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 Table of Contents  
ORIGINAL ARTICLE
Year : 2016  |  Volume : 15  |  Issue : 1  |  Page : 24-29

Seroprevalence of cytomegalovirus antibodies among antenatal clinic attendees in Abakaliki, Nigeria


1 Department of Obstetrics and Gynaecology, Federal Ministry of Health, Abuja, Nigeria
2 Department of Obstetrics and Gynaecology, Ebonyi State University, Abakaliki, Nigeria

Date of Web Publication10-Jun-2016

Correspondence Address:
Odidika Ugochukwu Joannes Umeora
P. O. Box 980, Abakaliki, Ebonyi State, 480 001
Nigeria
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/2384-5589.183883

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  Abstract 


Context: Cytomegalovirus infection is potentially neurotoxic to the fetus when it occurs during pregnancy. The prevalence is not known within our population. Aims: To determine the seroprevalence of Cytomegalovirus antibodies in pregnant Nigerian women at a tertiary health facility in Southeast Nigeria. Methods: This was a laboratory-based cross sectional descriptive study. Pregnant women who consented to the study were recruited from the antenatal clinics of the Teaching Hospital. Blood samples were collected from them and analysed using ELISA techniques. The relationships between positive CMV antibodies and socio-demographic variables were analysed using Chi square test and linear regression analysis. Results: Two hundred and four (204) serum samples were analysed. CMV seroprevalence was 96.08%. Two hundred and one (98.5%) participants were not aware of CMV infection. Lower socioeconomic class was associated with increased seroprevalence of Cytomegalovirus (P=0.004). Multiparous women were more likely to acquire CMV infection than primigravide women (P=0.009). There was a strong association between maternal place of residence and CMV seropositivity (P=0.023). The association between increasing maternal age and CMV seropositivity did not achieve statistical significance (P=0.246). Conclusion: Cytomegalovirus seroprevalence is high among participants and awareness of this disease is low. There is need to create further awareness of this disease.

Keywords: Abakaliki, cytomegalovirus, fetus, prenatal care, seroprevalence


How to cite this article:
Anuma ON, Umeora OU. Seroprevalence of cytomegalovirus antibodies among antenatal clinic attendees in Abakaliki, Nigeria. Afr J Med Health Sci 2016;15:24-9

How to cite this URL:
Anuma ON, Umeora OU. Seroprevalence of cytomegalovirus antibodies among antenatal clinic attendees in Abakaliki, Nigeria. Afr J Med Health Sci [serial online] 2016 [cited 2020 Oct 23];15:24-9. Available from: http://www.ajmhs.org/text.asp?2016/15/1/24/183883




  Introduction Top


Cytomegalovirus (CMV) infection in pregnancy may cause mental retardation, congenital deafness, and damage to the fetus following vertical transmission.[1],[2] The infection affects 1–2% of all pregnancies [3] and its transmission rate varies between 24% and 75%, averaging 40%.[4],[5] Congenital lesions are more serious when following primary infection [6] than with re-infection or reactivation during pregnancy.[7] Prenatal infections of CMV infection have more severe fetal consequences, and infection in the first trimester may affect the sequence of organogenesis leading to congenital malformation while infection in the second and third trimesters may cause neurological impairment or growth restrictions in the fetus.[8] Other consequences of congenital CMV infection include hepatomegaly, chorioretinitis, and sensorineural hearing loss in the newborn,[9] thrombocytopenia with petechiae and purpura, hepatitis, pneumonitis, and faulty neurologic development consisting of microcephaly, optic atrophy, aplasia of various parts of the brain and microphthalmia.[3] Stagno et al.[6] reported that 10% of fetuses infected with CMV are symptomatic at birth, 20–30% do not survive due to severe lesions and the great majority present with delayed neurological manifestations such as bilateral neurosensory deafness and mental retardation. The symptomatic infants who survive are more likely to develop long-term neurological sequelae including hearing loss, visual impairment, psychomotor delay, and mental retardation.[6] Symptoms and debilitating sequelae are relatively rare among infants who become infected following a re-infection or reactivation of CMV.[7]

