and Paula Briggs2
(1)
Department of Obstetrics and Gynaecology, Monash University, Clayton, Victoria, Australia
(2)
Sexual and Reproductive Health, Southport and Ormskirk Hospital, Southport, UK
Varicella (Chicken Pox)
Definition
Varicella Zoster Virus (VZV) is a DNA virus of the herpes family. Infection results in a vesicular eruption of the skin.
Incidence
It is estimated to occur in 3 in 1,000 pregnancies
Aetilogy and Pathogenesis
The virus is transmitted by vesicular fluid from the blisters or respiratory fluid. The incubation period is 1–3 weeks. The person is infectious for 48 h before the rash appears and until after the lesions crust over. The virus remains dormant in the dorsal root ganglia of the sensory nerves, and can be reactivated along the nerve root distribution as shingles.
Infection can be prevented by immunisation before pregnancy using a live attenuated vaccine.
Clinical Assessment
History
The primary infection is a typical viral illness associated with flu- like symptoms. A characteristic itchy maculo-papular rash develops.
Examination
The rash is maculo-papular initially, followed quickly by a vesicular eruption.
Investigations
Blood sample for varicella zoster (IgG)
Culture from the vesicular fluid
PCR testing from maculopapular rash or scabs
Treatment
Medical
Prevention – Women pre-pregnancy should be asked about a history of chicken pox (this is 97 % reliable as an index of immunity). If this is negative, their immunity should be checked for varicella antibodies. If they are VZV negative, immunisation should be undertaken. As the immunisation is with an attenuated strain of live VZV, pregnancy should be avoided for 3 months following immunisation.
Contact during pregnancy – If the contact is definitely confirmed, and the woman has no history of previous infection, her immunity should be checked as a matter of urgency. If it is confirmed that she is not immune, Varicella Zoster Immunoglobulin (VZIG) should be administered. This is effective up to 10 days after contact.
Developing chicken pox during pregnancy –
Women who develop chicken pox during pregnancy should commence antiviral therapy within 24 h of the rash appearing (Aciclovir 800 mg, five times a day for 7 days). VZIG is of no benefit once the chicken pox rash has established.
Complications
Pneumonitis, neurological symptoms, haemorrhagic rash.
Prognosis
The infection may be transmitted to the foetus resulting in Foetal Varicella Syndrome. This is uncommon, but can cause eye defects, limb deformity and neurological abnormalities.
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