Annals of Tropical Paediatrics International Child Health
ISSN: 0272-4936 (Print) 1465-3281 (Online) Journal homepage: http://www.tandfonline.com/loi/ypch19
Nosocomial respiratory syncytial virus infection in a newborn nursery H. O. Okuonghae, M. U. Nwankwo, A. A. Okolo & K. E. Schuit To cite this article: H. O. Okuonghae, M. U. Nwankwo, A. A. Okolo & K. E. Schuit (1992) Nosocomial respiratory syncytial virus infection in a newborn nursery, Annals of Tropical Paediatrics, 12:2, 185-193, DOI: 10.1080/02724936.1992.11747567 To link to this article: http://dx.doi.org/10.1080/02724936.1992.11747567
Published online: 13 Jul 2016.
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Citing articles: 6 View citing articles
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Date: 06 August 2017, At: 22:24
Annals of Tropical Paediatrics (1992) 12, 185-193
Nosocomial respiratory syncytial virus infection in a newborn nursery H. O. OKUONGHAE, M. U. NWANKWO, A. A. OKOLO & K. E. SCHUIT*
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Department of Child Health, University of Benin, Nigeria and* Department of Pediatries, Children's Hospital, Pittsburgh, USA (Received 7 November 1991)
Summary The nosocomial spread of respiratory syncytial virus (RSV) was studied in a new born nursery in Benin City, Nigeria at a time the virus was known to be highly prevalent in the community. Nasopharyngeal washings were obtained from babies on admission and, thereafter, every 4 days until discharged. Questionnaires were administered to medical personnel with upper respira tory tract infection (URTI). RSV was detected by an ELISA technique. A total of 56 babies were studied, made up of 33 preterm and 23 full term babies. Fourteen of the 56 babies (25° 0 ) developed RSVinfection. Eleven babies (20.8° 0 ) acquired the infection nosocomially. The infected babies were ali symptomatic and sorne had significant morbidity. One preterm baby died following acquisition of RSV. The study demonstrated that medical personnel working in our new born nursery were a major contributor to the spread of nosocomial RSV infection. Babies hospitalized for more than 4 weeks were more likely to acquire RSV infection. Control measures are outlined for the reduction of nosocomial spread of RSV infection in our newborn nursery.
Introduction Respiratory syncytical virus is the most important viral respiratory pathogen in infants and young children. 1- 3 The virus bas been recognized as the major cause ofbronchiolitis and pneumonia in young children. 4 In a recent study from the University of Benin Teaching Hospital (UBTH), 55° 0 of children aged 2 months to 3 years admitted for lower respiratory tract infection were infected with RSV. 5 In temperate climates, RSV infection occurs in regular yearly out breaks during the winter or early spring. Very little is known
Reprint requests to: Dr H. O. Okuonghae, Department of Paediatrics, Faculty of Medical Sciences, University of ]os, PMB 2084, ]os, Nigeria.
about the epidemiology of the disease in the tropics. In Trinidad, which is semi-tropical, RSV was noted to occur in the rainy season. 6 In a previous study in Benin, RSV was found to occur ali year round with a peak during the rainy season. 7 There are few reports in the literature of RSV infection in the new born. Earl y reports of RSV infection in neonates suggested that the illness was usually mild and non-specifie in babies less than 3 weeks of age.B-9 However, recent reports suggest that the virus can produce severe respiratory disease in neonates. 10' 11 The risk for nosocomial acquisition of RSV infection increases during epidemies. Nosocomial RSV infection bas been associated with increased mortality among hospitalized infants. 12- 13 The purpose of this study was to examine prospectively nosocomial
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H. O. Okuonghae et al.
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the ward is 20. At the time of the study, there were 14 cots and six incubators. There were, in addition, two functioning radiant heaters for resuscitation of babies. Rooms 3 and 6 bouse four patients, each containing two inMaterials and methods cubators and two cots, while rooms 5 and 'BBA' cater for six patients, each with two Studyarea incubators and four cots. The study was undertaken in the University Babies are nursed in cots or incubators, of Benin Teaching Hospital, Benin City depending on their condition and maturity at (UBTH) between July and September 1988. the time of admission. Occasionally, they are The hospital serves Bendel State and the taken to the radiant heater for resuscitation neighbouring states. It is located in the rain when they develop acute problems. The two forest area of West Mrica at an altitude of functional resuscitaires were in rooms 3 and 5 78 metres. There are two seasons: the rainy during the period of the study. season, which usually starts in April and There are occasions when two or more terminates in October, and the dry season babies are under radiant heaters. When in from November to March. The temperature incubators, much of the babies' routine care is high ali year round (23-34°C). is given through ports which are normally kept closed by hard plastic covers when not in use. Babies may be removed from the incuDescription of the nursery bators for feeding and routine nursing care. The Special Care Baby Unit (SCBU) at the During the period of study, babies were University of Benin is adjacent to the Labour cared for by an average of eight nurses during Ward. lt is made up of four wards (rooms) the moming shift, six nurses during the (Fig. 1). Rooms 5 and 6 are reserved for aftemoon shift, and four nurses at night. The babies delivered in the hospital, while rooms nurses were not limited to any area of the 3 and 'BBA' are for babies referred from ward. Five paediatric and three obstetric other centres. The bed/incubator capacity of residents (rotating through the Neonatology
RSV infection in a new born nursery at a time when the disease was highly prevalent in the community.
