the bacteria in 1894
during the pandemic
that began in China in
the 1860s.



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Reservoirs :
• urban rats :
• are the most important
  reservoirs for the
  plague bacillus,
• but field mice, cats,
  camels, chipmunks,
  prairie dogs, rabbits,
  and squirrels can be
  important animal
  reservoirs as well.
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   vector for transmission .
Xenopsylla cheopis.
 • It is the rat flea, which
   is he most important
   vector for transmission
   of plague .
 • Ticks and human lice
   have been identified



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              Pathophysiology
• When a rat flea ingests a
  blood meal from an animal
  infected with Y pestis, the
  coagulase of the bacteria
  causes the blood to clot. The
  bacilli multiply in the blood clot,
• the flea inoculates thousands
  of these bacilli into a host's
  skin during subsequent blood
  meals.
• The bacilli migrate to the
  regional lymph nodes, are
  phagocytosed by the
  polymorphonuclear cells and
  mononuclear phagocytes, and
  multiply intracellularly.
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            Pathophysiology
Involved lymph nodes show dense •
concentrations of plague bacilli,
 destruction of the normal architecture, and •
medullary necrosis. With subsequent lysis of
the phagocytes,
 bacteremia can occur and may lead to •
invasion of distant organs in the absence of
specific therapy.
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                 Clinical
•   History :
•   Travel to endemic areas.
•    history of a flea bite,
•   close contact with a potential host,
•    exposure to dead rodents or rabbits
    should heighten consideration of a plague
    diagnosis.

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         History :Bubonic plague
• Patients most commonly present with this form of
  plague.
• The incubation period varies but usually lasts 2-6
  days.
• Patients have a sudden onset of high fever, chills,
  and headache.
• Patients also experience body aches, extreme
  exhaustion, weakness, abdominal pain, and/or
  diarrhea.
• Painful, swollen lymph glands (buboes) arise,
  usually in the groin, axilla, or neck.

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History. Meningeal plague
• Fever, headache, and nuchal rigidity
• Buboes are common with meningeal
  plague.
• Axillary buboes are associated with
  an increased incidence of the
  meningeal form.



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History. Pharyngeal plague
    • Pharyngeal plague results from
      ingestion of the plague bacilli.
    • Patients experience sore throat,
      fever, and painful cervical lymph
      nodes.




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History. Pneumonic plague
• Pneumonic plague is highly
  contagious and transmitted by
  aerosol droplets.
• Patients have an abrupt onset of
  fever and chills, accompanied by
  cough, chest pain, dyspnea, purulent
  sputum, or hemoptysis.
• Buboes may or may not appear in
  pneumonic plague.
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         History. Septicemic plague
• Septicemic plague is observed in elderly patients
  and causes a rapid onset of symptoms.
• Patients experience nausea, vomiting, abdominal
  pain, and diarrhea. (Diarrhea may be the
  predominant symptom.)
• Patients exhibit a toxic appearance and soon
  become moribund.
• Buboes are not observed with septicemic plague.
• This form of plague is associated with a high
  mortality rate.

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            Physical :Bubonic plague
• Vesicles may be observed at
  the site of the infected flea
  bite.
• With advanced
  disease pustules, carbuncles,
  or papules may be observed
  in areas of the skin drained by
  the involved lymph nodes.
• A generalized papular rash
  of the hands and feet may
  be observed.        rabiezahran@gawab.com
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        Physical :Bubonic plague
• Buboes are unilateral, oval,
  extremely tender lymph
  nodes and can vary from 2-
  10 cm in size. Femoral
  lymph nodes are most
  commonly involved.
• Hepatomegaly and
  splenomegaly often
  occur, causing
  tenderness.
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   Physical
• Pharyngeal plague :
• causes pharyngeal erythema and painful
  and tender anterior cervical nodes.
• Pneumonic plague :
• causes fever, lymphadenopathy,
  productive sputum, or hemoptysis.



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          Physical
• Septicemic plague
• toxic appearance tachycardia,
  tachypnea, and hypotension.
  Hypothermia is common.
• Generalized purpura may be
  observed and can progress to
  necrosis and gangrene of the
  distal extremities.
• No evidence of lymphadenitis
  or bubo formation is apparent.
  Patients may die from a high
  level of bacteremia.
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  Septicemic plague
 •necrosis
    and
gangrene of
 the distal
extremities.

