INTERNATIONAL JOURNAL OF LEPROSY^ Volume 61, Number 4

Printed in the U.S.A.

Intrafamilial Transmission of Leprosy inVellore Town, Indial

Renu George, P. S. S. Rao, Rachel Mathai, and Mary Jacob2

Studies have been reported on the patternof leprosy in urban arcas (6' 7' 12) but nonehave been reported on the risk among con-tacts in such populations. Published data onthe risks of intrafamilial transmission ofleprosy are mostly from rural arcas (3.5' 9' I").Due to various demographic, environmen-tal and social factors, both the extent of in-trafamilial transmission as well as the un-derlying factors may bc diffcrent in urbanarcas. Passive surveillance of urban arcashas not been found to be successful by otherworkers (2). While cohort studies on leprosypatients and their families resident in anurban population might be done, they canbe expensive, frustrating and subject tolosses from observation. We have attempt-ed a hospital-based study to determine therisk and extent of transmission Within afamily in rclation to characteristics of boththe index case and contacts. This paper pre-sents the findings and also shows how amodel for active surveillance of contactscould be integrated into the general healthservices of any hospital.

MATERIALS AND METHODSVellore town, the capital of North Arcot

and Ambedkar Districts, covers an arca of15 sq. kms. and has a population of 1722 467.Christian Medical College Hospital is a ma-jor tertiary care center located in this town,and our study was done in the Dermatologyand STD Clinic of this hospital. The clinic,for survey of contacts, is conducted once aweek in the afternoon so as to reduce theinconvenience for those at work and school.Each family is examined annually by a doc-tor and services are rendered free. Noticeof the date of examination is given by letter

' Recei‘ ed for publication on 2 April 1993; acceptedfor publication on 28 June 1993.

2 R. George, M.D.; R. Mathai, F.R.C.P.; M. Jacob,M.N.A.M.S., Department of Dermatology; P. S. S. Rao,Dr. P.H., Department of Biostatistics, Christian Med-ical College and Hospital, Vellore, South India 632004.

about 2 weeks in advance. An average of4-5 families are examined every weck andthose familics who default are visited at theirhomes by a social worker. Contacts whodevelop leprosy are registered as new casesand treated.

The study period extended from 1968 to1991, and included ali families currentlyunder surveillance or released within thelast 2 years. The index cases and their fam-ilies included in the study resided in theurban arca.

A proforma for each index case was filledwith demographic data and details of thedisease, such as the duration ofdisease priorto registration, past antileprosy treatment,number of persons living in the family orhousehold defined as people living in closecontact with each other under the same roofand partaking of food from the same kitch-en. For each contact, details recorded wereage at registration, sex, relationship to theindex case, and details of clinical exami-nation (such as the presence of patches,thickened nerves, and arcas of sensory loss).A slit-skin smear for acid-fast basilli (AFB)from four sites was done at each yearly visitfor each contact of index cases with multi-bacillary (MB) leprosy. The contacts whowere detccted to have leprosy at the sametime of examination of the index cases werelabeled as co-prevalent cases.

Patients were classified as indeterminate(Indet), tuberculoid (TT), borderline tuber-culoid (BT), borderline borderline (BB),borderline lepromatous (BL), lepromatous(LL) and primary neuritic (N) on the basisof clinical features and the results of skinsmears which were done for ali patients inthe bordcrline and lepromatous groups.During the earlier part of the study patientswith borderline features wcre classified asdimorphous based on the Madrid classifi-cation (4).

Person years (PYR) of follow up werecomputed for each contact and used as thedenominator for the computation of inci-

550

61, 4^George, et al.: Intraianrilial Transniission^551

TABLE 1. Age and sex distribution of index cases by type of leprosy.

Age (yr)

Classification 0-15 16-30 > 30 Total

Male Female Male Female Male Female

Indet. 3 3 1 1 12TT 4 3 3 3 8 1 22BT 5 3 0 3 5 3 19Dimorphous 4 1 7 3 14 4 33IIL o 1 O 2 5 O 8LL 0 0 4 3 16 25Ncuritic 0 O O 0 0 1 1

Total 15 11 17 16 49 12 120

dence rates. Specific rates were computedby sex, age, type of leprosy, and smear inindex cases as well as by age and sex ofcontacts. Tests for proportion were done us-ing z and x 2 tests.

