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

Abstract

Virus Watch (VW) data on adenovirus isolations were reviewed together with newly available serologic results. This permitted classifying persons shedding virus as newly infected (143 persons) or recrudescent excretors (105 persons) and detection of 45 new infections not revealed by isolations. Mode of excretion after new infection varied with virus type, the per cent excreting only fecally being 49 with type 2, 67 with types 1 and 5, and 77 with other types. Combined respiratory and fecal excretion was related to young age and to illness. Two classes of infection were recognized, unrelated to adenovirus type: 1) abortive, resulting in brief excretion and little or no illness; and 2) persistent, resulting frequently in illness and characterized by long continued intermittent (recrudescent) excretion. Persistent infection resulted in prolonged intra-familial spread but its implication to health is unknown. Seroconversion was demonstrated in 75% of new infections studied. Serologic methods, in decreasing order of sensitivity, were neutralization, hemagglutination-inhibtion (HI), and complement fixation (CF). Both CF and HI antibodies were long persistent. Surveillance based on virus isolations from index members of families revealed 79% of infections in index persons and 64% of household invasions. Infections occurred throughout the year but were least frequent in the summer. Type 2 was continuously present and by far the most abundant although type 1 may have predominated before the VW began. The only sharp outbreak was due to type 5. Virus spread within households progressed slowly and was sharply and inversely related to age. Of all new adenovirus infections 45% were illness-associated (43% for type 2 and 59% for type 5). These figures are believed to closely reflect the true pathogenicity of adenoviruses. Their estimated contribution to all infectious illness was 2.4% (4.5% in infants) and to febrile illness was 77% (10.6% in infants).