Pertussis should be considered in infants with apnea or severe coughing illnesses of any duration, and in older children or adults with prolonged cough (eg, longer than 2 weeks), especially if accompanied by inspiratory whoop or household exposure to a prolonged cough illness (strength of recommendation [SOR]: B, based on consecutive cohort studies with poor reference standards). Coughing paroxysms, posttussive vomiting, and absence of fever, while typical of pertussis, are of little help in distinguishing it from other causes of prolonged coughing illnesses (SOR: B, based on consecutive cohort studies with poor reference standards)

Brown, Maureen O'Reilly

St. Anna, Leilani

University of Missouri: MOspace

C L I N I C A L  I N Q U I R I E S74 JANUARY 2005 / VOL 54, NO 1 · The Journal of Family Practicemadol hydrochloride). 1998. Available at: www.fda.gov.10. Murray L, ed. Physicians’ Desk Reference. 58th ed.Montvale, NJ: Thomson PDR; 2004:2496.What are the indications for evaluating a patient with cough for pertussis?■ EVIDENCE-BASED ANSWERPertussis should be considered in infants withapnea or severe coughing illnesses of any dura-tion, and in older children or adults with pro-longed cough (eg, longer than 2 weeks), especial-ly if accompanied by inspiratory whoop or house-hold exposure to a prolonged cough illness(strength of recommendation [SOR]: B, based onconsecutive cohort studies with poor referencestandards). Coughing paroxysms, posttussivevomiting, and absence of fever, while typical ofpertussis, are of little help in distinguishing itfrom other causes of prolonged coughing illnesses(SOR: B, based on consecutive cohort studieswith poor reference standards). ■ EVIDENCE SUMMARYPertussis is an important cause of cough in allage groups. Ten prevalence studies of adoles-cents and adults seeking medical attention for aprolonged cough (defined variously as >1–4weeks) found acute pertussis in 12% to 32%.1While cough longer than 2 weeks, inspiratorywhoop, posttussive vomiting, coughing parox-ysms, and absence of fever are commonly associ-ated with pertussis, relatively few studies haveassessed the sensitivities and specificities ofthese symptoms. The Table summarizes resultsfrom 5 cohort series of children and adults withlaboratory-confirmed pertussis. Comparisongroups were variously defined by negative per-tussis cultures, negative pertussis serology, orserologic confirmation of other respiratory infec-tions. Likelihood ratios (LR) were calculatedfrom the data presented in each paper.The magnitude and variability of these likeli-hood ratios suggest that individual symptoms maybe of limited help in distinguishing pertussis fromother causes of prolonged cough. Combinations ofsymptoms may be slightly more helpful. In a studycomparing 10 patients with culture-confirmed per-tussis with 10 patients with serologically con-firmed mycoplasma pneumonia, the combination ofcough >14 days and whoop had a sensitivity of80%, a positive LR (LR+) of 8 and a negative LR(LR–) of 0.22.2 A cohort series of children aged <5years with suspected pertussis compared 33 withpositive cultures to 55 with negative cultures. Theconstellation of spasmodic cough and lymphocyto-sis (>10,000) had a sensitivity of 83%, a LR+ of2.5, and a LR– of 0.25. Cough >14 days withwhoop and vomiting had a sensitivity of 67%, aLR+ of 3.2, and LR– of 0.42.3Infants aged <6 months with pertussis are at par-ticular risk for atypical presentations and seriouscomplications. In a US series of 18,500 infants withpertussis, apnea was seen in 64% of infants under 1month and in 44% between 6 and 11 months. Fortypercent of the 6- to 11-month-olds had received atleast 3 doses of pertussis vaccine.4 A British study of126 infants