The presence of IgM antibodies in the serum of pregnant women may represent either a primary infection or a recurrent infection. High titers of IgG antibodies may represent a preconceptional immunity to CMV infection following a primary infection and has been associated with reduced risk of transplacental transmission of CMV infection. Therefore, accurate information of the serological status of the pregnant woman by the obstetricians could assist in identifying women at high risk of having fetuses with congenital malformation and institute measures to diagnose and undertake fetal surveillance of mildly affected fetuses or counsel the couples for termination of pregnancy in grossly affected fetuses.

CMV infection is more common in developing countries [10] and seroprevalence varies greatly with a variety of epidemiological factors [11] Okwori et al.[12] in Bida, Nigeria reported a seroprevalence of 84.2% among pregnant mothers, while Kassim et al.[13] in a study of CMV antibodies in breast milk and sera of mother-infant pairs, reported a seroprevalence of CMV infection in mothers to be 91%. A seroprevalence of between 40% and 90% has been reported from other parts of the world including India.[3],[14]

There are few reports [12],[13] on the seroprevalence of CMV antibodies among pregnant women accessing prenatal care in Nigeria, and no such reports have been documented in Ebonyi State and the South East geopolitical zone. This study is aimed at determining the seroprevalence of CMV antibodies among antenatal clinic attendees in Ebonyi State University Teaching Hospital (EBSUTH), Abakaliki.


  Materials and Methods Top


Study population

This study includes all pregnant women who were booked at EBSUTH from January 1, 2010, to December 31, 2010. The exclusion criteria were those who refused consent and those with unknown gestational age. The educational status of the women and their husbands' income were used for determination of the socioeconomic status of the pregnant women as advocated by Olusanya et al.[15] Considering a formula for the calculation of sample size in a cross-sectional study as proposed by Daniel [16] a sample size of 204 was gotten.

Study design

This study is a laboratory based descriptive cross-sectional study involving 204 pregnant women who booked for antenatal care at EBSUTH and enlisted voluntarily to participate in the study. They signed informed consent form before enlistment into the study. A questionnaire containing information on age, marital status, awareness of CMV, residential location, parity, educational status, occupation, previous history of miscarriage, previous history of delivery of a malformed baby, history of fever in the index pregnancy, socioeconomic status, and place of residence was administered to each participant by the researchers before collecting blood samples.

Bioethical issues

This research was granted ethical approval by the Research and Ethics Committee of EBSUTH, Abakaliki. Clients who were seropositive for CMV antibodies were referred to the feto-maternal unit for further evaluation and management at no additional cost. Where applicable they were referred to the clinical psychologist for counseling.

Data management and analysis

Information collected was recorded on a data collection sheet designed for the study. The coded data were then fed into the computer using EPI info (2005) version 3.3.2 program (CDC Atlanta USA). Chi-square test and linear regression analysis were used as a statistical tool for analysis. A P < 0.05 was considered significant.


