Sensitivity to tuberculin and to a nonmammalian sensitin in Mandalay District, Burma

MYCOBACTERIAL DISEASES Sensitivity to tuberculin and to a nonmammalian sensitin in Mandalay District, Burma 'rf!En4 NYUNT,1 P. GALLEGO GARBAJOSA,2 M. MATEJKA,3 C. T. TAMONDONG,4 MG MG GYI,5 & J. GULD 6 Delayed hypersensitivity that can be demonstrated with either a strong dose of tubercu- lin or a conventional dose of a sensitin prepared from certain nonmammalian myco- bacteria (mycobacteria of Runyon Groups 11 and III, e.g., Mycobacterium avium), is known to be highly prevalent in most tropical and many subtropical areas and rare in many temperate zones. Whether such sensitivity interacts significantly with tuberculosis or with leprosy is not known. A study of reactions to tuberculin (PPD-S) and to a sensitin prepared from M. intracellulare (PPD-B) was carried out in villages close to an area in which a clinical trial of the preventive effect ofBCG against leprosy was being conducted. The population had not been vaccinated with BCG. Some of the villages were in river valleys that become flooded every year for a long period during the rainy season; others were on slopes above the area subject to floods. The findings showed that sensitivity to the nonmammalian sensitin was prevalent in the area, and thus confirmedprevious findings oflow-grade tuberculin sensitivity in Burma and neighbouring countries. No difference in this prevalence was jound between flooded and nonflooded villages. The phenomenon of low-grade, nonspecific sensi- tivity was first demonstrated by Palmer et al. (1). It is closely linked with sensitivity to avian tuberculin (2, 3) and to sensitins prepared from mycobacteria of Runyon Groups II and III (4). It therefore seems reasonable to assume that the phenomenon is caused by mycobacteria of those species. Because nonspeci- fic sensitivity causes cross-reactions to ordinary tuberculin, it rather complicates epidemiological I Director, Disease Control, Department of Health, Ministry of Health, Rangoon, Burma. 2 WHO Medical Officer and Team Leader, Leprosy BCG Trial Team, Mandalay, Burma. 'Former WHO Scientist, Leprosy BCG Trial Team, Mandalay, Burma. ' WHO Statistician, Leprosy BCG Trial Team, Manda- lay, Burma. I Medical Officer (Team Leader), National Leprosy Con- trol, Department of Health, Ministry of Health, Mandalay, Burma. I WHO Medical Officer, Tuberculosis, Division of Com- municable Diseases, World Health Organization, 1211 Geneva 27, Switzerland. Requests for reprints should be addressed to this author. studies of tuberculous infection and also the public health use of the tuberculin test. It was suggested by Palmer & Long (5) that such sensitization could act as a " natural vaccination " against tuberculosis. However, this hypothesis has remained an inference from retrospective observa- tions and has not been confirmed by more recent data (6). The present study was undertaken in 1971 in conjunction with a controlled trial being conducted in Mandalay District, Burma, on the possible pre- ventive effect of BCG vaccination against lepro- sy (7). Since possible cross-reactions resulting from delayed hypersensitivity would be crucial to the interpretation of such a study, it was considered necessary to examine and record the prevalence of sensitization caused by avian or related mycobacte- ria in the area. This sensitivity is known to be correlated with climate, being less frequent in high mountains (8) and in temperate zones (9). It is not unreasonable to assume that it is caused by orgati- isms normally propagated elsewhere than in mam- 3323 63 - BULL. WORLD HEALTH ORGAN., Vol. 52, 1975 64 THEIN NYUNT ET AL. malian hosts, and any further ecological associations would thus be of interest. The area covered by this study includes both river valleys that are flooded for much of the rainy season and slopes above the reach of floods (referred to, in the following text, as "flooded lands " and " dry lands ", respectively). POPULATION, MATERIAL, AND METHODS The villages selected a were close to, but not included in, the BCG-leprosy trial area, and had not been covered previously by the mass BCG vaccina- tion teams-generally because they were less acces- sible. Although the fact that these villages had not been covered had been revealed by surveys of BCG scars, every person included in the present study was again examined for the presence of a scar that might have resulted from BCG vaccination, and persons with such scars have been excluded from the data presented below. The whole population was included in the examination: 1 078 persons in the flooded lands and 936 persons in the dry lands. The age distribution of the study population is shown in the next column. Skin testing was carried out by intradermal injec- tion in