Endemicity of Diphtheria in an Indian Population in Northwestern Ontario Author(s): T. KUE YOUNG Source: Canadian Journal of Public Health / Revue Canadienne de Sante'e Publique, Vol. 75, No. 4 (July/August 1984), pp. 310-313 Published by: Canadian Public Health Association Stable URL: http://www.jstor.org/stable/41988862 . Accessed: 10/06/2014 23:13 Your use of the JSTOR archive indicates your acceptance of the Terms & Conditions of Use, available at . http://www.jstor.org/page/info/about/policies/terms.jsp . JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact
[email protected]. . Canadian Public Health Association is collaborating with JSTOR to digitize, preserve and extend access to Canadian Journal of Public Health / Revue Canadienne de Sante'e Publique. http://www.jstor.org This content downloaded from 62.122.72.78 on Tue, 10 Jun 2014 23:13:54 PM All use subject to JSTOR Terms and Conditions http://www.jstor.org/action/showPublisher?publisherCode=cpha http://www.jstor.org/stable/41988862?origin=JSTOR-pdf http://www.jstor.org/page/info/about/policies/terms.jsp http://www.jstor.org/page/info/about/policies/terms.jsp Endemicity of Diphtheria in an Indian Population in Northwestern Ontario T. KUE YOUNG, M.D. M.ScJ Despite cases of the diphtheria marked decline in Canada in the since incidence the 1930s, of clinical large cases of diphtheria in Canada since the 1930s, large numbers of toxigenic strains of Corynebacterium diphthe- riae continue to be isolated each year, especially among certain population groups. Jellard and associates reported on diphtheria infection in northern Alberta and the western Arctic settlements for more than a decade and noted that over 90% of the 6,000 isolations were from Native Indians, Metis, and Inuit. Substantial differences in the clinical and epidemiological features between diphtheria infection in the Native and Caucasian Canadian were also found.14 This paper reviews the epidemiological patterns of diph- theria infection in the Sioux Lookout Zone in northwestern Ontario and discusses the implications for control measures. The Zone is a health service area for some 10,000 Cree- Ojibwa Indians living in 25 isolated remote communities.5 It is located within the subarctic boreal forest belt of Central Canada and socioeconomic conditions and health status of the population are generally poor compared to Canadians nationally.67 ■Department of Social and Preventive Medicine, University of Manitoba. This work was conducted when the author was with the Sioux Lookout Zone, Medical Services Branch, Health and Welfare Canada. Reprint requests to Dr. Young at the Department of Social and Preventive Medicine, Faculty of Medicine, University of Manitoba, 750 Bannatyne Avenue, Winnipeg, Manitoba R3E 0W3 METHODS Laboratory data on biotype, toxigenicity, and site of cul- ture as well as health service records on immunization sta- tus, clinical indications for testing, and the outcome of contact investigations were collected on all Indian residents of the zone from whom C. diphtheriae had been isolated between 1975 and 1982. Sources of data include the registry of positive cultures maintained by the Provincial Public Health Laboratory in Thunder Bay and notification records kept at Zone headquarters in Sioux Lookout. Additional information was obtained from patients' medical files kept in the Zone Hospital and peripheral nursing stations. RESULTS Positive cultures of C. diphtheriae were obtained from 58 individuals during the 8-year period. No deaths occurred - the last diphtheria death in the Sioux Lookout Zone was recorded in 1970 in a patient with myocarditis. The ages ranged from 3 months to 32 years (Table I), but the majority of isolates were from children - 86% were under 10 and 64% under 5 years of age. Table II indicates that 85% of the positive cultures were from discharging ears with a few from the upper respiratory tract (nose, pharynx, and tonsils) and skin. All the mitis biotypes were non-toxigenic while most gravis strains were toxigenic. No intermedius strains were isolated. 