  Results Top


Two hundred and four pregnant women were enrolled consecutively into the study. The characteristics of the study population are as summarized in [Table 1]. The participants' ages ranged from 18 to 40 years with a mean age of 27.37 ± 5.31 years. Majority belonged to social Classes 4 and 5 (70.1%). Two hundred and one women (98.5%) were not aware of CMV infection. Fifty-six (27.5%) had spontaneous abortions in the past. None of the women had given birth to a congenitally malformed baby. [Table 2] shows that the CMV Seroprevalence for both IgG and IgM antibodies was 96.1%. However, the seroprevalence of CMV IgG antibodies was 94.6% while that of IgM antibodies was 43.6%. An overview of the seroprevalence of CMV according to social class is presented in [Table 3]. The lower the socioeconomic class, the higher the proportion of seropositive women with about 66.2% seropositive cases occurring in social Classes 4 and 5. The difference in CMV seropositivity observed in this study between the various social class were statistically significant (χ2 = 13.18, P = 0.004). The linear regression analysis showed that P = 0.012. As shown in [Table 4], there was a clear trend of rising seroprevalence with increasing parity from 26.5% in nulliparas to 69.6% in those from para one and above. This was statistically significant (χ2 = 9.34, P = 0.009). Linear regression analysis (F = 8.18, P = 0.039) done showed that there was a strong relationship between parity of the pregnant women and CMV seropositivity. [Table 5] reviewed the association of residence of the client with CMV seropositivity. There was a strong positive association between the location of residence and acquisition of CMV (χ2 = 5.16, P = 0.023). [Table 6] shows the distribution of CMV antibodies by age group. There was a clear trend in the distribution of CMV infection starting from 8.82% seroprevalence in the 15–20 years age group and rising steadily till it peaks at 26–30 age groups (34.8%) then declined to 13.73% and 8.82% in the 31–35 and 36–40 years age groups, respectively. There was, however, no statistically significant difference in the observed trends (χ2 = 5.43, P = 0.246). Linear regression analysis (F = 2.26, P = 0.118) done showed that there was no relationship between the various age groups and CMV seropositivity.
Table 1: Sociodemographic characteristics of the 204 study participants

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Table 2: Serologic pattern of cytomegalovirus infection in pregnant women

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Table 3: Seroprevalence of cytomegalovirus among socioeconomic classes

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Table 4: Seroprevalence of cytomegalovirus and parity of pregnant womenxs

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Table 5: Residence and seroprevalence of cytomegalovirus among pregnant women

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Table 6: Distribution of cytomegalovirus infection by age group (years)

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  Discussion Top


The epidemiology of human CMV infection in a given obstetric population, and the relative importance of different modes of transmission, is likely to be determined by the cultural practices of the population relating to breastfeeding,[17] child rearing, child care arrangements,[18] sexual orientations and behavior,[19] socioeconomic status, hygienic measures, and the health-care system.[20]

Maternal CMV infections may be prevented by simple hygienic precautionary measures such as frequent and thorough hand washing.[4] Despite this opportunity to prevent infection in mothers and subsequent disability especially neurological disability in their offspring, anecdotal evidence suggests that the general public has little awareness or knowledge of CMV.[20] In this study, 201 (98.5%) pregnant women who enrolled for the study were not aware of CMV infection. In a similar study in the United States of America, Jiyeon et al.,[20] surveyed 643 women, and only 142 (22%) had heard of congenital CMV infection compared with 97% who had heard of down syndrome and 98% had heard of HIV/AIDS.

The CMV seroprevalence for both IgG and IgM antibodies for this study was 96.1%. This was similar to an earlier study done in Ife by Kassim et al.[13] who reported a seroprevalence of 91%[13] but was higher than 84.2% reported by Okwori et al. in Bida.[12] It was also similar to reports from other developing countries such as Turkey 94.9%,[21] Egypt 96%,[22] and India 91.05%[23] but differs from those reported in developed countries such as, France 51.5%,[24] Japan 77.5%,[25] Finland 70.7%,[26] USA 58%,[27] and United Kingdom 45.9%.[28] The differences between CMV seroprevalence reported in this study and other developing countries compared to developed countries could be explained by differences in socioeconomic conditions, hygienic conditions, breastfeeding practices, overcrowding, source of drinking water, place of abode, and type of toilet facilities.[29] The role of socioeconomic status as a risk factor for acquisition of CMV was confirmed in this study following linear regression analysis. The reason may relate to poor hygienic living condition, overcrowding, poor toilet facilities, and less likelihood of proper hand washing among women in the lower socioeconomic groups compared to those in the upper socioeconomic class.

