From <@uga.cc.uga.edu:owner-mednews@ASUACAD.BITNET> Mon Mar 6 10:12:35 1995 with BSMTP id 0555; Mon, 06 Mar 95 10:03:41 EST UGA.CC.UGA.EDU (LMail V1.2a/1.8a) with BSMTP id 0594; Mon, 6 Mar 1995 09:10:13 -0500 HICNet Medical News Digest Mon, 06 Mar 1995 Volume 08 : Issue 06 Today's Topics: [MMWR] Trends in Sexual Risk Behavior Among High School Students [MMWR] Update: Influenza Activity [MMWR] Availability of Draft Recommendations for HIV Counseling... [MMWR] Erratum: Vol 44 #5 [MMWR - March 3, '95] Exposure of Passengers and Flight Crew to ... +------------------------------------------------+ ! ! ! Health Info-Com Network ! ! Medical Newsletter ! +------------------------------------------------+ Editor: David Dodell, D.M.D. 10250 North 92nd Street, Suite 210, Scottsdale, Arizona 85258-4599 USA Telephone +1 (602) 860-1121 FAX +1 (602) 451-1165 Internet: mednews@stat.com Bitnet: ATW1H@ASUACAD Mosaic WWW *Asia/Pacific: http://biomed.nus.sg/MEDNEWS/welcome.html *Americas: http://cancer.med.upenn.edu:3000/ *Europe: http:/www.dmu.ac.uk/0/departments/pharmacy/archive/www/MEDNEWS/welcome.h tml Compilation Copyright 1994 by David Dodell, D.M.D. All rights Reserved. License is hereby granted to republish on electronic media for which no fees are charged, so long as the text of this copyright notice and license are attached intact to any and all republished portion or portions. The Health Info-Com Network Newsletter is distributed biweekly. Articles on a medical nature are welcomed. If you have an article, please contact the editor for information on how to submit it. If you are interested in joining the automated distribution system, please contact the editor. Associate Editors: E. Loren Buhle, Jr. Ph.D. Dept. of Radiation Oncology, Univ of Pennsylvania Tom Whalen, M.D., Robert Wood Johnson Medical School at Camden Douglas B. Hanson, Ph.D., Forsyth Dental Center, Boston, MA Lawrence Lee Miller, B.S. Biological Sciences, UCI Dr K C Lun, National University Hospital, Singapore W. Scott Erdley, MS, RN, SUNY@UB School of Nursing Jack E. Cross, B.S Health Care Admin, 882 Medical Trng Grp, USAF Albert Shar, Ph.D. CIO, Associate Prof, Univ of Penn School of Medicine Stephen Cristol, M.D. MPH, Dept of Ophthalmology, Emory Univ, Atlanta, GA Subscription Requests = mednews@stat.com anonymous ftp = vm1.nodak.edu; directory HICNEWS FAX Delivery = Contact Editor for information ---------------------------------------------------------------------- To: hicnews Students Trends in Sexual Risk Behavior Among High School Students -- United States, 1990, 1991, and 1993 Since the early 1980s, adolescents in the United States have experienced high rates of unintended pregnancies (1) and sexually transmitted diseases (STDs) (2), including HIV infection (3). Since 1990, CDC's Youth Risk Behavior Surveillance System has enabled measurement of priority health-risk behaviors among high school students at the national, state, and local levels (4). This report examines data from the 1990, 1991, and 1993 national Youth Risk Behavior Survey (YRBS)* to describe trends in selected self-reported sexual risk behaviors among U.S. high school students. The YRBS employed a cross-sectional, three-stage, cluster sample of students in grades 9-12 in public and private schools in all 50 states and the District of Columbia. For 1990, 1991, and 1993, sample sizes were 11,631, 12,272, and 16,296, respectively, and the overall response rates were 64%, 68%, and 70%, respectively. To enable separate analysis of black and Hispanic students, schools with high proportions of these students were oversampled; numbers of students in other racial groups were too small for meaningful analysis. A weighting factor was applied to each student record to adjust for nonresponse and oversampling. Trends were assessed only for sexual risk behaviors measured by questions identically worded in each survey year. To determine temporal differences, 95% confidence intervals were calculated for each estimate by using SUDAAN (5). From 1990 to 1993, the percentages of high school students remained constant for those who reported ever having had sexual intercourse (i.e., sexually experienced), ever having had sexual intercourse with four or more partners, having had sexual intercourse during the 3 months preceding the survey (i.e., sexually active), having used alcohol or drugs before last sexual intercourse, and having used birth control pills at last sexual intercourse (Table 1). In contrast, the percentage of those who reported condom use at last sexual intercourse increased significantly, from 46.2% in 1991 to 52.8% in 1993 (Table 1); however, subgroup analyses indicated a significant increase in condom use only among females (from 38.0% to 46.0%) and blacks (from 48.0% to 56.5%) (Table 2). Reported by: Div of Adolescent and School Health, National Center for Chronic