Incidence of Rubella Antibodies among Pregnant Women in a Tertiary Care Hospital

Full text

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Incidence of Rubella

Antibodies among

Pregnant Women in a

Tertiary Care Hospital

INTRODUCTION

Rubella was first described in the mid-eighteenth century. Friedrich Hoffmann made the first clinical description of rubella in 1740, which was confirmed by de Bergen in 1752 and Orlow in 17581,2. The teratogenic property of rubella was discovered by an Australian ophthalmologist Gregg, who in 1941 observed a sudden increase in congenital cataract in infants and related it to maternal rubella3. The observations from different countries soon con-firmed that maternal rubella induces congenital malformations of differ-ent kinds, the commonest being the triad of cataract, deafness and cardiac defects. Further progress had to wait till rubella virus was isolated in tissue culture in 19624. The virus can be transmitted to the foetus through the placenta and is capable of causing serious congenital defects like congenital rubella syndrome (CRS), abortion and still birth3. Primary maternal rubella virus infection especially during the first 12 weeks of pregnancy may lead to CRS, the outcome of which is a tragic consequence for both the infant and the parents. The risk of foetal infection is about 90% during 1st trimes-ter, when the majority of these infants suffer from congenital malformation in the form of deafness, cataract, congenital heart disease, mental retarda-tion and even foetal death5. Most infections are usually subclinical and the affected children may born apparently well, but subsequently develop the evidence of mental retardation and other disabilities.

Diagnosis of rubella by clinical evidence may not be reliable and does not give a complete picture of the situation because nearly one half of indi-viduals infected with this virus are asymptomatic6. Following the rubella vaccination practices, the incidence of rubella has been reduced drastically but the WHO still estimates that more than 110,000 children are born with

Rathore Praveen K1, Amritesh Kumar2, Anamika Vyas3, Rajesh Bareja4*, Amar S Dalal5

1 Department of Microbiology, Jodhpur

Medical College & Hospital, Boranada, Jodhpur, Rajasthan, India – 342012

2,3,5 Department of Microbiology, Geetanjali

Medical College & Hospital, Udaipur, Rajasthan, India – 313001

4 Department of Microbiology, S.R.M.S.

Institute of Medical Sciences, Bhojipura, Bareilly, Uttar Pradesh – 243202

 Address reprint requests to

*Rajesh Bareja, Assistant professor, Department of Microbiology, SRMS Institute of Medical Sciences, Bhojipura, Bareilly, Uttar Pradesh 243202, India E-mail: rajeshbareja@gmail.com

 Article citation: Praveen RK, Kumar A, Vyas A, Bareja R, Dalal AS. Incidence of rubella antibodies among pregnant women in a tertiary care hospital. J Pharm Biomed Sci

2016;06(02):110–114.

Available at www.jpbms.info Statement of originality of work: The manuscript has been read and approved by all the authors, the requirements for authorship have been met, and that each author believes that the manuscript represents honest and original work.

Source of funding: None.

Competing interest / Conflict of interest: The author(s) have no competing interests for financial support, publication of this research, patents, and royalties through this collaborative research. All authors were equally involved in discussed research work. There is no financial conflict with the subject matter discussed in the manuscript.

Disclaimer: Any views expressed in this paper are those of the authors and do not reflect the official policy or position of the Department of Defense.

NLM Title J Pharm Biomed Sci CODEN JPBSCT

2230-7885 ISSN No

ABSTRACT

Background In itself, the disease is trivial but rubella in pregnant women may lead to congenital malformations in the baby.

Aims and Objective This study was aimed to determine and analyse the prevalence of rubella antibodies among pregnant women.

Materials and Methods A total of 100 pregnant women were included in this study. Out of 100 pregnant women, 38 cases were from 1st trimester, 35 from 2nd trimester and 27

cases from 3rd trimester. About 2–3 ml of blood sample was collected aseptically from

pregnant women at the antenatal clinic and was processed accordingly for detection of IgG and IgM antibodies specific for rubella virus by enzyme-linked immunosorbent assay (ELISA).

Results Out of 100, 94% and 7% of pregnant women were seropositive for anti-rubella IgG and IgM antibodies, respectively.Highest seropositivity for rubella IgG was found in age group 20–25 years (97.61%) followed by 26–30 years (91.89%).Higher sero-positivity for rubella IgG antibodies was observed in female residents of rural areas (94.59%) as compared to those residents of urban areas (93.65%).

