Acta PRdiatr Scand 80: 795-797, 1991
lnvasive Haemophilus influenzae Infections in Household Contacts of Patients with Haemophilus influenzae Meningitis and Epiglottitis B. TROLLFORS From the Department of Paediatrics, University of Goteborg, Ostra Hospital, Goteborg, Sweden
ABSTRACT. Trollfors, B. (Department of Paediatris, University of Giiteborg, Giiteborg, Sweden). Invasive Haemophilus influenzae infections in household contacts of patients with Haemophilus influen= meningitis and epiglottitis. Acts Paediatr Scand 80: 795,1991. In a retrospective nation-wide Swedish study of Haemophilus influenzae meningitis and epiglottitis, a total of 500 cases of culture-verified meningitis and 841 cases of epiglottitis fulfilling strict clinical criteria were found during a three-year period. Eight families with two cases of these infections occurring with an interval of less than 60 days were identified. Four of the secondary cases occurred in siblings and four in mothers of the index case. %o of the secondary cases were twins to the index case. This shows that the risk of developing invasive H. influenzue infections is considerably increased in both siblings and parents of patients with invasive infection. Rifampicin prophylaxis, which is recommended in the United States for family contacts, would, however, prevent less than 1 96 of all invasive infections with H. influenzue. Key words: Haemophilus influenzae, secondav cases, rifmpicin prophylaxis.
Several studies from the United States have shown that siblings of patients with Haemophilus influenzae meningitis have a considerably increased risk of developing invasive H. influenzae infections during one to six months after occurrence of the index case (1-6) and the American Academy of Pediatrics recommends rifampicin prophylaxis to all family members in a household with one case if one member is younger than four years (7). In Europe, this issue has, to my knowledge, only been discussed in one case report (8). Since the incidence and age distribution of invasive H. influenzae infections differ between countries, it is important that the risk of secondary cases is estimated in several populations. In this study, families with more than one case were identified during a retrospective nationwide study on H. influenzae meningitis and epiglottitis in Sweden (9, 10).
METHODS This study was based on retrospective studies of the incidence of H. influenzae meningitis (9) and epiglottitis (10) in Sweden during the period 1981-1983. Information was obtained from all departments of paediatrics otorhinolaryngology, infectious diseases, neurosurgery and forensic medicine on patients with these two diagnoses during the 3-year period. A total of 470 children and 30 adults with culture-verified H. influenzae meningitis and 485 children and 356 adults with epiglottitis fulfilling certain clinical criteria (10) were found. Blood cultures had been obtained from 290 children and 185 adults with epiglottitis. H. infuenzae was isolated from 267 (929’0) and 185 (539’0) of these, respectively. From the patient records, all families with more than one case were identified. Furthermore, all cases occurring within the same county with an interval of less than 60 days were identified. No pairs of patients with the same family name were found among these cases.
796 B. Trollfors
Acta Paediatr Scand 80
RESULTS Eight families with two cases of H. influenzae meningitis or epiglottitis were found (Table 1). No family had more than two cases. All index cases were children. Four secondary cases occurred in siblings and four in mothers of the index case. In four families the manifestations of disease differed between the index case and the secondary case. DISCUSSION The study shows that the risk of developing H. influenzae meningitis or epiglottitis in siblings of a child with either of these diseases within 60 days of diagnosis of the index case is considerably higher than in the general population. The incidence of these two diseases in Swedish children under the age of 15 years is 20/100000/year (9, 10). Although it is not known how many siblings were exposed to the 951 child index cases, the number can be estimated to be in the order of 500-1 OOO, since the fertility rate or Swedish women during the period studied was 1.65 (1 1). Among these siblings, 4 secondary cases in children occurred. Two of the secondary cases were, however, twins to the index case. Twins probably have a higher risk of secondary disease than other siblings (4, 8, 12). The study also showed a considerably increased risk of invasive H. influenzae disease in parents of children with the disease. Four of the eight secondary cases were mothers of the index case. Three large-scale North American studies of secondary disease in household contacts did not reveal any secondary cases in adults (1,3,4) but in another study two secondary cases in parents of children with H. influenzae meningitis were found (1 3). According to one study, the H. influenzae type b strains that cause meningitis and
Table 1. Characteristics of index and secondary cases of Haemophilus influenzae meningitis (Men) or epiglottitis (Epigl)
Index case Secondary case Index case Secondary case Index case Secondary case Index case Secondary case Index case Secondary case Index case Secondary case Index case Secondary case Index case Secondary case
Age
Sex
2 years 4 years 2 years 2 years 1 year 1 year 1 year 26 years 25 days 31 years 3 months 20 years 5 years 10 months 2 years 27 years
M M M M M M F F M F M F M M M F
" H . influenzae isolated from blood. Blood cultures not performed.
