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Vaccine 28 (2010) 7202–7206

Contents lists available at ScienceDirect

Vaccine

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ubella: Serosusceptibility among Egyptian females in late childhood andhildbearing period

ohamed Hashema,∗, Mohamed Hasan Huseinb, Doa’a A. Salehb, Rehab Abdelhaib,man Eltahlawyc, Hala Esmatd, Nagah. Horeeshb, Mounir Abdallae, Nadia Moustafad,many El-Goharyd, Nahed Azzazie, Amr Kandeele

International Health Division, Department of Epidemiology & Preventive Medicine, University of Maryland School of Medicine, Baltimore, MD, USADepartment of Community Medicine, Faculty of Medicine, Cairo University, Cairo, EgyptNational Research Center, Environmental Health Department, Cairo, EgyptCentral Public Health Laboratory, Ministry of Health, EgyptCommunicable Disease Control Department, Ministry of Health, Egypt

r t i c l e i n f o

rticle history:eceived 4 April 2010eceived in revised form 8 August 2010ccepted 12 August 2010

a b s t r a c t

Our objective was to determine age-specific rubella susceptibility among Egyptian females. This wasa cross-sectional survey in eight randomly selected communities, with the largest number of reportedrubella cases in the 2007 Rubella surveillance. A sample of 5672 females between the ages of 6 and45 years were interviewed. Of those 602 blood samples were obtained and tested for rubella IgG. The

vailable online 25 August 2010

eywords:ubellapidemiologymmunization

proportion of seronegative females was 9.7%. The highest proportion of susceptible females was in theages between 6 and 25 years and the highest risk of susceptibility was among unmarried females [oddsratio (OR) = 7.2]. The knowledge of interviewed females about rubella, the vaccine and the effect rubellainfection on pregnancy and on the fetus was very limited. In conclusion more vaccination coverage isneeded, with simultaneous increase of public awareness to minimize the susceptible female population.

emalesgypt

. Introduction

Rubella is usually a mild, self-limited illness in children anddults, characterized by fever and rash and its importance for pub-ic health relates to the teratogenic effects in pregnant women. Theirus is able of crossing the placenta causing serious consequences,uch as fetal death, miscarriages, stillbirths, and congenital rubellayndrome (CRS) may occur as a result of intrauterine infection,articularly during the first trimester of pregnancy [1,2]. The occur-ence of congenital defects is as high as 85% if infection occursuring the first 4 weeks of gestation, 20–30% during the secondonth, and 5% during the third or fourth month [2].The primary objective of rubella immunization program is

revention of congenital rubella infection and CRS [3]. Active

mmunization programs using live, attenuated virus have elim-nated or greatly reduced rubella incidence and CRS in someeveloped nations [4–6]. Nevertheless, an estimated 110,000

nfants with CRS are born each year worldwide [7,8]. A key strat-

∗ Corresponding author at: 3 Haras Street, Garden City Cairo 11451, Egypt.el.: +20 2 3761 2727.

E-mail address: mhashem@epi.umaryland.edu (M. Hashem).

264-410X/$ – see front matter © 2010 Elsevier Ltd. All rights reserved.oi:10.1016/j.vaccine.2010.08.056

© 2010 Elsevier Ltd. All rights reserved.

egy for preventing rubella and CRS is ensuring sufficient populationimmunity through natural disease or vaccination programs thatachieve high coverage [8,9].

In Egypt, the MOH made major progress towards reducing theburden of communicable diseases through the Expanded Programof Immunization (EPI) which started in 1988. In 1999, rubella vac-cine was integrated in the MOH EPI combined with measles andmumps (MMR) for children at age of 18 months. In parallel MMRvaccine was also given to school children at the age of school entry(6 years) in year 2001 and for three successive years. As a result ofthese vaccination strategies it was expected that about 86% (95%vaccine efficacy and 90% coverage) of children aged 18 months to10 years would be immune to rubella. However, levels of protec-tion may be even less than expected as reports of vaccine efficacyunder optimum clinical trial conditions do not guarantee that avaccine will be as effective in routine use [10]. Furthermore, thecampaign that started in 2001 targeted school children only withno account on non-school attendants or absentees. Furthermore, it

is not clear whether children in private schools were vaccinated ornot. Accordingly, it is expected that more than 15% of children aged6–10 years of age are not protected against rubella and it is plausiblethat rubella continues to circulate for some years among this agegroup. No sero-prevalence studies were done over the years, mak-

M. Hashem et al. / Vaccine 2

Table 1Confirmed reported rubella cases by governorate during the period 1st January to30th September 2007 according to records of MoHP.