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Nosocomial RSVin a newborn nursery
Unit) and one consultant paediatrician are assigned to the unit. Three doctors (including those from other units of the Department of Child Health, UBTH) took calls daily from 4 p.m. till 8 a.m. the following day. Other support staff included wardmaids, three to five daily. Mothers were encouraged to visit their babies and to breast-feed or produce expressed breast milk. Handwashing with soap and water up to the elbow was required between contacts with patients. Nursing staff wore scrub uniforms while doctors did not cover up their street clothes when in the Unit. Face masks were not wom routinely, except when carrying out special procedures, e.g. lumbar puncture, exchange blood transfusion, etc. One hundred and fifteen babies admitted consecutively into the SCBU during the rainy season (July-September 1988) were recruited for the study. Informed consent was obtained from parents at the commencement of the study. All patients were evaluated on admission and clinical features noted. A daily review was made of the physical findings. Notes were made of places in the Unit where babies were admitted, and, if into incubators, when they were transferred from the incubators. Special attention was paid to babies admitted to the same room as babies admitted with respiratory symptoms. Relevant laboratory work-up, including sepsis screening and chest X-rays, were done when necessary. Questionnaires were answered by staff members of the Unit who bad an upper respiratory tract infection during the study period, taking into account when they developed the symptoms and the duration of illness. A persona! observation of all medical and support staff for respiratory symptoms was maintained by one of the investigators (HOO). Sample collection
Nasopharyngeal secretions were obtained on admission and every 4 days until the infant
187
was discharged. Nasopharyngeal secretions were obtained using a neonatal mucus extractor attached to a suction pump. With the infant lying on his side, the neonatal mucus extractor was passed via the nostrils into the nasopharynx. Collection was facilitated by introducing 2-5 ml of phosphatebuffered saline through the nostril into the nasopharynx, and immediately sucking it back into the mucus trap. The samples were kept in dean tubes, coded and stored at -40°C prior to assay. Virus detection
RSV surface antigen was detected by ELISA (Ortho-Diagnostic Systems Inc., Raritan, New Jersey). The RSV antigen detection was run according to the manufacturer's protocol. The validity of this technique bas been demonstrated previously. 5•14 Infection was said to have been acquired nosocomially (for referred cases) if RSV was detected more than 7 days after admission, or when two previous samples were negative for RSV. Statistical analysis
Statistical analysis was done by the Student's t-test, Chi-square test and Fisher's exact test, where appropriate.
Results During the study period, a total of 115 babies were admitted to the Special Care Baby Unit (SCBU). Ofthese, 56 (48.7%) were included in the study. The other babies were excluded from the study because they spent less than 4 days in the Unit and were discharged before nasal washing could be obtained. The study population was made up of 30 boys and 26 girls (M:F = 1.2:1) and consisted of 33 preterm babies and 23 term babies. Twenty-nine of the 56 babies were delivered in UBTH and admitted to the SCBU for various reasons. The other 27 babies were
188
H. O. Okuonghae et al. TABLE 1. Characteristics of 14 infected and 42 uninfected babies Babies infected
Babies uninfected
1.3:1 35.2 (33.9) 30-40 (30-40) 2132 (1831) 1000-3950 (1000-3650) 5.2 (2.0) 1-19 (1-9) 21.9 (22.7) 4-44(4-44) 17.3 (22.8)
1.1:1 35.5 28-42 2099 800-4100 3.0 1-12
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Characteristics M:F Mean gestational age (weeks) Range Mean weight on admission Range Mean age on admission (days) Range Mean age when RSV -positive (days) Range Duration of hospitalization when RSV-positive (days) Range Total duration of hospitalization (days) Range
3-44(4-44) 29.9 (37.6)
26.5
5-52 (5-52)
4-154
pvalue
NS
NS NS
NS
Figures in parentheses are for those who developed nosocomial RSV infection; NS: Not significant.
referred to the Unit from other peripheral hospitals and matemity centres. Their ages on admission ranged from a few hours to 19 da ys. Fourteen of the 56 babies (25~ 0 ) developed RSV infection. Three of these bad community-acquired RSV infection, and 11 (20. 8%) acquired the infection nosocomially. The difference in the mean gestational ages of the two groups of infants was not statistically significant. Table 1 summarizes the characteristics of the babies studied. Nosocomial infection was acquired at a mean of25 days after admission with a range of 9-44 days. Only one baby bad positive RSV antigen in two consecutive samples.
Frequency of clinica/ signs/symptoms in infected babies
Fig. 2 illustrates the frequency of clinical signs in infected babies. Dyspnoea, rhinitis and fever were the predominant signs/ symptoms observed in babies. Others were
Nt.mber of patients
2
3
4
5
6
7
8
44
60 Dyspnoeo
40
56
Rhinitis
22
80 Fever
44 Vomiting
33 Cough
22 Diorrhoeo Apnoeo Conjunctivitis
FIG. 2. Frequency of clinical signs and symptoms occurring in 14 infected babies, 5 full-term ( •) and 9 preterm (0) babies (figures in percentages).
vomiting, cough, diarrhoea, apnoea and conjunctivitis. The predominant features of infection in full-term babies were fever, dyspnoea, cough and rhinitis. None of the
Nosocomial RSVin a newborn nursery
== =
189
= c::J CJ
1 July
1
AUQUst
S.ptt~mber
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FIG. 3. Flow chart showing period when RSV was identified in 14 infected babies ( • ). Period when members of staff had URTI is also illustrated ( 0 ).
term babies developed apnoea or conjunctivitis. Rhinitis, dyspnoea and vomiting were the common features in preterm babies. Fever was not a common symptom in preterm babies. However, apnoea and conjunctivitis occurred only in premature babies. Fig. 3 is a flow chart showing the period when RSV was identified in 14 infected babies and the period when members of staff had URTI. Three clusters of infected babies were identified: cases 4 and 10; cases 7, 9, 11, 12, 13 and 14; and cases 1, 2, 5, 6, and 8. The first two clusters of infected babies were associated with medical personnel with upper respiratory tract infection, while the last cluster was not.
Duration of viral shedding Only one infant had positive RSV infection on two consecutive nasal washings. The other babies had positive RSV on only one occasion. Thus, the duration of shedding among these children was between 4 and 8 da ys.
