Joyce M. Geiman

Respiratory Syncytial Virus Infections within Families

To examine intrafamily spread of respiratory syncytial virus infections and their associated illnesses, 36 families with 188 members were studied during an outbreak of such infections. Nurses visited every three to four days to obtain specimens for viral isolation and interview household members. The virus infected 44.4 per cent of families, and 21.9 per cent of all members. All age groups had appreciable attack rates (with a range of 16.8 per cent in adults to 29.4 per cent in infants). In infected families, 45.9 per cent of members became infected, including 10 of 16 infants. Secondary attack rate for all ages was 27 per cent, and that for infants 45.4 per cent. An infants older sibling appeared most likely to introduce the virus into the family. Associated acute respiratory illnesses occurred in 94.9 per cent of cases, and appeared more severe than those not associated with respiratory syncytial virus. When the virus was introduced into a family the high attack rate produced an illness of age-related severity.

Respiratory syncytial virus infections in infants: quantitation and duration of shedding.

Infants hospitalized with respiratory syncytial virus infection were studied to delineate the quantitative shedding patterns and duration of shedding of RSV. Nasal wash specimens collected daily from 19 infants contained a mean maximal titer of 4.34 log10 50% tissue culture infective doses per milliliter. On admission, the mean titer was 4.14 log10 TCID50, with no consistent decline until after Day 6. The mean duration of shedding for 23 patients until they were virus negative was 6.7 days with a range of 1 to 21 days. Quantities of RSV shed were significantly greater in infants less than one month of age and in infants with evidence of pulmonary consolidation on chest roentgenogram. Shedding extended for a significantly longer time in infants with lower respiratory tract disease than in those with clinical manifestations limited to the upper respiratory tract.

Interferon production in children with respiratory syncytial, influenza, and parainfluenza virus infections

To better understand the recovery process of infants with lower respiratory tract disease due to respiratory syncytial virus, the production of interferon by 129 children (ages 10 days to 24 months) with RSV infection was compared to that of 20 children with influenza (ages 1 to 36 months), and 37 children with parainfluenza virus infection (ages 4 to 66 months). Interferon assays of 285 nasal washes from children with RSV revealed that interferon production occurred in only 5 (4%) of the children. Significantly more children infected with infleunza virus, 55% (P less than 0.001), and parainfluenza virus, 30% (P less than 0.001), produced interferon. In addition, the quantity of interferon produced by children with RSV (geometric mean titer = 2) was significantly less than that of children with influenza (GMT = 26.8, P less than 0.001) and parainfluenza virus (GMT = 23.5, P less than 0.001). In the children infected with RSV, in constrast to those with influenza, interferon detection was not associated with diminished shedding of virus.

Parainfluenza viral infections in children: Correlation of shedding with clinical manifestations

Children presenting with acute respiratory disease to a private group practice in the fall of 1975 were studied to: (1) evaluate the efficacy in a pediatric office of a simple technics of obtaining nasal washes for the diagnosis of parainfluenza virus infections and (2) to determine the quantities of virus shed in relation to clinical characteristics. The nasal wash technic proved feasible for an office or clinic. Parainfluenza virus type 1 was recovered from 26 (74%) of 35 children with croup and from 40 (56%) of the total 72 children presenting with any form of respiratory illness. Virus was recovered significantly more often from children with croup and from those of younger age. The mean quantity of virus in 26 nasal washes was 2.97 log10 TCID50/ml. The shedding of greater quantities was correlated with younger age and the more frequent occurrence of laryngitis, pharyngitis, and fever.

A new effect of the rex gene of phage λ: Premature lysis after infection by phage T1

Abstract When phage T1 infects bacteria lysogenic for lambda, lysis is premature and burst sizes are small. This has been shown to be an effect of the lambda rex gene.

CONTROL OF NOSOCOMIAL RESPIRATORY SYNCYTIAL VIRUS|[lpar]|RSV|[rpar]| INFECTIONS

RSV has been the major cause of nosocomial infections on our infant wards, affecting 45% of infants hospitalized for ≥ 1 week, and 42% of the staff. We evaluated methods to control the hospital spread of RSV during a community RSV outbreak. Methods included isolation of all infants with respiratory illness; strict handwashing, gowns, secretion precautions, cohorting of staff to ill infants, but no masks. Every 3-4 days all infants and staff were examined and nasal washes obtained. Of 123 infants admitted; 36 had RSV. Of 87 contact infants, 42 were hospitalized for ≥ 1 week. Nosocomial illness occurred in 8 or 9% of contact infants and in 19% of those hospitalized for ≤ 1 week. Three had pneumonia and 1 died. Of 43 staff, 24 or 56% acquired RSV (60% of nurses and doctors, 38% of medical students). Symptomatic illness occurred in 83% and 46% missed work. Hence, these procedures reduced infant nosocomial infection by over half, but did not affect staff infection rates. This suggests that staff continue to be infected while closely caring for infected babies, perhaps by self-inoculation of contaminated secretions from their hands or fomites, or by large droplets while holding infants. However, with handwashing and changing gowns between rooms, but without masks, staff did not appear to transmit RSV to neighboring un-infected infants.