The Donation and Sale of Blood by Intravenous Drug Users U-M
:P;A:rRE-o
Dale D. Chitwood, PhD, J. Bryan Page, PhD, Mary Comeiford, MSPH, JamesA. Inciardi, PhD, Clyde B. McCoy, PhD, Edward Trapido, ScD, and Shenghan Lai, PhD, MPH
Intodution Because HIV infectivity precedes
antibody formation,1,2 blood service organizations must rely on self-reported history and physical signs to exclude intravenous drug users (IVDUs) from donor pools. The exclusion of IVDUs is also important because they are at high risk for the human lymphotropic viruses (HTLVIIII),3'4 which can be transmitted through infected blood5,6 but forwhich blood services do not routinely screen. In spite of increased donor exclusion efforts, IVDUs continue to donate and sell blood.7 Nelson and colleagues8 studied the blood donation histories of a predominately Black cohort of IVDUs from the Baltimore metropolitan area and reported that 27.1 percent had donated or sold blood between 1978 and 1988. Data from other geographic areas have not been reported. We studied a tri-ethnic cohort of IVDUs in Miami-Dade County, Florida, which has the highest number of cases of AIDS (acquired immunodeficiency syndrome) attributable to parenteral drug use in the Southeastern United States.9 As part of this investigation, we assessed the seroprevalence of HIV-1 and HTLV-I/II among the study sample, compared IVDUs who donated/sold blood with those who did not, compared donors with sellers, and examined the association of drug treatment with the donation/sale of blood.
Methods Between June 1987 and August 1988, 915 IVDUs in South Floridawere enrolled in a longitudinal study to determine HIV-1 serostatus and associated risk behaviors (22.8 percent were HIV seropositive at baseline). Seven hundred and four participants were recruited from drug treatment facilities in South Florida (eight methadone maintenance clinics, three residential drug-free programs, and one residential detoxification facility). An additional 211 subjects not enrolled in a drug treatment program were recruited directly from the streets. All subjects had used a
drug or drugs intravenously at some time since January 1, 1978. All participated on a voluntary basis, gave informed consent, were tested for HIV-1 serostatus, and received pre- and post-test counseling. As part of a structured questionnaire, participants answered questions concerning their most recent donation or sale of blood. All were assured these data would be kept fully confidential and would not be disclosed to anyone including treatment center staff. Participants were paid a fee after completion of venipuncture and interview. All sera were tested for the presence of antibodies to HIV-1. Residual sera, available on 874 of the study participants, were tested subsequently for antibodies to HTLV-VI/. Because of cross-reactivity, the assay did not differentiate between antibodies to HTLV-I or HTLV-II. Serum was determined to be positive for antibodies to HIV-1 after two positive ELISAs (enzyme-linked immunosorbent assay) determined with Abbott Enzyme Immunoassay and a confirmatory positive Western Blot following the Centers for Disease Control protocols using viral lysate from Hillcrest Biologicals. A radioimmune assay utilizing an in-house 1"Iionated core protein (p24), purified from human virus, was the antigen for detecting antibody to HTLV-I/II. Serum samples were tested at dilutions of 1:10 and 1:100, which bracket the dilution levels of maximum sensitivity for sera of all titers. Sera were evaluated in terms of percent-bound counts using a high-titered reference seFrom the Comprehensive Drug Research Center, Department of Oncology, Biopsychosocial Center for the Study of AIDS, and the Department of Psychiatry, University of Miami School of Medicine, all authors except Inciardi who is with the Division of Criminal Justice, University of Delaware, Newark, DE. Address reprint requests to Dale D. Chitwood, PhD, Research Associate Professor, School of Medicine, Universityof Miami, 1550 N.W. 10th Avenue, Room 301, Miami, FL 33136. This paper, submitted to the Journal May 9, 1990, was revised and accepted for publication November 20, 1990. Editores Note: See also related editorial on page 561 of this issue.
American Journal of Public Health 631
Public Health Bnefs
or blood products has diminished significantly, but has not disappeared.10-12 Screening for antibodies to HTLV-I/II is not routinely conducted. Several IVDUs who donated or sold blood currently test
rum at 1:100 dilution as the 100 percent standard. Sera were scored as positive if the percent-bound counts were greater than 5 percent at the 1:100 dilution. Logistic regression analysis was used to evaluate the possible association between demographic characteristics of IVDUs and their behavior regarding the donation or sale of blood since 1985.
