To the Editor: In his article on the prevention of meningococcaldisease, Gardner (Oct. 5 issue)1 notes that both active andpassive smoking may be risk factors for the disease but doesnot address the issue of exposure to smokers as differentiatedfrom exposure to smoke. Contact with smokers rather than smokeis now recognized as a critical risk factor, most likely owingto higher rates of carriage and coughing among smokers.2,3,4The case–control study by Coen et al. of 144 teenage survivorsof meningococcal disease showed that older teens are more atrisk from exposure to smokers than to smoke.4 In two studies,significant odds ratios for meningococcal disease (3.8 and 9.1)were reported for children whose mothers smoked.2,3 A remarkable37% of cases were reported as being attributable to exposureto smokers in one of the studies,2 and we estimate that 60%of cases were attributable to exposure to smokers in the otherstudy.3 Public health messages should underscore the need tostop smoking, not merely the need to limit smoking to outsidethe home.
Gardner also mentions that deficiency in the terminal complementpathway is responsible for increased risk but does not mentionthe much more common deficiency of mannose-binding lectin. Recentwork has demonstrated that a deficiency of this protein, whichis responsible for activation of the alternative complementpathway, is a critical factor. The frequency of homozygous variantswas significantly higher among 194 children with meningococcaldisease than among control subjects (odds ratio, 6.5; 95% confidenceinterval, 2.0 to 27.2). The fraction of cases attributed tomannose-binding lectin variants was 32%.5
Robert Booy, M.D. Mary Iskander, M.B., B.S. National Centre for Immunisation Research and Surveillance Westmead 2145, Australia robertb2{at}chw.edu.au
Russell Viner, M.D. University College London Hospitals London NW1 2PG, United Kingdom
Dr. Booy reports receiving research support from CSL, Sanofi,Roche, and Wyeth.
References
Gardner P. Prevention of meningococcal disease. N Engl J Med 2006;355:1466-1473. [Free Full Text]
Fischer M, Hedberg K, Cardosi P, et al. Tobacco smoke as a risk factor for meningococcal disease. Pediatr Infect Dis J 1997;16:979-983. [CrossRef][Web of Science][Medline]
McCall BJ, Neill AS, Young MM. Risk factors for invasive meningococcal disease in southern Queensland, 2000-2001. Intern Med J 2004;34:464-468. [CrossRef][Web of Science][Medline]
Coen PG, Tully J, Stuart JM, Ashby D, Viner RM, Booy R. Is it exposure to cigarette smoke or to smokers which increases the risk of meningococcal disease in teenagers? Int J Epidemiol 2006;35:330-336. [Free Full Text]
Hibberd ML, Sumiya M, Summerfield JA, Booy R, Levin M. Association of variants of the gene for mannose binding lectin with susceptibility to meningococcal disease. Lancet 1999;353:1049-1053. [CrossRef][Web of Science][Medline]
To the Editor: The article by Gardner identifies close contactsof an index patient with meningococcal disease who would needchemoprophylaxis. These contacts include people who have beendirectly exposed to the patient's oral secretions, includingthrough kissing. However, saliva itself is thought to have aninhibitory effect on meningococcus, probably owing to the presenceof other oropharyngeal flora.1 This has been supported by astudy of 258 college students in the United Kingdom, in whichmeningococcal carriage in the tonsils, nasopharynx, and salivawas examined. The overall carriage rate was 34.9% (90 of 258students), but only one swab from saliva (0.4%) was positivefor meningococcus.1 The Australian national guidelines now recommendthat chemoprophylaxis not be used purely on the basis of activitiessuch as nonintimate kissing (even on the mouth) or sharing offood, drinks, cigarettes, or bongs.2 However, intimate kissing,especially with multiple partners, is a risk factor for meningococcaldisease.3 Certainly, as Gardner suggests, endotracheal intubationand mouth-to-mouth resuscitation would constitute sufficientexposure to warrant chemoprophylaxis; however, the risk associatedwith these activities is probably related to aerosolizationof meningococci rather than exposure to saliva.
Sanjaya N. Senanayake, M.B., B.S. Canberra Hospital Canberra 2606, Australia sanjaya.senanayake{at}act.gov.au
References
Orr HJ, Gray SJ, Macdonald M, Stuart JM. Saliva and meningococcal transmission. Emerg Infect Dis 2003;9:1314-1315. [Web of Science][Medline]
Changes to the management of meningococcal disease in Australia. Commun Dis Intell 2004;28:278-279. [Medline]
Tully J, Viner RM, Coen PG, et al. Risk and protective factors for meningococcal disease in adolescents: matched cohort study. BMJ 2006;332:445-450. [Free Full Text]
The author replies: Clinical Practice articles in the Journalfocus on management considerations, and space constraints allowfor only a limited discussion of basic science and public healthissues. Dr. Booy and colleagues provide additional insightsin both areas. First, they note that in addition to the long-recognizedincreased risk of invasive meningococcal disease from activeand passive smoking, there is an increased risk from exposureto people who smoke (presumably because these people have increasedcolonization with Neisseria meningitidis). It is notable that,despite the recognition of smoking as a risk factor for bothinvasive meningococcal disease1 and invasive pneumococcal disease,2the Advisory Committee on Immunization Practices of the Centersfor Disease Control and Prevention has failed to include smokersamong the high-risk groups for which immunization against thesediseases is recommended.1,3 Second, their mention of a deficiencyof mannose-binding lectin in the pathophysiology of invasivemeningococcal disease is welcome.
Dr. Senanayake discusses the Australian guidelines for chemoprophylaxis,which define persons considered to be close contacts of a patientwith meningococcal disease more specifically than do the U.S.guidelines. Noting that saliva is a much less likely sourceof N. meningitidis than material taken from the nasopharynxor tonsils, the Australians do not consider "nonintimate kissing"or shared ingested or smoked materials to constitute significantexposure. Accordingly, the Australian recommendations for chemoprophylaxisare more restrictive than the U.S recommendations.1 I applaudthe effort to define the at-risk contacts more precisely butanticipate that parsing the definition too finely will resultin many gray areas and may make the guidelines difficult toimplement.
Pierce Gardner, M.D. Stony Brook University School of Medicine Stony Brook, NY 11794
References
Prevention and control of meningococcal disease: recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR Recomm Rep 2005;54:1-121. [Medline]
Nuorti JP, Butler JC, Farley MM, et al. Cigarette smoking and invasive pneumococcal disease. N Engl J Med 2000;342:681-689. [Free Full Text]
Prevention of pneumococcal disease: recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR Recomm Rep 1997;46:1-24. [Medline]
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