SEROLOGICALCONFIRMATIONOFMEASLES INCHILDREN …

ORIGINAL ARTICLE*

Journal of Saidu Medical College 2012; 2(1)

SEROLOGICAL CONFIRMATION OF MEASLES IN CHILDRENADMITTED WITH CLINICAL DIAGNOSIS OF MEASLES.

Israr ul Haq, Ashfaq Ahmed, Muhammad Ali Jan, Ihsan ul Haq, Muhammad BashirDepartment of Pediatrics Saidu Teaching Hospital Swat.

ABSTRACT

Objective: To determine the frequency of IgM antibodies in clinically diagnosed cases of measles.Design: Cross-sectional, descriptive studyPlace and duration: Department of Pediatrics, Saidu Group of Teaching Hospital, Saidu Sharif, Swat(from 1st Jan 2010-31 Dec 2011).Patients and method: A total of 150 patients of measles clinically diagnosed were enrolled for the study.Detailed history, demographic profile and vaccination status were recorded. Blood samples were collectedfrom all subjects for measles serology by observing WHO protocol.Results: Out of 150 patients, 57% (86) were male and 43% (64) were female with mean age of 38.28±30.99months. Out of these 150 patients, 66% (99) were positive for measles IgM antibodies, while 34% (51) werenegative for measles IgM.Out of 51 measles negative patients 11.8% (6) were positive for rubella.Conclusion: Diagnosing measles on clinical features alone is reasonable but not specific and IgM may beused to confirm the diagnosisKey words: Measles, IgM antibodies, children, vaccination status

INTRODUCTIONMeasles is a severe, vaccine-preventable viraldisease that causes extensive morbidity andmortality in large parts of the world 1. Measlescontinues to be a major cause of childhoodmorbidity and mortality worldwide, with anestimated one million fatal cases each year2.

Measles is usually diagnosed clinically3 4 and mostof the studies in our country are based on clinicaldiagnosis alone56,7. Although Koplik spot ispathgnomonic and has high diagnostic power, it ispresent in 60 to 70% of patients at the time ofpresentation 8. The WHO case definition ofmeasles requires the presence of fever and rashwith one or more of these symptoms: cough,coryza or conjunctivitis4. However, these clinicalpresentations can readily be confused with otherrash-associated conditions, particularly those dueto viruses such as roseola infantums, humanherpesvirus-6 (HHV-6), rubella, dengue andparvovirus4 , 9. An antibody-capture EIAconfiguration for the detection of measles-specificIgM has proven more sensitive and specific (97%and 99% respectively) and reduces the chance of a

false positive result due to rheumatoid factor10

When the clinical presentation is suspicious formeasles, serologic studies and virus isolation fromthe blood, nasopharyngeal swabs and urineadvised". The laboratory confirmation of cases ofmeasles is a vital aspect of surveillance at allstages of control programs because clinicaldiagnosis is unreliable12. The mainstay oflaboratory confirmation is the detection ofmeasles specific immunoglobulin ( IgM )antibodies in serum sample313.

IgM antibodies against measles virus increasewith the onset of the rash and last for about onemonth3 ". This is the most useful diagnostic tool,and the result can be obtained within a fewhours10 ". The sensitivity of IgM antibodiesincreases if blood is taken after seventy two hoursof onset of rash310. This study is an attempt todetermine the frequency of IgM antibodies inclinically diagnosed cases of measles.

Material and methods:This cross-sectional descriptive study was »,

conducted at Department of Pediatrics, Saidu

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group of teaching hospital, Saidu Sharif, Swat,from 31s' Dec 2010 to 3 Is' Dec 2011. Clinicallydiagnosed patients of measles, admitted inPediatrics unit Saidu teaching hospital wereincluded in the study. A total of 150 patients, bothmale and female below age of 15 years wereenrolled. Informed consent from respectiveparents was taken. Blood samples were collectedfrom all the patients after 72 hours of appearanceof rash according to WHO protocol 1 ’ enrolled.Informed consent from respective parents wastaken. Blood samples were collected from all thepatients after 72 hours of appearance of rashaccording to WHO protocol ’ . Blood samples weresent to National Institute of Health (NIH)Islamabad for measles and rubella IgM antibodiesand results were received through WHO focalperson

Results:Out of 150 patients, 57% (86) were male and 43%(64) were female

.

