A Study of Blood Groups and Leprosy in the Population of Colonia Tovar
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I NT ERNATIONAL JOU RN A L O F LEP ROSY Volume 3:). N u mber 4 Prin/n / hi U .S. A . ~, A Study of Blood Groups and Leprosy in the Population of Colonia Tovar, Venezuela 1. ~ Michel F. Lech at, Thomas Bile and Enrico Rasi 3 As a preli min ary trial fo r a larger study ers, ,vho li ve around the church, the popu of geneti c polymorphism and leprosy, a lation is scattered in small farms in th e sm vey of ABO blood groups was undertak vall ey or foo thills. The households are oft en en among leprosy patients and nonl eproti c constituted by three generati ons, grandpar controls in the isolate of Colonia Tovar in ents, parents and children. Venezuela. The German popu lation of the region, however, is not limited to Coloni a Tovar. STUDY AREA As the popul ati on increased over the las t Colonia Tovar is located in a valley cov hundred years, a few satellite haml ets de ering approxim ately 13 square miles, at an veloped in nearby vall eys beyon d th e altitude of 6,000 feet in th e State of Ar mountains. As the years passed, some peo agua, in the northern part of Venezuela. ple moved to the nearest Creole villages or The population constitutes a genetic iso even to the ci ty of La Victoria. Cultural, late, consistin g almost exclusively of per linguistic and breedi ng characteristics have sons of German ancestry, descendants of been diluted progress ively as the distance immigrants who settled in the valley be from the center of the settlement in tween 1843 and 1856. It is said that these creased. Recently, with the opening of a settlers numbered 146, representing no road connecting Coloni a Tovar and patronyms. For the mos t part they ori gi Caracas, important changes have com nated from a few villages in the Black menced in the community, which is now Forest, Germany. Since then the population rapidly losin g its earli er characteristics. The has lived in a state of relative isolati on, no village has a health center, with a phys ician road having connected the valley to the in charge, helped by three auxiliary-nurses. rest of the country until the 1950's. Census data are extensive and apparent The s urro undin ~ mountainous area is al ly close to co mplete, the whole population most unpopulated, except for a few scat having been followed up for the last 12 tered families of Creole extraction, born of years by the Servicio de Dermatologia San Spanish and/ or Indian ancestry. The result itaria (leprosy service) of Aragua State. has been high inbreeding of the group. The data include distribution of the popu Apart from shopkeepers and skilled work- lation by household, with information on sex, age and family relationshio for each 1 Received for publica ti on 26 September 1966. member of the household. In 1962 census 2 T h is work was supported in pa rt by the Divi estimates gave a total German population si6n de Dermatologia Sanitaria, Min isterio de San i dad y Asistencia Soc ial of VeneI'I ela. and the Leon of 1,028 in Colonia Tovar ( 1,107 have left ani Wood Memorial by Train ing Gran t 5 T I AI the isolate and live elsewhere). 220, National Institute of All ergy and In fectious The prevalence of leprosy in the commu Di seases, National Instillites of Health, Bethesda, Maryland 200 14. nity is high. It is not known how and when 3 M. F. Lechal. M.D .. P rofessor of Epidemiology, the disease was introduced. A survey made School of Public Health, Lou vai n Un ive rsity, Brus in 1942 revealed 32 confirmed cases of sels, Belgium; T. Bi le, M.D.. Medico J efe del Servicio de De rmatologia San itaria del Edo. Aragua. leprosy and 9 suspects among 808 persons Ca ll e Felix Maria Paredes No. 20, Oeste. La Vi c examined (H) . Cases were sent to the Cabo toria. Edo. Aragua: E. R as i, M.D., Med ico Adju n to de la Di vision de Derma tologia San ita ria, Luneta Blanco Leprosarium, near Caracas, where a Mercedes, Ed ift cio Catll che, Car a~ a s. Venezp ela. at one tim e 29 pati ents fr om Col onia Tovar 4$8 35, 4 Lechat et. al.: Blood Groups & Leprosy, Colonia Tovar, Venezuela 489 were isolated. In 1950 COllvit (3) foulld the Servicio de Dermatologia Sanitaria in 113 cases among 1,126 persons examined, La Victoria for conditions other than lep who constituted nearly all the population at rosy. that time. The prevalence, therefore was Characteristics of the sample. The age 100.4/ 1,000, a figure in sharp contrast to the distribution of cases and controls is