Factors inftuencing the risk of RSV infection Table II shows the risk factors associated with RSV infection in infected and uninfected babies. None of the risk factors mentioned was found to be statistically significant for the acquisition of RSV infection. Location in the ward played a major role in the acquisition of RSV infection. Ali RSVinfected babies were admitted into rooms 3, 5
and BBA. Five babies acquired RSV infection in room 3, five in room 5 and four in BBA. No baby nursed in room 6 acquired RSV infection. Fig. 4 shows the number and percentage of babies acquiring RSV infection according to length of hospital stay. Fifteen per cent of babies admitted for 1-7 days acquired RSV infection and the same number of babies acquired the infection during the 2nd week. Furthermore, 60~ 0 of the babies acquired the infection when they were hospitalized for a period of up to 4 weeks.
Discussion Nosocomial infections constitute a major problem since they contribute to morbidity, sometimes prolong hospitalization, and increase costs. In newbom nurseries, nosocomial spread has long been recognized as an important mode of transmission of bacterial infections like salmonellosis and enteropathogenic E. coli. 15 Hall et al. have recently drawn attention to the importance of nosocomial RSV infections in infant wards in tempera te climates. 12 This study suggests that nosocomial spread of RSV, which occurred in 21° 0 of the babies studied, may be a significant problem even in the hot, humid climate of Benin City. Medical personnel working in our new born nursery were major contributors to the nosocomial spread ofRSV. The infected babies were ali symptomatic and sorne had significant morbidity. The
190
H. O. Okuonghae et al. II. Analysis of risk factors associated with RSV infection in neonates
TABLE
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Risk factor Prematurity (37 weeks) Respiratory distress syndrome Underlying cardiac disease Nasogastric tube feeding Assisted ventilation Endotracheal tube Neonatal tetanus Neurological disease Bacteraemia Congenital defects Operation Born before arrivai (BBA)
Infected babies (n= 14)
Uninfected babies (n = 42)
p value
9 (64) 1 (7) 4 (29) 7 (50) 5 (36) 1 (7) 2 (14) 0 (0) 3 (21) 0 (0) 0 (0) 10 (71)
24 (57) 6 (14) 2 (5) 19 (45) 9 (21) 1 (2) 0 1 (2) 7 (17) 4 (10) 1 (2) 17(41)
NS 1.072 0.171 NS 0.91 2.78 0.118 0.75 1.15 0.61 0.75 NS
Numbers in parentheses are percentages; Fisher's Exact test was used to analyse the risk factors, except for prematurity, nasogastric tube feeding and BBA, where Chi-square test was applied; NS: not significant.
24 22
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100
18
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8 6
30
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20
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FIG. 4. Number and percentage of babies who acquired RSV infection according to length of hospital stay ( 0 uninfected babies; • infected babies;--- percentage of babies infected).
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N osocomial R SV in a newborn nursery
manifestations differed between term and preterm babies. Babies with congenital heart disease and those hospitalized for more than 4 weeks were found to be prone to acquire RSV infection. The rate ofnosocomial infection (21 %) in this study is lower than that (32%) reported by Hall et al. in their study of children less than 24 months of age. 12 Sterner et al., who studied children aged 1-13 months in Stockholm over a 2-month period, reported a 100% rate of acquisition of RSV infection. 8 A similarly high attack rate has also been reported by Kapikian et al. in a closed institutional population. 16 The low rate of nosocomial infection in this study may be related to the fact that the babies were nursed in rooms and not in open wards. Another factor that could influence the rate of nosocomial transmission may be variations in the duration of viral survival in secretions on hands and fomites, under different climatic conditions. Most studies on nosocomial RSV infection have been done in temperate climates. The RSV has been shawn to be maximally stable at 60°;0 relative humidity, and only 10% of infectivity has been found to remain at a temperatue of 37°C after 24 hours. 17 RSV from nasal secretions of infants with acute infection has been shawn to remain infectious on countertops for over 6 hours and on elath and paper tissues for 30 minutes in tempera te elimates. 18 The infectivity rate of the virus in the hot, humid climate of tropical countries has not been determined. The low rate of nosocomial acquisition of RSV in this study may weil be due to a decreased survival of the virus in our environment. Moreover, 65% of RSV -positive babies in this study had only upper respiratory illness and it has been shawn that viral shedding is heavier in patients with lower respiratory tract infection. 16 ' 18 In this study, nosocomial infections were associated with severe disease. Full-term babies were more likely to develop lower respiratory infection than preterm babies. Three of five full-term babies had radiologi-
191
cally confirmed pneumonia following acquisition of RSV, wh ile only two of nine preterm babies had pneumonia. Rhinitis, dyspnoea and vomiting were the common clinical features in preterm babies while term babies tended to have fever, dyspnoea, rhinitis and cough (Fig. 2). One preterm baby had apnoeic attacks, but survived the infection. The only child who died from nosocomial RSV infection was a preterm baby who was admitted with presumed septicaemia but in whom ali bacteriological cultures proved sterile. The child died 5 days after his nasal aspirate was found positive for RSV. lt has previously been assumed that severe RSV infection is uncommon in infants less than 4 weeks old. 8 Severe disease of the type seen in this study has, however, recently been reported by sorne other workers. 10 ' 11 The transmission of RSV infection has been thought to occur either by direct inhalation of large viral particles and droplets or by inoculation of nasal mucosa or conjunctiva by contaminated secretions. Small particle aerosols are thought to be unstable and therefore not important in transmission. Hospital personnel are also important in the spread of the infection, either by direct spread or through fomites. 19 ' 20 Our data demonstrate that transmission of RSV infection can occur by direct baby-ta-baby contact, but ward personnel were probably more instrumental in the transmission of infection. W e observed clustering of infected babies and medical staff with respiratory infection (Fig. 3). The first baby admitted to the Unit with RSV probably infected sorne medical staff who subsequently infected other babies in the ward. The second cluster occurred when two members of staffhad upper respiratory tract infection. The last cluster occurred when no members of staff had upper respiratory tract infection. Here, the transmission of RSV might have involved staff members carrying contaminated secretions from baby to baby. Three rooms in the Unit were identified as being involved in the transmission of RSV
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H. O. Okuonghae et al.
