Vol.3, No.6, 362-365 (2011)
opyright © 2011 SciRes. Openly accessible at http://www.scirp.org/journal/HEALTH/
Incidence of rubella IgM antibodies in individuals with
febrile rash illness attending clinics in Akwa Ibom State,
Nigeria, 2006-2009
Bassey Enya1*, Moses Anietie Effiong2, Udo Sunde Moffat2, Bassey Emem3
1World Health Organization Office, Abuja, Nigeria; *Corresponding Author: bassey69@yahoo.com
2Department of Medical Microbiology and Parasitology, Faculty of Clinical Sciences, University of Uyo, Uyo, Nigeria;
amoses264@yahoo.com, sundeudo@yahoo.com
3Department of Obstetrics and Gynaecology, Faculty of Clinical Sciences, University of Uyo, Uyo, Nigeria.
Received 8 March 2011; revised 20 April 2011; accepted 5 May 2011.
Background: Rubella is an infectious disease of
public health importance because infection ac-
quired during early pregnancy often results in
foetal abnormalities that are classified as con-
genital rubella syndrome (CRS). The burden of
rubella infection in most developing countries is
however not well documented because of lim-
ited epidemiological data. Methods: Between
2006 and 2009, 781individuals with febrile rash
illness seen in clinics in Akwa Ibom State were
screened for rubella specific IgM antibodies
using the ELISA technique. Statistical analysis
was done using Graph prime version 5.3 statis-
tical package at 95% confidence interval. The
level of significance w as established at P = 0.05
using Fisher’s exact two-tailed values. Results:
Of 781 individuals screened for rubella specific
IgM antibodies, 94 (12%) were found to be posi-
tive. Incidence of 8.7% recorded in 2006 gradu-
ally rose to 9.3% in 2007, 11.6% in 2008 and
14.3% in 2009. Those in the reproductive age
group (> 16 years) were most affected (51.7%).
However, this w as not statistically significant (P
= 0.228). Females (17.4%) were more suscepti-
ble than males (6.2%) (P < 0.0001) an rural
dwellers (12.8%) more susceptible than urban
dwellers (10.5%) (P = 0.416). Conclusion: The
study shows that the incidence of rubella in
Akwa Ibom State, Nigeria is high. The lowest
incidence was however found among individu-
als below the reproductive age. Thus, the find-
ings of this study can be used by polic y makers
to model the introduction of routine rubella
vaccinati on into the c ount ry’ Exp anded Program
on Immunization Schedule (EPI).
Keywords: Rubella-IgM Antibodies; Febrile Rash
Illness; Akwa Ibom State
Rubella virus infection usually causes a mild disease
in humans, but infection during early pregnancy often
leads to severe congenital abnormalities [1]. Although
the incidence of such abnormalities has declined consid-
erably as a consequence of rubella immunization, the
immunization rates are not optimal and infections during
pregnancy still occur. According to the world health or-
ganization (WHO) report [2], only 105 (49%) of 214
countries had introduced rubella vaccine in their national
immunization programme [2].
Although rare, complications such as thrombocyto-
paenia, encephalitis, Guillain-Barré syndrome, myocar-
ditis and pericarditis may appear in adults [3]. The most
serious consequences of the infection occur in newborns,
particularly if the mother acquired the infection during
the first trimester of gestation. This manifests in the form
of congenital rubella syndrome (CRS) which may in-
clude miscarriage, severe alterations in the growth and
development of the foetus, and intra-uterine death [3].
In surviving infants, the usual clinical manifestations
of CRS are deafness, cardiac disease, mental retardation,
eye defects and insulin dependent diabetes mellitus,
hepatitis, haemolytic anaemia [4] Congenital Rubella
Syndrome is a disastrous systemic disease which can be
prevented by vaccination during infancy and adoles-
cence. WHO estimates that worldwide more than
100,000 children are born with CRS each year, most of
them in developing countries [5]. Findings from a recent
study in Nigeria reported the detection of anti-IgM ru-
bella antibodies as a marker for recent rubella (as rec-
ommended by WHO) in 3.9% of pregnant women in the
B. Enya et al. / Health 3 (2011) 362-365
Copyright © 2011 SciRes. Openly accessible at http://www.scirp.org/journal/HEALTH/
first trimester in Makurdi, Nigeria [6].