RESULTSProfile of index cases. A total of 120

index cases (81 males, 39 females) were reg-istered. The age, sex and type of leprosy areshown in Table 1; 50.8% of the cases werebetween 31 and 60 years and 21.6% wereyounger than 15 years of age; 50% of thepatients were in the borderline group.

In 86% of the families the head of thehousehold was literate; 10% of them hadachieved a college-level education, 104(86.6%) were nuclear families.

The classification by the different types ofleprosy and the results of skin smears forAFB are given in Table 2. All patients inthe lepromatous part of the spectrum werepositive as were 15 of 33 with dimorphousand 5 of 19 with BT disease. Skin smearswere negative in patients with Indet and TTleprosy. The duration ofdisease was reliablyknown in 1 1 1 of 120 cases, and 20% carneto the hospital within 6 months of the onsetof the disease. These included 4 Indet, 6

TT, 5 BT, 5 dimorphous, 3 LL, and 1 pa-tient with primary neuritic leprosy; 86 of120 (71.7%) of the patients denied havingtaken any prior treatment.

Profile of contacts. Five-hundred-twocontacts were registered; 14 were found tohave the disease during the first visit andwere classified as co-prevalent cases. Of theremaining 488 contacts, 78 (15.9%) wereexamined only once during the first surveyand were not included in the determinationof PYR among the contacts. The total cu-mulative years of follow up in the remaining410 contacts was 2725 years; 41 (14 males,27 females) of the contacts under surveil-lance defaulted after varying periods of fol-low up. Half of them were in the O to 14age group; 27 of 41 (65.8%) defaulted after5 years of follow up. Sixty-five percent ofchildren in the O to 14 age group completed5 years of follow up.

Incidence rates. Fourteen contacts de-veloped leprosy, of whom 12 (85.7%) werein the O to 14 age group; the remaining 2were in the 35 to 64 age group. The malefemale (M:F) ratio was 1:1. The incidencerate (IR) per 1000 PYR was 5.1 and variedby age at registration and sex as shown inTable 3. There was no gender bias and the

TABLE 2. Types of leprosy in the index cases and results of skin smears for acid-fastbacilli (AFB).

Skin smearforresult

Leprosy classification

AFB Indet. TT BT Dimorphous BL LL Ncuritic

NegativePositiveTotal

12O

12

77O

145

19

181533

O88

02525

1O

1

Male^FemaleMale^FemaleNo. contacts Rate/1000 PYRAge of.

contact(yr)

Person-years offollow up

Male^Female

Contacts developedleprosy

Male^Female

l41

2Indet.TT 1BTBBBLLL

1^—^120-4 11.6 2.95-14 6.4 4.1

>15 3.3 O

Ali 7.3 2.8

PYR = Person years of contact.

552^ International Journal of Leprosy^ 1993

TABLE 3. Incidence rates by sex and age of contacts at registration.

0-4 51 35 498 277 5 1 10.04 3.605-14 65 77 514 436 4 3.89 9.14

15-34 40 71 160 43235-64 29 41 184 221 9.04> 65 1 — 3 —Total 186 224 1359 1366 7 7 5.15 5.12

PYR = Person years of contact.

risk was highest in contacts younger than15 years of age, being 6.9 in males and 7.01in females.

The IR was 7.3 per 1000 and 2.8 per 1000among contacts of MB and paucibacillary(PB) cases, respectively; the difference wasnot statistically significant (Table 4).

The disease spectrum in contacts includ-ed 9 with TT, 3 Indet, and 2 BT leprosy;12 of 14 (85.7%) were detected within thefirst 5 years of surveillance.

Leprosy in contacts by characteristics ofthe index cases. The characteristics of the11 index cases whose contacts developedleprosy were analyzed. The M:F ratio of the11 index cases was 4.5:1; the overall M:Fratio of the index cases was 2:1. None of thecontacts of index cases less than 15 yearsold developed the disease; 7 of 1 1 (63.3%)of the source cases were between 31 and 60years of age, the remaining were in the 16to 30 age group. Table 5 shows the type ofleprosy in the index cases and in the contactswho developed leprosy. The disease spec-trum included 6 patients with LL, 2-cachwith TT and dimorphous, and 1 with In-deter Ieprosy; 8 ofthem were in the MB part

TABLE 4. Incidence rate ainong contactsby age and skin-sulcar residis (per 1000PYR").

índex case

Smear positive^Smear negative

of the spectrum. In three families there were2 contacts who each developed leprosy. Thesource in all was LL. The duration ofdiseaseprior to registration was known in only 9 of11 index cases; the average duration was55.3 months. The relationships to the con-tacts were: parent in 7, spouse in 2, andgrandparent in 2; husband and wife wereinfected in 2 families.