infection. Rooms 3 and 5 housed the two functional resuscitaires in the Unit and there were occasions when these facilities were shared by more than one baby. Baby -to-baby contact occurred quite commonly in these rooms. The BBA rooms were also identified as high risk areas for acquisition of RSV infection. The mothers are in close proximity to their babies nursed in these rooms in an unenclosed cubicle just opposite the nursery and may have contributed to RSV infection. Three of the last cluster of five cases were BBAs. It is noteworthy that no baby acquired RSV infection in Room 6 which only admits babies delivered in UBTH. The two hospital-born preterm babies in the last cluster were nursed in a radiant heater and required intensive resuscitation. They were therefore exposed to many risks of infection. Four of 14 babies (29%) nursed in incubators acquired RSV infection as against seven of 42 babies (17%) nursed in cots. Th us, the incubator was not found to be protective against acquisition of RSV infection, as was previously reported from this Unit. 21 Babies in incubators were probably infected by staff, either directly or through contaminated hands or fomites, or by contact with infected babies under the radiant heater. Infected babies who were nursed in incubators did not, however, transmit RSV to their contact babies in the same room. Analysis of risk factors associated with nosocomial RSV infection showed that babies with congenital heart disease and those hospitalized for more than 4 weeks were prone to acquire RSV infection. The increased risk of RSV infection in babies with congenital heart disease may be related to more frequent handling by medical personnel and/orto their duration of hospitalization. Other risk factors, e.g. born before arrivai (BBA), nasogastric tube feeding, and endotracheal intubation, were not related to increased incidence of RSV infection, as was noted by Valenti et a/. 10 The risk of acquisition of RSV infection was related to the duration ofhospitalization. Whereas only 15% of babies admitted for 1
week acquired the infection, the proportion rose to 60% of babies admitted for up to 4 weeks (Fig. 4). Two babies hospitalized for neonatal tetanus for 30 and 37 days, respectively, both acquired RSV infection. In a study by Hall et al., the chance of acquisition of RSV infection in hospitalized infants rose from 45% in those admitted for 1 week to 100% in those hospitalized for more than 4 weeks. 12 This study has demonstrated a significant rate of nosocomial acquisition of RSV infection in a newborn nursery with severe illness in many babies and the death of a preterm baby, probably as a result of RSV infection. These findings demand that concerted efforts be made to prevent the occurrence of nosocomial RSV infections. The pattern of transmission of RSV infection observed in this study suggests two main modes of transmission of the virus: first, from infected hospital personnel to babies and secondly from infected baby to uninfected baby. lt is therefore necessary that hospital staff with upper respiratory tract infection should avoid contact, in as far as is possible, with newborns, particularly those identified to be high risk babies. Also, ali babies suspected of respiratory infection should be nursed in isolation wards until the nature of their illness is determined. Efforts should therefore be made to identify RSV infection as soon as possible (e.g. by using the ELISA method). The use of incubator care for babies suspected or known to have RSV infections could limit the spread of the virus in the nursery. Thorough handwashing by ali medical personnel is recommended at ali times but is specially important in between handling newborn babies. Adequate hand-washing facilities must be provided in ali newborn units. The number of visitors entering the newborn nursery should be limited as much as possible, particularly during the rainy season, to avoid contact with community-acquired RSV infections. The use of antiviral agents, e.g. Ribavirin, by infected patients may be useful in
Nosocomial RSV in a newborn nursery reducing the duration of viral shed ding and the incidence of disease.
11
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References 1 Loda FA, Clyde WA, Glezon WP, Senior RJ, Sheaffer CI, Denny FW. Studies of the role of viruses, bacteriae, and M. pneumonia as causes of lower respiratory tract infections in children. J Pediatr 1968; 72:161-76. 2 Kim HW, Arrobio JO, Brandt CD, et al. Epidemiology of respiratory syncytial virus infection in Washington D.C. 1. Importance of the virus in different respiratory disease syndromes and temporal distribution of infection. Am J Epidemiol 1973; 98:216-25. 3 Parrott RH, Kim HW, Brandt CD, Chanock RM. Respiratory syncytial virus in infants and children. Prev Med 1974; 3:473-80. 4 Chanock RM, Parrott RH. Acute respira tory disease in infancy and childhood: present understanding and prospects for prevention. Pediatries 1965; 36: 21-39. 5 Dym AM, Schint KE, Nwankwo MU, Omene JA. Respiratory syncytial virus and acute lower respira tory infections in Benin City, Nigeria. Pediatr Infect Dis 1986; 6:717-18. 6 Spence L, Barratt N. Respiratory syncytical virus associated with acute respiratory infection in Trinidadian patients. Am J Epidemiol1968; 88:257. 7 Nwankwo MU, Dym AM, Schint KE, Offor E, Omene JA. Seasonal variation in respiratory syncytial virus infections in Benin City. Trop Geogr Med 1988;4:309-14. 8 Stemer G, Wolontis S, Bloth B, Hevesy GD. Respiratory syncytial virus: an outbreak of acute respiratory illness in a home for infants. Acta Paediatr Scand 1966; 655:273-9. 9 Neligan GA, Steiner H, Garner PS, McQuillin J. Respiratory syncytial virus infections of the newborn. Br Med J 1970; 3:146-7. 10 Valenti WM, Clarke TA, Hall CB, Manegus MA, Shapiro DL. Concurrent outbreaks of rhinovirus and respiratory syncytial virus in an intensive care
12
13
14
15
16
17
18
19
20
21