Disease Prevention and Health Promotion, CDC. Editorial Note: During the 1980s, the proportion of adolescents who reported being sexually experienced increased substantially in the United States (6). The findings in this report indicate that, from 1990 through 1993, the proportion of high school students who reported being sexually experienced remained stable, while an increasing percentage of sexually active students used condoms, thereby reducing their risk for unintended pregnancy and STDs, including HIV infection. The sex, grade, and race/ethnicity findings in this report may assist in identifying groups with higher prevalences of sexual risk behaviors. However, the underlying causes (e.g., education levels, economic factors, or cultural influences) for within-subgroup differences could not be addressed in this study. In 1991 and 1992, two health outcomes associated with sexual risk behaviors--live births and gonorrhea--also declined. Live-birth rates among 15-19-year-olds decreased in 40 states and the District of Columbia, increased in eight states, and were stable in two states. In addition, rates of gonorrhea decreased among 15-19-year-old males in 45 states and the District of Columbia and among 15-19-year-old females in 41 states and the District of Columbia. Of the 41 areas reporting declines in live- birth rates, 34 also reported declines in gonorrhea rates for both males and females; six other states reported declines for either males or females. Overall, live-birth rates for adolescents decreased significantly (2%) (7), and gonorrhea rates decreased significantly among both adolescent males and adolescent females (20% and 13%, respectively) (8). The plateau in the proportion of high school students who reported being sexually experienced, the increasing rates of condom use among high school students, and the decreasing rates of live births and gonorrhea among adolescents may reflect, in part, efforts to reduce risks for HIV infection and other STDs among adolescents. For example, since 1986, CDC has collaborated with local, state, and national health and education agencies, national and community-based organizations, and the media to increase development, implementation, and awareness of HIV-prevention education programs for youth. Despite the decreases in live-birth rates and gonorrhea rates and the increases in condom use, the findings in this report document that many adolescents continue to be at risk for HIV infection, other STDs, and unintended pregnancy because they engage in unprotected sexual intercourse. Efforts to assist all adolescents in delaying first sexual intercourse and increasing condom use among those who do engage in sexual intercourse must be emphasized by health, education, and social service agencies and providers. The data presented in this report and other data describing changes in rates of pregnancy, abortion, live birth, and gonorrhea among adolescents during the 1980s and 1990s have been summarized by state and for the nation in a new CDC monograph**, Adolescent Health: State of the Nation--Pregnancy, Sexually Transmitted Diseases, and Related Risk Behaviors Among U.S. Adolescents (8). References 1. Ventura SJ, Taffel SM, Mosher WD, Henshaw S. Trends in pregnancies and pregnancy rates, United States, 1980-88. Hyattsville, Maryland: US Department of Health and Human Services, Public Health Service, CDC, 1992. (Monthly vital statistics report; vol 41, no. 6, suppl). 2. Wasserheit J. Effect of changes in human ecology and behavior on patterns of sexually transmitted diseases, including human immunodeficiency virus infection. Proc Natl Acad Sci U S A 1994;91:2430-5. 3. Lindegren ML, Hanson C, Miller K, Byers RH Jr, Onorato I. Epidemiology of human immunodeficiency virus infection in adolescents, United States. Pediatr Infect Dis J 1994;13:525-35. 4. Kolbe LJ, Kann L, Collins JL. Overview of the Youth Risk Behavior Surveillance System. Public Health Rep 1993;108(suppl 1):2-10. 5. Shah BV, Barnwell BG, Hunt PN, LaVange LM. SUDAAN user's manual, release 5.50. Research Triangle Park, North Carolina: Research Triangle Institute, 1991. 6. CDC. Premarital sexual experience among adolescent women--United States, 1970-1988. MMWR 1991;39:929-32. 7. NCHS. Advance report of final natality statistics, 1992. Hyattsville, Maryland: US Department of Health and Human Services, Public Health Service, CDC, 1994. (Monthly vital statistics report; vol 43, no. 5, suppl). 