COURSE:Medical Microbiology

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CYTOMEGALOVIRUS DISEASE

• In normal hosts
• (a) If acquired by contact -- 1o attack is
  asymptomatic or mononucleosis with subclinical
  hepatitis.
• (b) If by transfusion -- post-transfusion
  syndrome fever and mononucleosis, FUO,
  granulomatous hepatitis.
• In hosts with impaired T-cell immunity and in
  fetuses
• Fetus -- cytomegalic inclusion disease (TORCH)
  syndrome petechial rash, hepatosplenomegaly,
  thrombocytopenia, anemia, CNS damage, low birth
  weight. Most congenital CMV infections are subtle
  (mental retardation, partial deafness, eye
  disease or asymptomatic). CMV is a common
  infectious cause of congenital abnormality.

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CMV Routes of Infection

• 1. Saliva
• 2. Sexual contact
• 3. Transfusion
• 4. Organ transplant (usually renal)

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CMV Diagnosis

• Difficult on clinical data aloneviral culture
  (2-4 weeks), serology by indirect
  immunofluorescence, cytology on concentrated urine

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CMV Treatment

• The antiviral drugs, cidofovir and ganciclovir,
  are the drugs of choice for CMV retinitis and
  pneumonitis- ganciclovir is more toxic than
  cidofovir.
• Experimental live attenuated vaccines are being
  developed but unknown efficacy or safety.

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EPSTEIN-BARR VIRUS

• EBV is a herpesvirus first seen by electron
  microscopy of neoplastic cells from a Burkitts
  lymphoma (BL) in 1964.
• Antibody to EBV is found in sera of almost all
  patients with BL or nasopharyngeal carcinoma.
• Antibody to EBV was found in 80 of low-income
  adults in Philadelphia and 100 of adults in
  developing countries most didnt have BL.
• EBV usually results in infectious mononucleosis
  (IM) in North America and BL in Africa and other
  parts of the world.

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EBV Disease Characteristics

• EBV can be cultured in normal human B lymphocytes
  (virus attaches to complement C3b receptor) which
  then begin to behave like neoplastic lymphoma
  cells. These cells undergo blastogenesis and
  begin secreting vast amounts of polyclonal
  (heterophile) immunoglobulins.
• Infection is followed by the prompt appearance of
  cytotoxic T cells which proceed to turn off
  activated B cells (the atypical lymphocytes are
  the T cells).
• Heterophil Ab ( IgM antibodies which agglutinate
  sheep and horse RBCs) appears in 80 of patients
  with IM. These antibodies appear approximately
  four weeks after onset of symptoms, but are not
  EBV specific antibodies.

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Epatein-Barr Virus (EBV) Infection
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Diagnostic Procedures For Herpesviruses

• 1. Cell Culture Cell rounding gt fusion gt giant
  cell formation (HSV)
• 2. Immunofluorescence Intense nuclear
  staining for all herpesviruses
• 3. ELISA and Western Blot Specificity based
  on glycoprotein
• 4. PCR
• 5. TORCH Serologic assay

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TORCH - Syndrome

• Toxoplasma To
• Rubella R
• Cytomegalovirus C
• Herpes Simplex H

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Chickenpox lesions
Zoster lesions