: m4m

£Female 64 Male 86 m

mI --M

V* V. •m

Figure 1. Sex of the patients

All patients were less than 15 years of age. Themean age of the patients was 38.28±30.99 months.Majority (84%) of the patients were below the ageof five years, whereas 26% (39) were infants, andamong infants 17.9% (7) were below 9 months.

Out of 150 patients, 66% (99) were positive formeasles IgM antibodies, while 34% (51 ) werenegative for measles IgM. Table 1 shows sex wisestatus of measles IgM.

Table 1: Sex wise measles IgM status

Results Male (%) Female (%) Total (%)

Measles IgM Posit ive 53 ( 61 6 ) 46 ( 71.9 ) 99 ( 66 )

Measles IgM Negative 33 ( 38 4 ) 18 (28.1 ) 51 (34 )

Total 86 64 150

Out of 51 IgM negative, 11.8% (6) were positivefor rubella IgM. No IgM for rubella were detectedin IgM positive patient for measles. Proportion ofSeropositivity in different age groups is shown inFig.2100

90

80

70

60

50

40

30

20

10

0Infants

iit4

1

Clinical Measles

IgM Positivity

I5-15 Years

Figure 2. Proportion of seropositivity amongclinically diagnosed measles in various age groups

Seven patients were below 9 months and out ofthem 6 (86%) were measles IgM positive. Among32 patients of ages between 9 months to 1 year, 28(87.5%) were seropositive. Out of 87 (58%)patients between 1-5 years, 56 (64%) wereseropositive, and only 11 (46%) of 24 patientsbetween 5 to 15 years were positive for measlesIgM. All patient included in study wereunvaccinated.

Discussion:Measles IgM antibodies has been used in manystudies for confirmation of measles as the goldstandard4 with sensitivity and specificity of morethan 90 to 98% °. Using IgM in our study we notedthat 34% clinically diagnosed cases were negativefor IgM though we collected blood after 72 hoursof rash to increase the sensitivity’ 10. Almostsimilar results has also been published by Husainet al in 200914. In their study 30.1% were

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seronegative14. In three studies in SuburbanKhartoum in 1999, 2000 and 2002, IgMseronegativity was observed in 25 to 28% ofclinically diagnosed measles2'4'15. This means thepredictive positive value of only clinicaldiagnosed cases is 70 to 75% in most of the studies.Helfand et al' 6 also found 72% IgM positive casesin their study

Cohen et al5 in there survey of suspected measlesoutbreak in Rawalpindi tested eleven cases ofsuspected measles and only 2 were positive formeasles and 6 were positive for Rubella. Thismeans that if there is mixed outbreak the positivepredictive value of clinical diagnosis furtherdecrease5. Similarly in the first 35 weeks of anenhanced surveillance programme in England andWales, it was reported that only 3.7% (n=3442) ofnotified measles cases were confirmed in thelaboratory". In another survey in South Africa 5%were positive for measles IgM in 220 cases ofclinically suspected measles9. This emphasizes theimportance of confirmation of clinically suspectedmeasles cases.

In our study we also noted that all the cases wereunvaccinated which is a question mark on thevaccination coverage reported by EPI programme.We also noted that eighty threes percent of patientswere below five year of age, similar percentage hasbeen reported in other studies from Pakistan andIndia6' 7 I 7.

Conclusion:Diagnosing measles on clinical basis is reasonablebut not hundred percent reliable and needlaboratory confirmation, particularly duringmixed outbreaks. Immunization coverage in thedistrict is poor.

Recommendations:Any patient with febrile exanthm who needadmission in infectious disease unit should bescreened for measles. All the clinically diagnosedmeasles not confirmed by laboratory should

receive measles vaccine. Moreover, there is a needof strengthening the EPI programme to achievemeasles elimination from the country.

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Address for correspondenceIsrar ul Haq,Department of Pediatrics,Saidu Teaching Hospital Swat.Email: [email protected]: 0333-9480955

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