Exposure rate of VZV among women attending antenatal care clinic in Sri Lanka - a cross sectional study

Abstract

BackgroundVaricella or chickenpox was not a notifiable disease until 2005 in Sri Lanka and only a few studies have been conducted on the epidemiology of VZV infection in the country. The anti­VZV IgG sero-prevalence among antenatal women is extremely limited and thus a selected group of antenatal clinic attendees were chosen to determine the exposure rate to VZV infection.MethodsWomen attending the antenatal clinic at Teaching Hospital, Peradeniya, Sri Lanka were selected for the study and 3 mL of venous blood was collected from 181 participants and the demographic data was obtained through a pre­tested questionnaire. Sera of the women were then tested for the presence of anti­VZV IgG using ELISA (HUMAN Diagnostics, Germany). Data was analysed using the SPSS statistical software for Windows, Version 12.0.ResultsOf the 181 antenatal women who took part in the study, 141 were positive for anti­VZV IgG giving a sero-prevalence of 77.9% for the past exposure to VZV. Of the 141 anti­VZV IgG positive women, 43.3% (n = 61) were from urban, 41.8% (n = 59) were from rural and 14.9% (n = 21) were from estate populations (an ethnic population living in small settlements in the tea estates whose ancestors were brought from India during the British colonial period to work in the tea plantations in Sri Lanka). Out of the 88 antenatal women with a positive history for varicella, 85 (96.6%) were positive for anti-VZV IgG. The highest number of anti­VZV IgG positivity was seen in the 31–35 age group, which was 85.0% of the total number of antenatal women included in that category. An increase in the anti­VZV IgG sero-prevalence with increasing age was also noted in the study sample.ConclusionExposure rate of VZV infection as confirmed by anti­VZV IgG in the present study sample of antenatal women was 77.9%. Age specific, population based future sero-prevalence studies should be conducted in Sri Lanka to understand the anti-VZV IgG status in the country.

Susceptibility for varicella and factors associated with immunity among pregnant women in a tertiary care hospital in Sri Lanka- a cross-sectional study

“…There is also a possibility of waning antibody titres following infections during early life. These findings are comparable to the results of other Sri Lankan [15] and international studies [21, 25].…”

“…This is comparable to the 62% rate detected in the study done among women of childbearing age in Colombo district [14]. However, the study conducted among pregnant women in Peradeniya, Sri Lanka detected a slightly higher seroprevalence of 77.9% [15]. This could be due to differences in climatic factors of the two areas, where Peradeniya is situated in the central province of the country, in a cooler climatic zone and Colombo is situated in the western province in a warmer area.…”

“…A recent Sri Lankan study conducted in the district of Colombo had shown that varicella seroprevalence rose from 34.5% in the 10–19 year age group to 63.1% among the 20–39 year age group and then to about 75% in those above 40 years of age [14]. A study carried out among antenatal mothers in Sri Lanka also reported an increasing seroprevalence rate with advancing age with an average rate of 77.9% [15].…”

“…Prior to implementation of any specific prevention strategies for the women of reproduction age group it is essential to assess the susceptibility of this population. Only a few studies had been conducted so far aiming this population in recent past, two of which detected discrepant seroprevalence rates of 62% [14] and 77.9% [15]. Additional data will be useful for developing vaccination policies for this population and to predict susceptibility.…”

Epidemiology and factors influencing varicella infections in tropical countries including Sri Lanka

“…However, in the recent past, one of our studies reported an increased exposure rate of 78% to VZV in a group of antenatal women aged between 18 and 45 years. Moreover, in the study sample, those that were more than 40 years had a sero-prevalence of 100% to anti-VZV IgG and thus an increment in the exposure rate to VZV was noted with increasing age [14].In a more recent study conducted in Sri Lanka, the overall anti-VZV IgG sero-prevalence in the women of childbearing age was 62% and it was as low as 37% in the 15-19 years age group [35].…”