Epidemiology of viral infections and evaluation of the potential benefit of OM-85 BV on the virologic status of children attending day-care centers

Abstract

Viral investigations were performed during 4 winter seasons (88/89, 89/90, 92/93, 93/94) in children attending day-care centers (DCCs) in the Rhône Département in eastern France. Over the total observation period of 4 winter seasons, 780 children were screened with a nasal swab for the presence of viruses. Of those, 230 (29.5%) had a positive viral culture. The viruses identified were respiratory syncytial virus (RSV), influenza A and B virus, parainfluenza virus, coronavirus, rhinovirus, adenovirus and enterovirus. During that time, 83 epidemic events in 47 DCC were recorded. A particular virus was judged to be causally related to an epidemic if the identical virus was isolated in > or = 3 children during the same outbreak of respiratory diseases. Thus, in 51 cases (61.4%) of all epidemics, the following viruses were responsible for an epidemic: RSV (n = 23), coronavirus (n = 10) (only during the season of 1993-1994), influenza A virus (n = 6), rhinovirus (n = 4), enterovirus (n = 4), adenovirus (n = 3) and parainfluenza virus (n = 1). Except for the somewhat surprising accumulation of coronavirus epidemics during the winter of 1993-1994, there were only minor seasonal variations from one year to another. As expected, RSV accounted for about one third of all respiratory tract infections in children attending DCCs and was therefore the most important single causative agent. These results are compared with data from children who did not attend a DCC and were cared for in a private practice.(ABSTRACT TRUNCATED AT 250 WORDS)

Fig. 1

Viral diagnostic procedure, for details see text.

Fig. 2

Seasonal distribution of all the individually isolated viruses over the two winters, 1992-1993 (a) and 1993-1994 (b). Rhino = rhinovirus; RSV = respiratory syncytial virus; ADV = adenovirus; Echo = echovirus; Inti A = influenza A virus; Infl B = influenza B virus; Coro = coronavirus.

Fig. 3

Cumulative seasonal distribution of the epidemic episodes over the two winters, 1992-1993 and 1993-1994.

Fig. 4

Viruses identified as probable causative agent of a particular epidemic; isolation of ≥ 3 times the same virus for a given epidemic (for abbreviations see fig. 2).

Fig. 5

Number (N) of positive RSV and influenza A viral diagnosis in the OM-85 BV-treated group (75 children) and in the placebo group (70 children).

Fig. 6

Comparison of the relative proportion of individual viral diagnosis between children <3 years attending an outpatient facility (a) and children attending DCCs (b) (1992-1993 and 1993-1994).