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nursery. Epidemiology and associated risk factors. J Pediatr 1982; 100:722-6. Meissner HL, Murray SA, Kiernan MA, Snydman DR, Mclntosh K. A simultaneous outbreak of respira tory syncytial virus and para-influenza virus type 3 in a newborn nursery. J Pediatr 1984; 104: 680--4. Hall CB, Douglas Jr RG, Geiman JM, Messner MK. Nosocomial respiratory syncytial virus infection. N Engl J Med 1975; 293:1343-6. Hall CB, Kopelman AE, Douglas RG, Geiman JM, Miagher MP. Neonatal respiratory syncytial virus infection. N Engl J Med 1979; 300:393-6. Bromberg K, Tannis G, Daidone E, et al. Comparison of ortho RSV. J Clin Microbiol 1985; 22: 1071-2. Freedman RM, Ingram DL, Gross 1, Ehrenkranz RA, Warshaw JB, Baltimore RS. A half century of neonatal sepsis at Yale, 1928 to 1978. Am J Dis Child 1981; 135:140-5. Kapikian AZ, Bell JA, Mastrota FM, Johnson KM, Huebner RJ, Chanock RM. An outbreak of febrile illness and pneumonia associated with respiratory syncytial virus infection. Am J Hyg 1961; 74:234--48. Hall CB, Douglas Jr RG, Geiman JM. Quantitative shedding patterns of respiratory syncytial virus in infants. J Infect Dis 1975; 132:151-6. Hall CB, Douglas Jr RG, Geiman J. Respiratory syncytial virus infections in infants: Quantitative and duration ofshedding. J Pediatr 1976; 89:11-15. Chanock RM, Kim HW, Vargosho AJ, et al. Respiratory syncytial virus. 1. virus recovery and other observations during the 1960 outbreak of bronchiolitis, pneumonia and minor respiratory diseases in children. JAMA 1961; 176:647. Sims DG, Downham MAPS, Webb JKG, Gardner PS, Weightrnan D. Hospital cross-infection on children's wards with respira tory syncytial virus and the role of adult carriage. Acta Paediatr Scand 1975; 64: 541-5. Nwankwo MU, Dym A, Schuit KE, Okolo AA, Omene JA, Olomu IN. Neonatal respiratory syncytical virus infection in Benin. Nig J Paediatr 1987; 3,4:79-82.
ISSN: 0272-4936 (Print) 1465-3281 (Online) Journal homepage: http://www.tandfonline.com/loi/ypch19
Nosocomial respiratory syncytial virus infection in a newborn nursery H. O. Okuonghae, M. U. Nwankwo, A. A. Okolo & K. E. Schuit To cite this article: H. O. Okuonghae, M. U. Nwankwo, A. A. Okolo & K. E. Schuit (1992) Nosocomial respiratory syncytial virus infection in a newborn nursery, Annals of Tropical Paediatrics, 12:2, 185-193, DOI: 10.1080/02724936.1992.11747567 To link to this article: http://dx.doi.org/10.1080/02724936.1992.11747567
Published online: 13 Jul 2016.
Submit your article to this journal
View related articles
Citing articles: 6 View citing articles
Full Terms & Conditions of access and use can be found at http://www.tandfonline.com/action/journalInformation?journalCode=ypch19 Download by: [University of Calgary]
Date: 06 August 2017, At: 22:24
Annals of Tropical Paediatrics (1992) 12, 185-193
Nosocomial respiratory syncytial virus infection in a newborn nursery H. O. OKUONGHAE, M. U. NWANKWO, A. A. OKOLO & K. E. SCHUIT*
Downloaded by [University of Calgary] at 22:24 06 August 2017
Department of Child Health, University of Benin, Nigeria and* Department of Pediatries, Children's Hospital, Pittsburgh, USA (Received 7 November 1991)
Summary The nosocomial spread of respiratory syncytial virus (RSV) was studied in a new born nursery in Benin City, Nigeria at a time the virus was known to be highly prevalent in the community. Nasopharyngeal washings were obtained from babies on admission and, thereafter, every 4 days until discharged. Questionnaires were administered to medical personnel with upper respira tory tract infection (URTI). RSV was detected by an ELISA technique. A total of 56 babies were studied, made up of 33 preterm and 23 full term babies. Fourteen of the 56 babies (25° 0 ) developed RSVinfection. Eleven babies (20.8° 0 ) acquired the infection nosocomially. The infected babies were ali symptomatic and sorne had significant morbidity. One preterm baby died following acquisition of RSV. The study demonstrated that medical personnel working in our new born nursery were a major contributor to the spread of nosocomial RSV infection. Babies hospitalized for more than 4 weeks were more likely to acquire RSV infection. Control measures are outlined for the reduction of nosocomial spread of RSV infection in our newborn nursery.
Introduction Respiratory syncytical virus is the most important viral respiratory pathogen in infants and young children. 1- 3 The virus bas been recognized as the major cause ofbronchiolitis and pneumonia in young children. 4 In a recent study from the University of Benin Teaching Hospital (UBTH), 55° 0 of children aged 2 months to 3 years admitted for lower respiratory tract infection were infected with RSV. 5 In temperate climates, RSV infection occurs in regular yearly out breaks during the winter or early spring. Very little is known
Reprint requests to: Dr H. O. Okuonghae, Department of Paediatrics, Faculty of Medical Sciences, University of ]os, PMB 2084, ]os, Nigeria.
about the epidemiology of the disease in the tropics. In Trinidad, which is semi-tropical, RSV was noted to occur in the rainy season. 6 In a previous study in Benin, RSV was found to occur ali year round with a peak during the rainy season. 7 There are few reports in the literature of RSV infection in the new born. Earl y reports of RSV infection in neonates suggested that the illness was usually mild and non-specifie in babies less than 3 weeks of age.B-9 However, recent reports suggest that the virus can produce severe respiratory disease in neonates. 10' 11 The risk for nosocomial acquisition of RSV infection increases during epidemies. Nosocomial RSV infection bas been associated with increased mortality among hospitalized infants. 12- 13 The purpose of this study was to examine prospectively nosocomial
186
H. O. Okuonghae et al.
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6
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~
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Milk ki tchen
Sleeping- in rooms
FIG. 1. Plan of the Special Care Baby Unit in UBTH.