310 Canadian Journal of Public Health Vol. 75, July/ August 1984 The persistent isolation of Corynebacterium diphther- iae in a remote isolated Indian population in northwest- ern Ontario is investigated and the clinical and bacterio- logical characteristics of the cases and carriers described. The great majority of isolations were from discharging ears in young children , most of whom had had adequate immunization. The epidemiological pattern is compared with other populations in North America and the impli- cations for public health practice discussed. On étudie ici l'isolement persistant du Corynebacte- rium diphtheriae dans une population indienne isolée du Nord-ouest de l'Ontario et l'on décrit les caractéristiques bactériologiques et cliniques des cas et des porteurs. La majorité du produit isolé provenait de décharges des oreilles enfants très jeunes, dont la plupart des ces jeunes avaient été immunisés. L'échantillon épidémiologique est comparé avec d'autres populations d'Amérique du Nord, et l'on étudie les implications sur la santé publique. This content downloaded from 62.122.72.78 on Tue, 10 Jun 2014 23:13:54 PM All use subject to JSTOR Terms and Conditions http://www.jstor.org/page/info/about/policies/terms.jsp Infections were reported from 13 communities of the Zone but two in particular accounted for half the cases. Figure 1 shows the seasonal incidence by month of isola- tion. The largest number of infections were observed in the fall and winter. Figure 1. Seasonal incidence of isolation of C. diphtheriae, 1975-1982. Diphtheria organisms were usually found in mixed cul- tures with beta-hemolytic streptococci and Staphylococcus aureus. Among ear discharges other organisms such as Enterobacter, Klebsiella , Pseudomonas and E. coli were also occasionally cultured. The clinical presentations were usually mild - the classi- cal obstructive membranous pharyngitis was not seen. All the positive cultures from ears were from acute and chronic otitis media. None of these showed toxic manifestations and should be considered only as carriers. There were 3 skin infections - 2 non-toxigenic mitis from a 32 year-old man with leg ulcers and a 13 year-old boy with an infected skin graft, and a toxigenic gravis from a 4 year-old girl with acute glomerulonephritis associated with impetigo. The 6 pharyn- geal cases, all of which grew toxigenic gravis, illustrate the difficulty in deciding if the infection constituted a "case" or a "carrier": - 4 month-old female, with one previous diphtheria tox- oid, presented with fever and periauricular abscess; nasopharyngeal swab grew diphtheria and streptococci; both were also cultured when the abscess drained into the external auditory meatus; - 6 year-old male, fully immunized, presented with fever and a whitish exudate, but no membrane, in the pharynx; - 8 year-old female, fully immunized, presented with cer- vical adenitis, though the classical "bull neck" was not seen; - 3 year-old male, fully immunized, presented with tonsillitis; - ÌVi year-old female, fully immunized, presented with febrile convulsions; a septic "work-up" in hospital included a throat swab which grew diphtheria; - 1 1 year-old female, fully immunized, asymptomatic con- tact of her 4 year-old sister who had toxigenic gravis skin infection. The names of household contacts were obtained from official Indian band lists and community informants. The medical records of these contacts were searched to deter- mine if they had undergone contact investigation. From 18 index cases with toxigenic strains, 72 household contacts were identified, of whom 39 were investigated bacteriologi- cally. Only 3 additional carriers (2 toxigenic and 1 non- toxigenic) were discovered. No contact investigations were undertaken in 7 of the index cases. Contact tracing was not consistently carried out for non-toxigenic carriers. Other types of contact such as those at school or at work could not be determined in this retrospective record review. The immunization status at the time of infection was determined for 53 individuals, classified into "full", "inade- TABLE I Age-Sex Distribution of Persons With Diphtheria Infections under 1 yr. 1-4 yr. 5-9 yr. 10-14 yr. 15 yr. & over Total Male 5~ ~~ 11 4 i 2 23 Female 8 13 9 4 1 35 Total 13 24 13 5 3 58 Cumulative % 22% 64% 86% 95% 100% TABLE II Distribution of Diphtheria Infection by Biotype, Toxigenicity, and Site of Culture Site of Culture Biotype Toxigenicity Ears Respiratory Tract Skin Total Gravis toxigenic 13 6 1 20 (34.5%) non-toxigenic 3 0 0 3 ( 5.2%) Mitis non-toxigenic 33 0 2 35 (60.3%) TOTAL 49 (84.5%) 6(10.3%) 3(5.2%) 58 (100%) July/August 311 This content downloaded from 62.122.72.78 on Tue, 10 Jun 2014 23:13:54 PM All use subject to JSTOR Terms and Conditions http://www.jstor.org/page/info/about/policies/terms.jsp quate" or "lapsed", modified from Ontario Ministry of Health notification criteria (see legend in Table III). The majority (77%) of infections occurred in people who had had full immunizations against diphtheria. Immunization was not found to be associated with either toxigenicity or the site of infection (Table III). DISCUSSION Diphtheria infection is a persistent public health problem among Native Indians in northern Canada. The frequent