Respiratory Virus Infections in Children Hospitalized in Montreal, 1968 - 1972

Respiratory Virus Infections in Children Hospitalized in Montreal, 1968 - 1972Author(s): L.P. SPENCE, H.R. BRODIE and A.M. MASSONSource: Canadian Journal of Public Health / Revue Canadienne de Sante'e Publique, Vol. 66, No.3 (MAY/JUNE 1975), pp. 209-212Published by: Canadian Public Health AssociationStable URL: http://www.jstor.org/stable/41987448 .

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Respiratory Virus Infections in Children Hospitalized

in Montreal, 1968 - 1972

LP. SPENCE, M.B., M.R.C.Path., F.R.C.P.CC),1'2 H.R. BRODIE, B.Sc., M.D., C.M.1 and AM. MASSON, M.D.1

A study of acute respiratory virus infections was undertaken in children hospitalized in Montreal from 1968 to 1972. Virological studies were carried out on 1342 children during this period and viruses were isolated from 314 nasopharyngeal aspirates. Among the viruses isolated were respiratory syncytial , parainfluenza types 1 , 2 and 3, influenza types A and B, several adenovirus serotypes, herpes simplex , rhinoviruses and enteroviruses. Respiratory syncytial virus was found in association with bronchiolitis and pneumonia and the parainfluenza viruses in association with croup and pneumonia . The adenoviruses and influenza viruses were associated with pneumonia as well as upper respiratory tract infections , bronchiolitis and croup . The adenoviruses and parainfluenza viruses were endemic among the children throughout the period of study , whilst the influenza viruses and respiratory syncytial virus were associated with outbreaks of respiratory disease . A small outbreak was also associated with adenovirus type 7. The study demonstrates the important role played by respiratory viruses in admission of children to hospital in Montreal

p ROM May 1968 to April 1972, virological investigations were carried out

1. Departments of Microbiology and Immuno- logy and Pediatrics, McGill University, and The Montreal Children's Hospital, Montreal, Canada.

2. Present address: Department of Medical Microbiology, University of Toronto, Banting Institute, 100 College Street, Toronto, Ontario, Canada.

on children admitted to the Montreal Children's Hospital with acute respiratory infections. Their objective was to deter- mine which respiratory viruses were infecting children in Montreal during the four-year study period, as well as the periodicity and seasonal occurrence of each virus, and to assess the public health importance of the viruses isolated.

Methods As many children as possible admitted

to two medical wards of the hospital with acute respiratory infections were investigated. Nasopharyngeal secretions were collected from the patients by the Auger suction technique (1). Two ml. of trans- port medium (50% tryptose phosphate broth in Hanks' balanced salt solution) were added to each aspirate and the diluted secretions were treated with penicillin, streptomycin and amphotericin B, and inoculated into two tubes of HEp 2 (carcinoma of nasopharynx) cell culture and two tubes of primary Rhesus monkey kidney cell culture. During the last two years of the study specimens were also inoculated into two tubes of W138 (human embryonic lung) cell culture. The cells were purchased from a commercial source and were maintained in a main- tenance medium consisting of medium 199 (49%), Eagle's minimum essential medium (49%), heat inactivated foetal agammaglobulin calf serum (2%) with penicillin, streptomycin and amphotericin B. Inoculated Rhesus monkey kidney cultures were incubated on roller drums and inoculated HEp 2 and W138 cell

cultures were incubated stationary. The temperature of incubation was 35°C and the period of incubation was not less than two weeks.

Myxoviruses and paramyxoviruses were recognised in infected cell cultures by haemadsorption of guinea pig erythro- cytes and other viruses by cytopathic effect. Viruses were identified by means of complement fixation, haemadsorption inhibition, hemagglutination inhibition and tissue culture neutralization tests.

Results From May 1968 to April 1969, 621

children with acute respiratory infections were admitted to the two medical wards. Of these, 304 were investigated. In the following year 415 children were admitted and 313 were investigated. The number of admissions for 1970-71 and 1971-72 are not available, but 281 children were investigated in the former period and 444 in the latter. The total number of children investigated during the four-year period was 1342. Admis- sions were generally higher in the winter months and fell to the lowest level in August.

