VIRUSES ASSOCIATED WITH ACUTE RESPIRATORY INFECTIONS

VIRUSES IN ACUTE RESPIRATORY INFECTION IN A GENERAL COMMUNITY

The aetiology of acute respiratory infections between September 1962 and August 1963 was studied in two general practices in Cambridge. These practices were reasonably representative of the permanent community of Cambridge.

There were 592 spells of acute respiratory infection in the combined practices, representing an incidence of 11·4 spells per 100 persons. Children aged 0–4 had the highest rates (51·6 spells per 100 persons).

It was possible to establish a diagnosis in 62·5% of cases investigated. Influenza and parainfluenza infections featured prominently, being responsible between them for 46·6% of all respiratory infections investigated. From September 1962 to January 1963, parainfluenza viruses were prevalent, causing acute laryngo-tracheo-bronchitis in children (croup), and an influenza-like illness in adults. From February to April 1963, influenza A (Asian) was epidemic, a clinical diagnosis of influenza being frequently confirmed by laboratory studies at this time. There were nine cases of Eaton agent infection, seven of which had PAP, the other two being family contacts who later developed influenza-like illnesses.

Adenovirus (four cases), and RS virus (three cases) were not prevalent to any large extent in Cambridge during the survey.

AN AETIOLOGICAL STUDY OF RESPIRATORY INFECTION IN CHILDREN, EDINBURGH CITY HOSPITAL, 1961-1963

The findings are described of a combined clinical, bacteriological and virological study which included all children admitted to the City Hospital, Edinburgh, with acute respiratory infection and whooping cough during the winters 1961–62 and 1962–63. During the first winter 131 cases aged 0–12 years and in the second winter 133 aged 0–6 years were examined. The respiratory illnesses were divisible into upper respiratory tract infection, bronchitis, pneumonia, and whooping cough; many of the cases of whooping cough had respiratory complications with bronchitis or pneumonia.

Paired sera, a throat swab and a faecal specimen were taken from each child and investigated vircdogically. Over both winters the highest total virus isolation rate was found in the group suffering from upper respiratory disease. Approximately two-thirds of the total number of patients from whom virus was isolated and from whom both acute and convalescent sera were available gave a serological response to the homologous virus; the highest proportion of these patients occurred in the pneumonia and URTI groups. The groups of viruses associated with a fourfold or greater rise in antibodies occurred in the following proportions of the cases: myxovirus 9 %; adeno virus 7 %; entero virus 4 %; herpes simplex 3 %.

Bacterial pathogens were isolated from 37 % of patients in 1961–62 and from 49 % in 1962–63,Staph. pyogenesbeing the most common pathogen. Isolation of pneumococci was facilitated during the second year by the examination of a nasal swab. Pre-admission chemotherapy did not significantly alter the bacterial isolation rates. Agglutination studies were carried out on forty clinical cases of whooping cough admitted during the two winters and thirty-two showed significant stable titres toBordetella pertussis; only 9 (18 %) of these cases gave a history of prophylactic immunization.

A third of the patients had neither bacterial nor viral pathogens.

The findings in this survey illustrate the need for further intensive virological and bacteriological studies of acute respiratory infections in early childhood.

Acute viral bronchiolitis in infancy: epidemiology and management

Acute bronchiolitis due to viral agents (RSV, parainfluenza, influenza, adenovirus) is a relatively frequent disease of infancy. Seasonal epidemic pattern have been recognized, and nosocomial infections in pediatric wards occur. Until age 2 years most children have experienced some form of airway disease attributable to RSV. Some patients require hospital treatment; about 15% of our patients had to be transferred to the intensive care unit. Bronchiolitis seems to be frequently the first manifestation of asthma and we found higher IgG antibody titers to viruses causing bronchiolitis in children with asthma than in controls. Retrospective analysis of the charts of 147 cases of bronchiolitis revealed considerable uncertainty regarding therapeutic concepts. Mainstays of conservative therapy include oxygen, adequate hydration (often IV), and sometimes bronchodilators (based on the clinical impression of effectiveness in the individual patient). Mist therapy and secretolytic agents remain popular, although no clinical effect has been demonstrated. Attention should be directed toward the relief of upper airway obstruction caused by swelling, secretions, and nasogastric tubes. Oxygen administration in infants with coexisting chronic airway disease (e.g., BPD) and bronchiolitis may cause CO2 retention. Bronchodilators can cause hypoxia and increase bronchial compressibility by reducing smooth muscle tone. However, in severe cases a trial under pulse oximetry control seems worthwhile. Steroids seem to bring no clinical improvement, except in infants with protracted wheezing after bronchiolitis and patients with preexisting BPD.

Adenovirus type 21 bronchopneumonia in infants and young children

An epidemic of bronchopneumonia in infants and young children, with adenovirus type 21 infection, was observed in Auckland, New Zealand, in 1977. Eighteen children, four to 44 months of age, with clinical and radiologic evidence of bronchopneumonia are described. Several of the children were seriously ill but there were no deaths. When reviewed six to 12 months after diagnosis, six children had clinical signs and 13 had radiologic signs of residual pulmonary disease. There were no detectable pulmonary sequelae in two children. Three children were lost to follow-up and could not be evaluated. Adenovirus type 21 bronchopneumonia is a serious illness and an important cause of chronic bronchopneumopathy in infants and young children.