aged <5 months admitted to the pedi-atric intensive care unit with apnea, bradycardia, orrespiratory failure found that 20% had pertussis.Apnea as a predictor of pertussis had a sensitivity of68% and a specificity of 60%.5Pertussis should be considered early in theevaluation of young infants with cough. In a case-control study comparing 15 fatal cases of pertus-sis with 32 who survived (infants aged <6months), the mean number of days from symptomonset to hospital admission were 5.3 (fatal) and8.6 (survivors). Rates of apnea on admission were40% and 52%.6 A case series of 9 infants aged <7weeks requiring admission to an intensive careunit for pertussis found that 8 had been sick forless than 4 days at the time of admission. All 9presented with poor feeding and cough, and 5 hadexperienced apnea.7■ RECOMMENDATIONS FROMC L I N I C A L  I N Q U I R I E SJANUARY 2005 / VOL 54, NO 1 · The Journal of Family Practice 75C O N T I N U E DOTHERSThe Centers for Disease Control and Preventionand the World Health Organization describe theclinical case definition for pertussis as a cough illness lasting at least 2 weeks with at least 1 ofthe following: paroxysms of coughing, inspiratorywhoop, or posttussive vomiting, without otherapparent cause. Laboratory criteria for diagnosisinclude a positive Bordetella pertussis culture or a positive polymerase chain reaction (PCR) for B pertussis.8,9Maureen O’Reilly Brown, MD, MPH, Swedish FamilyMedicine Residency, Seattle, Wash; Leilani St. Anna, MLIS, AHIP, University of Washington Health SciencesLibrary, SeattleREFERENCES1. von König CHW, Halperin S, Riffelman M, Guiso N.Pertussis of adults and infants. Lancet Infect Dis 2002;2:744–750.2. Davis SF, Sutter RW, Strebel PM, Orton C, Alexander V,Sanden GN et al. Concurrent outbreaks of pertussis andMycoplasma pneumoniae infection: clinical and epidemio-logical characteristics of illnesses manifested by cough.Clin Infect Dis 1995; 20:621–628.3. Strebel PM, Cochi SL, Farizo KM, Payne BJ, Hanauer SD,Baughman AL. Pertussis in Missouri: evaluation ofnasopharyngeal culture, direct fluorescent antibody test-ing, and clinical case definitions in the diagnosis of per-tussis. Clin Infect Dis 1993; 16:276–285.4. Tanaka M, Vitck CR, Pascual FB, Bisgard KM, Tate JE,Murphy TV. Trends in pertussis among infants in theUnited States, 1980–1999. JAMA 2003; 290:2968–2975.5. Crowcroft NS, Booy R, Harrison T, Spicer L, Britto J, MokQ et al. Severe and unrecognised: pertussis in UK infants.Arch Dis Child 2003; 88:802–806.6. Mikelova LK, Halperin SA, Scheifele D, et al. Predictors ofdeath in infants hospitalized with pertussis: a case-controlstudy of 16 pertussis deaths in Canada. J Pediatr 2003;143:575–581.7. Smith C, Vyas H. Early infantile pertussis; increasinglyprevalent and potentially fatal. Eur J Pediatr 2000;159:898–900.8. Pertussis (Bordetella pertussis) (Whooping cough).Epidemiology Program Office, Centers for Disease Controland Prevention. Last updated April 7, 2004. Available at:www.cdc.gov/epo/dphsi/casedef/pertussis_current.htm.Accessed on December 8, 2004.9. Vaccines, Immunizations and Biologicals: Pertussis. Geneva,Switzerland: World Health Organization; 2003. Availableat: www.who.int/vaccines-surveillance/deseasedesc/RSS_pertus.htm. Accessed on December 8, 2004.10. Wirsing von Konig CH, Rott H, Bogaerts H, Schmitt HJ. Aserologic study of organisms possibly associated with per-tussis-like coughing. Pediatr Infect Dis J 1998;17:645–649.11. Granström G, Wretlind B, Granström M. Diagnostic valueof clinical and bacteriological findings in pertussis. J Infect1991; 22:17–26.Clinical features of pertussisHistory Sensitivity Specificity LR+ LR–Cough >2 weeks3,12 84%–100% 35%–36% 1.3–1.5 0–0.44Cough >3 weeks3,12 