Midterms (Book)

• Maculopapular exanthem


  Rash consisting of both macules (flat discolored areas) and papules (raised lesions)
• Measles (Rubeola)


  A common and highly contagious childhood exanthem associated with serious complications
• Measles infection is seen worldwide, is common among children and young adults, but the incidence decreased dramatically since a vaccine has been developed and used worldwide
• The measles infection is limited to humans and there is no animal reservoir or host
• Rubeola virus


  The etiologic agent for measles, belongs to the family of paramyxoviruses, has only one stable serotype, is an enveloped virus with a single-stranded RNA genome
• Rubeola virus


  • Has two antigens on the envelope - hemagglutinin (H antigen) and fusion protein (F protein)
  • Hemagglutinin is the viral attachment protein and the target of neutralizing antibodies
  • The fusion of the viral protein with the host membrane is mediated by the fusion protein resulting in the formation of multinucleated giant cells known as syncytia formation
• Mode of transmission for measles

  Transmitted through inhalation of respiratory droplets, contagious even before the onset of symptoms but most contagious during the prodromal period
• Clinical findings of measles

  1. Initial stage: high-grade fever with cough, coryza (common cold or runny nose), and conjunctivitis with photophobia

  2. Appearance of pathognomonic enanthem Koplik's spots after 2 days of prodrome

  3. Followed by appearance of maculopapular rashes that undergo branny desquamation

  4. Fever persists as the temperature continues to increase as the rashes appear, and the child is sickest at this point

  5. Fever subsides once all the rashes have appeared throughout the body
• Diagnosis of measles is based primarily on the clinical manifestations
• Treatment and prevention of measles

  • Treatment is symptomatic and supportive
  • Prevention is done through administration of a live attenuated vaccine given in combination with mumps and rubella (MMR) at 2 years of age
  • Immune globulin may be given to exposed susceptible individuals such as those who are immunocompromised
• Rubella (German Measles)


  One of the common viral exanthems in childhood together with measles, chickenpox, fifth disease, and roseola
• Rubella is a benign infection in children, however infections in adults can be more severe especially when acquired during the first 2 weeks of pregnancy, when organ development occurs
• Rubella virus


  A single-stranded RNA virus under the genus Rubivirus and is a member of the Togaviridae family, there is only one stable serotype and humans are the only hosts
• Mode of transmission for rubella

  Mainly spread through inhaling respiratory droplets, but transplacental transmission can also occur when a seronegative mother becomes infected during pregnancy
• Clinical findings of rubella

  1. Manifests with fever, followed by the appearance of maculopapular rashes that lasts for 3 days

  2. Rashes are pruritic and unlike measles do not undergo desquamation

  3. Associated with conjunctivitis without photophobia, post-auricular or occipital lymphadenopathy, and arthralgia

  4. Pearly white dot-like lesions known as Forchheimer spots can be present in the palate

  5. Fever usually disappears as the rashes appear

  6. Natural infection leads to lifetime immunity
• Congenital rubella is the most serious outcome, associated with high mortality for the infected baby during pregnancy and during the first year after birth
• Diagnosis of rubella is based primarily on the clinical manifestations, confirmed by presence of anti-rubella-specific IgM
• Treatment and prevention of rubella


  • Treatment is mainly symptomatic and supportive
  • Prevention involves administration of vaccine (MMR vaccine) at 2 years of age as part of the immunization program for infants, with the primary goal of reducing the number of seronegative women and lowering the incidence of congenital infection
  • The vaccine is contraindicated in pregnant women
• Roseola Infantum (Exanthem Subitum or Sixth Disease)

  Caused by human herpes virus 6 (HHV6) that belongs to the family Herpesviridae, primarily infects lymphocytes particularly CD4 T cells, and is latent in T cells and monocytes
• Mode of transmission for roseola


  Still unknown, but respiratory transmission and oral secretions are most likely because the virus replicates in the salivary glands
• Clinical findings of roseola

  1. Manifested by sudden onset of high-grade fever followed by a generalized rash that lasts for 2 days

  2. May also cause a spectrum of illness including fever without rash, rash without fever, encephalitis, hepatitis, and more serious infections

