Last Updated : 12/30/2010
M R Lokeshwar, S B Bavdekar, Nitin Shah, Poonam Shahani

varicella zoster virus (VZV)

, one of the eight human herpesviruses, causes two illnesses : a primary infection, chickenpox and a recurrent infection, herpes zoster, resulting from reactivation of latent virus from dorsal sensory ganglia. Chickenpox is one of the most highly infectious diseases where 90% of susceptible develop the disease following exposure to a close contact. The infection spreads mainly through air-borne transmission (droplet infection), although the vesicular lesions in both varicella and zoster are full of infectious VZV. Transplacental infection of the fetus during maternal infection can be considered as the third mode of transmission.

Chickenpox has a characteristic exanthem that manifests after the prodromal symptoms such as fever, headache, malaise and anorexia. The skin lesions appear on the trunk, scalp, face and extremities. The rash progresses in stages over a one-week period-macule, papule, vesicle, pustule and crusted lesion. An immunocompetent child develops 250 to 500 vesicles. The child is infectious to others from 2 days prior to the onset of skin lesions until the lesions have crusted (1). In immunocompetent children, the commonest complication is a secondary bacterial infection, although pneumonitis, hepatitis, encephalitis, arthritis, pericarditis, Reye's syndrome, Guillain-Barre syndrome, Bell's palsy, transverse myelitis and glomerulonephritis are known to occur. The immunocompromised individuals are prone to develop a severe course of disease, which carries a higher risk of death due to complications.

Chickenpox is commonly an infection of young children, in whom it usually follows a milder course. This is especially true in temperate climates e.g. over 90% of the US population experiences this infection by the age of 15 years (2). In contrast, in tropical climates there is an increase in the number of cases occurring at older age. This has important health implications- the disease itself is more severe and complications are more common and more serious (3). Thus, what Trousseau wrote in 1869 that "no physician has ever seen a patient die of chickenpox, though of course there may be fatal issue from some complications independent of exanthematous fever", is no longer true. Chickenpox is becoming more frequent in adult population and with this, number of patient who suffer the sequelae of infection including death also will go up (2).

Maternal chickenpox during pregnancy
In temperate climates, chickenpox is unusual in adulthood. Similarly, it is an uncommon disease in women during their childhood bearing years. In the USA, varicella during pregnancy is estimated to occur in only 5-10 per 10,000 pregnancies (4,5). In UK, the reported annual incidence in adult aged 15-44 years is 3 per 1000 (6). However, the situation could be different in countries outside the temperate zone. Serological studies have shown that only up to 30% of student and staff nurses aged 17-20 years in Vellore had complement-fixing antibodies to chickenpox (6) and as many as 28% of young adults aged 15-25 years had no antibodies against varicella (7). Similarly, Weller (8) reported that in tropical and subtropical regions 20-50% of infections occur in teenagers and adults.

Questionnaire study done at UK in 18/30 units comprising of 1,64,000 deliveries over two years period reported 98 cases of varicella during pregnancy in almost one case per 2000 deliveries (5). However, it is likely that this represents a significant under reporting as many of milder cases would not necessarily be bought to attention of obstetricians.

Kjersem and Jespen noted increased incidence of varicella in Tamil refugees in Denmark, which included pregnant women (9). Thus it appears that although in temperate zone countries only about 10% of pregnant women could be susceptible to varicella infection; this figure could be much higher in tropical and subtropical regions.

In non-tropical countries 89-90% of pregnant women have been exposed to varicella during childhood and therefore have immunity. However 10% who are susceptible should be identified.

Serological testing

should be done at initial pregnancy booking visits, so that those who are susceptible can be identified. There is strong correlation between history and checkup and presence of VZV antibodies so that serological testing needs to be offered only to 15.25% who cannot recall having had chickenpox. Immunocompromised patients, particularly those with BM transplants, leukemia, steroid therapy, or other disorders associated with depressed cell mediated immunity, are perceived to be at high-risk complications. Analysis of death certificates for 100 of fatal chickenpox cases during 1985-90 showed immunocompromised state to be an important factor in individuals over one year age (6)

Though primary varicella infection in adulthood usually has a more severe course than childhood chickenpox and carries a higher complication rate, the natural history of chickenpox in pregnancy is poorly defined. The earlier reports indicating increased incidence of complications (10,11) and a high mortality of 41%(10) have not been substantiated over time (1,12). Still many experts believe that pregnancy is one of the risk factors for severe varicella (13). However, a recent review has blamed this perception on a bias towards reporting severe cases during pregnancy (14).

If a mother develops varicella infection during pregnancy, there are consequences for her fetus and neonate due to transplacental transfer of infection. These potential consequences depend on the timing of infection (Table 1) and include intrauterine death, Fetal varicella syndrome, and congenital varicella zoster in infancy. The frequency of transplacental transmission has been reported in two large prospective studies. The study performed in New York (15) reported an increase of congenital anomalies (7.4%) associated with first-trimester chickenpox, which was higher than that in control population (3.4%). However, no significant increase in fetal wastage occurred when compared with the control group. Another prospective study recently reported that as many as 12.3% of asymptomatic newborns could be judged to have been infected after maternal varicella infection, on the basis of specific IgM positivity rate in the cord blood (12).

Table 1 : Potential consequences of maternal varicella infection during pregnancy

Timing of maternal infection Consequences for fetus neonate or infant

Early pregnancy

 Spontaneous abortion, fetal varicella Syndrome.

At any stage

 Intra-uterine death, herpes zoster during first  year of life.

Near term Congenital varicella or neonatal varicella.


Contributor Information and Disclosures

M R Lokeshwar, S B Bavdekar, Nitin Shah, Poonam Shahani
PD Hinduja Hospital and Medical Research Centre, Mahim, Mumbai-16.

First Created : 2/25/2001


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