Epidemiology

Journal of Infection (1979) 1, 95-102

Epidemiology Communicable Disease Surveillance Centre, 61 Colindale Avenue, London NW9 5EQ This is the first of a series of epidemiological reports from the new C o m m u n icable Disease Surveillance Centre (CDSC) of the Public Health Laboratory Service, in which it is intended to discuss subjects of current epidemiological interest in communicable disease, and to present any other aspects of the work of the Centre which it is felt would be of interest to readers of The Journal o f Infection. It is intended subsequently to develop this Epidemiology Page in association with the Communicable Diseases (Scotland) Unit. The Communicable Disease Surveillance Centre

This Centre was set up by the Public Health Laboratory Service on behalf of the D e p a r t m e n t of Health and Social Security and the Welsh Office on 1 January, 1977. The initial appointments were Dr N. S. Galbraith as Director, and Dr J. R. H. Berrie, Senior Medical Officer seconded from the DHSS. During 1977 two other senior appointments were made, Dr N. D. Noah and Dr S. E. J. Young. Early in 1978, the first regionally based Community Physician was appointed, Dr R. Mayon-White in Oxford. It is h o p e d to appoint a further C o m m u n i t y Physician to the team based at Colindale, and two others based in regional Public Health Laboratories during the next 12 months. CDSC became responsible for the compilation of the Communicable Disease R e p o r t (CDR) in February, 1977, and in N o v e m b e r of that year took over national responsibility for the co-ordination and control of communicable disease from the DHSS. The Centre's main functions are to assist and support Medical Officers for Environmental Health, and others, in the investigation and control of communicable disease, in communicable disease surveillance and in teaching and training in the epidemiology of communicable disease. A description of the factors leading to the setting up of the Centre has been published (Galbraith, 1977) and the work of the Centre was described in 1977 in the C D R and in a report circulated to m e m b e r s of the British Society for the Study of Infectious Disease. Clinicians who do not already receive the C D R and would like to do so, or who would like to visit CDSC, are invited to write to the Director.

N. S. Galbraith, Director, Communicable Disease Surveillance Centre. 0163-4453/79/010095+08 $01.00/0

© 1979 The British Society for the Study of Infection

96

Epidemic Infections in 1978 Several infections have been epidemic in 1978. There have been large outbreaks of whooping cough, Mycoplasma pneumoniae infections, and rubella, whilst mumps has been more prevalent than usual; and amongthe viruses reported to CDSC, adenovirus types 4 and 7, parainfluenza type 3, coxsackie types B2 and B3 and echovirus types 3 and 11 have each caused outbreaks at some time during the year.

Whooping cough As is now well known, the cyclical pattern of whooping cough in this country has been reasonably stable since the incidence began to fall in the late 1950s, and the epidemic that began in mid-1977 was expected. Nevertheless both the pattern and extent of the current epidemic, as assessed by statutory notifications, have been different (Fig. 1): the sudden further increase in numbers in August, when the outbreak should have begun to wane, has been unusual, and the numbers notified in the current epidemic have been much higher than expected. Mycoplasma pneumoniae infections An outbreak ofMycoplasmapneumoniae infections had also started in 1977, and has continued so far throughout 1978 (Fig. 2). Although a large number of reports of this organism to the PHLS have been from laboratories in Wessex and the South West, infection has clearly been widespread in England and Wales (Table I). Lower respiratory infection has, of course, been 2000 I

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1975

1976

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Fig. 1. Weekly notifications of whooping cough, England and Wales, mid-1973 to 1978.

Epidemiology

97

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Fig. 2. 1978--Rubella, mumps and mycoplasma.

the most common clinical manifestation reported (Table II), and children aged 5-9 years the most commonly affected group, although infection has been common at all ages from one year to 64 years (Table III). Rubella Of the other infections that have been especially prevalent this year, rubella is of particular interest. Laboratory reports to CDSC (Table IV) suggest that 1978 has seen an outbreak of unusual size. However reports of clinical infection from selected practices to the Royal College of General Practitioners' Research Unit in Birmingham suggest that the incidence of rubella this year was not unusually high--and indeed, a little lower than in 1968, when the last considerable outbreak was recorded. Statistics from five large urban local health authorities, where rubella is statutorily notifiable, in general support the R C G P data; and abortions notified to the Office of Population Censuses and Surveys (OPSC) on the grounds of 'substantial risk of child being born abnormal', which tends to follow the seasonal distribution of rubella, again have been high in 1978, but not unusually so. Mumps Although mumps is endemic in England and Wales, it varies in incidence from year to year, and 1978 was a 'high' year, both according to CDSC