Governorate Reportedrubella cases

Governorate Reportedrubella cases

Alexandria 2702 Menia 138Giza 1256 Port-Saied 120Cairo 1131 Gharbia 110Kafr El-Sheikh 1100 Sharkia 110New Valley 803 Fayoum 106Assiut 723 North Sinai 66Dakahlia 595 Red Sea 62Suze 427 Sohag 28Bahira 363 South Sinai 18Damietta 325 Quena 13Qualiobia 325 Beni-Swef 11

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Ismailia 279 Luxor 7Matrouh 225 Aswan 5Menofiea 182 Total 11,230

ompiled from: Communicable Disease control Department, MoHP (2007).

ng it difficult to discuss the effectiveness of the rubella vaccinationrogram in Egypt.

Since 2002, the laboratory based surveillance system estab-ished by the MOH in Egypt for measles and rubella has beenignificantly improved. A highly-performing surveillance systemas established for the early detection of suspected rubella cases

nd laboratory confirmation of a suspected case with a positivelood test for rubella-specific IgM antibodies. Between 2002 and005 several rubella outbreaks were reported. In 2002, 70% of theeported cases were children aged 6–10 years and 16% were aged1–15 years. Similarly in 2003, rubella outbreaks occurred mainlymong children aged 5–15 years with 49% in the ages (6–10) yearsnd 38% in the ages (11–15) years. Whereas in 2005 the outbreakshifted towards the older age group and adolescents with 70% of theeported cases of rubella were aged 11–20 years (38% and 32% in the1–15 and 16–20 age groups, respectively) and 10% occurred in the1–25 years age group. About half of all the reported cases were inemales (Source: MOH Communicable Disease Control DepartmentCDCD] 2005 – personal communication). The main aim of this studyas to determine the overall and age-specific rubella susceptibility

n Egyptian females in late childhood and the childbearing periodi.e. 6–45 years]. Additionally, assess the knowledge and identifyome risk factors associated with susceptibility. Finally assist thegyptian MOH in developing an optimal vaccination strategy byargeting females who are susceptible to rubella and ensuring highevels of rubella immunity among women in the childbearing ageo prevent congenital rubella infection and CRS.

. Methodology

.1. Study design and sampling

This community-based cross-sectional study was conductedn eight districts in two Egyptian governorates: Giza and Beniuef.These two governorates were selected according to the fol-owing criteria:

Both show two appreciably different reported recent rubella inci-dences. For purposes of comparison, both governorates were atthe upper and the lower spectra of reported incidence rates inan outbreak of rubella between January 1st till September 30th2007, with a total of 11230 reported cases (Table 1). The Commu-

nicable Disease Control Department (CDCD) of MOH provided theconfirmed number of cases by governorate. Giza was the secondhighest governorate with 1256 reported cases, while Beni-Suefhad the third least reported number of cases with 11 reportedcases (Table 1).

8 (2010) 7202–7206 7203

• Inclusion of urban and rural areas to detect the difference inrubella susceptibility.

• Short traveling time, from and back to Central Lab of the MOHPlocated in Cairo, to enable longer time for data collection, as wellas ensuring safety and quick serum separation of blood samples.

Cairo (where the MOHP Central Lab is located) and Alexandriawere excluded because of the socio-ecomic and cultural mixes thatare more than could be handled by a reasonable sample, in additionto the many squatter areas with no distinct rural areas. Moreover,health care facilities and practices vary in different areas of Cairo.All these factors may result in bias when presenting the commonsituation of rubella knowledge and susceptibility.

Two urban districts and two rural districts were chosen by theMOH CDCD in Giza governorate. Four districts in Beni-Swef gov-ernorate were selected in the same purposive sampling method. Aprimary health care center catchment area was chosen to representeach district.

2.2. Field work

Field world was conducted by four teams; each composed of afield supervisor, two interviewers, and one nurse. Prior to initiat-ing data and sample collection, we first determined the numberof streets and the boundaries of the chosen area surrounding thehealth care center. We then projected that 30% of the streets in thisarea will be surveyed. The first street was randomly selected thenevery third or fourth streets were identified to complete 30% cov-erage of the area. All the houses in the selected streets were visiteduntil 40–50 houses were completed, when the street did not con-tain enough houses another street was randomly selected from adistant area.