isolation of toxigenic strains poses a dilemma in manage- ment to health workers not familiar with the disease. Tradi- tional medical textbooks tend to concentrate on the discus- sion of classical clinical diphtheria which is now seldom seen, and shed little light on the epidemiological significance and management of carriers and mild cases. In North America diphtheria epidemics continue to be reported in the general population8 9 as well as among skid row residents1011 and in rural areas adjacent to Indian set- tlements.12 In Canada Jellard found that while isolations were more frequent among Indians they suffered less severe clinical illness.1 However, the continuous presence of carri- ers in the community perpetuates transmission. The incidence of diphtheria infection in the Sioux Look- out Zone was approximately 1/1000 population per year during the period under study. This was much less than the approximately 10/ 1000 per year reported from the Native population of northern Alberta and the western N.W.T. M There may have been underestimation in the Sioux Lookout Zone for logistical reasons - the vast distances between the communities and the laboratory, failure of specimens to survive the long transit time in the mail, and a tendency of health workers to treat infections empirically without obtaining appropriate cultures probably accounted for the lower incidence. However the same conditions also apply in the N.W.T. so that the observed difference cannot be entirely explained as a reporting artifact. This study highlights several issues which are important in the control of diphtheria in the Native population: (1) Immunization and infection: During the 1 970s and early 1 980s there was a high level of immunization coverage of the population in the Sioux Look- out Zone; over 90% of the children had a complete or partial primary series against diphtheria, pertusis, tetanus and poliomyelitis. The majority of cases and carriers identified in this study were also well immunized. High incidence of diphtheria infections has been reported in other areas with a high proportion of the population immunized,13-3 and epi- demics have continued despite mass campaigns to improve coverage.9 However, immunization appears to prevent the infection from developing into severe clinical illness and death. 14 Miller showed that whereas the infection rates were similar between those fully immunized and those never immunized, the latter had a 30-fold higher risk of developing clinical disease.15 Another relevant issue is the use of fluid (non-adsorbed) toxoid which is still the practice in Ontario in 1983. Sekla showed that 30% of children aged 2-3 years had inadequate diphtheria antibody levels despite 4 doses of vaccine.16 There is thus the possibility that clinical illness may still occur, given the high prevalence of infections in the com- munity and the possibility of vaccine ineffectiveness despite good coverage. Jellard suggested that the decline in the number of isolations in the N.W.T since 1979 could be the result of a change in policy to using adsorbed vaccines.2 (2) Contact investigations: The low yield from contact investigations among house- hold members and the rarity of family clusters suggests that efforts devoted to contact investigation after the discovery of a carrier or case have not been productive. The fact that an individual may be positive on culture at one time and negative on another due to sampling variation adds to the difficulty of eradicating the organism from the community. (3) Role of fomites: Belsey studied extensively environmental contamination with C. diphtheriae by skin carriers.17 I did not investigate whether environmental contamination existed in the Zone but the poor socioeconomic status, housing standards and level of hygiene in many communities suggest that fomite transmission may also play a role in the persistence of diphtheria. TABLE III Immunization Status of Persons With Diphtheria Infection Toxigenicity Site of Infection Total Immunization Status Toxigenic Non-toxigenic Respiratory Skin Ears No. % Full 15 26 6 2 33 4~' TL4 Inadequate/ Lapsed 3 6 0 1 8 9 17.0 None 0 3 0 0 3 3 5^6 Notes: 1. Immunization records were not available for 5 individuals. 2. Classification of immunization status is modified from Ontario Ministry of Health criteria on notification forms: full - primary series or primary series and booster completed within 10 years of infection lapsed - when time period between infection and completion of primary series or primary series and booster is greater than 10 years inadequate - incomplete primary series anytime prior to infection none - never received diphtheria toxoid 3. Only 1 person (non-toxigenic, skin) fell into the "lapsed" category - this is therefore combined with the "inadequate" category 4. 