Leprosy in contacts of multiple-case fam-ilies. Eleven multiple-case families weredetected at registration (Table 6). Threefamilies had two co-prevalent cases each;10 of 14 (71.4%) of the co-prevalent caseswere on treatment at the time of registra-tion. In this group 25 persons had the dis-case (11 index cases and 14 co-prevalentcases), 7 were lepromatous and 18 nonlep-romatous. Of the 43 contacts, 28 (65%)were in the O to 14 age group. The cumu-lative years of follow up in the contacts ofmultiple-case families was 528 years; only1 contact developed the disease, the IR inthis group being 1.8.

In five families the co-prevalent case wasprobably the index case taking finto consid-eration the age of the person, the older per-

TABLE 5. Leprosy in index cases versusleprosy in contacts.

Type ofleprosy ^

contact det.'n^In- TT BT Dimor- BL LL Neuriticphous

Age ofcontact

(yr)

Type of leprosyin index case

61, 4^George, et al.: Intrafamilial nansmission^553

TABLE 6. Sex, age, type of leprosy, and relationship of the index and co-prevalent cases.

Index case Co-prevalent case

Scx Age range Diseasc typc(yr) SexAge range

(yr) Relationship Discasc type

31-6016-300-5

TTLLTT

5-145-14> 65

SonSonGrandfather

Indet.TTBT

31-60 BT 5-14 Son TT31-60 BT 5-14 Son TT0-5 IIT 15-34 Father DL

E 16-30 IIT 35-65 Nlother-in-law BT16-30 LL 35-65 Mother DL

E' 16-30 1ndet. (i) F 15-34 Mother LL(ii) F 5-14 Sibling TT

16-30 LL (i) F 5-14 Sibling BT(ii) F 5-14 Sibling TT

F 31-60 BL (1) M 31-60 Husband BT(ii) M 0-5 Son TT

" In fwe familics the co-prevalent case was identified as the primary case in view of the age of the patient.

son probably having acquired the diseaseearlier. The characteristics of these indexcases and the contacts were analyzed to seeif the pattern was similar to the rest of thesource cases and their contacts. It was seenthat although the ages of the source caseswere similar to the single-case families wherecontacts developed the disease there weremore females among the index cases. Thedisease spectrum was similar, 60% were lep-romatous. Although the major age group atrisk among contacts in the single-case fam-ilies was children younger than 15 years,contacts aged 16 to 30 years were also foundto be susceptible in this group. However,considering the long incubation period, thesecontacts may have been infected duringchildhood. Among the contacts who devei-oped leprosy, one each had Indet and LL,and three were in the tuberculoid part of thespectrum.

DISCUSSIONThe results from other studies done in

urban areas (26 7, 12 ) and our results haveshown a higher prevalence ofleprosy amongadults. Although the study was done in anurban arca and the majority of cases or thehead of the household were literate only 20%of the index cases carne to the hospital with-in 6 months of the onset of the disease. Thisemphasizes a large reservoir of untreated orinadequately treated persons with leprosyin the community. Data from this studyshow that there was no added risk to con-

tacts living in multiple-case families, in-cluding those families where there were threemembers with leprosy. This is contrary tothe observations of Jesudasan, et ai. whofound a statistically significant higher riskamong multiple-case families of nonlepro-matous index cases (5). Our data on theoverall risk among household contacts, agegroup at risk, and the type ofleprosy amongthe contacts compared favorably with re-sults ofother workers (5.9. ")). It is noted that12 of 14(85.7%) contacts developcd the dis-case within the first 5 years of follow up. Astudy done by Mathur, et al. also found that,irrespective of the type of disease in the in-dex case, the maximum number of contactsdeveloped disease with 5 years of contact(8). Results of our study suggest that the riskof infection is from within the family ratherthan from outside, even in a leprosy-en-demic arca, as suggested by Jesudasan, etal. (5).

Although a greater number of contacts ofMB leprosy developed the disease, the dif-ference in incidence rates among contactsof MB and PB leprosy was not statisticallydifferent. It, however, points to the fact thatPB leprosy is still a potential source of in-fection and cannot be ignored (').