Interval (days) 60 40 1
2 3 3 23 19
Manifestation Epigl." Epigl." Epigl." Epigl." Epigl.' Epigl.' Men Men Epigl Men Epigl." Men Epigl." Epigl.' Men Epigl." Epigl.*
+
Relation to index case Brother Twin brother Twin brother Mother Mother Mother Brother Mother
Acta Paediatr Scand 80
Secondary invasive H. influenzae infections 797
epiglottitis usually belong to different subtypes (14). Host factors, e.g. age, must also be important for the manifestation of the infection. In four of the eight families described here, the two affected members had different manifestations. In conclusion, this study shows an increased risk of invasive H. influenzae infections in both siblings and parents of children with invasive disease. Whether this increased risk warrants rifampicin prophylaxis to all household contacts, as is recommended in the United States and suggested from Finland (7, 8), can be discussed. Even if an effective prophylaxis were used, less than 1 % of all cases of invasive H. influenzae infection would be prevented. REFERENCES 1. Glode MP, Daum SD, Goldmann DA, Leclair J, Smith A. Haemophilus influenzae type b
meningitis: a contagious disease of children. Br Med J 1980; 2: 899-901. 2. Band JD, Fraser DW, Ajello G. Prevention of Haemophilus influenzae type b disease. J Am Med Assoc 1984; 251: 2381-86. 3. Filice GA, Andrews Jr JS, Hudgins MP, Fraser DW. Spread of Haemophilus influenzae. Am J Dis Child 1978; 132: 757-59. 4. Ward JI, Fraser DW, Baraff LJ, Plikaytis BD. Haemophilus influenzae meningitis. A national study of secondary spread in household contacts. N Engl J Med 1979; 301: 122-26. 5. Campbell LR, Zedd AJ, Michaels RH. Household spread of infection due to Haemophilus influenzae type b. Pediatrics 1980; 66: 1 15-1 7. 6. Granoff DM, Basden M. Haemophilus influenzae infections in Fresno county, California: a prospective study of the effects of age, race and contact with a case on incidence of disease. J Infect Dis 1980; 141: 40-46. 7. American Academy of Pediatrics. Revision of recommendation for use of rifampin prophylaxis of contacts of patients with Haemophilus influenzae infection. Pediatrics 1984; 74: 301-02. 8. Eskola J, Takala A, Kayhty H et al. Secondary cases of invasive disease caused by spread of Haemophilus influenzae type b. J Infect 1987; 14: 233-36. 9. Trollfors B, Claesson BA, Strangert K, Taranger J. Haemophilus influenzae meningitis in Sweden 1981-1 983. Arch Dis Child 1987; 62: 1220-23. 10. Trollfors B, N y l h 0, Strangert K. Acute epiglottitis in children and adults in Sweden 1981-1983. Arch Dis Child 1990; 65: 491-94. 11. Official Statistics of Sweden. Population changes 1981-1984. Part 3. The whole country and counties. National Central Bureau of Statistics, Stockholm, Sweden. 12. Kaplan SL, Mason EO. Haemophilus influenzae type b disease in twins. J Pediatr 1983; 102: 264-66. 13. Plouffe JF, Powell DA. Serious infections in adults exposed to children with Haemophilus influenzae type b meningitis. Ann Intern Med 1981; 94: 785-86. 14. Takala A, van Alphen L, Eskola J, Palmgren J, Bol P, Makela PH. Haemophilus influenzae type b strains of outer membrane subtypes 1 and Ic cause different types of invasive diease. Lancet 1987; 11: 647-50. Submitted April 1 1, 1990. Aecepted Oct. 3, 1990 (B. T.) Department of Paediatrics University of Goteborg, Ostra Hospital S-416 85 Goteborg, Sweden
lnvasive Haemophilus influenzae Infections in Household Contacts of Patients with Haemophilus influenzae Meningitis and Epiglottitis B. TROLLFORS From the Department of Paediatrics, University of Goteborg, Ostra Hospital, Goteborg, Sweden
ABSTRACT. Trollfors, B. (Department of Paediatris, University of Giiteborg, Giiteborg, Sweden). Invasive Haemophilus influenzae infections in household contacts of patients with Haemophilus influen= meningitis and epiglottitis. Acts Paediatr Scand 80: 795,1991. In a retrospective nation-wide Swedish study of Haemophilus influenzae meningitis and epiglottitis, a total of 500 cases of culture-verified meningitis and 841 cases of epiglottitis fulfilling strict clinical criteria were found during a three-year period. Eight families with two cases of these infections occurring with an interval of less than 60 days were identified. Four of the secondary cases occurred in siblings and four in mothers of the index case. %o of the secondary cases were twins to the index case. This shows that the risk of developing invasive H. influenzue infections is considerably increased in both siblings and parents of patients with invasive infection. Rifampicin prophylaxis, which is recommended in the United States for family contacts, would, however, prevent less than 1 96 of all invasive infections with H. influenzue. Key words: Haemophilus influenzae, secondav cases, rifmpicin prophylaxis.
