Epidemiol. Infect. (1990), 105, 419-434 419 Printed in Great Britain A review of outbreaks of infectious disease in schools in England and Wales 1979-88 C. JOSEPH1, N. NOAH2, J. WHITE1 AND T. HOSKINS3 'Public Health Laboratory Service, Communicable Disease Surveillance Centre, 61 Colindale Avenue, London NW9 5EQ 2Kings College School o Medicine and Dentistry, Bessemer Road, London SE5 9PJ 3 Christs Hospital, Horsham, Sussex (Accepted 20 May 1990) SUMMARY In this review of 66 outbreaks of infectious disease in schools in England and Wales between 1979-88, 27 were reported from independent and 39 from maintained schools. Altogether, over 8000 children and nearly 500 adults were affected. Most of the outbreaks investigated were due to gastrointestinal infections which affected about 5000 children; respiratory infections affected a further 2000 children. Fifty-two children and seven adults were admitted to hospital and one child with measles died. Vaccination policies and use of immunoglobulin for control and prevention of outbreaks in schools have been discussed. INTRODUCTION The prevention and control of infectious disease outbreaks in schools are important not only because of the number of children at risk but also because of the potential for spread of infection into families and the wider community. Moreover, outbreaks of infection in such communities may lead to serious disruption of children's education and the curtailment of school activities. Details made available of 66 school outbreaks to the Communicable Disease Surveillance Centre between 1979 and 1988 are analysed in this paper and policies for prophylaxis, for example immunoglobulin and vaccination are described. SOURCES OF INFORMATION Information on outbreaks in schools between 1979 and 1988 was obtained from reports of investigations in which the Public Health Laboratory Service (PHLS) Communicable Disease Surveillance Centre (CDSC) had been asked to assist [1] and Communicable Disease Report (CDR) inserts (Table 1). In addition, information was collected on outbreaks reported by the Medical Officers of Schools Association (MOSA) weekly surveillance reporting scheme to CDSC [2]. The MOSA/CDSC scheme The Medical Officers of Schools Association, founded in 1884, represents doctors who have responsibility for preventing and controlling infectious diseases in 420 C. JOSEPH AND OTHERS independent boarding schools [3]. Wrhile many school doctors have systematically collected their own data on children's sickness, a voluntary weekly reporting scheme to CDSC was established in 1979, originally for the rapid detection of cases of influenza in a national sample of boarding school children and then adapted for other infectious diseases. By 1989, a total of 59 schools were participating in this surveillance scheme. The data derived from the scheme is heavily biased towards children in the 13-18 year age group, attending schools in South East England. RESULTS Between 1979 and 1988 CDSC assisted in, or otherwise received information on, 66 outbreaks in schools. In addition to these reports, 98 outbreaks of respiratory infection, 83 of gastrointestinal disease and 20 viral and other outbreaks were recorded from the MOSA weekly returns to CDSC in children who boarded at independent schools (Table 1). The 66 reviewed outbreaks affected almost 8500 children and over 450 adults (Table 2). Respiratory infections Influenza Altogether, 8 investigated outbreaks of influenza were reported from 10 schools, 7 of which were independent boarding schools, 1 a maintained residential school and 2 primary schools. Five outbreaks were caused by influenza A virus, two by influenza B virus and in one, part of a community outbreak, both A and B viruses circulated. Attack rates in each of the schools varied from 23 % (275/1196) to 63 % (38/60). Where it was possible to obtain attack rates by age, they were higher in younger children than older children. Influenza vaccine had been offered each year to the children in five boarding schools but appeared to confer little protection; attack rates were higher in the vaccinated than the unvaccinated children in three of the schools (Table 3). In the remaining schools which did not routinely vaccinate, overall attack rates in the outbreaks that were investigated were similar to those found in the 'vaccinated' schools. There were no admissions to hospital although reported complications included 33 ear infections, 4 lower respiratory infections (1 with pneumonia), 2 mild cases of acute nephritis and 1 case each of urticaria and post-influenzal depression. Other respiratory infections Seven other respiratory outbreaks were investigated, six in independent boarding schools and one in a maintained residential approved school. Four outbreaks were of group A streptococcal infection and affected about one third of the children. One was an explosive outbreak in which 45 % (34/76) of the boys and 43 % (17/40) of the staff in a boys' residential