Eligible study participants were all the females in the selectedhouses in the ages between 6 and 45 years who provided aninformed consent for study participation. Trained interviewersinterviewed the eligible females using an abridged standardizedprobing questionnaire that contained socio-demographic data,questions on risk factors, rubella immunization and knowledge. Weestimated that testing the sera of 522 females for rubella-specificIgG antibodies will yield a prevalence of 5% (±1.5%) sero-negativefemales with 95% confidence and 90% power. Accordingly, the fieldsupervisors ensured that between 350 and 400 eligible femaleswere interviewed daily and of those 35–40 blood samples wereobtained. A total of 602 females consented to provide the 5 ml ofblood to test for rubella-specific IgG antibodies and answered adetailed standardized questionnaire that covered more details onknowledge of rubella disease, immunization, and knowledge aboutCRS. The crowding in the house, practice of immunization and preg-nancy outcomes were also included in this structured close endedquestionnaire.

2.3. Blood samples and testing

A 5 ml blood sample was withdrawn from 602 females (10.6% ofall interviewed females) by well-trained medical personnel apply-ing “Universal Precautions” [11,12]. Each specimen was labeledwith the same identifier of the corresponding questionnaire. Allinfection control measures were observed during blood samplingand handling, including the use of a safety box for disposal ofneedles and syringes. The safety boxes were finally disposed of

by incineration in the Cairo University Hospital incinerator. Bloodspecimens were transported from the field to the Central Labo-ratories in Cairo in compliance with the WHO guidelines for thesafe local surface transport of Infectious Substances and DiagnosticSpecimens (WHO/EMC/97.3).

7204 M. Hashem et al. / Vaccine 28 (2010) 7202–7206

Table 2Results of serum testing among studied females.

Result Number Percent

Susceptible (negative IgG) 58 9.7

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proportion of vaccinated females is partly due to the majority ofinterviewed females (90%) were older than 10 years i.e. were bornbefore the routine vaccination began.

The opinion of females on who would be targeted for vaccinationwas explored and responses varied appreciably. Table 6 shows that

Table 3Exposure, geographical and social factors relation to rubella susceptibility.

Factors Number Percentsusceptible

Odds ratio Fisher exactP value

Ever married* 275 2.5Never married 323 15.8 7.2 <0.00001Working/studying 165 13.3Not working** 433 8.3 N.S.Know rubella 243 8.2Does not know 355 10.7 N.S.Contacted case 57 8.8Did not contact 541 9.8 N.S.Had rubella 12 16.7Do not remember and no 586 9.6 N.S.Had immunization 6 16.7Do not remember and no 592 9.6 N.S.Giza 312 8Beni Sweef 286 11.5 N.S.

Immune (positive IgG) 540 90.3

Total 598 100.0

Specimens collected were centrifuged at 3000 × g for 10 min toeparate the sera. The separated sera was stored in cryo vials at20 ◦C until tested at Central Laboratories in Cairo MOH central

aboratories using the quantitative enzyme-linked immunosor-ent assay (ELISA) kit “BEIA Rubella IgG Quant kit manufacturedy Techno Genetics, a diagnostic company of Bouty group” foretection of IgG antibodies to rubella virus, in human serum orlasma samples. Calibration curve was created by plotting theean of optical density (OD) for each calibrator concentration

gainst the IgG anti-rubella concentration (IU/mL). A best fit curveas drawn through the points of the graph. The concentration of

gG anti-rubella in the unknown samples was determined usinghe standard curves. Sample with IgG anti-rubella concentration15 IU/mL was considered positive, whereas sample with IgG anti-ubella concentration <8 IU/mL was considered negative. Sampleith IgG anti-rubella concentration between 8 and 15 IU/mL was

onsidered borderline.

.4. Data analysis

The pre-coded questionnaires and laboratory data were enteredor analysis on SPSS package version 15.0. The laboratory serumesults were used as dichotomous data of negative and positive.he negative indicated rubella susceptibility, while positive meantmmune to rubella. The statistical analyses were done to test

hether the susceptible females show significant difference thanhe immune ones. The tests used included student’s “t” test and2 of significance. Forward step-wise logistic binary regressionnalysis was also used to account for confounders. To control foronfounding effect of the studied variables, a multi-variate analysisas done to single out the related factors to the rubella susceptibil-

ty using forward stepwise binary logistic regression analysis. ThegG test result was used as the dependant variable. A P = 0.05 forariable entry and P = 0.1 for variable removal from the model wassed.