3 infants (2 non-toxigenic/ ear, 1 toxigenic/ respiratory) were under 4 months old at time of infection but had received toxoid once or twice as appropriate for their age. These infants were classified as "full." 5. Chi-square tests were performed with two categories of immunization ("full" and "other") vs. toxigenicity: 1 df, Chi-square 0.56, p > 0. 1 ; and vs site of infection- 2 df Chi-square 2.07, p> 0.1 312 Canadian Journal of Public Health Vol. 75 This content downloaded from 62.122.72.78 on Tue, 10 Jun 2014 23:13:54 PM All use subject to JSTOR Terms and Conditions http://www.jstor.org/page/info/about/policies/terms.jsp (4) Role of skin infection: In the Sioux Lookout Zone C. diphtheriae was not reco- vered from the skin in as high a proportion as was reported from Western Canada. There may have been underutiliza- tion of laboratory investigations as there is no lack of impe- tigo in the Zone, where it is a major health problem espe- cially in the late summer. Normal skin has even less likelihood of being swabbed and cultured. Belsey reported that skin carriers were more important during non- epidemics while respiratory spread represented the major mode of transmission during epidemics. A higher percen- tage of people exposed to skin carriers acquired the infection than those exposed to respiratory carriers, and the skin infection persisted longer.18 Among white school children a much higher carrier rate resulted from exposure to a skin case than to a respiratory case.12 (5) Role of otitis media: The high incidence of otitis media among Native popula- tions across Canada is well recognized. 19 20 Since diphtheria is usually isolated with other pathogens it is believed that it is not the causative organism. It has been suggested that diph- theria reaches the inner ear via the skin of the external auditory canal rather than from the nasopharynx via the Eustachian tube.2 In this study over 60% of the strains isolated from the ear and skin were non-toxigenic mitis. Unless the problem of otitis media among Native children is controlled, eradication of diphtheria infection is unlikely to be achieved. (6) Treatment of carriers: Erythromycin is the drug of choice with a 97% efficacy compared to 84% for a single intramuscular dose of benza- thine penicillin.21 The former has usually been used in the Sioux Lookout Zone but post-treatment culture was not consistently done to confirm eradication. Among the 58 individuals only 2 had second infections - in one case the infections were 3 years apart and in the other only 1 month apart, the latter possibly the result of treatment failure. While benzathine penicillin may be less efficacious, it has the advantage of simplicity of use and good compliance. (7) Definition of diphtheria: The distinction between "case" and "carrier" remains a problem and probably leads to incorrect conclusions about national trends. There should be an intermediate category of clinical diphtheria infection without the classical toxic signs and symptoms when reporting the disease to official health agencies. CONCLUSIONS It is frustrating for public health professionals that diph- theria should persist in communities where immunization coverage is good, where efficacious therapy exists and is freely available, and where the population is relatively iso- lated but accessible to surveillance by an organized health service. Better documentation of treatment outcome by cul- tures and better transport of specimens may contribute to improved control. The data indicates that contact tracing is often hit-and-miss, and a prospective study should be done to better elucidate the effectiveness of this practice. The use of adsorbed vaccines, the superiority of which has recently been reviewed,22 should be considered. A more systematic search for carriers - for example in schools and at well baby clinics - may be tried in one or two communities to see if it would be a worthwhile undertaking. However, ultimately improvement in socioeconomic conditions is necessary for better control of diphtheria infection in Indian communities. REFERENCES I. Jellard CH. Diphtheria infection in North West Canada: 1969, 1970, and 1971 . J Hy g (Camb) 1972; 70: 503-10. 2. Jellard CH. Diphtheria in northern Alberta and the MacKenzie and Inuvik Zones of the Northwest Territories, 1969-1981. Can Dis Weekly Rep 1982; 8: 57-9. 3. Dixon JMS, Thorsteinson S. Diphtheria bacilli isolated in Alberta in 1967 from the throat, nose, ears and skin. Can Med Assoc J 1969; 101: 204-7. 