Results Of the 915 IVDUs interviewed, 153 (16.7 percent) reported that they had donated or sold blood since January 1, 1985; four out of five (80.4 percent) of these 153 IVDUs had sold blood. A total of 22.8 percent of the study population tested positive for HIV-1 (Table 1). Of the 153 IVDUs who had contnbuted blood, 19.6 percent tested positive for antibodies to HIV-1 at the time of interview. Of the subjects who had donated or sold blood, 5.7 percent of those tested for HTLV-III were positive. Serostatus at the time they donated/sold their blood is unknown. When IVDUs who had donated or sold blood were compared with IVDUs who had not done so in a logistic regression, males and IVDUs who were not in treatment were more likely to have donated/sold blood (Table 2). No differences were observed by ethnic or age group. The demographic characteristics of IVDUs who had donated and those who had sold blood were also compared (data 632 American Journal of Public Health
not shown). Donors were differentiated from sellers only by treatment status. Of those in treatment who had sold/donated blood, 68.5 percent had sold; 98.8 percent of the IVDUs from the street had sold rather than donated.
Discussion Although participation in the study wasvoluntary, results indicate that the donation and sale of blood by IVDUs is not restricted to the Northeastern United States, and that the sale of plasma or blood accounts for almost all IVDU involvement in the blood supply. The percentage of IVDUs in South Florida (16.7 percent) who donated or sold blood between 1985 and 1988 was virtually identical to the 15.0 percent reported by Nelson and colleagues8 for a cohort of IVDUs in Baltimore. At least four out of five IVDUs from both Miami (80.4 percent) and Baltimore (88.1 percent) who contributed blood during that time period had sold blood or plasma at a commercial service rather than donated at a voluntary blood center. Blood services utilize blood screening procedures to ensure that the supply is as safe as possible, but the elimination of high-risk donors remains an unfinished task in the overall plan to protect the blood supply. Since the initiation of blood screening for HIV antibodies and the utilization of the Cohn fractionation process and pasteurization procedures, the risk of a recipient receiving HIV infected blood
positive for HIV-1 and/or HTLV-VII. It must be emphasized that there is no way to ascertain the serostatus ofthese IVDUs at the time of their last donation or sale. Whether any of the blood contnbuted by these IVDUs became part of the blood supply is unknown, but it is evident that members of this high-risk group continue to donate/sell blood. The elimination of the sale of blood by IVDUs is a difficult matter. As long as commercial centers exist, IVDUs will attempt to sell their blood. Two characteristics of commercial blood centers facilitate this selling behavior: commercial blood centers which advertise that they pay cash for blood or plasma attract active drug users who do not have stable sources of income; commercial blood centers often are located in inner-city neighborhoods where poverty and drug use are prevalent. Commercial blood centers must take a more careful approach in the selection of potential sellers. It is imperative that the screening process at commercial blood services be intensified to identify potential sellers who inject drugs or have a history of IV drug use. Commercial blood centers should employ highly qualified individuals, who have had experience with IVDUs, to screen potential sellers for eligibility. Included in the screening process should be a rigorous check for track marks (scarring caused by repeated injections) on arms and other indications of IV drug use.
Drug treatment programs can play an important role in the reduction in the number of IVDUs who donate or sell blood. Educational intervention with past sellers and donors in treatment could have an immediate positive impact. Blood services, both voluntary and commercial, have an enormous responsibility to exclude IVDUs from their contributor pool. It is incumbent upon these services to staff the blood centers with highly qualified persons who can identify and exclude high-risk persons who continue to donate or sell blood. El
Acknowledgments Supported in part by grants ROIDA04433 from the National Institute on Drug Abuse, and P50MH424-55 from the National Institute of Mental Health.
May 1991, Vol. 81, No. 5
Public Health Bnefs
References 1. Imagawa DT, Lee MH, Wolinsky SM, et ak Human immunodeficiency virus type 1 infection in homosexual men who remain seronegative for prolonged periods. N Engl J Med 1989; 320:1458-1462. 2. Ward JW, Holmberg SD, Allen JR, et ak Transmission of human immunodeficiency virus (HIV) by blood transfusions screened as negative for HIV antibody. N Engl J Med 1988; 318:473-478. 3. Mildvan D, Des Jarlais D, Sotheran J, etal: Prevalence and significance ofHTLV-I in a cohort of IV drug users in New York. IV International Conference on AIDS, Stockholm, June 12-16, 1988. 4. Robert-Guroff M, Weiss SH, Giron JA, et at Prevalence of antibodies to HTLV-I,
5.