A trial of adenine arabinoside in genital herpes

Twenty-four episodes of genital herpes in 22 men, all confirmed by virus isolation, were studied in a double blind trial. They were treated either with 3% adenine arabinoside (Ara-A) in petrolatum ointment base or with the base alone applied four times daily for one week. The lesions were counted and sketeched on days 0, 2, and 7. There was no demonstrable advantage to be gained from the use of Ara-A ointment. The results of the Papanicolaou smears and virus isolation agreed in the diagnosis of 75% of cases. The presence of continuing lesions or fresh ones in some patients after the acute phase of the initial or recurrent attack of herpes necessitates the man taking precautions on resuming sexual intercourse.

Respiratory syncytial and other viruses associated with respiratory disease in infants

Diagnosis by virus isolation and serology was attempted in 377 cases of respiratory-tract infection in infants under one year of age admitted to hospital during two winters. A diagnosis of infection with respiratory syncytial (R.S.) virus was made in 40%, rhinovirus in 6·1%, adenovirus in 3·7%, parainfluenza in 2·1%, enterovirus in 1·9%, and influenza in 1·3%. R.S.-virus infections were more severe than others and occurred mostly in the first five months of life, with a peak at two months. Rhinovirus infections occurred at all ages, and often involved the lower respiratory tract. Of the 12 deaths, only 1 (due to R.S. virus) was not associated with a contributory cause. Maternal antibody to R.S. virus did not notably affect the incidence or severity of R.S.-virus infections.

Bronchiolitis obliterans, bronchiectasis, and other sequelae of adenovirus type 21 infection in young children

A remarkably high incidence of bronchiectasis and other pulmonary sequelae was observed in young children affected during an epidemic of severe lower respiratory tract infections apparently caused by adenovirus type 21. The histopathological findings are described in four cases in which one or both lungs were obtained for examination at intervals ranging from two months to three years after the acute infections. Widespread bronchiolar obliteration (bronchiolitis obliterans) was a striking finding in all four. The severity of bronchial inflammation and of bronchiectasis was proportional to the time elapsed since the acute infections. Bronchiolar obliteration is a likely sequel of the necrotizing bronchiolitis which may occur during acute adenovirus infections. The role of bronchiolar obliteration in the pathogenesis of bronchiectasis and other chronic lung disease is discussed. Adenoviruses may be a major cause of post-infectious bronchiectasis in childhood.

Bronchopneumonia with serious sequelae in children with evidence of adenovirus type 21 infection

Twenty-five cases of severe pneumonitis occurring among children aged 3 to 18 months were observed in Auckland, New Zealand, in 1965. An apparent relationship was established between a uniform disease picture and recovery of adenovirus type 21. Two died, and of the survivors 60% had permanent lung damage, probably resulting from obliterative bronchiolitis. Twenty per cent. were left with proved bronchiectasis. The possible relationships of adenovirus pneumonia to malnutrition or a genetic factor on the one hand and to the development of bronchiectasis on the other are discussed.

Virus infections and respiratory disease of childhood

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Histopathology of fatal adenovirus infection of the respiratory tract in young children

Type 7 adenoviruses were isolated from lung tissue obtained at the necropsies on five children aged 8 to 15 months. The clinical and radiological findings were those of bronchiolitis and pneumonia. Four children had an extensive necrotizing bronchitis and bronchiolitis. The surviving bronchial epithelium, and all bronchial epithelium in the fifth case, was proliferating. There was evidence that this proliferation was a virus-induced effect and not reparative. There was virus tropism to alveolar lining cells with a pneumonia showing mononuclear cellular reaction, necrosis, and hyaline membranes. Distinctive necrotizing lesions were found in the bronchial glands of all cases. Two contrasting types of intranuclear inclusions were present in all lesions and their significance and inter-relationships are discussed. These pathological changes are specific for infections by a limited number of adenovirus serotypes.

A comparative virological study of children in hospital with respiratory and diarrhoeal illnesses

Between October 1963 and April 1965, 113 children with respiratory disease and 113 children with diarrhoeal disease were matched for age and time of entry into hospital and studied by virus isolation and serological techniques.

Infections with respiratory syncytial (RS) virus, parainfluenza virus and herpes simplex virus respectively were found in 29, 11 and 12 children in the respiratory illness group but in only 1, 2 and 4 children in the diarrhoeal group. Rhinoviruses were isolated from 10 children in each group and in seven cases were associated with lower respiratory disease. Adenovirus infections were found in nine children with respiratory disease and eight with diarrhoea. Of the 40 enteroviruses isolated 16 were associated with respiratory disease and 24 with diarrhoea.

A poor or delayed serological response in children under 4 months with RS virus infection was observed. Addition of unheated rabbit serum increased the sensitivity of the neutralization test with RS virus.

These findings indicate that respiratory syncytial and parainfluenza virus infections were clearly associated with respiratory illness but the pathogenic role of the other viruses was not clear.