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                 Risk factors
•   Flea bite.
•   Contact with a patient or a potential host.
•   Contact with sick animals or rodents.
•   Residing in endemic areas of plague (eg,
    southwestern United States).
•   Presence of a food source for rodents in the
    immediate vicinity of the home.
•   Camping, hiking, hunting, or fishing.
•   Occupational exposure (eg, researchers,
    veterinarians)
•   Direct handling or inhalation of
    contaminated tissues or tissue fluids.
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         Differential Diagnoses
• Acute Renal Failure
  Pharyngitis, Bacterial           • Syphilis
  Anthrax                            Disseminated Intravascular
  Pneumonia, Bacterial               Coagulation
  Brucellosis                        Lymphogranuloma
  Catscratch Disease                 Venereum (LGV)
  Rocky Mountain Spotted           •
  Fever                              Tularemia
  Cellulitis                         Lymphoma, B-Cell
  Sepsis, Bacterial                  Typhus
  Chancroid                          Malaria
  Septic Shock
  Dengue Fever

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          Laboratory Studies
• Leucocytosis with a predominance of neutrophils is
  observed, Leukemoid reactions may be observed,
  more commonly in children.
• Peripheral blood smear shows toxic granulations and
  Dohle bodies.
• Thrombocytopenia is common, and levels of fibrin
  degradation products may be elevated.
• Serum transaminase and bilirubin levels may be
  elevated.
• Proteinuria may be present, and renal function test
  findings may be abnormal.
• Hypoglycemia may be observed.
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        Laboratory Studies

• Blood culture results are often positive for Y
  pestis in patients with bubonic plague and
  septicemic plague. Y pestis may be observed on a
  peripheral blood smear.
• Lymph node aspirates often demonstrate Y
  pestis. In patients with pharyngeal plague, Y
  pestis is cultured from throat swabs.
• Cerebrospinal fluid (CSF) analysis in meningeal
  plague may show pleocytosis with a predominance
  of polymorphonuclear leukocytes. Gram stain of
  CSF may show plague bacilli. Limulus test of CSF
  demonstrates the presence of endotoxin.
• Gram stain of sputum often reveals Y pestis.
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              Imaging Studies

• On chest x-ray films, patchy
  infiltrates, consolidation, or a
  persistent cavity is observed in
  patients with pneumonic plague.
• ECG reveals sinus tachycardia
  and ST-T changes.
• Obtain a CT scan of the head in
  a patient with altered mental
  status.
• Nuclear imaging may help in
  localizing areas of lymphadenitis
  and meningeal inflammation.

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      Other Tests
• Direct immunofluorescence testing
  of fluid or cultures may aid in rapid
  diagnosis.
• A passive hemagglutination test
  (performed on serum from a patient
  in acute or convalescent stages) with
  a 4-fold or greater increase in titer
  suggests plague infection.

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                 Procedures
• Aspiration of lymph node (bubo)
  – Inject 1 mL of sterile saline into the bubo with a 20-gauge
    needle; after withdrawing several times, aspirate the
    fluid. Gram stain of the aspirate reveals gram-negative
    coccobacilli and polymorphonuclear leucocytes.
  – Wayson stain of the aspirate shows plague bacilli as
    light-blue bacilli with dark-blue polar bodies.
  – Examination of the aspirate of the fluid from the inguinal
    lymph nodes shows a characteristic bipolar appearance
    that resembles a closed safety pin.
• Lumbar puncture for CSF analysis
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                  Treatment
• Medical Care :
                  • Precautions.
  – Place all patients thought to have plague and signs of
    pneumonia in strict respiratory isolation for 48-72
    hours after starting antibiotic therapy.
  – Report patients thought to have plague to the local
    health department and to the World Health
    Organization.
  – Alert laboratory personnel to the possibility of the
    diagnosis of plague. All fluid specimens must be
    handled with gloves and mask to prevent
    aerosolization of the infected fluids.
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                 Treatment
• Medical Care :
        • Supportive therapy
 – Hemodynamic monitoring and
   ventilatory support are performed as
   appropriate.
 – Intravenous fluids, epinephrine, and
   dopamine are necessary for correction
   of dehydration and hypotension.