Conclusion Prevention of morbidity and mortality from rubella infection depends on prevention of infection in childbearing women and early recognition of maternal infection.

KEYWORDS ELISA, IgG, IgM, pregnant women, rubella

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CRS each year worldwide. It is estimated that 85% of the world’s disabled children live in less developed coun-tries7. The endemicity of rubella has been well estab-lished in India. Sero surveys conducted in India have also confirmed that 6–47% of women are susceptible to rubella infection8.

Clinical diagnosis of rubella tends to be unreliable as there is several rash-like illnesses such as measles virus and parvovirus B19 mimic rubella. Laboratory confir-mation of clinically diagnosed patients is essential for the diagnosis of rubella virus, especially when patient is pregnant or if a neonate is born with CRS3.

No other study has been conducted in our setting till date. It is, therefore, considered worthwhile to deter-mine the rubella seroprevalence in pregnant women to monitor their immune status and their susceptibility to rubella infection.

MATERIALS AND METHODS

This prospective study was conducted during January to December 2013 in the antenatal clinic (ANC) of the institute. The study comprised 100 pregnant women in different trimesters of pregnancy that expressed inter-est and gave their consent. Ethical approval for the study was obtained from the ethical committee of the institute. Pregnant women presenting with or without history of adverse pregnancy outcome i.e. spontaneous abortion, premature labour or abnormal babies (congenitally mal-formed or stillborn) were included in the study. Pregnant women below 20 years of age and those above 45 years of age, patients undergoing in vitro fertilization (IVF) for infertility, immunocompromised and autoimmune disor-der patients were excluded from the study.

Collection and processing of blood samples

About 2-3 ml of single blood sample for detection of rubella antibodies was collected aseptically by venipunc-ture using a sterile disposable needle in a vacutainer from pregnant women at the antenatal clinic by trained phlebotomist/nursing staff under the supervision of the investigators. The blood sample was allowed to stand at room temperature for blood clotting, there-after, sample was transported to the laboratory at the Department of Microbiology. All the specimens were centrifuged at 2,500 rpm for 5 minutes, to separate the sera and were stored at –20°C until analysis9. Sera sam-ples were anal ysed for detection of anti-rubella IgM and IgG anti bodies using enzyme-linked immunosor-bent assay (CalBiotech, CA, from Allianz BioInnovation, Maharashtra, India). The assays were carried out accord-ing to manufacturer’s instructions.

RESULTS

This study comprised three categories of 100 pregnant women out of which 38 cases were from 1st trimester,

35 from 2nd trimester and 27 cases were from 3rd tri-mester. The majority of pregnant women (79%) were in the age group 20–30 years (Table 1). Out of 100, 94% and 7% of pregnant females were seropositive

Table 1 Distribution of pregnant women according to variable (n = 100).

Variables Number Percentage

Age group

20–25 42 42%

26–30 37 37%

31–35 16 16%

36–40 05 5%

Obstetric history

Bad obstetric history 35 35%

No bad obstetric history 65 65%

Gestational age

1st trimester 38 38%

2nd trimester 35 35%

3rd trimester 27 27%

History of vaccination

Immunised 34 34%

Non-immunised 66 66%

Parity

Primigravida 42 42%

2nd gravida 38 38%

3rd gravida 14 14%

4th gravida 4 4%

5th gravida and above 2 2%

Area

Rural 36 36%

Urban 64 64%

Socioeconomic group

Lower 7 7%

Middle 39 39%

Upper 54 54%

Education level

Illiterate 7 7%

Primary 9 9%

Secondary 23 23%

Sr. secondary 4 4%

Graduate 24 24%

Postgraduate 33 33%

Occupation

Housewife 84 84%

Private job 10 10%

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for anti-rubella IgG and IgM antibodies, respectively. Seropositivity for rubella IgG antibodies was statistically significant (p = 0.05) in the 1st trimester of pregnancy as compared with 2nd trimester (Table 2).