4. Gourlai B, Boyland B, von Heitz R, et al. Diphtheria - Northwest Territories (MacKenzie and Inuvik Zones). Can Dis Weekly Rep 1981; 7: 53-4. 5. Young TK. Primary health care for isolated Indians in northwestern Ontario. Public Health Rep 1981; 96: 391-7. 6. Young TK. Changing patterns of health and sickness among the Cree- Ojibwa of northwestern Ontario. Med Anthropol 1979; 3: 191-223. 7. Young TK. Self-perceived and clinically assessed health status of Indi- ans in northwestern Ontario: analysis of a health survey. Can J Public Health 1982; 73: 272-7. 8. McCloskey R V, Eller JJ, Green M, et al. The 1 970 epidemic of diphthe- ria in San Antonio. Ann Intern Med 1971; 75: 495-502. 9. Zalma VM, Older JJ, Brooks GF. The Austin, Texas, diphtheria outbreak. JAMA 1970; 211: 2125-9. 10. Cockcroft WH, Boyko WJ, Allen DE. Cutaneous infections due to Corynebacterium diphtheriae. Can Med Assoc J 1973; 108: 329-31. 1 1. Pedersen AHB, Spearman J, Tronca E, et al. Diphtheria on skid row, Seattle, Washington, 1972-75. Public Health Rep 1977; 92: 336-42. 12. Koopman JS, Campbell J. The role of cutaneous diphtheria infection in a diphtheria epidemic. J Infect Dis 1975; 131: 239-44. 13. Murphy WJ, Maley VH, Dick L. Continued high incidence of diphthe- ria in a well-immunized community. Public Health Rep 1956; 71: 481-6. 14. Mumford RS, Ory HW, Brooks GF, Feldman RA. Diphtheria deaths in the United States 1959-70. JAMA 1974; 229: 1890-3. 15. Miller LW, Older J, Drake J, Zimmerman S. Diphtheria immuniza- tion: effect upon carriers and the control of outbreaks. Am J Dis Child 1972; 123: 197-9. 1 6. Sekla L, Stackiw W, Drewniak M. An evaluation of the immune status of Manitobans to diphtheria, pertusis and tetanus. Can J Public Health 1980; 71: 227-80. 17. Belsey MA. Isolation of Corynebacterium diphtheriae in the environ- ment of skin carriers. Am J Epidemiol 1970; 91: 294-9. 18. Belsey MA, LeBlanc DR. Skin infection and the epidemiology of diphtheria: acquisition and persistence of C. diphtheriae infections. Am J Epidemiol 1975; 102: 179-84. 19. Baxter JD. Observations on the evolution of chronic otitis media in the Inuit of the Baffin Zone, NWT. J Otolaryngol 1982; 11: 161-6. 20. Lupin AJ. Ear disease in Western Canadian Natives with a note on treatment by tympanoplasty. J Otolaryngol 1976; 5: 116-21. 21. McCloskey RV, Green MJ, Eller J, Smilock J. Treatment of diphtheria carriers: benzathine penicillin, erythromycin, and clindamycin. Ann Intern Med 1974; 81: 788-91. 22. Cameron J. Immunization against diphtheria, pertusis (whooping cough) and tetanus in Canada: the benefits from the use of adsorbed vaccine. Can J Public Health 1982; 73: 404-9. Received: September 2, 1983 Accepted: September 21, 1983 July/August 313 This content downloaded from 62.122.72.78 on Tue, 10 Jun 2014 23:13:54 PM All use subject to JSTOR Terms and Conditions http://www.jstor.org/page/info/about/policies/terms.jsp Article Contents p. 310 p. 311 p. 312 p. 313 Issue Table of Contents Canadian Journal of Public Health / Revue Canadienne de Sante'e Publique, Vol. 75, No. 4 (July/August 1984), pp. 257-328 Front Matter From the Editor's Desk [pp. 257-257] EDITORIAL QUARANTINE AND OUT-MODED REGULATIONS [pp. 261-262] LA QUARANTAINE ET LES RÈGLEMENTS DÉMANDÉS [pp. 264-265] Measles Elimination — Identification of the Unimmunized Child [pp. 266-268] Re-Evaluation of Immune Status to Measles, Mumps and Rubella Viruses in the Canada Health Survey Population and the Indochinese Refugee Population [pp. 270-272] Sequellae of School-Related Injuries: School and Parent Perspectives [pp. 273-276] Scoliosis: To Screen or Not to Screen [pp. 277-280] Determining and Costing Outcome Measures of School Screening Programs [pp. 281-284] Alcohol Consumption in Healthy Women: Relationship to γ-Glutamyl Transferase Activity, Mean Corpuscular Volume and Hormonal Status [pp. 285-288] Correlation entre la satisfaction de la vie, la perception de l'état de santé et les activités chez les personnes agées [pp. 289-293] Characteristics of Clients Generating High Administrative Workload in a Long-Term Care Program [pp. 294-300] A Geriatric Assessment Unit in a Long-term Care Facility [pp. 301-303] Le Rince-Bouche Fluoré en tant que Mesure Préventive en Santé Communautaire: Article de Revue [pp. 304-309] Endemicity of Diphtheria in an Indian Population in Northwestern Ontario [pp. 310-313] HEALTH TOPIC Hepatitis B Immune Status of Health Workers: Survey of a Regional Hospital in New Brunswick [pp. 314-317] Giardiasis — A Recent Investigation [pp. 318-320] FEATURES BOOK REVIEWS Review: untitled [pp. 320-321] Review: untitled [pp. 321-321] Review: untitled [pp. 321-321] LETTERS [pp. 323-325] Back Matter