both forearms, the tuberculin and sensitin being given alternately in the right and left arms. Reading of the reactions was done three, or occa- sionally four, days later by measuring the diameter of the induration in millimetres. The reading was done blindly-i.e., the reader did not know whether the tuberculin test had been performed in the right or in the left arm. The dose of tuberculin was 5 international units of PPD-S-the batch originally made by Seibert for standard purposes, and used for many years by Palmer in his epidemiological studies. The dose of sensitin was 5 " units " of PPD-B, prepared later with the same technique at the Center for Disease Control, Atlanta, GA, USA, from a strain of the " Battey " organism (M. intracellulare). The mate- rials were shipped by air, in dilutions ready for use, from Atlanta to Mandalay. RESULTS The reactions were found to be distributed in the nonsymmetrical way characteristic of a population with both specific and nonspecific sensitivity-i.e., a All these villages were in Madaya township, except for one, which was in Shwebo township. some persons reacted markedly to both the tuber- culin and the sensitin, though more strongly to the former, whereas others had no significant tuberculin reaction but still showed weak or moderate reactions to the sensitin. For both tests, the frequency of reactions increased with age, but otherwise the pat- tern was the same for different age groups and was not much influenced by sex. Results for the age group 5-9 years, for both sexes, are shown in Tables 1 and 2 as the correlation of reactions to PPD-S and to PPD-B for flooded and for dry lands, respectively.b The reactions to PPD-S do not fall clearly into " positive" and " negative" groups. Persons with larger reactions to PPD-S may also be seen to have larger reactions to PPD-B, on the average, than those more clearly negative to PPD-S. It seems reasonable to assume that many of the reactions to PPD-S (especially in or near the range 6-11 mm) are cross-reactions due to nonspecific sensitivity. In this age group the prevalence of infection with tuberculosis (as revealed by PPD-S) in low, in both flooded and dry lands. In the higher age groups, infection with tuberculo- sis could be demonstrated more clearly from the reactions to PPD-S. Taking, somewhat arbitrarily, a reaction of 12 mm or more to PPD-S as positive, the following results were obtained (both sexes): Flooded lands Dry lands No. No. No. No. Age examined positive examined positive 0-4 187 2 142 5 5-9 180 6 138 10 10-14 149 11 150 24 15-24 175 31 135 42 25-39 171 51 159 66 40 + 216 98 212 125 In both the flooded and dry lands the prevalence of infection was higher in males than in females. For persons of 15 years and older, the distribution was: Males Females No. No. No. No. examined positive examined positive flooded lands 258 106 304 74 dry lands 223 119 283 114 b The complete correlation tables have been deposited in the WHO Library and single photocopies may be obtained by professionally interested persons on request to: Chief Libra- rian, World Health Organization, 1211 Geneva 27, Switzer- land. TUBERCULIN SENSITIVITY Table 1. Correlation of reactions to 5 international units of PPD-S and to 5 " units " of PPD-B in children of both sexes, aged 5-9 years (flooded lands) Size of reaction to PPD-B (mm) 0-1 2-3 4-5 6-7 8-9 10-11 12-13 14-15 16-17 18-19 20-21 Total 0-1 11 2-3 7 4-5 1 E E 6-7 '? 8-9 - a IL X. 10-11 - 0 12-13 - c 0 ° 14-15 - 0 16-17 - 0 a, 18-19 - .N 20-21 - 22-23 - 24-25 - 14 4 3 10 11 2 2 13 9 2 15 16 4 1 7 11 4 1 1 2 3 1 2 1 2 1 1 2 82 81 18v 5 3 5 2 2 Total 19 23 33 26 36 24 9 4 4 2 - 180 Table 2. Correlation of reactions to 5 international units of PPD-S and 5 " units " of PPD-B in children of both sexes, aged 5-9 years (dry lands) Size of reaction to PPD-B (mm) 0-1 2-3 4-5 6-7 8-9 10-11 12-13 14-15 16-17 18-19 20-21 0-1 15 2-3 1 4-5 1 E E 6-7 8-9 czCL 0~L- 10-11 - 12-13 - a 0 *g 14-15 - 16-17 - 0 *) 18-19 -N cn 20-21 - 22-23 - 24-25 - 8 13 9 9 2 1 - 1 3 9 6 1 3 7 1 10 5 3 5 4 1 1 2 1 2 _ _ _ - - - 1 - - - - - - - - 1 1 - - - 1 - - - - - 1 - - _ _ _ _ - 3 - 1 - _ - - 1 - - 50 48 22 6 1 2 2 4 I Total 17 19 25 20 19 18 7 8 3 2 - 138 65 1 1 1 THEIN NYUNT ET AL. The tendency towards a lower prevalence of tuber- culous infection in the flooded lands is probably only of trivial epidemiological significance. Reactions to PPD-B (among non-reactors to PPD-S) and their prevalence are not different in the flooded and dry lands-or only insignificantly so. DISCUSSION The findings are in agreement with previous find- ings of low-grade sensitivity in Burma (WHO Tuber- culosis Research Office, unpublished data, 1955) and neighbouring countries. The lack of difference in reactions to PPD-B between the flooded and dry lands