the ward is 20. At the time of the study, there were 14 cots and six incubators. There were, in addition, two functioning radiant heaters for resuscitation of babies. Rooms 3 and 6 bouse four patients, each containing two inMaterials and methods cubators and two cots, while rooms 5 and 'BBA' cater for six patients, each with two Studyarea incubators and four cots. The study was undertaken in the University Babies are nursed in cots or incubators, of Benin Teaching Hospital, Benin City depending on their condition and maturity at (UBTH) between July and September 1988. the time of admission. Occasionally, they are The hospital serves Bendel State and the taken to the radiant heater for resuscitation neighbouring states. It is located in the rain when they develop acute problems. The two forest area of West Mrica at an altitude of functional resuscitaires were in rooms 3 and 5 78 metres. There are two seasons: the rainy during the period of the study. season, which usually starts in April and There are occasions when two or more terminates in October, and the dry season babies are under radiant heaters. When in from November to March. The temperature incubators, much of the babies' routine care is high ali year round (23-34°C). is given through ports which are normally kept closed by hard plastic covers when not in use. Babies may be removed from the incuDescription of the nursery bators for feeding and routine nursing care. The Special Care Baby Unit (SCBU) at the During the period of study, babies were University of Benin is adjacent to the Labour cared for by an average of eight nurses during Ward. lt is made up of four wards (rooms) the moming shift, six nurses during the (Fig. 1). Rooms 5 and 6 are reserved for aftemoon shift, and four nurses at night. The babies delivered in the hospital, while rooms nurses were not limited to any area of the 3 and 'BBA' are for babies referred from ward. Five paediatric and three obstetric other centres. The bed/incubator capacity of residents (rotating through the Neonatology
RSV infection in a new born nursery at a time when the disease was highly prevalent in the community.
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Nosocomial RSVin a newborn nursery
Unit) and one consultant paediatrician are assigned to the unit. Three doctors (including those from other units of the Department of Child Health, UBTH) took calls daily from 4 p.m. till 8 a.m. the following day. Other support staff included wardmaids, three to five daily. Mothers were encouraged to visit their babies and to breast-feed or produce expressed breast milk. Handwashing with soap and water up to the elbow was required between contacts with patients. Nursing staff wore scrub uniforms while doctors did not cover up their street clothes when in the Unit. Face masks were not wom routinely, except when carrying out special procedures, e.g. lumbar puncture, exchange blood transfusion, etc. One hundred and fifteen babies admitted consecutively into the SCBU during the rainy season (July-September 1988) were recruited for the study. Informed consent was obtained from parents at the commencement of the study. All patients were evaluated on admission and clinical features noted. A daily review was made of the physical findings. Notes were made of places in the Unit where babies were admitted, and, if into incubators, when they were transferred from the incubators. Special attention was paid to babies admitted to the same room as babies admitted with respiratory symptoms. Relevant laboratory work-up, including sepsis screening and chest X-rays, were done when necessary. Questionnaires were answered by staff members of the Unit who bad an upper respiratory tract infection during the study period, taking into account when they developed the symptoms and the duration of illness. A persona! observation of all medical and support staff for respiratory symptoms was maintained by one of the investigators (HOO). Sample collection
Nasopharyngeal secretions were obtained on admission and every 4 days until the infant
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was discharged. Nasopharyngeal secretions were obtained using a neonatal mucus extractor attached to a suction pump. With the infant lying on his side, the neonatal mucus extractor was passed via the nostrils into the nasopharynx. Collection was facilitated by introducing 2-5 ml of phosphatebuffered saline through the nostril into the nasopharynx, and immediately sucking it back into the mucus trap. The samples were kept in dean tubes, coded and stored at -40°C prior to assay. Virus detection
RSV surface antigen was detected by ELISA (Ortho-Diagnostic Systems Inc., Raritan, New Jersey). The RSV antigen detection was run according to the manufacturer's protocol. The validity of this technique bas been demonstrated previously. 5•14 Infection was said to have been acquired nosocomially (for referred cases) if RSV was detected more than 7 days after admission, or when two previous samples were negative for RSV. Statistical analysis
Statistical analysis was done by the Student's t-test, Chi-square test and Fisher's exact test, where appropriate.
Results During the study period, a total of 115 babies were admitted to the Special Care Baby Unit (SCBU). Ofthese, 56 (48.7%) were included in the study. The other babies were excluded from the study because they spent less than 4 days in the Unit and were discharged before nasal washing could be obtained. The study population was made up of 30 boys and 26 girls (M:F = 1.2:1) and consisted of 33 preterm babies and 23 term babies. Twenty-nine of the 56 babies were delivered in UBTH and admitted to the SCBU for various reasons. The other 27 babies were
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H. O. Okuonghae et al. TABLE 1. Characteristics of 14 infected and 42 uninfected babies Babies infected
Babies uninfected
1.3:1 35.2 (33.9) 30-40 (30-40) 2132 (1831) 1000-3950 (1000-3650) 5.2 (2.0) 1-19 (1-9) 21.9 (22.7) 4-44(4-44) 17.3 (22.8)
1.1:1 35.5 28-42 2099 800-4100 3.0 1-12
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Characteristics M:F Mean gestational age (weeks) Range Mean weight on admission Range Mean age on admission (days) Range Mean age when RSV -positive (days) Range Duration of hospitalization when RSV-positive (days) Range Total duration of hospitalization (days) Range
3-44(4-44) 29.9 (37.6)
26.5
5-52 (5-52)
4-154
pvalue
NS
NS NS
NS
Figures in parentheses are for those who developed nosocomial RSV infection; NS: Not significant.
referred to the Unit from other peripheral hospitals and matemity centres. Their ages on admission ranged from a few hours to 19 da ys. Fourteen of the 56 babies (25~ 0 ) developed RSV infection. Three of these bad community-acquired RSV infection, and 11 (20. 8%) acquired the infection nosocomially. The difference in the mean gestational ages of the two groups of infants was not statistically significant. Table 1 summarizes the characteristics of the babies studied. Nosocomial infection was acquired at a mean of25 days after admission with a range of 9-44 days. Only one baby bad positive RSV antigen in two consecutive samples.