. Results

The field work was accomplished in 16 days over 3 weekstarting from the third week of November until the first week ofecember 2007. Eight days were spent in each governorate with 2ays in every community served by the chosen health center. Theverage daily interviews done by each team was 91 ± 2.9 whichields 5670 interviews with an average of 364 ± 11.7 completednterviews per team. Six hundred and two blood samples wereollected and two samples did not reach the laboratory in good con-ition. Another two serum samples were unfit for IgG examination.esults of serum testing of the valid 598 blood samples showedlow proportion of rubella susceptibility among studied females

9.7%), while the majority were immune (Table 2). The two studiedovernorates, showed no difference as regards the proportion ofubella susceptibility. The mean age of rubella susceptible females

as 16.1 ± 5.2 years, which was significantly younger (P < 0.0001)

han immune females (21.9 ± 8.6 years). Fig. 1 demonstrates thathe young age examined females were more susceptible to rubellanfection, especially in the age group 10–14 years. There was aoticeable steady decrease in percents of susceptible females after

Fig. 1. Proportion of rubella – susceptible females in Egypt November and December2007.

the age of 14 years, and by the age of 30 years, the susceptibilitypercent was negligible.

Other factors including knowledge and exposure to rubella aswell as geographic and social characteristics were examined in rela-tion to rubella susceptibility. Results of bivariate analysis showedthat the never married females were significantly more susceptibleto rubella. On the other hand, all the other studied factors showedno association with IgG results (Tables 3 and 4). Accordingly, onlyyoung and unmarried females showed significantly higher propor-tions of rubella susceptibility. Concerning knowledge of femalesabout rubella it was found that the commonly used word for rubellais “German Measles” and this is commonly used both by the physi-cians and lay people. It was important to know whether femalesknow about measles, and whether they can differentiate betweenmeasles and rubella. One fifth of the 5672 interviewed femalesdid not know the word measles. One half knew measles only,while about one quarter knew both types i.e. measles and Ger-man measles. Table 5 shows an unexpected minority of the females(3.6%) stating their knowledge about German measles only.

The markedly low knowledge about the disease was accompa-nied by a still lower knowledge about vaccine availability. Fig. 2shows that among the 15% of females who knew about the vaccine,only 81 females (1.4%) were sure of being vaccinated. This small

Rural 426 10.1Urban 172 8.7 N.S.

N.S. = statistically not significant.* Ever married women included the widows and divorced.

** Not working females include homemakers (housewives) and girls not studying.

M. Hashem et al. / Vaccine 28 (2010) 7202–7206 7205

Table 4Result of forward stepwise using “Wald” statistics.

Factors Wald significance Estimated relative risk

Marital status 0.000002 7.2*

Age in years 0.054Governorate 0.237Urban–rural residence 0.252History of rubella infection 0.255History of contact with

rubella case0.301

Knowledge about rubella 0.527Working and studying

status0.561

History of rubellaimmunization

0.675

* Never married is at a higher risk of susceptibility to rubella (low immunity).

Table 5Knowledge about measles and rubella.

Knowledge No. %

Never heard of measles 1149 20.3Do not know types 1278 22.5Only measles 1557 27.5Only rubella 203 3.6Both types 1485 26.2

Total 5672 100.0

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Table 7Female’s knowledge about the effect of rubella infection on both mother and fetus.

Effect on mother or fetus No. Percent

Know 105 17.5

Fig. 2. Knowledge and practice of rubella vaccine.

ne third of these females did not think about vaccination (34.4%).little more than another third (38.8%) thought about giving the

accine to all the suggested three groups included in this close-nded question. The last third of them show a mix of opinion, whichere probably based on impulsive guess. About one in every sixth

emale (17.5%) knew that there is an effect on both mother and heretus when she got infected with rubella during pregnancy, while

ore than half (54.7%) of them did not know that rubella infection

an affect both mother and fetus (Table 7). The IgG test result wassed as the dependant variable in a forward stepwise binary logis-ic regression analysis, and the independent variables included theight variables presented in Table 3 together with age. Only onetep concluded the analysis and the marital status was included,

able 6emale’s opinions about targeted groups for rubella vaccination.

Target for vaccination No. %

Children, girls, women 233 38.8Children and girls 80 13.3Young children only 63 10.5Girls before marriage only 8 1.3Children and women after birth 8 1.3Do not know 208 34.7

Total 600 100.0

Do not know 328 54.7Not sure 167 27.8

Total 600 100.0

while all the others were unqualified to enter the equation. TheR square estimates by two methods; Cox & Snell, and Nagelkerkeboth indicated that the marital status share only 5.6–11.7% of thechanges in IgG result.

4. Discussion

In spite of the rubella vaccination strategy which has beenadopted by MOH in Egypt since 1999 to immunize all the 18months old children with MMR vaccination, there are still someconcerns. MOH had expressed these concerns as the epidemiologyof rubella is changing rapidly in Egypt with shifting of the averageage for those infected towards the older age, which was noticedthrough the rubella surveillance reports. This age shift may leadto increase in proportion of susceptible among post-pubertal girlsand females in their early childbearing years. Because high suscep-tibility rates translate to high risk of natural infection and becauserubella epidemics are inevitably followed by CRS it is logical toattempt preventing such events by vaccination. Furthermore theeffectiveness of this immunization strategy adopted by the Egyp-tian MOH was not been evaluated for neither rubella nor the CRSoccurrences.