It is important to evolve a hospital-basedsurveillance program for contacts ofleprosypatients since the early detcction and treat-ment of contacts developing leprosy are im-portant measures to reduce the reservoir ofinfection in the community. We have in-

554^ International Journal of Leproso^ 1993

tegrated the contact surveillance programinto the existing hospital scrvices since thiswill reduce stigmatization and social prob-lems arising therein. The existing resourcesand services of the health caro personnelhave been utilized. Hcalth education is giv-en to increase the awareness of the diseaseand the importance of periodic surveillanceof family members. Interest in the familyencourages both compliance in patients andfamily members to come to the hospital.Data from our study and by other workershas shown a greater risk of acquiring thedisease in children younger than 15 yearsof age ( 5 "). Further, because the majoritydeveloped the disease within 5 years of sur-veillance, a hospital-based survey should bedesigned to focus on contacts younger than15 years of age for a period of 5 years. Com-pliance was also seen to be better the first 5years in our study. This will help to reducethe load on the overburdened health caresystem in urban arcas.

Revankar, et al. have shown that treat-ment of leprosy can be integrated success-fully into the general health services in ur-ban arcas ("). However, the feasibility ofhospital-based surveillance of contacts ofpersons with leprosy has not been studied.The present study recommends that contactsurveillance should be integrated into theexisting hospital services since treatment ofthe index cases alone would only partiallyaddress the problem of control of the trans-mission of leprosy.

SUMMARYA hospital-based study was done from

1968 to 1991 to determine the risk and ex-tent of intrafamilial transmission of leprosyin relation to the characteristics of the indexcases and contacts in urban arcas in India.Families were examined by doctors an-nually. Skin smears were done for contactsof multibacillary (MB) leprosy patients.Person years of follow up were computedfor each contact and used as the denomi-nator for computation of incidence rates.Specific rates were computed by age, sex,type of leprosy, smear in index cases, age atregistration, and sex of contacts.

Of the 120 index cases (81 males, 39 fe-males) 44% were MB; 410 contacts (186males, 224 females) and 14 co-prevalentcases were registered. The cumulative years

of follow up was 2725 years. Fourteen con-tacts developed the disease (9 TT, 3 inde-terminate, and 2 BT); 85.7% were in the 0-14 age group; 12 of 14 patients were de-tected to have leprosy during the first 5 years.Thc incidence rate (IR) was 5.1/1000 (males5.15, females 5.12). The IR was 7.3/1000and 2.3/1000 among contacts of MB andpaucibacillary leprosy patients (p < 0.05).Thc IR in multiple-case familics was 1.8.The importance of active surveillance by ahospital-based survey is emphasized. Itshould be designed to focus on childrenyounger than 15 years and should be limitedto 5 years of follow up.

RESUMENDe 1986 a 1991 se realizó un estudio con control

hospitalario para determinar cl riesgo y el grado de

transmisión intrafamiliar de la lepra en relación a Ias

características de los casos índice y sus contactos, enáreas urbanas de la India. Las famílias se examinaron

anualmente por doctores calificados. En los contactosde los pacientes multibacilares (MB) se recurrió a la

búsqueda de bacilos en extendidos de linfa cutánea.Para cada contacto se calcularon los afios de segui-

miento por persona y los resultados se usaron como

denominador para el cálculo de los valores de inci-

dencia. Los valores específicos se calcularon tomandoen cuenta la edad, el sexo, cl tipo de lepra, las baci-

loscopias en los casos índice, la edad al momento delregistro, y el sexo de los contactos.

De 120 cases índice (81 hombres, 39 mujeres), de

los cuales 44% fueron MB, se registraron 410 contactos(186 hombres, 224 mujeres) y 14 casos coprevalentes.

El tiempo acumulativo de seguimiento fue de 2725anos. Catorce contactos desarrollaron la enfermedad

(9 TT, 3 indeterminados, y 2 BT); 85.7% estuvieronen el grupo de edades entre los O y los 14 afios; 12 de

los 14 contactos se diagnosticaron como enfermos de

lepra en los primeros 5 anos. El índice de incidenciafue de 5.1/1000 (hombres 5.15, mujeres 5.12). Los

índices de incidencia fueron de 7.3/1000 en los con-

tactos de los pacientes con lepra multibacilar, y de 2.3/1000 en los contactos de los pacientes con lepre pau-cibacilar (p < 0.05). El índice de incidencia en las

famílias con múltiples casos fue de 1.8. Se enfatiza laimportancia de la vigilancia activa coordinada por el

centro hospitalario. Esta debe enfocarse a los ninosmenores de 15 afios y estar limitada a 5 anos de se-guimiento.