given in prevalence in the rest of the State of Ar Table 1 by ethnic groups, disease status, agua, 1.35/ 1,000. and sex. Among the Germans, 58.0 per cent After 1950, several surveys were made of the individuals were under 40 years of again by Convit et al. (1 ,2.4) , in con age, in .contrast to 65.2 per cent among the nection with studies of lepromin-reactivity Creoles. The patients were on the av e r a~e in the population. Thirty- two more cases older than the controls, 48.1 per cent of the were found, some of which had escaped patients being under 40, in con tras t to 64.9 detection in earlier surveys. In 1962 an per cent of th e controls. examination of the German population of The sample consisted of 448 individuals, Colonia Tovar revealed only two cases not including 174 males (38.8%), of whom 52 yet registered (r;). (29.9%) were cases of leprosy, and 274 females (61.2%), of whom 29 ( 10.6%) were SAMPLING AND TECHNICS affected by the disease. Among the 81 Sampling methods. Although random cases, 54 (66.7%) were of German extrac sampling from lists prepared beforehand tion, 16 (19.8%) of Crevle extraction, and from the registers of leprosy in the Division 11 ( 13.6%) of mixed extraction. Among de Dermatologia Sanitaria of th e Ministerio the 367 controls, 179 (48.8%) were of Ger· de Sanidad y Asistencia Social ill Caracas, man extraction, 165 (45.0%) of Creole ex was intended, the procedure soon ap traction, and 23 (6,3%) of mixed extraction. peared to be unworkable for practical and As far as possible, multiple sibs were psychologic reasons. Although the cooper excluded from the sample, through precise ation given by the personnel of the local instructions given to the health inspectors health center, as well as by the sanitary screening the individuals for blood tes ting. inspectors of the Servicio de Dermatologia Although it is believed that this purpose Sanitaria (leprosy service) was excell ent has been fulfilled to a major extent for and dedicated, summons of the selected those sibs sharing the same household, individuals yielded few attendances. It mostl y children, this goal probably was not should be remembered in this conn ection, achieved for old sibs living in different that this population had been subjected to households. Moreover, in the German pop numerous surveys, especially skin testing, ulation, the high degree of inbreeding im over the past few years. plies some degree of family relationship Cases and controls in the German isolate among all members of the population. were therefore included in the sample as The diagnosis of leprosy was ascertained volunteers. The population was invited to from the records of the Servicio de Derma cooperate in the survey. In addition, blood tologia Sanitaria (leprosy service) of Ar specimens were taken from individuals at agua State, which for the last few years was tending the local health center. Advantage in charge of leprosy surveillance in this was taken also of a local survey of the area. No attempt was made to classify handicapped for rehabilitation, conducted patients with respect to the type of leprosy, concurrently among the leprosy patients. since most of them were residual cases. Specimens from the Creole population Technics. The typing was performed im were obtained as opportunity arose in mediately after blood withdrawal, with use Colonia Tovar and the nearby city of La of grouping cards developed by Becton and Victoria. The sample consisted of mothers Dickinson Co., Baltimore, Maryland. Be attending the well-baby clinics at the local cause of djffi culties encountered in health center, persons submitted to serolog drawing blood from leprosy patients with ic test for syphilis on the occasion of re anesthetic hands, and from rural individu ques t for travel authorization, and persons als used to hard work, with call ous hands, attending the dispensary of E1 Consejo an<l blood WaS withdrawn from th ~ v<;l ins. Tbis 490 l nte'l'national Journal of Leprosy 1967 ..,;<O-l<ooNoo-l< 0 procedure did not raise any objections. In M I -~ •.C';l """" M I-- 0 contrast, first attempts to collect blood from 3 ~C'lC"l-.~ 0 o the fin gertips were strongly opposed by thc population. The collecti on of blood and technica l ____ ~~--~-y.-. ~I --g--·~--~--~--g--~-~----cl --~-- handling were carried out by local auxil O ooM NO><DN 0 C'i oo C'i~ciC'ici 0 iaries under the direct supervision of one of ~ I ~NN~ - 0 the authors for the first 381 specim ens. -----!----------- --- -- Later on, these procedures were conducted .