Rubella immunization is not included in Nigeria EPI
schedule and thus infections during pregnancy may still
occur. This study was undertaken to determine in a
cross-sectional surveillance survey, the incidence of ru-
bella virus in the Akwa Ibom State and to make an em-
pirical evaluation of the need for the introduction of ru-
bella vaccine in Nigeria.
2.1. Stud y Population
This study was conducted between January 2006 and
December 2009 among individuals presenting with feb-
rile rash illness in 324 health care facilities spread across
Akwa Ibom State. These health facilities were 296 pri-
mary and 28 secondary health care facilities that serve
the inhabitants of the state. A total of 781 consented pa-
tients were recruited for the study. The Blood specimens
were obtained between the first and 7 days of rash onset.
The mean age of subjects was 11.5 years ± 5.91 SD;
males were 372 and females, 409.
2.2. Sample Collection and Laboratory
Five [5] ml of blood was collected from each subject
into plain sterile bottle following an informed consent.
Blood samples were centrifuged and sera was separated
and stored at –20oC until used. Samples were analyzed
in batches for rubella specific IgM using commercial
Rubella ELISA kit no. BQ 026G (Bio-Quant Diagnostics,
San Diego, CA) in accordance with the manufacturer’s
instructions. Tests were read on a pre-programmed spec-
trophotometer Quantum II, dual wavelength 600 - 650
nm (Abbott, USA). The inability to include acute and
convalescence IgG antibody testing in this study to
augment IgM test result was a limitation.
2.3. Statistical Analysis
Results were presented on frequency tables by year.
The comparison of characteristics of subjects by age, sex
and setting was carried out using Graph Pad Prime ver-
sion 5.3 statistical package with relative risk (RR) at
95% Confidence Interval (CI). The level of statistical
significance was established at p 0.05 using Fisher’s
exact 2-tailed values.
2.4. Ethical Issues
Appropriate informed consent and ethical approval
were obtained from the subjects and authorities of the
health institutions respectively.
Of the 781 individuals screened for rubella specific
IgM antibodies, 94 (12%) were found to be positive (Ta-
ble 1). The incidence of 8.7% recorded in 2006 gradu-
ally rose to 9.3% in 2007, 11.6% in 2008 and 14.3% in
2009 (Figure 1).
Ta b le 2 illustrates the demographic characteristics of
individuals screened. The infection was observed to in-
crease with age. Those aged 21 years and above were
mostly infected with rubella (28.6%), while those aged
16 - 20 and 6 - 10 years recorded 23.1% and 15.9% re-
spectively. The lowest prevalence was seen in those aged
0-5 years. No statistical significant difference was estab-
lished between the age groups considered (p = 0.228).
However, the relative risk of acquiring rubella is high,
1.073 (95% CI 0.820 - 1.079). Females (17.4%) were
most susceptible to rubella than males (6.2%), and the
relationship was highly significant (p < 0.0001) with a
high relative risk of 1.94 (95% CI 1.35 - 2.98). Examin-
ing infection by location revealed that rural dwellers
(12.8%) were more susceptible to rubella than urban
dwellers (10.5%) and the relative risk was slightly low,
0.941 (95% CI 0.820 - 1.079). The variation of seroposi-
Table 1. Distribution of rubella IgM antibodies in individuals
with febrile rash illness by year, 2006 - 2009.
Year Number
screened Number posi-
tive Percentage
2006 150 13 8.7%
2007 108 10 9.3%
2008 146 17 11.6%
2009 377 54 14.3%
Total 781 94 12%
Figure 1. Incidence trend of rubella IgM antibodies in indi-
viduals with febrile rash illness, 2006 - 2009.