This study was conducted few months after the subsidence ofthe high secular wave of Rubella in Egypt during 2007. The twostudied governorates; Beni Suef with the lowest reported casesand Giza with the highest, showed no difference as regards theproportion of Rubella susceptibility. This may be explained by thehigher population density in Giza governorate compared to that inBeni-Suef governorate.

The seroprevalence of rubella antibodies in this sample of 598Egyptian females was high (90.3%). Other studies conducted in ruralareas of developing countries have estimated the prevalence tobe 80% and above [13–17]. In the present study the mean age ofrubella susceptible females (16 ± 5 years) was significantly youngerthan immune females (22 ± 9 years). More than 20% of the femalesbetween 10 and 15 years were susceptible to rubella infection.There was a noticeable steady increase in the proportion of sus-ceptible females under 15 years of age followed by a steep declineto rubella susceptibility which becomes negligible in females at 30years of age (Fig. 1).

Our study included 12 females below the age of 11 years, of thoseseven (58%) were rubella IgG negative with a lowest 95% confidenceestimate of 30%. This susceptibility proportion is twice as high as theexpected 14% based on the assumption that EPI immunization reg-imen has achieved a level of protection of 86% (95% vaccine efficacyand 90% coverage).

If childhood immunization coverage does not remain high,transmission patterns may shift toward adults, including women ofthe childbearing age and this may result in cases of CRS [7–9,13]. Anoptimal rubella vaccination strategy should be tailored to achievehigh protection levels to ultimately eliminate CRS. The proportionof the population which needs to be immune in order to confer herd

immunity to rubella is around 85–88% [18]. If the rubella immunepopulation (males and females), drop to levels below 85% this willundermine the herd immunity effect. Consequently, the indirecteffect of an immunization program below eradication levels is thatindividuals who experience infection are infected at an older age.

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nother interesting finding was published in the United KingdomUK) declaring that between year 1993 and 1996 an outbreak ofubella occurred among many young men, the infection was trans-itted to pregnant women who were susceptible as they were

mmigrants, not immunized [19]. Outbreaks still arise, usually inome countries where the vaccine is not as accessible and the cov-rage is low [20]. Universal immunization producing a high levelf community immunity is important in the control of epidemicsf rubella [21].

This study also revealed how the knowledge about rubella wasery limited among the interviewed females. Those who stated theynew about rubella were less than one third (30%), a great majorityf these females were able to differentiate between measles andubella, constituting 26% of all the interviewees. Only 15% knewbout the vaccination against rubella. The knowledge about theffect of rubella on both mother and fetus was stated only by 17.5%f the studied females. This demonstrates the need for health mes-ages to increase the awareness prior to vaccination campaigns. Theost significant finding was the high risk of susceptibility among

nmarried females, with an odds ratio (OR) of 7.2. No other studiedactors were associated with the sero-negative females.

Our data suggest that younger females were more likely toe immunologically naive, and remain potentially susceptible toubella. We also observed a markedly low knowledge about theisease, and that only 15% of females knew about the rubella vac-ine. The policy implication of these findings is that the sub-optimaloverage may be affected by lack of knowledge, particularly byoung females. The optimization of immunization coverage with aimultaneous program and public awareness campaigns to expandnowledge of the importance of rubella immunization and the con-equences of rubella infection during pregnancy, particularly therst trimester is extremely crucial. The study results were commu-icated with the MOH stakeholders with a recommendation thatass vaccination to unmarried females below the age of 25 years

s required to minimize the susceptible female population. Theseesults were adopted by policy makers and encouraged conductingf two nationwide MR vaccination campaigns. The first campaignas implemented in 2008 in the 10–20 age groups, and the secondas in 2009 in the 2–11 age groups.

cknowledgments

Financial support for this project was provided by EMRO/TDRmall grants scheme project number, IDNOSGS06/145. We would

lso like to thank the officials at the Health District at Giza andeni-Suef governorates, the physicians and staff members of theommunity Health Units in both governorates for their supporthat was instrumental in all aspects of data collection and interac-ions with the study participants. Finally we would like to express

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8 (2010) 7202–7206

our gratitude for Dr. Amal Bassili (focal point, EMPRO/TDR) for heradvice and tremendous support throughout the study.

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