8. CDC. Adolescent health: state of the nation--pregnancy, sexually transmitted diseases, and related risk behaviors among U.S. adolescents. Atlanta: US Department of Health and Human Services, Public Health Service, 1995; DHHS publication no. (CDC)099-4630. * The YRBS was not conducted in 1992. ** Single copies of this document are available from CDC's Division of Adolescent and School Health, National Center for Chronic Disease Prevention and Health Promotion, Mailstop K-33, 4770 Buford Highway, NE, Atlanta, GA 30341-3724; telephone (404) 488-5330. ------------------------------ To: hicnews Update: Influenza Activity -- New York and United States, 1994-95 Season Influenza activity in the United States during the current influenza season began in the Northeast, and during late January, spread to other regions of the country. This report describes influenza outbreaks in nursing homes in New York and summarizes national influenza surveillance data from October 2, 1994, through February 11, 1995. New York The first influenza outbreak reported to CDC during the 1994-95 season occurred in a 300-bed skilled-nursing facility in Long Island, New York. On November 30, 1994, eight residents on one 20-bed corridor developed influenza-like illness (ILI) (i.e., fever greater than or equal to 100 F [greater than or equal to 38 C] and cough). On December 1, nasopharyngeal swab specimens from these eight residents were submitted for rapid antigen testing; within 5 hours after transport to the laboratory, influenza type A was detected by enzyme immunoassay in six specimens. On the evening of December 1, 293 of the 299 residents in the facility each received 100 mg of amantadine hydrochloride as treatment for the eight ill residents and as prophylaxis against influenza A infection for the other 285 residents. Most (285 [95%]) residents had received influenza vaccine before the outbreak. On December 2, as part of the nursing home's contingency plan for influenza outbreaks, amantadine dosages were modified for individual residents based on estimated creatinine clearance (1,2), and prophylaxis was continued for 14 days. Other outbreak-control measures included confining ill residents to their rooms for at least 72 hours after the initiation of amantadine treatment and prophylaxis, confining all residents to their individual units, suspending group activities, and minimizing the assignment of nursing staff to multiple units. The amantadine dosage subsequently was discontinued for five residents and reduced for 13 residents because of side effects (primarily confusion and agitation); for most patients, side effects resolved within 48 hours of dosage adjustment. During the first 48 hours of amantadine prophylaxis and treatment, six additional residents developed ILI. Of the 14 residents who developed outbreak-associated ILI, five subsequently developed clinical pneumonia. During the 2-week period of amantadine prophylaxis, sporadic cases of febrile respiratory illness occurred in other units of the facility; however, there was no clustering of cases. Tissue culture of all eight nasopharyngeal specimens yielded influenza type A(H3N2). These isolates were further characterized at CDC; all were antigenically similar to the A/Shangdong/09/93 strain included in the 1994- 95 influenza vaccine. Influenza surveillance in New York state indicated increasing activity beginning in late November 1994. From December 1, 1994, through February 11, 1995, outbreaks associated with influenza type A(H3N2) in 46 other nursing homes were reported to the New York State Department of Health (NYSDOH); of these, 16 were reported from nursing homes in Long Island. For all 16 facilities, influenza type A infection was documented by rapid antigen detection; in 13 facilities, amantadine was administered as an outbreak-control measure. Outbreaks in five other nursing homes were caused by influenza type B and, in two nursing homes, by influenza types A and B. Based on findings of virologic surveillance in New York, influenza has occurred in persons in all age groups during the 1994-95 season. Of the 385 influenza virus isolates reported by laboratories in New York this season, 332 (86%) have been type A. United States From November 27, 1994, through January 21, 1995, most influenza activity was reported from the Northeast (3). However, during January 22- February 11, regional or widespread activity was reported from states in every region. Through February 11, World Health Organization collaborating laboratories reported 1282 influenza virus isolates; of these, 923 (72%) isolates have been type A and 359 (28%) have been type B. Of the influenza A isolates that have been subtyped, all have been type A(H3N2). The proportion of deaths attributable to pneumonia and influenza reported from 121 U.S. cities slightly exceeded the epidemic threshold during six of the 19 weeks from October 2, 1994, through February 11, 1995, but has not exceeded the threshold for any 2 consecutive weeks. Reported by: IH Gomolin, MD, Gurwin Jewish Geriatric Center, Commack, New York; HB Leib, MS, RJ Gallo, S Kondracki, G Brady, G Birkhead, MD, DL Morse, MD, State Epidemiologist, New York State Dept of Health. Participating state and territorial epidemiologists and state public health