6.
7.
8.
-II, and -III in intravenous drug abusers from an AIDS endemic region. JAMA 1986; 255:3133-3137. Williams AE, Fang CT, Slamon DJ, et ak Seroprevalence and epidemiological correlates of HTLV-I infection in US blood donors. Science 1988; 240:643-646. Okochi K: Transmission of HTLV-I (ATLV) through cellular components of blood donors carrying antibodies of the virus. In: Petricciani JC, Gust ID, Hoppe PA, Krijen HW (eds): AIDS: The Safety of Blood and Blood Products. New York: John Wiley & Sons, 1987; 231-233. Cleary PD, Singer E, Rogers TF, et al: Sociodemographic and behavioral characteristics of HIV antibody-positive blood donors. Am J Public Health 1988; 78:953-957. Nelson KE, Vlahov D, MargolickJ, Bernal M, Taylor E: Blood and plasma donations
9.
10.
11.
12.
among a cohort of intravenous drug users. JAMA 1990; 263:2194-2197. Centers for Disease Control: HIV/AIDS Surveillance Report. Atlanta: CDC, March 1990. Schorr JB, Berkowitz A, Cumming PD, Katz AJ, Sandler SG: Prevalence of HTLV-III antibody in American blood donors. N Engl J Med 1985; 313:385. Ness PM, Douglas DK, Harper M, Polk BF: Declining prevalence of HIV-seropositive blood donors. N Engl J Med 1990; 321:615. Neumann P, O'Shaughnessy M, Remis R, Tsoukas C, Lepine D, Davis M: Laboratory evidence of active HIV-1 infection in Canadians with hemophilia associated with administration of heat-treated factor VIII. J AIDS 1990; 3:278-281.
Hyperendemic Urban Blastomycosis A. Cesare Manetti, MD, MPH
Introdudion North American Blastomycosis is an elusive, cosmopolitan, systemic infection caused by the dimorphic fungus Blastomyces dermatitidis. First described by Gilcrest1 in 1894, the infection became known as "the Chicago disease" because of the number of cases seen from that area. Later it was referred to as North American blastomycosis as the extent of its wider distribution in the United States and Canada was discovered. Today the disease is correctly and simply referred to as blastomycosis, and its etiologic agent is known to be endemic in Europe, the Middle East, Africa and India. In the Mississippi and Ohio River valleys, where it is primarily endemic, blastomycosis occurs sporadically in humans, dogs and other mammals. Blastomycosis is considered rare, but its true incidence is not known since it is not reportable in most states. Outbreaks of blastomycosis are seldom observed, and those reported have offered unique opportunities to investigate the source of the infection. The nine outbreaks that have been described to date have mostly been associated with outdoor activities.2.3 All but one have occurred in non-urban locations, and six were observed in the Great Lakes region. In three of the outbreaks, it was possible to isolate B. demnatitidis from rotten wood at exposure sites, mostly in an environment
around waterways.3.4
One of the most baffling aspects of blastomycosis has been the difficulty encountered in demonstrating where the oganism lives in nature and where humans and animals contract the infection. Any unusual concentration of blastomycosis cases is of interest since it may offer some clues as to the natural habitat of B. dermattidis. This is a report of two hyperendemic foci of blastomycosis in an urban setting.
Methos Blastomycosis is not a reportable illness in the State of Illinois, nevertheless, a sufficient number of cases came to the attention of the director of the Winnebago County Health Department to suggest the need for an investigation of a possible underlying problem. A search of the files of three Rockford hospital pathology departments and of their respective medical records uncovered 32 cases of blastomycosis. They had all been diagnosed by one or more of three modalities, namely culture, histologic sections and cytologic examinaFrom the Department of Community Health Sciences, School of Public Health, University of Chicago; and the Department of Pathology, University of Illinois College of Medicine at Rockford. Address reprint requests to A. Cesare Manetti, MD, MPH, P.O. Box 4508, Rockford, IL 61110-4508. This paper, submitted to the Joumal May 15, 1990, was revised and accepted for publication November 2, 1990.