75%–97% 51%–59% 1.8–2.0 0.06–0.42Whoop3,10–12 37%–90% 49%–96% 1.6–9.2 0.18–0.66Posttussive 28%–84% 45%–84% 0.9–2.2 0.36–1.0vomiting3,10,11,13Paroxysms3,12,13 68%–94% 15%–45% 1.1–1.4 0.29–0.71Household 20%–50% 73%–91% 1.9–2.2 0.68–0.88exposure11,13Afebrile 62%–96% 12%–54% 0.8–1.1 0–1.7(temp <38ºC)11–13Lymphocytosis3 88% 57% 2.0 0.21LR+ = positive likelihood ratio: sensitivity/(1–specificity); † LR– = negative likelihood ratio: (1–sensitivity)/specificity.TA B L E  C L I N I C A L  I N Q U I R I E S76 JANUARY 2005 / VOL 54, NO 1 · The Journal of Family Practiceimpact the epidemiology of pertussis in the US.Michael Ohl, MD, University of Missouri–ColumbiaDoes quinine reduce leg cramps for young athletes?■ EVIDENCE-BASED ANSWERVery little evidence exists regarding the use ofquinine for cramps in young adult athletes.Quinine may be an effective treatment for heatcramps in athletes (strength of recommendation[SOR]: C, 1 case series involving 2 patients).Quinine is better established as an effective treat-ment for nocturnal leg cramps in the general adultpopulation (SOR: A, 1 meta-analysis and 2 ran-domized controlled trials).■ EVIDENCE SUMMARYLeg cramps (heat cramps) in athletes aredefined as painful involuntary muscle contrac-tions, usually in the large muscle groups of thelegs, which occur during or in the hours follow-ing exercise. Oral quinine is sometimes used totreat nocturnal leg cramps in the general adultand elderly populations. However, its use is controversial secondary to concerns regardingefficacy and safety.Efficacy of quinine in young athletes has notbeen well studied. A case series reported on 2 athletes: 1 college basketball player and 1 professional football player.1 The basketballplayer experienced heat cramps during gamesthat were resistant to hydration and dietary treat-ment. A regimen of 60 mg oral quinine sulfatetaken 1 hour before game time and again at half-time eliminated cramps during the first game andthe subsequent 15 games. The football player’sheat cramps were only partially improved withoral electrolyte repletion and oral hydration.However, he suffered no further cramps after ini-tiating a regimen of 120 mg oral quinine sulfate12. Heininger U, Cherry JD, Eckhardt T, Lorenz C,Christenson P, Stehr K. Clinical and laboratory diagnosisof pertussis in the regions of a large vaccine efficacy trialin Germany. Pediatr Infect Dis J 1993; 12:504–509.13. Wright SW, Edwards KM, Decker MD, Zeldin MH.Pertussis infection in adults with persistent cough. JAMA1995; 273:1044–1046.■ CLINICAL COMMENTARYInfants may have complications; evaluateif there is apnea or significant coughImmunity to pertussis wanes following vaccina-tion, leaving many adolescents and adults sus-ceptible to infection. In older children and adults,there is often little in the clinical presentationthat distinguishes chronic cough due to pertussisfrom that associated with other causes.Clinicians should consider evaluating for pertus-sis in older children and adults with chroniccough (>2 weeks) if there is reason to suspectthey have been exposed, if the cough is associat-ed with inspiratory whoop, or if the individual hashousehold or frequent contact with infants. Infants may suffer severe complications frompertussis, and should receive evaluation whenpresenting with apnea or significant cough of anyduration. In current practice, evaluation usuallyincludes obtaining a nasopharyngeal swab forculture and PCR, though these tests may beinsensitive, especially in later phases of illness.The usefulness of single, quantitativeimmunoglobulin G titers with comparison to pop-

What are the indications for evaluating a patient with cough for pertussis?

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