The distribution by disease of 1342 children investigated is given in Table I. Cases in which the diagnosis was in doubt were excluded from the analysis even if a respiratoiy virus was isolated. Pneumonia was the diagnosis most frequently made, with bronchiolitis second, and croup third. Also shown in Table I are the viruses isolated from these patients. 23.4% of the patients yielded viruses.

Canadian Journal of Public Health Vol. 66, May/June 1975 209



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210 Canadian Journal of Public Health Vol. 66



Among the viruses isolated were influenza types A and B, parainfluenza types 1, 2 and 3, respiratory syncytial virus, several adenovirus serotypes, herpes simplex virus, rhino viruses, and a number of enteroviruses.

The age distribution of the patients yielding viruses during the period from May 1968 to April 1971 is given in Table II. Highest recovery rates were in children under one year of age. Respiratory syncytial virus was isolated more frequently from children under six months of age and parainfluenza type I was isolated more frequently from children older than one year than from children younger than one year. Fatalities were associated with influenza A and adenovirus type 7.

The periodicity of the viruses is given in Fig. 1. Adenoviruses of various serotypes were isolated throughout the period of the study. In the spring of 1970, there was a small outbreak of respiratory disease associated with adenovirus tyçe 7 infection. Thirteen cases were recognised of which three were fatal. By contrast, the influenza viruses appeared in sharp, well-demarcated outbreaks. Influenza viruses were isolated from hospitalized

children every winter and these children proved to be very sensitive indicators of the presence of influenza viruses in the community. The presence of influenza B in Montreal in May 1969 would not have been appreciated if studies on hospitalized children had not been in progress, as the virus was not isolated from any other source. There were three outbreaks of influenza type A (A2/Hong Kong), the most severe occurring in the winter of 1971. Other influenza type A outbreaks occurred in the winters of 1968-69 and 1969-70. Influenza type B was also encountered in December 1970, and in February and March 1971.

Parainfluenza viruses were isolated very frequently but, unlike the adenoviruses, tended to be associated with outbreaks. The most severe of these outbreaks occurred in the winter of 1968-69 and was associated with parainfluenza type 1 . The three types of parainfluenza virus were isolated in every year of the study.

Respiratory syncytial virus was also recovered in every year of the study. There were five distinct episodes of respiratory syncytial virus activity. In three

years the virus appeared in November or December and persisted for five or six months. The last outbreak began in April 1972 and continued beyond the end of the study period. Soon after isolations of respiratory syncytial virus were made in Montreal in April 1972, cases of severe respiratory disease occurred in Eskimo children from the Frobisher Bay area. Three of these children died. Respiratory syncytial virus was isolated from six of the sick children (2).

The association of viruses with disease is shown in Table I. Each respiratory virus seemed to be capable of producing a broad spectrum of illness. However, respiratory syncytial virus was frequently found in association with bronchiolitis and pneumonia whilst the parainfluenza viruses were usually found in association with croup and pneumonia. Influenza types A and B viruses were found in association with croup and pneumonia and influenza type A with severe fatal pneumonia.

Discussion Previous reports have documented the

public health importance of respiratory

Figure 1. Periodicity of respiratory virus in Montreal, 1968-1972.

May/June 1975 211



viruses in Canada. McDonald (3) reviewed the history of influenza in Canada from 1921 to 1964 and estimated that the disease had killed about 17,000 Canadians during the 10-year period 1945-1964. Two-thirds of the deaths in the years preceding 1964 were in persons 65 years of age and over, and the re- maining one-third was distributed fairly evenly among the younger age groups. McLean and his colleagues (4) demonstrated the importance of the parainfluenza viruses in acute laryngotracheobronchitis in children in Toronto. Lafleur et al. (5) provided serological evidence of infection with respiratory syncytial virus in children with acute respiratory infections in Montreal and also isolated parainfluenza viruses and adenoviruses from children with respiratory infections. Parker et al. (6) reported illness and death in association with adenovirus infection in children in Manitoba.