American Journal of Public Health 633
:P;A:rRE-o
Dale D. Chitwood, PhD, J. Bryan Page, PhD, Mary Comeiford, MSPH, JamesA. Inciardi, PhD, Clyde B. McCoy, PhD, Edward Trapido, ScD, and Shenghan Lai, PhD, MPH
Intodution Because HIV infectivity precedes
antibody formation,1,2 blood service organizations must rely on self-reported history and physical signs to exclude intravenous drug users (IVDUs) from donor pools. The exclusion of IVDUs is also important because they are at high risk for the human lymphotropic viruses (HTLVIIII),3'4 which can be transmitted through infected blood5,6 but forwhich blood services do not routinely screen. In spite of increased donor exclusion efforts, IVDUs continue to donate and sell blood.7 Nelson and colleagues8 studied the blood donation histories of a predominately Black cohort of IVDUs from the Baltimore metropolitan area and reported that 27.1 percent had donated or sold blood between 1978 and 1988. Data from other geographic areas have not been reported. We studied a tri-ethnic cohort of IVDUs in Miami-Dade County, Florida, which has the highest number of cases of AIDS (acquired immunodeficiency syndrome) attributable to parenteral drug use in the Southeastern United States.9 As part of this investigation, we assessed the seroprevalence of HIV-1 and HTLV-I/II among the study sample, compared IVDUs who donated/sold blood with those who did not, compared donors with sellers, and examined the association of drug treatment with the donation/sale of blood.
Methods Between June 1987 and August 1988, 915 IVDUs in South Floridawere enrolled in a longitudinal study to determine HIV-1 serostatus and associated risk behaviors (22.8 percent were HIV seropositive at baseline). Seven hundred and four participants were recruited from drug treatment facilities in South Florida (eight methadone maintenance clinics, three residential drug-free programs, and one residential detoxification facility). An additional 211 subjects not enrolled in a drug treatment program were recruited directly from the streets. All subjects had used a
drug or drugs intravenously at some time since January 1, 1978. All participated on a voluntary basis, gave informed consent, were tested for HIV-1 serostatus, and received pre- and post-test counseling. As part of a structured questionnaire, participants answered questions concerning their most recent donation or sale of blood. All were assured these data would be kept fully confidential and would not be disclosed to anyone including treatment center staff. Participants were paid a fee after completion of venipuncture and interview. All sera were tested for the presence of antibodies to HIV-1. Residual sera, available on 874 of the study participants, were tested subsequently for antibodies to HTLV-VI/. Because of cross-reactivity, the assay did not differentiate between antibodies to HTLV-I or HTLV-II. Serum was determined to be positive for antibodies to HIV-1 after two positive ELISAs (enzyme-linked immunosorbent assay) determined with Abbott Enzyme Immunoassay and a confirmatory positive Western Blot following the Centers for Disease Control protocols using viral lysate from Hillcrest Biologicals. A radioimmune assay utilizing an in-house 1"Iionated core protein (p24), purified from human virus, was the antigen for detecting antibody to HTLV-I/II. Serum samples were tested at dilutions of 1:10 and 1:100, which bracket the dilution levels of maximum sensitivity for sera of all titers. Sera were evaluated in terms of percent-bound counts using a high-titered reference seFrom the Comprehensive Drug Research Center, Department of Oncology, Biopsychosocial Center for the Study of AIDS, and the Department of Psychiatry, University of Miami School of Medicine, all authors except Inciardi who is with the Division of Criminal Justice, University of Delaware, Newark, DE. Address reprint requests to Dale D. Chitwood, PhD, Research Associate Professor, School of Medicine, Universityof Miami, 1550 N.W. 10th Avenue, Room 301, Miami, FL 33136. This paper, submitted to the Journal May 9, 1990, was revised and accepted for publication November 20, 1990. Editores Note: See also related editorial on page 561 of this issue.
American Journal of Public Health 631
Public Health Bnefs
or blood products has diminished significantly, but has not disappeared.10-12 Screening for antibodies to HTLV-I/II is not routinely conducted. Several IVDUs who donated or sold blood currently test
rum at 1:100 dilution as the 100 percent standard. Sera were scored as positive if the percent-bound counts were greater than 5 percent at the 1:100 dilution. Logistic regression analysis was used to evaluate the possible association between demographic characteristics of IVDUs and their behavior regarding the donation or sale of blood since 1985.