Highest seropositivity for rubella IgG was found in age group 20–25 years (97.61%) followed by 26–30 year (91.89%) age group. The percentage seropositiv-ity for rubella IgG antibodies decreased with age (age group 20–35 years), reached 87.5% in the age group 31–35 years, though the difference in the percentage of positives in the various age groups were not statistically significant. However, 36–40 years age groups had the lowest susceptibility (Table 3).

Out of 100, 35% had bad obstetric history (BOH) and 65% had non-bad obstetric history (Tables 4, 5). Higher seropositivity for rubella IgG antibodies was observed in female residents of rural areas (94.59%) as compared to those residents of urban areas (93.65%). While seropositivity for rubella IgM antibodies were higher in urban population (7.93%) as compared to rural population (5.40%). The seropositivity for rubella IgM antibodies was higher in housewives (8.33%) as compared to working women.

DISCUSSION

Though, rubella is mainly a disease of childhood (3–10 years), over 70% cases occur in people more than 15 years of age and in the reproductive age. Rubella virus is one of the most teratogenic agents known. It can lead to disastrous consequences if acquired in early gestation, leading to foetal death, premature delivery and an array of congenital defects10–12.

There is considerable variation in the prevalence of rubella antibodies among pregnant women. The European women have relatively higher prevalence of rubella immunity (93.2%) as compared to African women (86.7%) and Asian origins (78.4%). In India, the reported figures vary from 53% to 94.1%11. The reason for this difference in immunity is difficult to explain. However, factors such as net birth rate, popu-lation density, opportunities for entry of virus, level of herd immunity at the time of virus introduction and ethnicity of the population may be responsible for this variation13. In the present study, overall prevalence of rubella IgG antibodies among pregnant women was 94% indicating immunity to rubella infection either by virtue of natural immunity or following immuni-sation that is consistent with the study done by Kharal and Khan13. Almost similar results were reported for rubella IgG antibodies in various studies by different authors14–16. However, other studies that involved a large group of pregnant women showed 67.8% and 85.9% rubella IgG antibodies17,18.

The present study showed highest seropositivity (97.61%) for rubella IgG in the age group 20–25 years followed by 91.89% and 87.5% in 26–30 and 31–35 years, respectively. However, 36–40 year age group had the lowest susceptibility. These results are in accor-dance with a study done by Gupta et al19. The number of seropositives and the titres of protective antibodies for rubella virus, increased with an increase in age. More frequent exposure to the virus in older age has been given as a possible explanation20. In contrast to the previous findings, this study demonstrated a decline of seropositivity with increasing age, possibly due to more frequent exposure to rubella virus in the younger age group, and the waning of seropositivity with an increase in age. Waning immunity is not important following Table 2 Relationship between duration of pregnancy

and rubella specific IgM and IgG antibodies (n = 100).

Gestational age Seropositive case number (%)

IgM IgG

1st trimester (n = 38) 1 (2.63) 36 (94.73)

2nd trimester (n = 35) 3 (8.57) 33 (94.28)

3rd trimester (n = 27) 3 (11.11) 25 (92.59)

7 94

Table 5 Relationship between rubella specific IgM and IgG antibodies with non-BOH and history of vaccination (n = 65).

History of

vaccination Non-BOH IgM positive number (%) IgG positive number (%)

Vaccinated 22 2 (9.09) 22 (100)

Non-vaccinated 43 4 (9.33) 39 (90.67)

Total 65 6 61

Table 4 Seropositivity of rubella specific IgM and IgG antibodies with BOH and history of vaccination (n = 35).

History of

vaccination BOH IgM positive number (%) IgG positive number (%)

Vaccinated 12 1 (8.33) 12 (100)

Non-vaccinated 23 0 (0.0) 23 (100)

Total 35 1 35

Table 3 Age-specific seropositivity of rubella antibodies (n = 100).

Age

group Number IgG positive number (%) IgM positive number (%)

20–25 42 41 (97.61) 2 (4.76)

26–30 37 34 (91.89) 4 (10.81)

31–35 16 14 (87.50) 1 (6.25)

36–40 5 5 (100) 0 (0.0)

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natural infection with rubella but it has been docu-mented that the antibody level declines over time in vac-cinated persons. Higher immunity in the younger age group could also be due to the persistence of immune response to measles-mumps-rubella (MMR) vaccination in childhood21,22.