laboratory directors. World Health Organization collaborating laboratories. Sentinel Physicians Influenza Surveillance System of the American Academy of Family Physicians. WHO Collaborating Center for Surveillance, Epidemiology, and Control of Influenza, Div of Viral and Rickettsial Diseases, National Center for Infectious Diseases, CDC. Editorial Note: Influenza vaccination is 70%-90% effective in preventing ILI in young, healthy adults when the vaccine antigens closely match the circulating influenza virus strains. Because of the decreased immunologic response among the elderly, the vaccine is less effective in preventing the occurrence of ILI in nursing home residents (i.e., 30%-40% effective) (4). However, vaccination of nursing home residents is associated with a substantial (i.e., 50%-60% effectiveness) reduction in the occurrence of serious complications and hospitalization and with preventing death (up to 80% effective); in addition, vaccination reduces the risk for outbreaks in nursing home settings (4,5). Antiviral agents are recommended as an adjunct to vaccination in controlling influenza type A. To control influenza A outbreaks in the nursing home setting, antiviral drugs should be administered to all residents, regardless of influenza vaccination status. Influenza outbreak-control measures used in the New York nursing home (e.g., rapid influenza A antigen detection and prompt initiation of antiviral treatment and prophylaxis to all residents) were based on recommendations of the Advisory Committee on Immunization Practices (ACIP) (3,6) and CDC and are actively promoted by NYSDOH. Although annual influenza vaccination of nursing home residents is considered a standard of care, use of antiviral agents as an adjunct to vaccination is less common, reflecting, in part, concern about side effects and, until recently, the protracted time required for laboratory confirmation of influenza type A. The use of amantadine as an adjunct for the control of influenza type A outbreaks in New York during the current season illustrates the usefulness of education about and promotion of the use of antiviral agents and rapid influenza diagnostic methods. In September 1994, NYSDOH mailed information to all health-care facilities in New York urging health-care providers to administer vaccine in accordance with the recommendations of the ACIP, to use rapid antigen-detection testing and viral culture when institutional outbreaks of ILI are initially recognized, and to use amantadine when appropriate. On December 20, the NYSDOH sent an electronic mail message to these institutions to report the rapid identification of influenza type A in the first nursing home outbreak and to reinforce the recommendations for influenza control measures in health-care facilities. Recommendations of the ACIP for use of amantadine and rimantadine, the two antiviral drugs currently available for treatment and prophylaxis of influenza type A, were published in MMWR on December 30, 1994 (4). These recommendations also provide information for assisting health-care providers in selecting the appropriate drug for specific patient groups but do not recommend preferential use of either drug. As influenza activity continues to increase in the United States, health-care providers should be informed about findings of local, state, and national influenza surveillance and be familiar with methods for rapid úÿ úÿ(Continued from last message) viral diagnosis. Updated information about national influenza surveillance is available through the CDC Information System by voice or fax (404) 332-4551. In addition, providers should develop contingency plans to control influenza outbreaks that include the use of rapid diagnosis. When possible, policy decisions regarding use of amantadine and rimantadine should be made before outbreaks occur. References 1. Gomolin IH, Leib HB, Arden NH, Sherman FT. Control of influenza outbreaks in the nursing home: guidelines for diagnosis and management. J Am Geriatr Soc 1995;43:71-4. 2. ACIP. Prevention and control of influenza: part II, antiviral agents-- recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR 1994;43(no. RR-15). 3. CDC. Update: influenza activity--United States, 1994-95 season. MMWR 1995;44:84-6. 4. Arden NH, Patriarca PA, Kendal AP. Experiences in the use and efficacy of inactivated influenza vaccine in nursing homes. In: Kendal AP, Patriarca PA, eds. Options for the control of influenza. New York: Alan R. Liss, 1986:155-68. 5. Patriarca PA, Weber JA, Parker RA, et al. Efficacy of influenza vaccine in nursing homes: reduction in illness and complications during an influenza A(H3N2) epidemic. JAMA 1985;253: 1136-9. 