Jpn. J. Infect. Dis., 55, 52‑54, 2002

Short Communication

Diphtheria Immunlty Of Different Age Groups in Turkey
Ufuk Beyazova*, ESref Galer, Aysegも1 Ybcell and Figen Sahin

Department of Pediatrics andJDepartment oflmmunoloBy, Gazi Universio, Faculo, of Medicine,Ankara, 77urkey(Received February 18, 2002. Accepted May 8, 2002)

SUMMARY: In Turkey, the immunization policy agalnSt diphtheria involves childhood vaccination, and noroutine booster dose is administered after 1 2 years of age, Information aboutthe immune status of the population
is important to predict the potential fわr epidemics, several of which have occurred recently ln neighboring

countries. The aim of this study was to assess the immune status of different age groups in Turkey against
diphtheria. A total of 497 blood samples were collected, and diphtheria antitoxin levels were measured by theEnzyme Linked Immunosorbent Assay method. Titers below 0. 1 IU/ml were considered to show insufrlCient

immunity. Overall, 35.8% of the population studied showed insufficient immunity against diphtheria. Immunity
rates varied significantly among different age groups (P< 0.01 ). Protective immunityrates were highest in the 3‑
to 6‑year age group (813%) and the oyer 60 age group (81･2%)I 1n subjects between the ages of 10 and 59 thepercentage ofpeople with insufrlCient lmmunitywas above 30%. The lowest immunity rate was observed in the20‑ to 29‑year age group. No slgniflCant difference was seen between males and females in terms of protective
effect of vaccination. This study indicates that people between the ages of 1 0 and 59 are susceptible to diphtheria
in oワf country･ Therefore, revaccination of adultswith tetanus‑diphtheria toxoids at eve.ry?pportunity(militaryseⅣlCe, pregnancy, admittance to emergency room) should be considered as an immunlZatlOn policy,of diphtheria vaccine in their 1 8th month. For subjects in older

Diphtheria was once vimlent disease responsible fわr highage groups, a questionnaire was completed to provide infわ‑a‑Porbidity and a high mortalityrate in children･ Widespreadtion abouHhe immunization status and history of diphtheria.

Immunization programs after the 1940s resulted in a sharp

Quantitation of diphtheria specific antibodies was done

decline in the incidence and mortality of the disease in many

using a COmmerCially available lgG‑specific Enzyme Linked

developed countries ( 1‑4).

lmmunosorbent Assay (ELISA) kit (ELISA Diphtheria/Diphtheria lgG, Virotech, order no: EN 129.00, Ch‑B/lot:In the early 1990S, diphtheria reemerged in Turkey's

northeast neighbors, the New Independent States of the fbmer
Soviet Union (5,6)･ The cauヲes Ofthis outbreak yere multi‑

70 1 1 5‑02, Genzyme Virotech GmbH, Riisselsheim, Germany)factorial, and one of the most Important factors was Insufficientthat accurately discriminates diphtheria antibody levels equal

population immunity. This epidemic gave rise to anxiety about
the immune status ofTurkey's population agalnSt diphtheria.
lt is well documented that there is a continuous decline im

to or higher than 0.1 IU/ml, while it has limited ability todifferentiate values below 0. 1 IU/ml (3). It has been suggested
that values of<0.1 IU/ml be considered to indicate susceptl‑

antibody titer after vaccination.against diphtheria (7‑9)I

bility, whereas su用cient immune protection can be expected

Absence of routine revacclnation ln adults might result in anincreaslng number ofsusceptible peopleinTurkey. The outbreakwhen it is equal to o.r above O･1 1U/ml (3,8)I

in neighboring countries highlighted the importance offollow‑

Testing for statistical sign捕cance ofimmunityrates in different

Statistical analysts Was perfb‑ed uslng SPSS Win 8･0･

up studies of the immune status of our population. The aim ofage and sex groups was perfbmed by uslng the chi‑square

this study was to determine the antibody levels for diphtheria

test. A P value of< 0.05 was considered statistically significant.

in different age groups in Ankara, Turkey.

Among the 497 blood samples obtained, 73 were cord blood

A total of497 blood samples were collected randomly舟om

samples, in 53 (72.6%) of which diphtheria antibody levels

members of the population who were admitted to Gazi

were below 0.1 IU/ml. Among the relllainlng 424 blood

University Hospltal斤om January to AugusH 997. Samples

ヲamPles, 152 (35･8%) had antibody titer <0･1 lU/ml, signify‑

were obtained from the cord blood of73 healthy mothers whoモng insufrlCient imrnunityagainst diphtheria･ Distribution oflmlmmityrates among different age groups is shown in Table 1 ,had delivered in obstetric clinics; 64 children (33 males andImmunity rates among different age groups varied significantly