The seropositivity of IgM antibody was observed in 6.5% by some authors in India23. The present study demonstrated 7% seropositivity for rubella IgM anti-bodies, indicating the recent infection. In other studies, 3–9% rubella IgM seropositivity had been shown in asymptomatic pregnant women13,23,24.

In the present study, 79% of pregnancies occurred in 21–30 year age group, indicating 7.59% risk of rubella infection during their pregnancies. The other authors had also observed the similar findings during their study8,18.

Multi-gravid (58%) as well as 1st trimester preg-nant women (38%) made up the majority of the sub-jects. Although most of the pregnant women were multi-gravid, the result of this study showed a higher prevalence in the primi-gravid women (IgG 95.24%, IgM 9.52%) than the multi-gravid women (IgG 93.1%, IgM 5.17%). This result, however, shows the multigra-vidity may not be a predisposing factor to rubella virus infections or immunity. The present study showed rubella IgG seroprevalence of 94.73% in 1st trimester, 94.28% in 2nd trimester and 92.59% in 3rd trimester pregnancies (Table 2). Olajide et al.9 also reported sim-ilar observations.

In the present study, the higher incidence of sero-positivity for IgG antibody was observed in women presenting with adverse pregnancy outcomes (100%) than that of the normal pregnancy (90.67%) outcome group (Tables 4, 5), suggesting that rubella could be a cause of repeated pregnancy wastage in those women. Similar evidence was seen in Bangladesh that higher (86.84%) incidence was seen in adverse pregnancy outcome group than the normal (80.65%) obstetric outcome group18. In India, some authors also pointed toward similar incidences in the adverse pregnancy out-come group (73.2%) than the normal (69.5%) obstetric outcome group17,25.

This study demonstrated that 2.85% women with BOH were seropositive for IgM antibodies (Table 4). Another study from Punjab reported 4.65% IgM sero-positivity among pregnant women with BOH26. If IgM antibodies are present in a pregnant woman, a current or recent infection with the organism is predicted. It is evident that maternal infections play a critical role in pregnancy wastage and their occurrence in patients with BOH as a significant factor.

In the present study, 34 pregnant women reported the history of rubella vaccination. Amongst them, 100% and 8.82% were seropositive for rubella IgG and IgM antibodies respectively (Tables 4, 5). Out of the 34 vac-cinated women, 12 of them had bad obstetric history. Out of 12, only one vaccinated woman, who was 23 year old in 1st trimester of third gravida belonging to the

rural area and upper socioeconomic class, was seropos-itive for rubella IgG and IgM antibodies. The reason for her bad obstetric performance can be attributed to other risk factors such as infection with teratogenic agents that were not looked for.

Among 66 non-vaccinated women, seropositivity for rubella IgG and IgM antibodies were found to be 93.93% and 6.06% respectively. Four non-vaccinated women with no history of bad obstetric performance were found positive for rubella IgM antibodies, indicat-ing recent asymptomatic infection that could lead to CRS. Many investigators have concluded that the risk of CRS can be minimised through vaccination21,22. Robertson et al.12 have also suggested that testing for rubella specific antibodies should be done in pregnant women in their first antenatal visit.

Seropositivity for IgM antibodies was higher (7.93%) in urban population than that of rural popu-lation (5.4%). This is attributed to crowded living con-ditions in urban areas that might increase the chances of exposure to rubella infection. Dowdle et al.4 and Yamamoto et al.27 found an urban-rural difference, with rural mothers being more susceptible than urban moth-ers. However, Gomwalk and Ezeronye28 found no dif-ference between urban and rural pregnant mothers in Nigeria.

Prevention of morbidity and mortality from rubella infection depends on the prevention of infection in childbearing women and early recognition of maternal infection. In India serological status of most women is not known before pregnancy. Thus, the present study suggests the need for antenatal screening for rubella. Hence, a baseline pre-pregnancy screening of all women and demonstration of high immunity places a woman at relatively no risk of rubella infection during preg-nancy29. Presence of natural immunity (IgG) is a param-eter of protection from infection during pregnancy, the same as offered by vaccination. Prescription of vacci-nation 1 to 3 months before planning a pregnancy in seronegative women will thereby further reduce the incidence of CRS.

CONCLUSION

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