Epidemiology

98 Table

I

3 9 20 11 5 48 66 22 34

20 22 14 4 5 39 36 30 89

Regional distribution." 1 978--first three quarters

=

Adenovirus 4 Adenovirus 7 Coxsackie B2 Coxsackie B3 Echovirus 3 Echovirus 11 Mumps Parainfluenza 3

M. pneumoniae Total population (1976) (× 10 ~)

8 23 3 21 2 95 33 62 60

-3 5 1 1 46 24 7 58

8 15 12 4 3 29 60 30 80

1 3 9 2 2 39 43 13 67

2 4 11 10 2 52 39 7 54

-6 17 7 3 36 62 11 70

7 11 40 6 6 32 83 34 217

26 144 4 33 29 39 -5 3 6 44 86 28 32 5 66 88 147

24 23 47 54 19 53 89 90 45

8 16 3 19 4 40 58 29 27

8 53 10 38 15 73 134 111 39

1 -7 2 5 40 32 28 39

1 5 5 6 9 13 -32

-2 2 7 1 14 6 57

260 226 273 191 94 762 846 551 1,203

31.2 35.7 45.5 18.0 34-6 37.0 35-8 28.8 26-6 22.2 31.7 51-7 24.9 40.6 27.7 15.4 33-5 542.0

Sources: from reports by hospital and public health laboratories to CDSC. Population estimates from OPCS Mortality Statistics 1976, Series DH5/3.

reports of virus isolations (Fig. 2), and to RCGP reports of clinical infection. Of 846 isolations reported to CDSC in the first three quarters of the year, 370 (43 per cent) were from cases of meningitis or encephalitis (Table II), and this high proportion illustrates one of the biases inherent in laboratory data. Table II Associated clinical features: 1978--first three quarters

Organism o

u~ Adenovirus 4 Adenovirus 7 Coxsackie B2 Coxsackie B3 Echovirus 3 Echovirus 11 Mumps Parainfluenza 3

M. pneumoniae

20 34 22 12 7 49 25 211 870

52 91 49 27 17 109 62 224 72

11 59 73 48 26 174 105 66 43

4 6 5 7 3 21 29 20 55

182 45 ---4 3 2 5

2 6 44 34 20 275 370 5 18

2 -22 10 -21 6 5 33

29 98 107 83 41 298 265 188 354

Source: from reports by hospital and public health laboratories to CDSC.

260 226 273 191 94 762 846 551 1,203

Epidemiology

99

Table III Age distribution 1978--first three quarters Organism Adenovirus 4 Adenovirus 7 Coxsackie B2 Coxsackie B3 Echovirus 3 Echovirus 11 Mumps Parainfluenza 3

M. pneumoniae

<1 m

1-11 m

1-4 yr

5 - 9 yr

-1 10 4 3 35 -5 --

18 29 52 29 22 130 20 186 7

22 70 83 75 37 203 243 227 70

12 38 40 25 10 107 287 41 182

1 0 - 1 4 yr 1 5 - 4 4 yr 4 5 - 6 4 yr 6 5 + 10 8 11 12 5 62 45 7 105

160 56 54 34 10 173 186 35 589

15 5 5 2 1 10 24 13 131

1 2 -2 2 6 6 8 36

N/K

Total

22 17 18 8 4 36 35 29 83

260 226 273 191 94 762 846 551 1,203

Source: from reports by hospital and public health laboratories to CDSC.

