36. Rubella

Question 1

What is Rubella?

Answer 1

• benign communicable exanthematous disease
• Caused by the rubella virus, members of the Rubivirus genus of the family Togaviridae
• Clinical manifestation of the severity varies with age
• ## Nearly half the people infected are asymptomatic

Question 2

What are the main complications of rubella?

Answer 2

The major complication of rubella is its teratogenic effects when pregnant women contract the disease, especially in the early weeks of gestation.

The virus can be transmitted to the fetus through the placenta and is capable of causing serious congenital defects, abortions, and stillbirths.

Question 3

What is postnatal rubella?

Answer 3

• rubella outside of the uterus
• entry = respiratory epithelium of the nasopharynx
• transmitted via aerosolized particles from the respiratory tract secretions of infected individuals.
• virus attaches to and invades respiratory epithelium.
• it then spreads hematogenously to regional and distal lymph nodes and replicates in the reticuloendothelial system.
• results in secondary viremia that occurs in 6-20 days after the infection.
• during this phase rubella virus can be recovered from different body sites: lymph nodes, urine, CSF, conjunctival sac, breast milk, synovial fluid, and lungs.
• Viremia peaks just before the onset of the rash and disappears shortly afterward.
• An infected person begins to shed the virus from the nasopharynx 3-8 days after exposure for 6-14 days after the onset of the rash.

Question 4

What is congenital rubella?

Answer 4

• fetal infection occurs transplacentally during the maternal viremic phase.
• mechanisms by which rubella causes fetal damage is not well understood.
• causes damage to the fetus

Question 5

What is the etiology of rubella?

Answer 5

• Rubella virus, from the Rubivirus genus of the Togaviridae family
• only one antigenic type of rubella virus is available
• humans are the only hosts
• single-stranded RNA virus

Question 6

What is the prognosis of rubella?

Answer 6

• Prognosis for post-natal rubella is good with full recovery
• Congenital rubella may have a poor outcome with severe multiple-organ damage. it can lead to debilitating disease and may result in growth delay, learning disability, mental retardation, hearing loss, congenital heart disease, and eye, endocrinological, and neurological abnormalities.

Question 7

What type of vaccine is available agasinst rubella?

Answer 7

live attenuated rubella vaccine

Question 8

What are the main complications of rubella (post natal)?

Answer 8

• joint involvement:
  arthraligia and arthritis in adolescents and adults
  women > men
  affects fingers, wrists, knees, and ankles
  massive effusions accompany rubella arthritis (symptoms may persist for 10-14 days)
  arthralgia begins with teh onset of teh rash and clears without sequelae within 2-30 days
• thrombocytopenia
  rare complication
  children more than adults
  girls more than boys
  self -limited and lasts from a few days to months
• neurologic manifestations
  rare complication and occurs more in children
  resolves without sequelae

Question 9

What precautions should people take?

Answer 9

• pregnant women: avoid any contact with people infected with rubella
• all susceptible people should be immunized
• No special precaution is necessary in the household setting of a child with congenital rubella syndrome
• parents should be counseled regarding potential serious risk to pregnant women exposed to the child

Question 10

What is the incubation period for rubella?

Answer 10

14-21 days after exposure to a person with Rubella

Question 11

What symptoms appear 1-5 days before the onset of rash in post-natal rubella?

Answer 11

Eye pain on lateral and upward eye movement (a particularly troublesome complaint)

Conjunctivitis

Sore throat

Headache

General body aches

Low-grade fever

Chills

Anorexia

Nausea

Tender lymphadenopathy (particularly posterior auricular and suboccipital lymph nodes)

Forchheimer sign (an enanthem observed in 20% of patients with rubella during the prodromal period; can be present in some patients during the initial phase of the exanthem; consists of pinpoint or larger petechiae that usually occur on the soft palate)

Question 12

What should you ask when congenital rubella is suspected?

Answer 12

The number of weeks of pregnancy when maternal exposure to rubella occurred (The risk of congenital rubella syndrome is higher if maternal exposure occurs during the first trimester.)

Maternal history of immunization or medical history of rubella

Evidence of intrauterine growth retardation during pregnancy

Manifestations suggestive of congenital rubella syndrome in a child

Question 13

What type of rash is seen in post-natal rubella?

Answer 13

• the rash in rubella is a discrete rose-pink maculopapular rash ranging from 1-4mm
• rashes in adults may be pruritic

Question 14

What is meant by “3-day measles” when talking about rubella?

Answer 14

• The synonym “3-day measles” derives from the typical course of rubella exanthem that starts initially on the face and neck and spreads centrifugally to the trunk and extremities within 24 hours. It then begins to fade on the face on the second day and disappears throughout the body by the end of the third day.

Question 15

is the fever high in post-natal rubella?

Answer 15

Fever is usually not higher than 38.5°C (101.5°F).

Question 16

How are the lymph nodes affected in post-natal rubella?

Answer 16

Enlarged posterior auricular and suboccipital lymph nodes are usually found on physical examination.

Question 17

How are the lymph nodes affected in post-natal rubella?