Results Of the 915 IVDUs interviewed, 153 (16.7 percent) reported that they had donated or sold blood since January 1, 1985; four out of five (80.4 percent) of these 153 IVDUs had sold blood. A total of 22.8 percent of the study population tested positive for HIV-1 (Table 1). Of the 153 IVDUs who had contnbuted blood, 19.6 percent tested positive for antibodies to HIV-1 at the time of interview. Of the subjects who had donated or sold blood, 5.7 percent of those tested for HTLV-III were positive. Serostatus at the time they donated/sold their blood is unknown. When IVDUs who had donated or sold blood were compared with IVDUs who had not done so in a logistic regression, males and IVDUs who were not in treatment were more likely to have donated/sold blood (Table 2). No differences were observed by ethnic or age group. The demographic characteristics of IVDUs who had donated and those who had sold blood were also compared (data 632 American Journal of Public Health
not shown). Donors were differentiated from sellers only by treatment status. Of those in treatment who had sold/donated blood, 68.5 percent had sold; 98.8 percent of the IVDUs from the street had sold rather than donated.
Discussion Although participation in the study wasvoluntary, results indicate that the donation and sale of blood by IVDUs is not restricted to the Northeastern United States, and that the sale of plasma or blood accounts for almost all IVDU involvement in the blood supply. The percentage of IVDUs in South Florida (16.7 percent) who donated or sold blood between 1985 and 1988 was virtually identical to the 15.0 percent reported by Nelson and colleagues8 for a cohort of IVDUs in Baltimore. At least four out of five IVDUs from both Miami (80.4 percent) and Baltimore (88.1 percent) who contributed blood during that time period had sold blood or plasma at a commercial service rather than donated at a voluntary blood center. Blood services utilize blood screening procedures to ensure that the supply is as safe as possible, but the elimination of high-risk donors remains an unfinished task in the overall plan to protect the blood supply. Since the initiation of blood screening for HIV antibodies and the utilization of the Cohn fractionation process and pasteurization procedures, the risk of a recipient receiving HIV infected blood
positive for HIV-1 and/or HTLV-VII. It must be emphasized that there is no way to ascertain the serostatus ofthese IVDUs at the time of their last donation or sale. Whether any of the blood contnbuted by these IVDUs became part of the blood supply is unknown, but it is evident that members of this high-risk group continue to donate/sell blood. The elimination of the sale of blood by IVDUs is a difficult matter. As long as commercial centers exist, IVDUs will attempt to sell their blood. Two characteristics of commercial blood centers facilitate this selling behavior: commercial blood centers which advertise that they pay cash for blood or plasma attract active drug users who do not have stable sources of income; commercial blood centers often are located in inner-city neighborhoods where poverty and drug use are prevalent. Commercial blood centers must take a more careful approach in the selection of potential sellers. It is imperative that the screening process at commercial blood services be intensified to identify potential sellers who inject drugs or have a history of IV drug use. Commercial blood centers should employ highly qualified individuals, who have had experience with IVDUs, to screen potential sellers for eligibility. Included in the screening process should be a rigorous check for track marks (scarring caused by repeated injections) on arms and other indications of IV drug use.
Drug treatment programs can play an important role in the reduction in the number of IVDUs who donate or sell blood. Educational intervention with past sellers and donors in treatment could have an immediate positive impact. Blood services, both voluntary and commercial, have an enormous responsibility to exclude IVDUs from their contributor pool. It is incumbent upon these services to staff the blood centers with highly qualified persons who can identify and exclude high-risk persons who continue to donate or sell blood. El
Acknowledgments Supported in part by grants ROIDA04433 from the National Institute on Drug Abuse, and P50MH424-55 from the National Institute of Mental Health.
May 1991, Vol. 81, No. 5
Public Health Bnefs
References 1. Imagawa DT, Lee MH, Wolinsky SM, et ak Human immunodeficiency virus type 1 infection in homosexual men who remain seronegative for prolonged periods. N Engl J Med 1989; 320:1458-1462. 2. Ward JW, Holmberg SD, Allen JR, et ak Transmission of human immunodeficiency virus (HIV) by blood transfusions screened as negative for HIV antibody. N Engl J Med 1988; 318:473-478. 3. Mildvan D, Des Jarlais D, Sotheran J, etal: Prevalence and significance ofHTLV-I in a cohort of IV drug users in New York. IV International Conference on AIDS, Stockholm, June 12-16, 1988. 4. Robert-Guroff M, Weiss SH, Giron JA, et at Prevalence of antibodies to HTLV-I,
5.