The CMV IgG seroprevalence in this study was 94.6% while that for IgM was 43.6%. The IgG seroprevalence correlates with findings from Benin Republic, 97.2% but differs from 2.9% reported for IgM antibodies.[30] This clearly indicates a higher recurrent rate or re-infection in the obstetric population in this study. The risk of fetal CMV infection and the potential for damage once infection has occurred are dependent on two main factors: The serostatus of the mother and the temporal proximity of CMV infection to pregnancy.[27] Women who enter pregnancy with CMV antibodies and thus infection sometime before conception have a 69% less chance of delivering congenitally infected infants compared with seronegative women who experienced primary infection during pregnancy.[3] This assertion was confirmed in this study since none of the 204 pregnant women that enrolled in this study had any history of delivering a congenitally malformed baby in the past despite the high titers of both the IgG and IgM antibodies reported in this study and the CMV infection may have been acquired in childhood long before they became pregnant. Findings from epidemiological studies suggest that preconceptional maternal CMV neutralizing antibodies can in most cases prevent significant fetal infection.[31] The limitations of this study were that the researchers did not follow-up the pregnant women till delivery and the placenta was not examined for histological evidence of CMV infection and the presence of interferons, but the overwhelming evidence of high maternal antibodies titers to CMV could reasonably explain the absence of congenital malformations in the offsprings of these mothers since the antibodies could confer some level of immunity in more than 69% of cases.

CMV infections impair cytotrophoblast expression of HLA-G, an important component of the mechanism that protects fetal cells from removal by maternal immune cell. Canyilmaz et al.[32] also observed that the rate of cervical CMV excretion was higher among women who had a history of spontaneous abortions. These findings probably explain the high rate of abortions (27.5%) observed in the women who enrolled for this study.

As observed in this study, the increasing prevalence of CMV infection with advancing maternal age was also corroborated in the study done by Susan et al.[33] Other studies have shown increasing seroprevalence with increased maternal age among pregnant women regardless of demographic groups.[34],[35] One will expect seroprevalence rates to increase with maternal age as was observed in this study because the presence of IgG antibodies represents cumulative exposures over time especially among women of low socioeconomic status. Despite the clear trend in CMV seropositivity observed in the various age groups, linear regression analysis, and Chi-square test (P > 0.05) did not confirm any significant association between age group and CMV seropositivity.

The significantly higher rates of CMV seropositivity (P < 0.05) reported in rural women in this study compared to those in urban women was confirmed by an Israeli study.[35] This could be explained by the relative poor hygienic condition in the rural areas, overcrowding in households, poor standard of living, and poor disposal of fecal matter from children.

The association of parity with increased CMV seropositivity as reported in other studies was confirmed in this study (P < 0.05). Multiparous women in this study were more likely to acquire CMV infection than their primiparous counterpart. Linear regression analysis showed a strong relationship between parity of the pregnant women and CMV seropositivity. Other explanation for the association of parity and CMV seroprevalence could be that women who have had more pregnancies also have on average, had more previous sexual partners.[29] Factors relating to child care, use of daycare arrangements, sexual activities, and socioeconomic status are other reasons to account for the strong association between parity and CMV seropositivity in this study.


  Conclusions Top


This laboratory-based descriptive cross-sectional study demonstrates that CMV infection is common among pregnant women in Ebonyi state. Low socioeconomic status, high parity and residence in rural areas are risk factors associated with the acquisition of CMV infection as demonstrated in this study.

Given the low awareness of CMV infection among pregnant women in this study, raising awareness of CMV infection among our pregnant women and their healthcare providers will be an important step. Such awareness can lead to improvement in hygienic behavior among pregnant women and immediately impacting on the congenital CMV disease acquisition and transmission rate.

Though CMV infection does not constitute a major public health problem in Nigeria, Vaccine development continues to be a major public health priority in most developed and developing countries where in utero CMV infection has been evidently linked to fetal congenital malformation. Until an effective CMV vaccine is licensed, education of young women regarding hygienic and behavioral approaches that can help prevent CMV transmission is essential. Obstetricians can lead the way in ensuring that appropriate counseling about the risks of CMV becomes a mainstay of prenatal care.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

 
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  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6]



 

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