  3. Roseola is the most common cause of febrile seizures in children
• Diagnosis of roseola is based on clinical manifestations
• Treatment and prevention of roseola

  Treatment is symptomatic, no vaccine is available for HHV6
• Erythema Infectiosum (Fifth Disease)

  Caused by parvovirus B19, a single-stranded DNA virus that belongs to family Parvoviridae, the smallest among the DNA viruses, targets the erythroid progenitor cells causing lysis
• Mode of transmission for fifth disease

  Transmitted by respiratory droplets and oral secretions, can also be transmitted by blood transfusions and vertical transmission from an infected mother
• Clinical findings of fifth disease

  1. Consists of a lytic stage with mild upper respiratory tract infections, followed by an immunologic stage characterized by a generalized lace-like rash most prominent over the face ("slapped cheek" appearance) and arthralgia

  2. In adults, leads to polyarthritis involving the wrists, knees, and ankles

  3. Most serious complication is aplastic crisis in patients with chronic hemolytic anemia, and in pregnant women it is associated with high risk of fetal death due to congestive heart failure (hydrops fetalis)
• Diagnosis of fifth disease is based on the clinical presentation of the patient, definitive diagnosis can also be accomplished through ELISA and polymerase chain reaction (PCR)
• There is currently no specific antiviral treatment or vaccine available for fifth disease
• Varicella (Chickenpox)


  A benign, self-limiting, and highly communicable infection in children but associated with severe infections in adults
• Varicella-zoster virus (VZV)


  The causative agent, a double-stranded, enveloped DNA virus that belongs to the Herpesviridae family, infects mucoepithelial cells and establishes latency in nerve ganglia
• Mode of transmission for varicella

  Most commonly transmitted by inhalation of respiratory droplets but may also be transmitted by direct contact with the lesions
• Clinical findings of varicella

  1. Characterized by fever and vesicular eruptions on the skin and mucous membranes

  2. The rashes are initially maculopapular which later becomes vesicular with associated intense pruritus

  3. The vesicles rupture and ulcerate and later leads to scab formation (crusts)

  4. The lesions appear in crops of different stages, and all the stages of the lesions (macule, papules, vesicles, ulcers, crust) appear simultaneously

  5. The vesicles are described as "teardrop on a pink base" or "dew drop on a rose petal"

  6. The lesions are superficial and do not leave permanent scars

  7. Complications include pneumonia (in adults) and encephalitis (in children)
• Diagnosis of varicella is based on clinical manifestations and a Tzanck smear of skin scrapings or swab from the vesicle to demonstrate the Cowdry type A inclusions and multinucleated giant cells
• Treatment and prevention of varicella


  • Treatment is mainly symptomatic, the drug acyclovir has been shown to be effective in reducing the course of the disease but it does not prevent latency and recurrent infections
  • Prevention is by administration of varicella-zoster virus vaccine, a live attenuated vaccine
• The success of vaccination against varicella is attributed to several factors, including: (1) there is only one, stable serotype; (2) there is no animal reservoir and humans are the only hosts; (3) there is no subclinical state; and (4) it is easily clinically recognizable
• Smallpox is listed among the Category A bioterrorism-biowarfare agents by the Centers for Disease Control and Prevention of the United States
• Variola virus


  The etiologic agent for smallpox, a member of the human poxviruses, the largest among the DNA viruses, shares antigenic determinants with animal poxviruses
• Mode of transmission for smallpox

  The primary mode is through inhalation, it can also be transmitted by direct contact with the lesions, dried virus, or contaminated materials like clothing
• Clinical findings of smallpox

  1. There are two variants - smallpox minor (1% mortality) and smallpox major (up to 40% mortality)

  2. Presents with fever and malaise, followed by the appearance of rashes that are macular that then become papular, later becoming vesicular, and eventually pustular

  3. Unlike chickenpox, the lesions of smallpox appear one stage at a time

  4. The lesions are deep-seated, leaving permanent scars

  5. In severe cases, the rashes may become hemorrhagic
• Diagnosis of smallpox is easy to recognize based on the symptoms, virus isolation can be done by growing of the virus in chorioallantoic membrane of embryonated eggs, and antibody assays can confirm the diagnosis