is a negative piece of evidence concerning the origin of the sensitizing organism. If the normal habitat of the sensitizing organism were an immobile medium, e.g., soil or flora, one would perhaps expect an annual protracted flooding of the land to have some influence. The negative finding thus implies that the sensitizing agent may be spread in other ways, e.g., through certain animal species or by dust. ACKNOWLEDGEMENTS The authors are particularly indebted to the staff of Tuberculosis Control, Department of Health, Rangoon, for their valuable assistance. The skin test solutions were supplied by Dr L. B. Edwards, Center for Disease Control, US Public Health Service, Atlanta, GA, USA. Mr K. Naganna, Statistical Officer, Tuberculosis Prevention Trial, Bangalore, India, organized the data processing. RESUME SENSIBILITi A LA TUBERCULINE ET A UNE SENSITINE D'ORIGINE NON MAMMALIENNE DANS LE DISTRICT DE MANDALAY (BIRMANIE) On sait qu'une hypersensibilite retardee, demontrable soit avec une dose elevee de tuberculine, soit avec une dose classique de sensitine pr6paree a partir de certaines mycobacteries d'origine non mammalienne (mycobac- teries des groupes Runyon II et III, par exemple Myco- bacterium avium), est tres fr6quente dans la plupart des regions tropicales et subtropicales, et rare dans de nom- breuses regions temperees, mais on ignore en revanche si cette sensibilit6 a une incidence importante sur la tuberculose ou la lepre. On a etudie les r6actions de la population a la tuber- culine (PPD-S) et a une sensitine preparee a partir de M. intracellulare (PPD-B) dans des villages proches d'une zone oiu l'on experimentait cliniquement la valeur pro- phylactique du BCG contre la lepre. Aucun programme de vaccination BCG de masse n'avait ete execute dans les villages choisis, et l'on a exclu des donnees presentees ici les quelques individus porteurs de marques de scarifi- cation, qui avaient donc ete vaccines anterieurement. Cer- tains des villages se trouvaient dans des vallees longue- ment inondees chaque ann6e pendant la saison des pluies, les autres etaient a flanc de colline, hors de portee des inondations. Dans chaque village, la totalite de la population a ete soumise it l'preuve, soit 1 078 personnes dans les zones inond6es et 936 dans les zones non inon- dees. La dose de tuberculine administree etait de 5 unites internationales de PPD-S, et celle de sensitine, de 5 < uni- tes * de PPD-B. Les deux materiels avaient ete foumis par le Center for Disease Control d'Atlanta (Georgie, Etats-Unis d'Amerique). La tuberculine et la sensitine ont chacune ete injectees au hasard, soit dans le bras droit, soit dans le bras gauche de chaque sujet. La lecture des reactions a et faite, sans que le lecteur sache dans quel bras a e pratiqu6e l'injection, trois ou quatre jours plus tard par mesure du diametre de l'induration, expri- mee en millimetres. La sensibilit6 a la sensitine (PPD-B) d'origine non mammalienne s'est revelee prevalente dans la zone etu- diee, comme il ressort des tableaux 1 (zone inondee) et 2 (zone non inondee) etablis pour le groupe d'age de 5 a 9 ans. Ce resultat confirme la faible sensibilite a la tuberculine, constate anterieurement en Birmanie et dans les pays voisins. On n'a pas relevee de difference entre les villages inondes et les villages non inondes quant aux reactions a la PPD-B. Si l'habitat normal de l'organisme sensibilisant etait un milieu immobile - sol ou flore par exemple - l'inondation annuelle prolongee du site devrait normalement exercer une certaine influence. 66 TUBERCULIN SENSITIVITY 67 Comme on n'a pas observe de difference, on est amene A penser qu'il existe d'autres modes de propagation de l'organisme sensibilisant, par exemple par certaines especes animales ou par la poussiere. La pr6valence d'une sensibilite specifique a la tuberculine a e moderee; chez les enfants de 10 a 14 ans, par exemple, elle etait de 12%. Les r6actions sp6cifiques par age et par sexe sont pre- sentees dans un tableau, insere dans le corps du texte. REFERENCES 1. PALMER, C. E. ET AL. Public health reports, 65: 1111- 1131 (1950). 2. WHO TUBERCULOSIS RESEARCH OFFICE. Bulletin of the World Health Organization, 12: 85-99 (1955). 3. HART, P. D'ARCY ET AL. Bulletin of the International Union against Tuberculosis, 32: 403-408 (1962). 4. EDWARDS, L. B. ET AL. Bulletin of the World Health Organization, 33: 405-412 (1965). 5. PALMER, C. E. & LONG, M. W. American review of respiratory diseases, 94: 553-568 (1966). 6. COMSTOCK, G. W. ET AL. American journal of public health, 64: 283-291 (1974). 7. BECHELLI, L. M. ET AL. Bulletin of the World Health Organization, 42: 235-281 (1970). 8. BATES, E. B. ET AL. Public health reports, 66: 1427-1442 (1951). 9. NYOwE, J. Bulletin of the World Health Organization, 22: 5-37 (1960).