school were affected within 1 week. In the other three, ongoing episodes of infection were described which continued from one school term to the next, in spite of school holidays. Two of the schools experienced outbreaks over two terms, while a third continued over five terms from February 1980 through to the summer term of 1981. Initial treatment with antibiotics of those with symptoms failed to control the outbreaks. All three schools took nose and throat swabs from all pupils and gave antibiotic treatment to children found to have positive cultures. Follow-up swabs showed one or two Infectious disease in schools 421 Table 1. Method of ascertainment of 66 outbreaks included in review in England and Wales 1979-88 Disease group Type of school CDSC/CDR MOSA* Respiratorv Maintained 3 Independent 6 6 Gastrointestinal Maintained 20 Independent 6 5 Viral infections Maintained 9 Independent 1 1 Other infections Maintained 7 Independent 2 Total Maintained 39 Independent 13 14 Total outbreaks 52 14 * A total of 201 outbreaks were reported from the MOSA/CDSC surveillance scheme during the period 1979-88. These comprised: respiratory, 98; gastrointestinal, 83; viral infections, 16; other infections, 4. Table 2. Summary of 66 outbreaks reviewed from schools in England and Wales 1979-88 No. admitted Number affected to hospital Disease Number of , AK A Deaths, group outbreaks Children Adults Children Adults children Respiratory Influenza 8 1596 62 Other respiratory 7 359 34 1 Gastrointestinal Campylobacter 9 3600 114 19 4 Hepatitis A 8 175 34 1 Shigella 5 814* 51 7 1 Food poisoning 5 155 17 Viral GI 3 398 24+ Other GI 2 233 16 Viral infections Measles 6 447 10 1 Rubella 1 39 Other 4 304 19 Other infections 8 309 84 15 1 Total 66 8429 455 52 7 1 * Includes 650 children and adults combined. treatment failures in each of the three schools but further treatment with antibiotics eradicated the infection and terminated the outbreaks. One outbreak of what was originally thought to be psittacosis in an independent boarding school was investigated in detail [4]. Twenty boys from a school population of 325, 2 teachers, 1 kitchen worker and 1 of the investigators became ill between May and July 1980. No avian source of infection could be found and sera examined some years later showed that the outbreak was caused by Chlamydia pneumoniae strain TWAR [5]. 422 C. JOSEPH AND OTHERS Table 3. Influenza vaccine efficacy in five school outbreaks Attack rate No. of Attack rate in Vaccine children No. of in vaccinated unvaccinated efficacy* in school cases (%) (%) (%) 1272 338 25 34 25(7, 40t) 1196 275 20 34 42(28, 53) 478 112 24 22 -7(-69, 32) 149 49 35 31 -12(-78, 30) 470 182 39 37 -5(-42, 23) *Vaccine efficacy = attack rate in unvaccinated-attack rate in vaccinated Vaccin efficacya attack rate in unvaccinated t 95 % confidence intervals, lower and upper. Two further respiratory outbreaks in independent boarding schools were investigated. In one, parainfluenza virus type 1 was isolated from 15 of 35 ill boys. In the other 75 boys were admitted to the school sanatorium over a period of 9 weeks with symptoms of fever and severe sore throat, and adenovirus type 7b was isolated from throat swabs from four of the boys. The outbreak ceased when the school term ended. Gastrointestinal infections Campylobacter Nine outbreaks of campylobacter infection were investigated. Seven were reported from independent boarding schools and two from maintained schools. Altogether around 3600 children and 114 adults were affected, with 19 children and 4 adults admitted to hospital. The vehicle of infection was contaminated or unpasteurized milk in five outbreaks. One school which used unpasteurized milk from its own farm had two outbreaks in the same year and illness was significantly associated with the consumption of milk in the second outbreak [6]. In another school which had two outbreaks, the first was caused bv contaminated water and in the second, unpasteurized milk inadvertently sent to the school on one occasion was suspected but not proven as the vehicle of infection. A fourth outbreak also occurred at a school which had its own farm from which it obtained pasteurized milk but it was believed that either raw milk was sent to the school by mistake or that the output pipe (which diverted milk into the pasteurized or raw milk storage tanks) was contaminated [7]. One outbreak affected children in several maintained infant and primary schools through the distribution of free school milk in the Luton and Dunstable area in 1979, and gave rise to around 2500 infections in children, the largest milk associated outbreak of campylobacter so far recorded in the UK [8]. Water was associated with campylobacter outbreaks in three schools. One school used a private bore hole supply in addition to mains water and it was shown that the highest attack rates in the school were amongst those who drank water supplied from the bore hole from which Campylobacter sp.