Enteroviruses

During 1978, Echovirus type 11 caused a large outbreak in England and Wales (Fig. 3); enteroviruses that produced lesser outbreaks were Coxsackie types B2 and B3 (Fig. 4), and Echovirus type 3. The Echovirus 11 outbreak was unusual in that it was heralded by a small increase in numbers reported towards the e n d of 1977 (Fig. 3). During this period there occurred an outbreak in a Special Care Baby Unit in Cambridge when three neonates died (Nagington, Wreghitt, Gandy, Roberton and Berry, 1978). Nevertheless the numbers of reports did not increase substantially until the third quarter of the year had almost begun, but then rose rapidly (Fig. 3) to reach levels comparable with those reached in the Echo 19 outbreak of 1975. Infection has been widespread, with slightly greater numbers reported from the North, North Western and South Western regions (Table I). Although there have been 11 reports so far of neonates who died, only a small proportion of reported infections (35 of 762, 4.6 per cent) were in this age group (Table III). This suggests that, as with many other viruses, infection with Echo 11 is rare, but serious, in very young babies. In common with many other enteroviruses, the specific clinical manifestation most often reported was meningitis or encephalitis, which accounted for 275 cases (36 per cent) (Table II). Clearly however, serious infections such as these are more likely to be investigated, and the true proportion of cases with meningitis or encephalitis is undoubtedly somewhat lower. Respiratory and gastrointestinal symptoms were also commonly associated with Echo 11 infection, but skin and eye manifestations were quite rare (Table II). The other enterovir-

Table IV Rubella--reports to CDSC 1967-78 Year

1967

1968

1969

1970

1971

1972

1973

1975

1976

1977 1978"

Total

550

794

542

429

747

691

1,155 1,141 1,345

728

667

*Weeks 1 - 4 4 (pro~smnal).

1974

3,346

100

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Fig. 3. 1978--Echovirus type 11.

uses caused smaller outbreaks, but the age distributions of infection in reported cases were similar to that for Echo 11. The clinical features associated with these other enteroviruses were also similar, although meningitis or encephalitis was rather less c o m m o n , especially with Coxsackie B2 and B3 infection. The geographical distributions however (Table I) showed some I00

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Epidemiology

101

differences: Echovirus type 3 was most c o m m o n l y found in the West Midlands and North Western Regions, Coxsackie B2 in the Wessex, West Midland, Oxford and South Western Regions, and Coxsackie B3 in the West Midland and North Western Regions. It should be noted however that these regional differences are based on locations of reporting laboratories, which do not necessarily correspond with the place of origin of the specimen.

Respiratory viruses Some mainly respiratory viruses have also caused outbreaks during the summer. Parainfluenza virus type 3 is predominantly a s u m m e r virus, and caused an outbreak in 1978 (Fig. 5), as it does every year. Outbreaks of infection with adenovirus types 4 and 7 also occurred during the s u m m e r (Fig. 6). Parainfluenza type 3 was most commonly reported in infants 1-11 months old, with croup being the most usual associated clinical feature; adenovirus type 7 was also c o m m o n in this age group as well as in those 1-4 years, with upper respiratory infection its most c o m m o n clinical manifestation; while adenovirus type 4 was most c o m m o n in adults aged 15-44 years, in w h o m it usually caused conjunctivitis. Conjunctivitis was also commonly reported with adenovirus type 7 (Table II), but this too was more characteristic of infection in young adults. Adenovirus type 4 infection was more localised than the others, with 144 (55 per cent) of the 260 infections from the South West of England, and a further 50 (19 per cent) from the two adjacent regions of West Midlands and Oxford (Table I). Conclusion

Many of these epidemics have been occurring concurrently, and most of t h e m have mainly affected children. But because there is no known measure of 150

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102

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Fig. 6. 1978--Adenovirus

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morbidity in this age group available at present, it has not been possible to j u d g e the i m p a c t o f all t h e s e i n f e c t i o n s acting t o g e t h e r o n this p o p u l a t i o n

group in 1978.

Norman D. Noah, Consultant Epidemiologist, Communicable Disease Surveillance Centre.

References Galbraith, N. S. (1977). A National Centre for the Surveillance and Control of Communicable Disease. Proceedings of the Royal Society of Medicine, 70, 889-93. Nagington, J., Wreghitt, T. G., Gandy, G., Roberton, N. R. C. and Berry, P. J. (1978). Fatal Echovirus 11 infections in outbreak in Special Care Baby Unit. Lancet, ii, 725.