6. ACIP. Prevention and control of influenza: part I, vaccines-- recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR 1994;43(no. RR-9). ------------------------------ To: hicnews Counseling... Availability of Draft Recommendations for HIV Counseling and Testing for Pregnant Women CDC is requesting public review and comment on the draft document U.S. Public Health Service Recommendations for HIV Counseling and Testing for Pregnant Women. This document is available from the CDC National AIDS Clearinghouse, P.O. Box 6003, Rockville, MD 20849-6003; telephone (800) 458-5231 or (301) 217-0023. Written comments must be received by April 10, 1995, and should be mailed to CDC's Technical Information Activity, Division of HIV/AIDS, Mailstop E-49, 1600 Clifton Road, NE, Atlanta, GA 30333; fax (404) 639-2007. ------------------------------ To: hicnews Erratum: Vol. 44, No. 5 In the article "Update: AIDS Among Women--United States, 1994," on page 81, the sentence beginning on the fourth line was incorrect. The sentence should read, "Women with AIDS reported in 1994 represented 24% of the cumulative total of 58,428 cases among women." ------------------------------ To: hicnews ... Exposure of Passengers and Flight Crew to Mycobacterium tuberculosis on Commercial Aircraft, 1992-1995 From January 1993 through February 1995, CDC and state health departments completed investigations of six instances in which passengers or flight crew traveled on commercial aircraft while infectious with tuberculosis (TB). All six of these investigations involved symptomatic TB patients with acid-fast bacillus (AFB) smear-positive cavitary pulmonary TB, who were highly infectious at the time of the flight(s). In two instances, Mycobacterium tuberculosis isolated from the index patients was resistant to both isoniazid and rifampin; organisms isolated from other cases were susceptible to all antituberculous medications. In addition, in two instances, the index patients were aware of their TB at the time of travel and were in transit to the United States to obtain medical care. However, in none of six instances were the airlines aware of the TB in these passengers. This report summarizes the investigations by CDC and state health departments and provides guidance about notification of passengers and flight crew if an exposure to TB occurs during travel on commercial aircraft. Investigation 1. A flight attendant had documented tuberculin skin test (TST) conversion in 1989 but had not received preventive therapy (1). While working on numerous domestic and international flights from May through October 1992, she developed a progressively severe cough, and pulmonary TB was diagnosed in November 1992. An investigation by CDC included TSTs of 212 flight crew who worked with the flight attendant from May through October and 247 flight crew who had not been exposed to her. The prevalence of positive TSTs among flight crew exposed to the flight attendant during August through October was higher than among crew exposed from May through June (25.6% versus 4.1%; p less than 0.01) and among unexposed flight crew (1.6%; p less than 0.01). TST conversion was documented in two crew members exposed only in August and October, respectively. TST positivity and conversions were not associated with aircraft type, but were associated with cumulative flight time exposure of greater than 12 hours. TST reactivity was assessed in 59 passengers registered in the airline's frequent flyer program who had traveled on flights worked by the flight attendant with TB during August-October. Of these, four (6.7%) were TST positive; all had traveled in October. The investigation indicated that the index patient transmitted M. tuberculosis to other members of the flight crew, but evidence of transmission to passengers was inconclusive (1). Investigation 2. During 1993, the Minnesota Department of Health conducted an investigation of a foreign-born (i.e., born outside the United States or Canada) passenger with pulmonary TB who traveled in the first class section of an aircraft during a 9-hour flight from London to Minneapolis in December 1992 (2). Of the 343 crew and passengers on the aircraft, TST results were obtained for 59 (61%) of 97 U.S. citizens and 20 (8%) of 246 non-U.S. citizens. TSTs were positive for eight (10%) persons--all of whom had received bacille Calmette-Guerin (BCG) vaccine or had a history of past exposure to M. tuberculosis. The investigation indicated no evidence of transmission of TB during the flight (2). Investigation 3. In March 1993, a foreign-born passenger with pulmonary TB traveled on a 1/2-hour flight from Mexico to San Francisco. This investigation included efforts by the San Francisco Department of Public Health to obtain information by mail from all 92 passengers on the flight; 17 persons could not be contacted because of invalid addresses. TSTs were positive in 10 (45%) of the 22 persons who were contacted and completed TST screening; nine of these TST-positive persons were born outside the United States. The