The demographic characteristics of the study population are shown in table I. The mean age was 25.01 years and their age ranged from18-38 years. Data showed that there was no significant association between the age of study subjects and the prevalence of anti CMV-IgM positivity (
=0.128). Prevalence of anti CMV-IgM positivity was more among 21-30 years age group which was not statistically significant. Prevalence of anti CMV-IgM positivity was significantly higher in pregnant women from urban area (
=0.05). Majority of the pregnant women of this study were Muslims (94.3%), housewives (88.3%), residents of urban areas (81%) and 68% of them had more than 5 years of schooling (table I).
Amongst the pregnant women 47 (15.67%) were of parity ≥ 3, 182 (60.66%) of parity 1-2 while 71 (23.67%) were primigravida. There was no association between parity/gravida and birth prevalence of CMV (
=0.95).
Data showed that there was no association between socioeconomic status and CMV infection (anti CMV IgM positivity) among pregnant women (p=0.287). Prevalence of CMV infection (anti CMV IgM positivity) was only 5.7% in upper class group (figure I).
Among the total 300 pregnant women,76.3% women were of average nutrition and 17.3% were of under nutrition (figure II) and there was no significant association between nutritional status and CMV infection among pregnant women (p=0.07) . No obese (BMI of 30 or higher) pregnant women was to be found among the study population.-a.
All 300 (100%) pregnant women were anti CMV IgG positive on their first visit. Among them, 180 (60%) were subsequently anti CMV IgM positive during different periods of their pregnancy. Among these 180 anti CMV IgM positive women 131 (43.7%) were positive in the first trimester, 35(11.7%) during their second trimester and 14 (4.6%) were positive during their third trimester. Birth prevalence of CMV IgM antibody was 1.3% among babies of anti CMV IgM positive mothers whereas none in CMV IgM negative mothers (OR 1.01, 95%CI .996-1.027). A significant (p<0.001) association of anti CMV-IgM positivity was demonstrated among anti CMV IgM positive mothers and their babies (table II).
Discussion
Cytomegalovirus (CMV) infection is a common viral infection in pregnancy.
9 Percentage of seropositivity varies among pregnant women from different countries and socioeconomic groups. A rough correlation exists between the prevalence of antibody and the socioeconomic conditions of the population. The prevalence of antibody is significantly higher in developing countries of Africa and Southeast Asia, whereas it is low in Europe, Australia, and parts of North America.
9 Various studies have demonstrated that the prevalence of antibody is significantly higher (85-100%) in India, 87.8% in Japan, 82% in Alabama, 100% in Entebbe and Fiji, whereas 57% in Washington USA and 44% in. Oxford UK.
10-13 Serological surveys from different parts of India have shown 80-90% prevalence of CMV IgG antibodies in women of childbearing age.
14 Satilmis et al showed the rate of seroprevalence was 98.5% among pregnant woman from Turkey.
15 This study demonstrated that 100% pregnant women were seropositive in their first antenatal visit, reflecting a high seroprevalance in Bangladesh. High seroprevalence (97%) was also observed in another study from Bangladesh.
16 Redwan et al showed 83.6% prevalence in Bagladeshi population.
17 Ashrafunnesa et al observed slightly lower but still a high prevalence (68.6%) in antenatal population in Bangladesh. Socioeconomic status, level of education might be responsible for the high prevalence of CMV.
18 CMV prevalence among pregnant women might also be affected by having children.
19,20 In this study, 91.3% pregnant women belong to middle class and below middle class groups, 66.3% had ≤10 years of schooling and 76.33% had children.
Pregnancy is associated with a functional immunosuppression and, thus, may increase the risk of acquiring infections.21Due to latency and periodic reactivation of CMV, transmission in utero may follow either primary or reactivation of latent infection. This study demonstrated that among all the CMV IgG seropositive women 180 (60%) became CMV IgM positive during some point of their pregnancy. As CMV seroprevalance is high in Bangladesh and mothers were already CMV IgG positive, these 180 (60%) cases may be considered as reactivation of CMV during pregnancy. The prevalence of congenital infection was 1.3% in this study. In India congenital CMV infection was observed in 2.4%.8In a study from Sapporo, Japan, the rate of congenital infection was reported to be 0.31%. Of them, 13.5% were symptomatic at birth, 5 to 17% of them were likely to develop progressive sensorineural hearing hearing loss within their first 4 years of life.
22
Congenital infection due to primary maternal infection is usually associated with more severe sequel.
6 Cytomegalovirus infection frequently occurs despite substantial humeral immunity in mothers, which is most often due to reactivation of latent virus.
23,24 In fact, in some populations intrauterine cytomegalovirus infections are predominantly associated with reactivation of maternal infections. Stagno et al reported that the prevalence of congenital infection was 3.4% in an immune population.
12 Despite the apparent lack of protection, maternal immunity may still exert a beneficial effect by reducing the virulence of infection in the fetus and developing infant. Recently it was demonstrated that reactivation or recurrent infection can cause severe fetal sequel despite maternal preexisting immunity. It has been suggested that the possibility of recurrences and unfavourable outcome may be related to reinfection by a new viral strain.
7 A study from India reported that all 9 (2.1%) CMV positive infants were born to mothers who were CMV seropositive at the first antenatal visit.
8 Among them one child had hepatosplenomegaly at birth while another child had mild unilateral hearing loss at 4 months of age. Another study from United Kingdom also showed symptomatic CMV infection at birth (18 %) in infants of the primary-infection group. After a mean follow-up of 4.7 years, one or more sequelae were seen in 25% of the primary-infection group and in 8% of the recurrent-infection group. Sensorineural hearing loss was found in 15 percent of those in the primary-infection group and in only 5% of those in the recurrent-infection group. Bilateral hearing loss was identified only among children in the primary-infection group (8%).
6
Conclusion
Based on this study, it may be concluded that CMV IgG seroprevalence is high among Bangladeshi women, and the rate of CMV reactivation is also high during pregnancy. Despite the protection of maternal immunity, a certain percentage of babies acquire congenital CMV infection. In this context, it may be recommended that a screening program for CMV IgG and IgM antibodies should be conducted at the first antenatal visit. Considering the high risk of mother-fetus transmission and fetal damage, prenatal diagnosis should be recommended to women with primary CMV infection. To determine the manifestations and long term sequel of congenital CMV infection, conduction of longitudinal studies are thus suggested.
Conflict of interest: There is no conflict of interest about this article.
Acknowledgements: The study was supported by Bangabandhu Sheikh Mujib Medical University (BSMMU) under (Health Nutrition & Population Sector Development Programme) HNPSDP Fund, Bangladesh.
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