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Rubella

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					                                        Rubella

Rubella a mild illness caused by infection with rubivirus, an RNA togavirus. Spread
of the virus is by droplets from the respiratory tract.

The true importance of rubella is the teratogenicity of the virus during the first
trimester of pregnancy, resulting in congenital rubella syndrome. It is for this reason
that there is an extensive immunisation program in the UK. Note that from October
2003, sero-negative women of child-bearing age and health workers who require
protection against rubella are to be offered the combined measles-mumps-rubella
(MMR) vaccine.

        prodromal symptoms - may be none in young children; symptoms may include
         fever, headache, malaise and upper respiratory symptoms
        pink macular rash - pink macules develop on the face and then spreads to the
         trunk and limbs. The rash appears over one or two days. It fades within four
         days, leaving neither staining or desquamation. In some patients no rash
         develops at all
        cervical lymphadenopathy - especially post-auricular and sub-occipital nodes
        grittiness of eyes and suffusion of conjunctivae


Cause – RNA virus

Incubation – 14-21 days

Infectivity – 5 days before and 5 days after the rash starts

Signs – usually mild; macular rash, suboccipital lymphadenopathy


Confirmation of acute rubella infection should be undertaken in all suspected
cases

Child:

        saliva samples are appropriate for a child

Adult:

        serological samples are essential in the case of a pregnant woman with
         suspected rubella infection (1)
        haemagglutination inhibition antibodies appear soon after the rash and reach
         peak titres in 6 - 12 days. A rapid rise in HIA titres in paired sera obtained 2
         weeks apart in patients presenting within 2 weeks of exposure confirms
         rubella. Alternative methods of confirming the diagnosis include
         examinination of serum for rubella-specific IgM or virus isolation
Baby:

       the foetus does not produce specific IgM until 23 weeks gestation and no
        methods able to detect these in cord blood are currently in use - PCR is being
        evaluated
       congenitally infected babies are identified by detecting rubella virus specific
        IgM in the infant's blood:
            o less than 3 months, 100% IgM positive
            o 3 to 6 months, 90% IgM positive
            o 6 to 12 months, 50% IgM positive



Treatment – symptomatic

       none. Prophylaxis by active immunization

       antenatal screening identifies mothers who will require vaccination during the
        puerperium. From October 2003, sero-negative women of child-bearing age
        and health workers who need to be protected against rubella will be offered
        the combined measles-mumps-rubella (MMR) vaccine (1). However
        pregnancy should be avoided for at least one month after receiving rubella-
        containing vaccine because the vaccination is live

       if rubella infection is suspected during pregnancy then expert advice should be
        consulted. The diagnosis should always be confirmed - via virus isolation, or
        antibody tests showing seroconversion or specific IgM. All pregnant women
        with suspected rubella or exposed to rubella must be investigated
        serologically, irrespective of a history of immunisation, clinical rubella or a
        previous positive rubella antibody test (2). Therapeutic abortion is generally
        recommended after proven infection during the first trimester. The doctor
        must counsel her as to the risks associated with congenital rubella syndrome

       vaccination with live attenuated virus is contraindicated during pregnancy and
        expert advice should be consulted regarding management. If gamma globulin
        is given soon after exposure there may be a reduced incidence of clinical
        infection. However there may still be subclinical infection present and the
        fetus may still become infected. The value of gamma globulin given to
        pregnant women who are exposed to rubella is disputed. There is a minimal
        rise in antibody after the gamma globulin injection is given; this however does
        not cause difficulty in interpretation of subsequent serological tests

Infected infants excrete virus for months and are a source of infection.

Immunization – live virus
Complications – small joint arthritis – malformations in utero – infection during the
first 4 weeks: eye abnormalities in 70%, during weeks 4-8 cardiac abnormalities in
40%; weeks 8-12 deafness in 30%

       thrombocytopaenia
       encephalitis and polyneuritis
   arthritis or arthralgia in adolescents
   congenital rubella syndrome

				
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posted:12/9/2011
language:English
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