other was a 75-year-old passenger who may have become infected with M. tuberculosis while residing outside the United States or during a period when TB was prevalent in the United States. The San Francisco Department of Public Health found no conclusive evidence of transmission during this flight. Investigation 4. In March 1993, CDC investigated a case of pulmonary TB in a refugee who traveled on flights from Frankfurt, Germany, to New York City (8-1/2 hours) and then to Cleveland, Ohio (1-1/2 hours) (3). Of 219 passengers and flight crew on both flights, 169 (77%) were U.S. residents; 142 (84%) of the U.S. residents completed TST screening. TSTs were positive in 32 (23%), including five persons who had converted from negative on initial postexposure testing to positive on follow-up testing. Of the 32 TST-positive persons, 29 had received BCG or were born and had resided in countries where TB is endemic, including all five TST converters. The five passengers who were TST converters had been seated in sections throughout the plane. Because none of the U.S.-born passengers on this flight had TST conversions, the investigation indicated that, although transmission could not be excluded, the positive TSTs and conversions probably were associated with prior M. tuberculosis infection, a boosted immune response from prior exposure to TB, or prior BCG vaccination. Investigation 5. In March 1994, a U.S. citizen with pulmonary TB and an underlying immune disorder who had resided long term in Asia traveled on flights from Taiwan to Tokyo (3 hours), to Seattle (9 hours), to Minneapolis (3 hours), and to Wisconsin (1/2 hour). Of 661 passengers on these four flights, 345 (52%) were U.S. residents. The Wisconsin Division of Health contacted the 345 U.S. residents and received reports about TST results from 87 (25%) persons; of these, 14 (17%) had a positive TST. All 14 persons had been seated more than five rows away from the index patient; nine of these persons had been born in Asia (including two with a known prior positive TST). Of the five who were TST-positive and U.S.-born, one was known to have had a positive TST previously, two had resided in a country with increased endemic risk for TB, and two were aged greater than or equal to 75 years. The investigation indicated that, although transmission of TB during flights could not be excluded, the positive TSTs may have resulted from prior M. tuberculosis infection. Investigation 6. In April 1994, a foreign-born passenger with pulmonary TB traveled on flights from Honolulu to Chicago (7 hours, 50 minutes) and to Baltimore (2 hours), where she lived with friends for 1 month. During that month, her symptoms intensified; she returned to Hawaii by the same route. Investigation in Baltimore determined that TST conversion had occurred in the 22-month-old child of her friends. The four flights included a total of 925 passengers and crew who were U.S. residents, of whom 755 (82%) completed TST screening; of these, 713 (94%) were U.S.- born. The investigation by CDC indicated no evidence of transmission on the flight from Honolulu to Chicago or the flight from Chicago to Baltimore. Of the 113 persons who had traveled on the flight from Baltimore to Chicago, TSTs were positive in three (3%), including two who were foreign-born. However, of the 257 persons who traveled from Chicago to Honolulu (8 hours, 38 minutes), TSTs were positive in 15 (6%), including six who had converted; two of these six persons apparently had a boosted immune response, while the other four had been seated in the same section of the plane as the index patient. Because of TST conversions among U.S.-born passengers, the investigation indicated that passenger-to-passenger transmission of M. tuberculosis probably had occurred. Reported by: C Hickman, MPH, KL MacDonald, MD, MT Osterholm, PhD, State Epidemiologist, Minnesota Dept of Health. GF Schecter, MD, TB Control Program, San Francisco Dept of Public Health; S Royce, MD, DJ Vugia, MD, Acting State Epidemiologist, California State Dept of Health Svcs. ME Proctor, PhD, JP Davis, MD, State Epidemiologist for Communicable Diseases, Bur of Public Health, Wisconsin Div of Health. S Bur, MPH, D Dwyer, MD, Maryland Dept of Health and Mental Hygiene. Surveillance and Epidemiologic Investigations Br, and Program Services Br, Div of Tuberculosis Elimination, National Center for Prevention Svcs; Div of Field Epidemiology, Epidemiology Program Office; Div of Quarantine, National Center for Infectious Diseases, CDC. Editorial Note: The investigations described in this report were undertaken to determine whether exposure to persons with infectious pulmonary TB was associated with transmission of M. tuberculosis to others traveling on the same aircraft. Two of these investigations indicated that transmission occurred (investigation 1, from flight attendant