Several studies from the United States have shown that siblings of patients with Haemophilus influenzae meningitis have a considerably increased risk of developing invasive H. influenzae infections during one to six months after occurrence of the index case (1-6) and the American Academy of Pediatrics recommends rifampicin prophylaxis to all family members in a household with one case if one member is younger than four years (7). In Europe, this issue has, to my knowledge, only been discussed in one case report (8). Since the incidence and age distribution of invasive H. influenzae infections differ between countries, it is important that the risk of secondary cases is estimated in several populations. In this study, families with more than one case were identified during a retrospective nationwide study on H. influenzae meningitis and epiglottitis in Sweden (9, 10).
METHODS This study was based on retrospective studies of the incidence of H. influenzae meningitis (9) and epiglottitis (10) in Sweden during the period 1981-1983. Information was obtained from all departments of paediatrics otorhinolaryngology, infectious diseases, neurosurgery and forensic medicine on patients with these two diagnoses during the 3-year period. A total of 470 children and 30 adults with culture-verified H. influenzae meningitis and 485 children and 356 adults with epiglottitis fulfilling certain clinical criteria (10) were found. Blood cultures had been obtained from 290 children and 185 adults with epiglottitis. H. infuenzae was isolated from 267 (929’0) and 185 (539’0) of these, respectively. From the patient records, all families with more than one case were identified. Furthermore, all cases occurring within the same county with an interval of less than 60 days were identified. No pairs of patients with the same family name were found among these cases.
796 B. Trollfors
Acta Paediatr Scand 80
RESULTS Eight families with two cases of H. influenzae meningitis or epiglottitis were found (Table 1). No family had more than two cases. All index cases were children. Four secondary cases occurred in siblings and four in mothers of the index case. In four families the manifestations of disease differed between the index case and the secondary case. DISCUSSION The study shows that the risk of developing H. influenzae meningitis or epiglottitis in siblings of a child with either of these diseases within 60 days of diagnosis of the index case is considerably higher than in the general population. The incidence of these two diseases in Swedish children under the age of 15 years is 20/100000/year (9, 10). Although it is not known how many siblings were exposed to the 951 child index cases, the number can be estimated to be in the order of 500-1 OOO, since the fertility rate or Swedish women during the period studied was 1.65 (1 1). Among these siblings, 4 secondary cases in children occurred. Two of the secondary cases were, however, twins to the index case. Twins probably have a higher risk of secondary disease than other siblings (4, 8, 12). The study also showed a considerably increased risk of invasive H. influenzae disease in parents of children with the disease. Four of the eight secondary cases were mothers of the index case. Three large-scale North American studies of secondary disease in household contacts did not reveal any secondary cases in adults (1,3,4) but in another study two secondary cases in parents of children with H. influenzae meningitis were found (1 3). According to one study, the H. influenzae type b strains that cause meningitis and
Table 1. Characteristics of index and secondary cases of Haemophilus influenzae meningitis (Men) or epiglottitis (Epigl)
Index case Secondary case Index case Secondary case Index case Secondary case Index case Secondary case Index case Secondary case Index case Secondary case Index case Secondary case Index case Secondary case
Age
Sex
2 years 4 years 2 years 2 years 1 year 1 year 1 year 26 years 25 days 31 years 3 months 20 years 5 years 10 months 2 years 27 years
M M M M M M F F M F M F M M M F
" H . influenzae isolated from blood. Blood cultures not performed.