RESUMEUne étude réalisée à partir de l'hopital a été réalisée

de 1968 à 1991 pour déterminer le risque et l'extension

dela transmission intra-familiale dela lépre en relation

avec les caractéristiques des cas index et des contactsdans des zones urbaines en Inde. Des familles ont étéexaminées chague année par des médecins. Des frottis

61, 4^George, et al.: Intrafanzilial Transmission^555

cutanés ont été prélevés chez les contacts de patientslépreux multibacillaires (MB). On a calculé le nombrede personnes-années d'observation pour chague con-tact et on l'a utilisé comme dénominateur pour le calculde taux d'incidence. On a calculé cies taux spécifiquespour l'âge, le sexe, le type de lèpre et les frottis cutanésdes cas index, l'âge à l'enregistrement et le sexc dcscontacts.

Parmi les 120 cas index (81 hommes, 39 femmes),44% étaient MI3; 410 contacts (186 hommes, 224femmes) et 14 cas co-prévalents on été enregistrés. Letotal cumulé d'années de suivi était de 2725 années.Quatorze contacts ont développé la maladie (9 TT, 3indéterminés et 2 I3T); 85.7% appartenaient au grouped'âges 0-14 ans; 12 des 14 contacts ont été détectéscomme ayant la lepre au cours des 5 premières années.Le taux d'incidence était de 5.1/1000 (hommes 5.15,femmes 5.12). Le taux d'incidence était de 7.3/1000et 2.3/1000 respectivement parmi les contacts de pa-tients lépreux MB et PB (p < 0.05). Le taux d'incidencedans les familles à cas multiples était de 1.8. L'im-portance de la surveillance active par enquêtes réaliséesà partir de l'hôpital est soulignée. Celles-ci devraientêtre planifiées de maniere à se concentrer sur les enfantsde moins de 15 ans et devraient se limiter à un suivide 5 ans.

Acknowledgment. We are grateful to Mr. David Sel-vapandian, 13.Sc., for help in data entry and analysisand to Mrs. Linda Robert for secretarial assistance.

REFERENCES1. 13RowN, J. A. K. Factors influencing the trans-

mission ofleprosy. Trans. R. Soc. Trop. Med. Hyg.53 (1959) 179-189.

2. GANAPATI, R., REVANKAR, C., PANDYA, S. S. andAcHARERAR, M. Y. Prevalence of leprosy among

inpatients in a general hospital—a survey in Bom-bay. Lepr. Rev. 51 (1980) 325-328.

3. GEORGE, K., JOHN, K. R., Muum, J. P. andJOSEPH, A. The role of intra-household contact inthe transmission of leprosy. Lepr. Rev. 61 (1990)60-63.

4. INTERNATIONAL CONGRESS OF LEPROSY, MADRID

1953. Report of Committee on Classification. Int.J. Lcpr. 21 (1953) 504-516.

5. JESUDASAN, K., I3RADLEY, D., SMITH, P. G. andCHRISTIAN, M. Incidence rates of leprosy amonghouschold contacts of"primary cases" Lcpr. India56 (1984) 600-614.

6. KAUR, S., KUMAR, B. and ROY, S. M. Endemicityofleprosy in the union territory ofChandigarh andsurrounding state. Lepr. India 54 (1982) 428-440.

7. MARSIIALL, J. T., AMAR, D. S. and RAMESH, H. C.Prcvalence of leprosy among slum dwellers, Lepr.India 53 (1981) 70-82.

8. MATHUR, N. K., SHARMA, M., BUMB, R. A. andYEGI, G. A study of multiple case familics. Lepr.India 56 (1974) 200-206.

9. RAO, P. S. S., JESUDASAN, K., MANI, K. and CHRIS-TIAN M. Impact of MDT on incidence rates ofleprosy among household contacts. Part 1. Base-line data. Int. J. Lepr. 57 (1989) 647-651.

10. RAO, P. S. S., KARAT, A. B. A., KALA1PERUMAL,V. G. and KARAT, S. Transmission of leprosywithin households. Int. J. Lepr. 43 (1975) 45-54.

11. REVANKAR, C. R., JIIA, S., DONGRI, V. V.,DESHPANDE, S. and GANAPATI, R. Integration ofleprosy into general health services in an urbanarca; a fcasibility study. Lepr. Rev. 53 (1982) 297—305.

12. Schgel, V. N., Ghorpade, A. and SAHA, K. Urbanleprosy—an appraisal from northern India. Lepr.Rev. 55 (1984) 159-166.

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