Incidence of rubella IgM antibodies in individuals with febrile rash illness attending clinics in Akwa Ibom State, Nigeria, 2006-2009

doi:10.4236/health.2011.36061

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Vol.3, No.6, 362-365 (2011)

doi:10.4236/health.2011.36061

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: [email protected]

2Department of Medical Microbiology and Parasitology, Faculty of Clinical Sciences, University of Uyo, Uyo, Nigeria;

[email protected], [email protected]

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.

ABSTRACT

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

1. INTRODUCTION

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

363363

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. MATERIALS AND METHODS

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

Testing

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.

3. RESULTS

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

Positive

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

364

tivity among rural-urban dwellers did not establish any

significance (p = 0.416).

4. DISCUSSION

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

RR(95%CI)

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)*

Sex

Male 372 23 6.2%

Female 409 71 17.4%

P < 0.0001

1.946 (1.35 - 2.98)

Setting

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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