to other flight crew, and investigation 6, from passenger to passenger). In investigation 6, transmission occurred on the return to Hawaii, when the index passenger was most symptomatic and on the longest flight. All persons with TST conversions were seated in the same section of the aircraft as the index passenger, suggesting that transmission was associated with seating proximity. Because the origins of all foreign-born passengers were countries in which TB is endemic and/or where BCG vaccine is routinely used, TST results from these passengers do not reliably represent recent infection. Among persons who could be contacted during the other investigations, low response rates constrained the interpretation of findings from those investigations. Investigations such as those described in this report are subject to two substantial constraints. First, because the investigation may be initiated several weeks to months following the time of the flight and exposure, passengers may not be readily located. With the exception of persons who are enrolled in frequent flyer programs, airline companies do not routinely maintain residence addresses or telephone numbers for passengers. Second, the time elapsed between the flight and when public health authorities and airline companies become aware of an exposure and when passengers are notified and tested limits the use of TSTs to assess for conversion. To interpret prevalent positive TST results, other possible reasons for a positive TST result must be considered, including prior exposure to TB, residence or birth in countries in which TB is endemic, and BCG vaccination. In the United States, an estimated 4%-6% of the total population is TST positive (4), and in developing countries, the estimated prevalence of M. tuberculosis infection ranges from 19.4% (in the Eastern Mediterranean region) to 43.8% (in the Western Pacific region) (5). To prevent exposures to TB aboard aircraft, when travel is necessary, persons known to have infectious TB should travel by private transportation (i.e., not by commercial aircraft or other commercial carrier). In addition, patients with infectious TB should at least be sputum smear-negative for AFB before being placed in indoor environments conducive to transmission (6). Three negative sputum smear examinations of specimens on separate days in a person on effective anti-TB therapy indicate an extremely low potential for transmission, and a negative culture virtually precludes potential for transmission (6). Decisions about a TB patient's infectiousness and ability to travel should be made on an individual basis. The risk for M. tuberculosis transmission on an aircraft does not appear to be greater than in other confined spaces. Based on a consideration of current evidence indicating low risk for transmission of TB on aircraft, need for notification of passengers and flight crew members may be guided by three criteria. First, the person with TB was infectious at the time of the flight. Persons who, at the time of flight, are symptomatic with AFB smear-positive, cavitary pulmonary TB or laryngeal TB are most likely to be infectious. Evidence of transmission to household and other close contacts also indicates infectiousness. Second, exposure was prolonged (e.g., duration of flight exceeded 8 hours). Third, priority should be given to notifying passengers and flight crew who were at greatest risk for exposure based on proximity to the index passenger (for example, depending on the aircraft design, proximity may be defined as seating or working in the same cabin section as the infected passenger). Notification should be conducted by the airline in coordination with local and state TB-control programs. References 1. Driver CR, Valway SE, Morgan WM, Onorato IM, Castro KG. Transmission of M. tuberculosis associated with air travel. JAMA 1994;272:1031-5. 2. McFarland JW, Hickman C, Osterholm MT, MacDonald KL. Exposure to Mycobacterium tuberculosis during air travel. Lancet 1993;342:112-3. 3. Miller MA, Valway SE, Onorato IM. Assessing tuberculin skin test conversion after exposure to tuberculosis on airplanes [Abstract]. In: Program and abstracts of the annual meeting of the American Public Health Association. San Francisco: American Public Health Association, 1993. 4. CDC. National action plan to combat multidrug-resistant tuberculosis. MMWR 1992;41(no. RR-11):1-48. 5. Sudre P, ten Dam G, Kochi A. Tuberculosis: a global overview of the situation today. Bull World Health Organ 1992;70:149-59. 6. American Thoracic Society. Control of tuberculosis in the United States. Am Rev Respir Dis 1992;146:1623-33. ------------------------------ End of HICNet Medical News Digest V08 Issue #06 *********************************************** --- Editor, HICNet Medical Newsletter Internet: david@stat.com FAX: +1 (602) 451-1165 Bitnet : ATW1H@ASUACAD