6.
7.
8.
-II, and -III in intravenous drug abusers from an AIDS endemic region. JAMA 1986; 255:3133-3137. Williams AE, Fang CT, Slamon DJ, et ak Seroprevalence and epidemiological correlates of HTLV-I infection in US blood donors. Science 1988; 240:643-646. Okochi K: Transmission of HTLV-I (ATLV) through cellular components of blood donors carrying antibodies of the virus. In: Petricciani JC, Gust ID, Hoppe PA, Krijen HW (eds): AIDS: The Safety of Blood and Blood Products. New York: John Wiley & Sons, 1987; 231-233. Cleary PD, Singer E, Rogers TF, et al: Sociodemographic and behavioral characteristics of HIV antibody-positive blood donors. Am J Public Health 1988; 78:953-957. Nelson KE, Vlahov D, MargolickJ, Bernal M, Taylor E: Blood and plasma donations
9.
10.
11.
12.
among a cohort of intravenous drug users. JAMA 1990; 263:2194-2197. Centers for Disease Control: HIV/AIDS Surveillance Report. Atlanta: CDC, March 1990. Schorr JB, Berkowitz A, Cumming PD, Katz AJ, Sandler SG: Prevalence of HTLV-III antibody in American blood donors. N Engl J Med 1985; 313:385. Ness PM, Douglas DK, Harper M, Polk BF: Declining prevalence of HIV-seropositive blood donors. N Engl J Med 1990; 321:615. Neumann P, O'Shaughnessy M, Remis R, Tsoukas C, Lepine D, Davis M: Laboratory evidence of active HIV-1 infection in Canadians with hemophilia associated with administration of heat-treated factor VIII. J AIDS 1990; 3:278-281.
Hyperendemic Urban Blastomycosis A. Cesare Manetti, MD, MPH
Introdudion North American Blastomycosis is an elusive, cosmopolitan, systemic infection caused by the dimorphic fungus Blastomyces dermatitidis. First described by Gilcrest1 in 1894, the infection became known as "the Chicago disease" because of the number of cases seen from that area. Later it was referred to as North American blastomycosis as the extent of its wider distribution in the United States and Canada was discovered. Today the disease is correctly and simply referred to as blastomycosis, and its etiologic agent is known to be endemic in Europe, the Middle East, Africa and India. In the Mississippi and Ohio River valleys, where it is primarily endemic, blastomycosis occurs sporadically in humans, dogs and other mammals. Blastomycosis is considered rare, but its true incidence is not known since it is not reportable in most states. Outbreaks of blastomycosis are seldom observed, and those reported have offered unique opportunities to investigate the source of the infection. The nine outbreaks that have been described to date have mostly been associated with outdoor activities.2.3 All but one have occurred in non-urban locations, and six were observed in the Great Lakes region. In three of the outbreaks, it was possible to isolate B. demnatitidis from rotten wood at exposure sites, mostly in an environment
around waterways.3.4
One of the most baffling aspects of blastomycosis has been the difficulty encountered in demonstrating where the oganism lives in nature and where humans and animals contract the infection. Any unusual concentration of blastomycosis cases is of interest since it may offer some clues as to the natural habitat of B. dermattidis. This is a report of two hyperendemic foci of blastomycosis in an urban setting.
Methos Blastomycosis is not a reportable illness in the State of Illinois, nevertheless, a sufficient number of cases came to the attention of the director of the Winnebago County Health Department to suggest the need for an investigation of a possible underlying problem. A search of the files of three Rockford hospital pathology departments and of their respective medical records uncovered 32 cases of blastomycosis. They had all been diagnosed by one or more of three modalities, namely culture, histologic sections and cytologic examinaFrom the Department of Community Health Sciences, School of Public Health, University of Chicago; and the Department of Pathology, University of Illinois College of Medicine at Rockford. Address reprint requests to A. Cesare Manetti, MD, MPH, P.O. Box 4508, Rockford, IL 61110-4508. This paper, submitted to the Joumal May 15, 1990, was revised and accepted for publication November 2, 1990.
American Journal of Public Health 633
