36. Rubella Flashcards
What is Rubella?
- 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
What are the main complications of rubella?
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.
What is postnatal rubella?
- 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.
What is congenital rubella?
- 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
What is the etiology of rubella?
- 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
What is the prognosis of rubella?
- 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.
What type of vaccine is available agasinst rubella?
live attenuated rubella vaccine
What are the main complications of rubella (post natal)?
- 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
What precautions should people take?
- 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
What is the incubation period for rubella?
14-21 days after exposure to a person with Rubella
What symptoms appear 1-5 days before the onset of rash in post-natal rubella?
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)
What should you ask when congenital rubella is suspected?
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
What type of rash is seen in post-natal rubella?
- the rash in rubella is a discrete rose-pink maculopapular rash ranging from 1-4mm
- rashes in adults may be pruritic
What is meant by “3-day measles” when talking about rubella?
- 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.
is the fever high in post-natal rubella?
Fever is usually not higher than 38.5°C (101.5°F).
How are the lymph nodes affected in post-natal rubella?
Enlarged posterior auricular and suboccipital lymph nodes are usually found on physical examination.
How are the lymph nodes affected in post-natal rubella?
Enlarged posterior auricular and suboccipital lymph nodes are usually found on physical examination.
How is the mouth affected in post-natal rubella?
The Forchheimer sign may still be present on the soft palate.
- tiny red spots
What is the classic triad presentation of congenital rubella syndrome?
- 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
What are other findings found in congenital rubella syndrome? (other than the classic triad)
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
What are teh differential diagnoses of rubella?
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
What lab studies need to be performed for the diagnosis of post-natal rubella?
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.
How is congenital rubella virus diagnosed?
- 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.
What is the treatment of post-natal rubella?
treatment is supportive
no specific antiviral agent is currently available for rubella
treat symptoms
what is the treatment of congenital rubella syndrome?
- 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.