Frequency of clinica/ signs/symptoms in infected babies
Fig. 2 illustrates the frequency of clinical signs in infected babies. Dyspnoea, rhinitis and fever were the predominant signs/ symptoms observed in babies. Others were
Nt.mber of patients
2
3
4
5
6
7
8
44
60 Dyspnoeo
40
56
Rhinitis
22
80 Fever
44 Vomiting
33 Cough
22 Diorrhoeo Apnoeo Conjunctivitis
FIG. 2. Frequency of clinical signs and symptoms occurring in 14 infected babies, 5 full-term ( •) and 9 preterm (0) babies (figures in percentages).
vomiting, cough, diarrhoea, apnoea and conjunctivitis. The predominant features of infection in full-term babies were fever, dyspnoea, cough and rhinitis. None of the
Nosocomial RSVin a newborn nursery
== =
189
= c::J CJ
1 July
1
AUQUst
S.ptt~mber
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FIG. 3. Flow chart showing period when RSV was identified in 14 infected babies ( • ). Period when members of staff had URTI is also illustrated ( 0 ).
term babies developed apnoea or conjunctivitis. Rhinitis, dyspnoea and vomiting were the common features in preterm babies. Fever was not a common symptom in preterm babies. However, apnoea and conjunctivitis occurred only in premature babies. Fig. 3 is a flow chart showing the period when RSV was identified in 14 infected babies and the period when members of staff had URTI. Three clusters of infected babies were identified: cases 4 and 10; cases 7, 9, 11, 12, 13 and 14; and cases 1, 2, 5, 6, and 8. The first two clusters of infected babies were associated with medical personnel with upper respiratory tract infection, while the last cluster was not.
Duration of viral shedding Only one infant had positive RSV infection on two consecutive nasal washings. The other babies had positive RSV on only one occasion. Thus, the duration of shedding among these children was between 4 and 8 da ys.
Factors inftuencing the risk of RSV infection Table II shows the risk factors associated with RSV infection in infected and uninfected babies. None of the risk factors mentioned was found to be statistically significant for the acquisition of RSV infection. Location in the ward played a major role in the acquisition of RSV infection. Ali RSVinfected babies were admitted into rooms 3, 5
and BBA. Five babies acquired RSV infection in room 3, five in room 5 and four in BBA. No baby nursed in room 6 acquired RSV infection. Fig. 4 shows the number and percentage of babies acquiring RSV infection according to length of hospital stay. Fifteen per cent of babies admitted for 1-7 days acquired RSV infection and the same number of babies acquired the infection during the 2nd week. Furthermore, 60~ 0 of the babies acquired the infection when they were hospitalized for a period of up to 4 weeks.
Discussion Nosocomial infections constitute a major problem since they contribute to morbidity, sometimes prolong hospitalization, and increase costs. In newbom nurseries, nosocomial spread has long been recognized as an important mode of transmission of bacterial infections like salmonellosis and enteropathogenic E. coli. 15 Hall et al. have recently drawn attention to the importance of nosocomial RSV infections in infant wards in tempera te climates. 12 This study suggests that nosocomial spread of RSV, which occurred in 21° 0 of the babies studied, may be a significant problem even in the hot, humid climate of Benin City. Medical personnel working in our new born nursery were major contributors to the nosocomial spread ofRSV. The infected babies were ali symptomatic and sorne had significant morbidity. The
190
H. O. Okuonghae et al. II. Analysis of risk factors associated with RSV infection in neonates
TABLE
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Risk factor Prematurity (37 weeks) Respiratory distress syndrome Underlying cardiac disease Nasogastric tube feeding Assisted ventilation Endotracheal tube Neonatal tetanus Neurological disease Bacteraemia Congenital defects Operation Born before arrivai (BBA)
Infected babies (n= 14)
Uninfected babies (n = 42)
p value
9 (64) 1 (7) 4 (29) 7 (50) 5 (36) 1 (7) 2 (14) 0 (0) 3 (21) 0 (0) 0 (0) 10 (71)
24 (57) 6 (14) 2 (5) 19 (45) 9 (21) 1 (2) 0 1 (2) 7 (17) 4 (10) 1 (2) 17(41)
NS 1.072 0.171 NS 0.91 2.78 0.118 0.75 1.15 0.61 0.75 NS
Numbers in parentheses are percentages; Fisher's Exact test was used to analyse the risk factors, except for prematurity, nasogastric tube feeding and BBA, where Chi-square test was applied; NS: not significant.
24 22
le
:.ë
20
100
18
90
16
80
14
70
_g
0
., .c
E ::>
60
12
50
10
z
40
8 6
30
4
20
2
10
~u .2! c:
.,
"' .2 ~
.,~ Cl.
Durotion of hospitalization (doys)
FIG. 4. Number and percentage of babies who acquired RSV infection according to length of hospital stay ( 0 uninfected babies; • infected babies;--- percentage of babies infected).