Our studies confirm the importance of respiratory syncytial virus, the influenza viruses, the parainfluenza viruses and adenoviruses in acute respiratory disease in Canadian children. Fortunately, mortality from acute respiratory infections in children has been low but the cost of caring for these children in hospital is high and the long-term effects of the infections on pulmonary function remain to be determined. In our study, respiratory syncytial virus infections occurred in very young infants and were usually associated with bronchiolitis and pneumonia. A retrospective study of 77 cases of respiratory syncytial virus infection in children in Montreal was reported by Brodie and Spence (7). The virus appeared in every year of this study and persisted in the community for several months. Influenza types A and B viruses were isolated during the study, and one child died from influenza type A pneumonia. Three influenza infections occurred in the neonatal unit of the

hospital and were described by Bauer et al. (8). Adenoviruses were isolated frequently during the study and one sero- type, adenovirus type 7, was associated with severe disease and deaths (9). The role of the parainfluenza viruses in the croup syndrome was again demonstrated. Parainfluenza type 1 virus produced a fairly big outbreak in the first year of the study. The radiologic features of these cases have been described (10).

Since better respiratory virus vaccines will become available in the future, epide- miological studies of respiratory viruses in Canada should be continued in order to make best possible use of these newer vaccines. It appears from our studies that an effective vaccine containing respiratory syncytial virus and parainfluenza type 1 virus would considerably reduce the morbidity from respiratory viruses in young children in Montreal. Unfor- tunately, such a vaccine is not available at the present time.

Studies in temperate and tropical climates have clearly demonstrated the public health importance of the respiratory viruses in children. This four-year study confirms the importance of many of these viruses in the admission to hospital of children in Montreal.

Les infections virales respiratoires aiguës des enfants hospitalisés à Montréal entre 1968 à 1972 ont été étudié. Les études virologiques furent faits de 1342 enfants pendant cette période et des virus ont été isolés de 314 aspirations du nasopharynx. Etaient isolés , virus respiratoire syncytial les virus paragrippaux 1, 2, et 3, grippal A et B , plusieurs sérotypes de l'adénovirus, herpès simplex , les rhino- virus , et les entérovirus. Le virus respiratoire syncytial était associé avec la bronchiolite et la pneumonie , les virus paragrippaux avec le croup et la pneumonie. Les adénovirus et les virus grippaux étaient associés avec la pneumonie, ainsi

qu'avec des infections des voies respirar toires supérieures , la bronchiolite, et le croup. Les adénovirus et les virus paragrippaux étaient endémiques parmi les enfants pendant la période entière de V étude, tandis que les virus grippaux et virus respiratoire syncytial étaient associés avec les premières manifestions de maladies respiratoires. Une petite mani- festation était aussi associée avec un adénovirus du type 7. L

' étude démontre le role important des virus respiratoires comme cause d'admission d'enfants aux hôpitaux de Montréal.

Acknowledgements This study was supported in part by

National-Provincial Health Grant No, 604-7-662. Reprint requests to L. Spence.

REFERENCES

1. Auger, W.J. An original method of obtain- ing sputum from infants and children with reference to the incidence of pneumococci in the nasopharynx. J. Pediat. 15: 640, 1939.

2. Marks, M. and Spence, L. Unpublished data.

3. McDonald, J.C. Influenza in Canada. Can . Med . Assoc. J. 97: 522, 1967.

4. McLean, D.M., Edwards, H.E., McQueen, E.J. and Petite, H.E. Myxovirus infections in acute laryngotracheobronchitis, Toronto, 1961-62. Ibid. 87: 998, 1962.

5. Lafleur, L., Poirier, R. and Martineau, B. Etude du virus respiratoire syncytial et autres virus dans les infections des voies respiratoires a l'hôpital Saint-Justine. Union Med . Can. 93: 521, 1964.

6. Parker, W.L., Wilt, J.C. and Stackiw, W. Adenovirus infections. Can . J. Public Health 52: 246, 1961.

7. Brodie, H.R. and Spence, L. Respiratory syncytial virus infections in children in Montreal - a retrospective study. Can. Med. Assoc. J. 109: 1199, 1973.

8. Bauer, C.R., Elie, K., Spence, L. and Stern, L. Hong Kong influenza in a neonatal unit. J.A.MJÍ. 223 : 1233, 1973.

9. Brown, R.S., Nogrady, M.B., Spence, L. and Wiglesworth, F.W. An outbreak of adenovirus type 7 infection in children in Montreal. Can. Med. Assoc. J. 108: 434, 1973.

10. DeLevie, M., Nogrady, M.B. and Spence, L. Acute laryngotracheobronchitis (croup): correlation of clinical severity with radiologic and virologie findings. Ann. Radiol. (Paris) 15: 193, 1972.

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Respiratory Virus Infections in Children Hospitalized in Montreal, 1968 - 1972