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         Treatment.
• Surgical Care
• Enlarging or fluctuant buboes require
  incision and drainage.
• Consultations
• Infectious disease specialists
• Pulmonary and critical care specialists
• General surgeons
• Neurologists

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          Medication :
• Streptomycin sulfate :
• is the preferred drug of choice to treat
  plague.
• Dosing:
• 30 mg/kg/day (up to a total of 2 g/day) in
  divided doses given IM, for a full course
  of 10 days of therapy or until 3 days
  after the temperature has returned to
  normal .
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       Medication :
• Doxycycline:
• Inhibits protein synthesis and thus
  bacterial growth by binding to 30S and
  possibly 50S ribosomal subunits of
  susceptible bacteria.
• Dosing
• Adult             100 mg PO/IV q12h
• Pediatric
• <8 years: Not recommended
  >8 years: 2-5 mg/kg/d PO/IV qd or divided
  bid; not to exceed 200 mg/d

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       Medication :
• Chloramphenicol :
• Binds to 50S bacterial ribosomal subunits
  and inhibits bacterial growth by inhibiting
  protein synthesis. Effective against gram-
  negative and gram-positive bacteria.
• Dosing
• Adult
• 500 mg PO/IV q6h
• Pediatric
• 50-75 mg/kg/d PO/IV divided q6h
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          Medication :
• Aminoglycoside antibiotic recommended
  when less potentially hazardous therapeutic
  agents are ineffective or contraindicated.
• Gentamicin:
• Dosing
• Adult
• 2 mg/kg IV loading dose with normal renal
  function; then, 1.7 mg/kg IV q8h for 10 d.


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      Medication :
Fluoroquinolones :
  such as ciprofloxacin, have been
  shown to have good effect against Y.
  pestis in both in vitro and animal
  studies. Ciprofloxacin is bacteriocidal
  and has broad spectrum activity
  against most Gram-negative aerobic
  bacteria,

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      Medication :
• Sulfonamides :
• The combination drug trimethoprim-
  sulfamethoxazole has been used
  both in treatment and prevention of
  plague.




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                 Prevention .
    • Prophylactic antibiotic therapy.
• The CDC recommends administering
  prophylactic antibiotics for a short time to :
• people who have been exposed to the bites
  of potentially infected rodent fleas during a
  plague outbreak.
• persons who have handled an animal
  known to be infected with the plague
  bacterium.
• persons who have had close exposure to a
  person or an animal thought to have
  pneumonic plague. rabiezahran@gawab.com
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        Prevention .
• Preferred antibiotics for prophylaxis
  against plague are :
• Doxycycline 100 mg PO q12h for 14-
  21 days (for patients > 8 y) and
  trimethoprim 160 mg/
  sulfamethoxazole 800 mg PO q12h
  for 14-21 days.


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          Prevention .
            • Plague vaccine
• Vaccination is of limited use and is not
  mandatory for entry into any country.
• The vaccine is not effective against the
  pneumonic form of plague.
• Plague vaccine is recommended for field
  workers in areas endemic for plague and for
  scientists and laboratory personnel who
  routinely work with the plague bacterium.
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         Prevention .
    • Environmental sanitation
• Remove food sources used by rodents.
• Make homes, buildings, or warehouses
  "rodent-proof."
• Trained professionals should apply
  chemicals to kill fleas and rodents.
• Trained professionals should fumigate
  cargo areas of ships and docks.
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       Complications.
• Acute respiratory distress syndrome.
• Chronic lymphedema from lymphatic
  scarring.
• Disseminated intravascular coagulation
• Septic shock.
• Super infections of the buboes
  by Staphylococcus and Pseudomonas
  species
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           Prognosis
• Untreated patients with plague
  have a mortality rate of
  approximately 50%; however, with
  appropriate therapy, the mortality
  rate drops to approximately 5%.


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• Wayson stain showing
  the characteristic
  "safety pin"
  appearance
  of Yersinia pestis, the
  plague bacillus




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• Fluorescence
  antibody positivity is
  observed as bright,
  intense green
  staining around the
  cell wall of Yersinia
  pestis, the plague
  bacillus.




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• Histopathology
  of lung in fatal
  human plague–
  fibrinopurulent
  pneumonia.




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• Histopathology of
  lung showing
  pneumonia with
  many Yersinia
  pestis organisms (the
  plague bacillus) on a
  Giemsa stain.




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• Histopathology
  of spleen in fatal
  human plague




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• Histopathology
  of lymph node
  showing
  medullary
  necrosis
  and Yersinia
  pestis, the plague
  bacillus




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• Histopathology
  of liver in fatal
  human plague .




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• Focal
  hemorrhages in
  islet of
  Langerhans in
  fatal human
  plague.




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               www.medicalppt.blogspot.com
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posted:1/24/2013
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