THE VIRUS WATCH PROGRAM: A CONTINUING SURVEILLANCE OF VIRAL INFECTIONS IN METROPOLITAN NEW YORK FAMILIES

Abstract

During 10,577 person-months of surveillance over a four year period 142 coxsackie and 76 echovirus infections were detected by virus isolation. Serology revealed 73 additional infections, 65 with coxsackie and 8 with echoviruses. Because of the large number of sero-types encountered (types A9 and Bl–5 coxsackieviruses, types 2, 3, 6, 9, 11, 12, 14, 15, 17, 18, 20, 25, and 26 echoviruses plus reovirus type 1), generalization of the findings must be confined to the two major virus groups. Overall, entero-virus infection was a relatively rare occurrence. Fecal excretion predominated but respiratory excretion also occurred, especially of coxsackieviruses. Excretion of relatively long duration (up to 70 days) was not uncommon for coxsackie but infrequent for echoviruses. Based on intra-household spread, infectivity of cox-sackieviruses was fairly high (76% of exposed susceptible! and 25% of immunes); for echoviruses, apparent infectivity was substantially lower (43% of susceptibles and a single immune). At least 49% of coxsackie and 55% of echo-virus infections were subclinical. Allowance for illness “expected” in the absence of the observed infections yielded attributable illness rates of 24 or 19% for coxsackie and 9.4 or 18.5% for echovirus infections (depending on whether “virus-fre” or “self” controls were used in the correction). The true rates are believed to be somewhat higher. All of the associated illness was mild (respiratory disease alone or accompanied by enteric disease, rash or other manifestation). This suggests that the more severe manifestations attributed to these agents are relatively rare or that the viral strains invading the VW families were of low virulence.