31 females) between 3 and 6 years of age who †ere followed

in well‑child clinics and had their routine vaccmations there;(P < 0.01). The highest percentages of protective levels ofand 360 healthy persons (167 males, 193 females) between

diphtheria antibodies were in the 3‑ to 6‑year and above 60‑

10 and 80 years of age, stratified by agewith approximately

year age groups; 20‑ to 29‑year age group had the lowest

50 subjects in each decade. The children in the 3‑ to 6‑year
age group had vaccination records in our well child clinics,

percentage of protective level of antibodies. Protection rates
did not differ significantly among age groups of subjects

which records confimed that they had received their last doses

between 10 and 39 (P> 0.05).
Protective levels of antibody 一iter (>0.1 IU/ml) against

diphtheria were found in 138 (69･0%) of the Tales and 134*Corre?.ponding author: Mailing address: Beril Sitesi 436･ Sokak

no:3, Umitk6y,Ankara, Turkey. Tel: +90‑3 12‑2141 000 ext. 6025,(59.8%) of the females. Protection rates ln males andFax: +90‑3 12‑2 150143, E‑mail: beyazova@tr.net

females were similar (P > 0.05). ln addition, no significant

52

Table 1. Immunity rates in difFerent age groups
lnsufrlcient

Protectiveimmunityimmunity(< 0.1 IU/ml)

years

12

10 and 39 lacked both revaccination and natural boosters

because diphtheria had been nearly eliminated in Turkey;

Total(‑ 0.1 IU/ml)

J7 (%)
3‑6

because diphtheria was yet prevalent. The subjects betweenn(%)

therefore, this constitutes the most susceptible group.
n(%)(18,7)

52 (81.3)

64 (100)

Some studies have reported that insufrlCient immunityrates
agalnSt diphtheria are more common among women than

10‑19 years

29 (43.2)

38 (56.7)

67 (100)

among. men (6,1 7)･ This difference was attributed to higher

20‑29 years

34 (57.6)

25 (42.4)

59 (loo)revacclnation rates in males resulting from military service or

30‑39 years

32 (46.4)

37 (53.6)

69 (100)

tetanus‑diphtheria vaccination in emergency departments at

40‑49 years

20 (32.2)

42 (67,8)62 (100)

the time of injury. Other studies reported no difFerence between

50‑59 years

16 (29.1)

39 (70.9)55 (100)

the sexes (4,1 1,1 8). ln our study, the protective antibody levels

9 (18.8)

39 (81.2)

48 (100)>60years

Tota1

152(35.8)272(64.2)

424

in males were higher than those in females, but the difference
was not statistically significant. We did not expect to find a(loo)difference between the sexes because in Turkey there is noP<0.01

revaccination for diphtheria during military service, and in
emergency departments only tetanus toxoid, as necessa】Y, lS

difference was found between females and males in terms ofglVen tO people.
In our study, antibody levels against diphtheria in cord

protection in different age groups.
In Turkey, the immunization of children is perf♭med byblood samples were also low. Ages of mothers from whom

the Ministry ofHealth all over the country (10). Vaccination

cord blood samples were obtained ranged between 16‑43

for diphtheria has been administered since 1937. Children(median age: 27)A Pasetti et al･ demonstrated a clos.e correla‑receive the last booster dose of tetanus‑diphtheria vaccine attion between matemal and newborn antibody tlterS, and12 years of age, and no subsequent routine booster dose is

the mean antibody liter determined in cord blood wasrecommended for adults. Routine immunization policies for

signはcantly higher than the matemal liter (19). We did not

DTP vaccines must be based on knowledge about a population's

study diphtheria antibody levels in the mothers in our study,

immunlty, and serologlCal studies are auseful tool in thisbut the low protective antibody levels in cord blood samples

respect. Althoughour study population does not represent thewere thought to be a renection oflow antibody levels amongwhole Turkish population, it does provide data on diphtheria

these young adults, glVen that the lowest antibody levels

immunlty, particularly glVen that immunization policy lnobserved in our study belonged to subjects in the 20‑ to 291

Turkey is standard over various regions (1 0).

year age group. Low antibody tiモer in cord blood means thatIn this study, we found that 35.8% of our study population

antibody liter in the newbom period will also be low, and any

had insufrlCient antibody levels against diphtheria (<0. 1 IU/

delay ln Pnmary Immunization of infants may cause a seriousml). lt is generally accepted that when the antibody level isrisk for them. This finding may be important for countries in

below the critical value, the subjects are unprotected against

which the vaccine coverage rate in early childhood is low.

diphtheria, and when more than 30% of a population is

Susceptible pregnant females represent an important gl.OuP,

unprotected there is the risk of epidemic (7). The mostwhich needs to be reimmunized to provide protection fわrsusceptible age group ln this study was that of subjects

newborns in the early months of life.

between 20 and 29 years, 57.6% of which had insufTICient

In conclusion, this study indicates that the preschool age

antibody levels against diphtheria. In subjects between theages of 1 0 and 49, Overall insufrlCient antibody rate was abovegroup ln Our population is protected agalnSt diphtheria as aresult of recent immunizations, and that a high proportion of30%, These findings are in agreement with the set of otherelderly people still have sufrlCient antibody levels. However,studies, in which the prevalence of insufTICient protection

given the graduahePlacement of natural immunityby lessagalnSt diphtheria among adults was shown to range fromdurable vaccine‑induced immunlty, antibody levels may

22.9% to 40% (4, 7, 1 1‑13). The highpercentage of insufficientdecrease in the elderly age group. Subjects between ages

protection against diphtheria found in our study was attributedof 10 and 59 seem to be susceptible. Such a large pool ofto lack of routine adult immunization. Similar findings insusceptible persons creates epidemic potential, Therefore,

previous studies may be due to the infrequency of adulttetanus‑diphtheria revaccination of adults should be considered

revaccination in those industrialized countries desplte its

as an immunization policy ln Our country. Opportunities forrecommendation. A recent study from Turkey revealed thatrevaccination of adults such as military seⅣice, pregnancy,

79. 1% of the study population had protective levels of anti‑and admittance to emergency rooms should be utilized.

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