Varicella Infection in Pregnancy - Consequences for Foetus and Neonate

Dr. Sayenna A Uduman, Dr. Abdul Kareem Uduman
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Abstract
Varicella is usually a benign and common childhood febrile exanthematous viral disease. But varicella infections can be serious, especially in adults including pregnant women and newly born infants. Maternal infection in pregnancy presents several management problems for clinicians. Unrecognized and unprotected maternal infection may cause severe pneumonia for the mothers and may lead to in-utero transplacental fetal transmission (Congenital varicella syndrome) and /or causing severe varicella disease and even death soon after birth (Neonatal varicella). A timely diagnosis of varicella in pregnant women is important to initiate earlier prophylactic and therapeutic measures in order to minimize varicella related maternal and neonatal complications.

Keywords: Maternal varicella, Pregnancy, Pneumonia, Congenital, Neonatal varicella , immediate immunoprophylaxis, Prevention.

Varicella Zoster Virus (VZV) infection is a member of the Herpesviridae family that causes primary varicella infection, known as chickenpox which may also be called by its International Committee on Taxonomy of Viruses (ICTV) name, as human herpes virus 3 (HHV-3). After primary varicella infection, the virus becomes latent in the dorsal root ganglia and may reactivate later as herpes zoster or shingles.
Varicella is now a vaccine preventable disease by routine childhood immunization. Varicella occurs in sero- susceptible individuals especially in adults including pregnant women, is often complicated and life threatening. In general, more than 90% of the antenatal population are seropositive and possess protective VZV IgG antibodies. Women from tropical and subtropical areas are more likely to be seronegative for VZV IgG and are therefore, more susceptible to the development of severe and complicated chickenpox. In these clinical settings, varicella infection affects three or more of every 1000 pregnancies (Observational data; KIMS Hospital Thiruvananthapuram, India 2017). Varicella pneumonia in pregnancy must be regarded as a medical emergency.

Maternal infection: First and second trimester infection can transmit VZV to their fetuses transplacentally resulting in Congenital-Varicella-Syndrome (CVS).
However, infants who are exposed to VZV in utero beyond 28 weeks of gestation, and more than 5 days before delivery (peripartum), generally are protected from severe infection by the transplacentally derived maternal IgG antibodies. Some of these infants may develop asymptomatic varicella infection in utero and may develop reactivated zoster manifestation in early childhood,
In contrast, neonatal or peripartum varicella, pregnant women when develops varicella rash around the time of delivery (i.e. onset of rash less than 5 days before delivery or within 2 days after delivery) often results in severe disseminated varicella in the newborn infant, which has substantial mortality.

Varicella complication in pregnant mothers:
Pneumonia has been reported to complicate 10 to 14% of chickenpox infections in pregnancy and the severity of the pneumonia seems to be increased in later gestation. More recent literature reports mortality of 0-14%, a reduction that has been attributed to antiviral therapy and improvements in ICU care facilities

Fetal and neonatal consequences of maternal varicella are:
CVS: is an extremely rare disorder in which affected infants have distinctive abnormalities at birth (congenital). The highest risk (2%) occurs when mothers are infected during weeks 13 to 20 of gestation. Rarely, cases of CVS have been reported in infants of women infected after 20 weeks of pregnancy, the latest occurring at 28 weeks gestation. The CVS has also been designated as fetal varicella syndrome, varicella embryopathy, or varicella fetopathy.
The typical features of CVS include a characteristic scarring skin lesion known as a cicatrix (in >60% of cases) that occurs often in a dermatomal distribution. Other clinical manifestations include hypoplastic limbs cataract, cortical atrophy or mental and developmental delays.

Neonatal Varicella: In contradistinction to CVS embryopathy, maternal varicella contracted during the period from 5 days prior to and 2 days following delivery can result in a severe acute varicella in the newborn, When maternal varicella occurs just before delivery, infants may be exposed to the virus . As a result, neonatal attack rate ranges from 24 % to 59%, and neonatal mortality may be as high as 30%. Death typically is from varicella pneumonia. Newborns who are exposed in this manner should be treated with varicella-zoster immune globulin (VariZIG) as soon as possible and certainly within the first 3 days of life. Polyclonal intravenous immunoglobulin (IVIG) is an alternative if variZIG is not readily available for use.

Diagnosis of maternal varicella: (should seek Infectious Diseases and Fetal Medicine Consultation for diagnosis and case management aspects)
Laboratory diagnosis of chickenpox usually is not required. Varicella is a clinical diagnosis because of the characteristic vesicular rash and its distribution. Also, a recent exposure and /or absence of prior varicella history is helpful
In doubtful cases, diagnosis of varicella rash can be confirmed by swabbing the base of the skin lesion or sending vesicle fluid for VZV PCR. Maternal serology testing can also be helpful and a positive VZV IgG antibodies in a single serum sample is supportive of the maternal immunity status

Diagnosis of Congenital and perinatal Infection
Definitive diagnosis of the CVS syndrome can be difficult. VZV-specific IgM is diagnostic but is not consistently detected. PCR and in situ hybridization also can be used if tissue is available. Women who develop varicella during pregnancy should be counseled about the fetal risks versus benefits of amniocentesis to detect VZV by polymerase chain reaction (PCR). Amniocentesis should not be performed before the skin lesions have completely healed. VZV-specific IgM is diagnostic but is not consistently detected. VZV DNA has a high sensitivity but a low specificity for the development of fetal varicella syndrome.
Prenatal diagnosis is possible using detailed ultrasound examination. A time lag of at least 5 weeks after the primary infection is advised because ultrasound performed at 4 weeks has failed to detect the deformities. Fetal MRI imaging can be useful to look for morphological details of fetal abnormalities.


References
Varicella Infection in Pregnancy - Consequences for Foetus and Neonate Varicella Infection in Pregnancy - Consequences for Foetus and Neonate 09/05/2018
Management: varicella in Pregnant women & their Newborn: >>
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