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N osocomial R SV in a newborn nursery
manifestations differed between term and preterm babies. Babies with congenital heart disease and those hospitalized for more than 4 weeks were found to be prone to acquire RSV infection. The rate ofnosocomial infection (21 %) in this study is lower than that (32%) reported by Hall et al. in their study of children less than 24 months of age. 12 Sterner et al., who studied children aged 1-13 months in Stockholm over a 2-month period, reported a 100% rate of acquisition of RSV infection. 8 A similarly high attack rate has also been reported by Kapikian et al. in a closed institutional population. 16 The low rate of nosocomial infection in this study may be related to the fact that the babies were nursed in rooms and not in open wards. Another factor that could influence the rate of nosocomial transmission may be variations in the duration of viral survival in secretions on hands and fomites, under different climatic conditions. Most studies on nosocomial RSV infection have been done in temperate climates. The RSV has been shawn to be maximally stable at 60°;0 relative humidity, and only 10% of infectivity has been found to remain at a temperatue of 37°C after 24 hours. 17 RSV from nasal secretions of infants with acute infection has been shawn to remain infectious on countertops for over 6 hours and on elath and paper tissues for 30 minutes in tempera te elimates. 18 The infectivity rate of the virus in the hot, humid climate of tropical countries has not been determined. The low rate of nosocomial acquisition of RSV in this study may weil be due to a decreased survival of the virus in our environment. Moreover, 65% of RSV -positive babies in this study had only upper respiratory illness and it has been shawn that viral shedding is heavier in patients with lower respiratory tract infection. 16 ' 18 In this study, nosocomial infections were associated with severe disease. Full-term babies were more likely to develop lower respiratory infection than preterm babies. Three of five full-term babies had radiologi-
191
cally confirmed pneumonia following acquisition of RSV, wh ile only two of nine preterm babies had pneumonia. Rhinitis, dyspnoea and vomiting were the common clinical features in preterm babies while term babies tended to have fever, dyspnoea, rhinitis and cough (Fig. 2). One preterm baby had apnoeic attacks, but survived the infection. The only child who died from nosocomial RSV infection was a preterm baby who was admitted with presumed septicaemia but in whom ali bacteriological cultures proved sterile. The child died 5 days after his nasal aspirate was found positive for RSV. lt has previously been assumed that severe RSV infection is uncommon in infants less than 4 weeks old. 8 Severe disease of the type seen in this study has, however, recently been reported by sorne other workers. 10 ' 11 The transmission of RSV infection has been thought to occur either by direct inhalation of large viral particles and droplets or by inoculation of nasal mucosa or conjunctiva by contaminated secretions. Small particle aerosols are thought to be unstable and therefore not important in transmission. Hospital personnel are also important in the spread of the infection, either by direct spread or through fomites. 19 ' 20 Our data demonstrate that transmission of RSV infection can occur by direct baby-ta-baby contact, but ward personnel were probably more instrumental in the transmission of infection. W e observed clustering of infected babies and medical staff with respiratory infection (Fig. 3). The first baby admitted to the Unit with RSV probably infected sorne medical staff who subsequently infected other babies in the ward. The second cluster occurred when two members of staffhad upper respiratory tract infection. The last cluster occurred when no members of staff had upper respiratory tract infection. Here, the transmission of RSV might have involved staff members carrying contaminated secretions from baby to baby. Three rooms in the Unit were identified as being involved in the transmission of RSV
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H. O. Okuonghae et al.
infection. Rooms 3 and 5 housed the two functional resuscitaires in the Unit and there were occasions when these facilities were shared by more than one baby. Baby -to-baby contact occurred quite commonly in these rooms. The BBA rooms were also identified as high risk areas for acquisition of RSV infection. The mothers are in close proximity to their babies nursed in these rooms in an unenclosed cubicle just opposite the nursery and may have contributed to RSV infection. Three of the last cluster of five cases were BBAs. It is noteworthy that no baby acquired RSV infection in Room 6 which only admits babies delivered in UBTH. The two hospital-born preterm babies in the last cluster were nursed in a radiant heater and required intensive resuscitation. They were therefore exposed to many risks of infection. Four of 14 babies (29%) nursed in incubators acquired RSV infection as against seven of 42 babies (17%) nursed in cots. Th us, the incubator was not found to be protective against acquisition of RSV infection, as was previously reported from this Unit. 21 Babies in incubators were probably infected by staff, either directly or through contaminated hands or fomites, or by contact with infected babies under the radiant heater. Infected babies who were nursed in incubators did not, however, transmit RSV to their contact babies in the same room. Analysis of risk factors associated with nosocomial RSV infection showed that babies with congenital heart disease and those hospitalized for more than 4 weeks were prone to acquire RSV infection. The increased risk of RSV infection in babies with congenital heart disease may be related to more frequent handling by medical personnel and/orto their duration of hospitalization. Other risk factors, e.g. born before arrivai (BBA), nasogastric tube feeding, and endotracheal intubation, were not related to increased incidence of RSV infection, as was noted by Valenti et a/. 10 The risk of acquisition of RSV infection was related to the duration ofhospitalization. Whereas only 15% of babies admitted for 1
week acquired the infection, the proportion rose to 60% of babies admitted for up to 4 weeks (Fig. 4). Two babies hospitalized for neonatal tetanus for 30 and 37 days, respectively, both acquired RSV infection. In a study by Hall et al., the chance of acquisition of RSV infection in hospitalized infants rose from 45% in those admitted for 1 week to 100% in those hospitalized for more than 4 weeks. 12 This study has demonstrated a significant rate of nosocomial acquisition of RSV infection in a newborn nursery with severe illness in many babies and the death of a preterm baby, probably as a result of RSV infection. These findings demand that concerted efforts be made to prevent the occurrence of nosocomial RSV infections. The pattern of transmission of RSV infection observed in this study suggests two main modes of transmission of the virus: first, from infected hospital personnel to babies and secondly from infected baby to uninfected baby. lt is therefore necessary that hospital staff with upper respiratory tract infection should avoid contact, in as far as is possible, with newborns, particularly those identified to be high risk babies. Also, ali babies suspected of respiratory infection should be nursed in isolation wards until the nature of their illness is determined. Efforts should therefore be made to identify RSV infection as soon as possible (e.g. by using the ELISA method). The use of incubator care for babies suspected or known to have RSV infections could limit the spread of the virus in the nursery. Thorough handwashing by ali medical personnel is recommended at ali times but is specially important in between handling newborn babies. Adequate hand-washing facilities must be provided in ali newborn units. The number of visitors entering the newborn nursery should be limited as much as possible, particularly during the rainy season, to avoid contact with community-acquired RSV infections. The use of antiviral agents, e.g. Ribavirin, by infected patients may be useful in
Nosocomial RSV in a newborn nursery reducing the duration of viral shed ding and the incidence of disease.
11
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