B. Enya et al. / Health 3 (2011) 362-365
Copyright © 2011 SciRes. Openly accessible at http://www.scirp.org/journal/HEALTH/
tivity among rural-urban dwellers did not establish any
significance (p = 0.416).
In developing countries, the extent of maternal rubella
infection is largely unknown. There are very few clinical
records of rubella infection and or congenital rubella
syndrome (CRS). Clearly, the first step in determining an
appropriate immunization policy for a given population
is to carry out a serologic survey, in order to determine
the seroprevalence of rubella antibodies [7]. In Nigeria,
rubella vaccine is not a component of the routine immu-
nization policy despite its being safe, effective and could
be readily added to national immunization programme at
minimal extra cost.
Rubella outbreaks may continue to occur unnoticed in
highly unimmunized populations due to efficient trans-
mission of the virus among susceptible individuals [8].
This study shows that the incidence of rubella virus
among patients with febrile rash illness in Akwa Ibom
State, Nigeria is high and that the incidence varied con-
siderably between age groups, sex and community set-
tings (urban and rural). The incidence of 12% found in
this study is slightly lower than 17.5% reported in Adane
province Turkey [9], but higher than 8.6% reported in
another study in Sana’a, Yemen [10] and 3.4% reported
in Eastern Turkey [11]. The reason for the observed dif-
ferences may be attributed to geographical variations
and different levels of rubella immunization coverage.
The yearly rise observed in the incidence of rubella
IgM antibodies from 8.7% in 2006 to 14.3% in 2009
may be due to the introduction of rubella case-based
Table 2. Demographic characteristics of rubella antibodies in
individuals with febrile rash illness (n = 781), 2006 - 2009.
Risk factors No.
Screened No.
Positive %
Positive P-value
Age (years)
Under 5 572 54 9.4%
6-10 124 22 17.7%
11-15 44 7 15.9%
16-20 13 3 23.1%
21+ 28 8 28.6%
P = 0.2276
1.073 (0.99 - 1.16)*
Male 372 23 6.2%
Female 409 71 17.4%
P < 0.0001
1.946 (1.35 - 2.98)
Rural 524 67 12.8%
Urban 257 27 10.5%
P = 0.4164
0.941 (0.82 - 1.08)
P-value (Fisher exact) 2-tailed, RR = Relative Risk at 95% Confidence
interval. *Compared Age bracket < 15 and > 15 years.
surveillance with laboratory support in 2006, which had
provided a better platform for data collection, collation
and analysis, and invariably to the none introduction of
rubella vaccination into the national routine immuniza-
tion schedule in Nigeria [6].
The susceptibility of the female population to rubella
in comparison to their male counterpart seen in this
study is different from a previous report [10], but in
consonance with the report by Suay et al. [12] which
documented that rubella antibody is marginally higher in
females than males. The higher percentage of rubella
IgM antibody positivity among those living in rural areas
than in urban settings observed in this study was incon-
sistent with a previous study that reported high rubella
IgM positivity among urban dwellers [13] and also with
the findings of Gomwalk and Ezeronye [14] who found
no difference between urban and rural mothers in Nige-
ria. The variation in serologic profiles between urban
and rural settings as found in this study might be due to
malnutrition, overcrowding and inadequate or lack of
supportive health care in rural communities [15].
This study shows that the highest incidence of rubella
IgM antibodies occurred among women of the reproduc-
tive age group having a high relative risk of infection.
Immunizing this population will however require a mul-
tifaceted approach [16]. These include the creation of
awareness among the general populace and healthcare
providers of the deleterious effects of CRS, vaccination
of pre-school age female children which should be in-
cluded in the national immunization programme and
active vaccination of unimmunized women of reproduc-
tive age group as part of routine medical and gynaeco-
logical care.
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