Answer 17

Enlarged posterior auricular and suboccipital lymph nodes are usually found on physical examination.

Question 18

How is the mouth affected in post-natal rubella?

Answer 18

The Forchheimer sign may still be present on the soft palate.
- tiny red spots

Question 19

What is the classic triad presentation of congenital rubella syndrome?

Answer 19

• Sensorineural hearing loss
  Studies have demonstrated that approximately 40% of patients with congenital rubella syndrome may present with deafness as the only abnormality without other manifestations.

Hearing impairment may be bilateral or unilateral and may not be apparent until the second year of life.

• Ocular abnormalities
  cataract, infantile glaucoma, and pigmentary retinopathy
  both eyes are affected in 80% patients
  Rubella retinopathy consists of a salt-and-pepper pigmentary change or a mottled, blotchy, irregular pigmentation, usually with the greatest density in the macula.
  The retinopathy is benign and nonprogressive and does not interfere with vision (in contrast to the cataract) unless choroid neovascularization develops in the macula.
• congenital heart disease
  including patent ductus arteriosus and pulmonary artery stenosis

Question 20

What are other findings found in congenital rubella syndrome? (other than the classic triad)

Answer 20

Intrauterine growth retardation, prematurity, stillbirth, and abortion

CNS abnormalities, including mental retardation, behavioral disorders, encephalographic abnormalities, hypotonia, meningoencephalitis, and microcephaly

Hepatosplenomegaly

Jaundice

Hepatitis

Skin manifestations, including blueberry muffin spots that represent dermal erythropoiesis and dermatoglyphic abnormalities

Bone lesions, such as radiographic lucencies

Endocrine disorders, including late manifestations in congenital rubella syndrome usually occurring in the second or third decade of life (eg, thyroid abnormalities, diabetes mellitus)

Hematologic disorders, such as anemia and thrombocytopenic purpura

Question 21

What are teh differential diagnoses of rubella?

Answer 21

Herpesvirus 6 Infection

Measles

Parvovirus B19 Infection

Pediatric Contact Dermatitis

Pediatric Cytomegalovirus Infection

Pediatric Enteroviral Infections

Pediatric Mononucleosis and Epstein-Barr Virus Infection

Pediatric Mycoplasma Infections

Pediatric Syphilis

Toxoplasmosis

Question 22

What lab studies need to be performed for the diagnosis of post-natal rubella?

Answer 22

serologic testing or by viral culture.
- The serologic diagnosis consists of demonstrating the presence of rubella-specific immunoglobulin M (IgM) antibody in a single serum sample
or
- observation of a significant (>4-fold) rise in rubella-specific immunoglobulin G (IgG) antibody titer between the acute and convalescent serum specimens drawn 2-3 weeks apart.

techniques for serological testing:

Enzyme-linked immunosorbent assay (ELISA)

Immunofluorescent assay (IFA)

Latex agglutination (LA) test

Hemagglutination inhibition (HI) test

Complement fixation (CF) test

Passive hemagglutination antibody (PHA) test

Hemolysis-in-gel test

Rubella viral cultures are time consuming, expensive, not readily available, and used mainly for tracking epidemiology of rubella virus during an outbreak.

Question 23

How is congenital rubella virus diagnosed?

Answer 23

• Congenital rubella in infants and children is diagnosed by viral isolation or by serologic testing
• viral isolation is the preferred technique in congenital rubella syndrome because rubella serology may be difficult to interpret in view of transplacental passage of rubella-specific maternal IgG antibody
• Congenital rubella syndrome has also been diagnosed using placental biopsy, rubella antigen detection by monoclonal antibody, and polymerase chain reaction (PCR).
• The same serologic testing methods (ELISA, IFA, LA, HI, CF) discussed for postnatal rubella can be used to detect specific antibodies in congenital infection
• Rubella-specific IgM antibody is actively produced by the fetus or neonate and may be detected in the cord blood or neonatal serum.
• Congenital rubella syndrome should be strongly suspected in infants older than 3 months if rubella-specific IgG antibody levels are observed and do not decline at the rate expected from passive transfer of maternal antibody (ie, equivalent of a 2-fold decline in HI titer per mo) in a compatible clinical situation.

Question 24

What is the treatment of post-natal rubella?

Answer 24

treatment is supportive
no specific antiviral agent is currently available for rubella
treat symptoms

Question 25

what is the treatment of congenital rubella syndrome?

Answer 25

• treatment is supportive
• provide vision screening and hearing screening for asymptomatic new-borns
• tx for symptomatic newborns:
  Babies with congenital rubella syndrome who develop respiratory distress may require supportive treatment in the ICU.

Hepatosplenomegaly is monitored clinically. No intervention is required.

Patients with hyperbilirubinemia may require phototherapy or exchange transfusions if jaundice is severe to prevent kernicterus.

True hemorrhagic difficulties have not been a major problem; however, IVIG may be considered in infants who develop severe thrombocytopenia. Corticosteroids are not indicated.

Infants who have a rubella-related heart abnormality should be carefully observed for signs of congestive heart failure. Echocardiography may be essential for diagnosis of heart defects.