Interval (days) 60 40 1
2 3 3 23 19
Manifestation Epigl." Epigl." Epigl." Epigl." Epigl.' Epigl.' Men Men Epigl Men Epigl." Men Epigl." Epigl.' Men Epigl." Epigl.*
+
Relation to index case Brother Twin brother Twin brother Mother Mother Mother Brother Mother
Acta Paediatr Scand 80
Secondary invasive H. influenzae infections 797
epiglottitis usually belong to different subtypes (14). Host factors, e.g. age, must also be important for the manifestation of the infection. In four of the eight families described here, the two affected members had different manifestations. In conclusion, this study shows an increased risk of invasive H. influenzae infections in both siblings and parents of children with invasive disease. Whether this increased risk warrants rifampicin prophylaxis to all household contacts, as is recommended in the United States and suggested from Finland (7, 8), can be discussed. Even if an effective prophylaxis were used, less than 1 % of all cases of invasive H. influenzae infection would be prevented. REFERENCES 1. Glode MP, Daum SD, Goldmann DA, Leclair J, Smith A. Haemophilus influenzae type b
meningitis: a contagious disease of children. Br Med J 1980; 2: 899-901. 2. Band JD, Fraser DW, Ajello G. Prevention of Haemophilus influenzae type b disease. J Am Med Assoc 1984; 251: 2381-86. 3. Filice GA, Andrews Jr JS, Hudgins MP, Fraser DW. Spread of Haemophilus influenzae. Am J Dis Child 1978; 132: 757-59. 4. Ward JI, Fraser DW, Baraff LJ, Plikaytis BD. Haemophilus influenzae meningitis. A national study of secondary spread in household contacts. N Engl J Med 1979; 301: 122-26. 5. Campbell LR, Zedd AJ, Michaels RH. Household spread of infection due to Haemophilus influenzae type b. Pediatrics 1980; 66: 1 15-1 7. 6. Granoff DM, Basden M. Haemophilus influenzae infections in Fresno county, California: a prospective study of the effects of age, race and contact with a case on incidence of disease. J Infect Dis 1980; 141: 40-46. 7. American Academy of Pediatrics. Revision of recommendation for use of rifampin prophylaxis of contacts of patients with Haemophilus influenzae infection. Pediatrics 1984; 74: 301-02. 8. Eskola J, Takala A, Kayhty H et al. Secondary cases of invasive disease caused by spread of Haemophilus influenzae type b. J Infect 1987; 14: 233-36. 9. Trollfors B, Claesson BA, Strangert K, Taranger J. Haemophilus influenzae meningitis in Sweden 1981-1 983. Arch Dis Child 1987; 62: 1220-23. 10. Trollfors B, N y l h 0, Strangert K. Acute epiglottitis in children and adults in Sweden 1981-1983. Arch Dis Child 1990; 65: 491-94. 11. Official Statistics of Sweden. Population changes 1981-1984. Part 3. The whole country and counties. National Central Bureau of Statistics, Stockholm, Sweden. 12. Kaplan SL, Mason EO. Haemophilus influenzae type b disease in twins. J Pediatr 1983; 102: 264-66. 13. Plouffe JF, Powell DA. Serious infections in adults exposed to children with Haemophilus influenzae type b meningitis. Ann Intern Med 1981; 94: 785-86. 14. Takala A, van Alphen L, Eskola J, Palmgren J, Bol P, Makela PH. Haemophilus influenzae type b strains of outer membrane subtypes 1 and Ic cause different types of invasive diease. Lancet 1987; 11: 647-50. Submitted April 1 1, 1990. Aecepted Oct. 3, 1990 (B. T.) Department of Paediatrics University of Goteborg, Ostra Hospital S-416 85 Goteborg, Sweden
