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An outbreak of rotavirus gastroenteritis on a pediatric unit
An outbreak of rotavirus on a pediatric unit Martha JoAnn James Los
Chapin, R.N. Yatabe, Ph.D. D. Cherry, M.D.
Angeles,
California
Rotaviruses were first observed by Bishop et al.’ in 1973 by electron microscopic examination of duodenal biopsy tissues from acutely ill infants and young children with diarrhea. Since that time, studies in many countries throughout the world have documented rotaviruses as a major cause of gastroenteritis in infants and young childrenFP4 The incubation period of rotavirus is approximately 1 to 3 days.5 Recently an enzyme-linked immunosorbent assay (ELISA) has become commercially available, making the detection of rotavirus antigen more practical in the hospital diagnostic laboratory.*’ 6 On Oct. 15, 198 1, this test was instituted on a routine basis at our hospital. Shortly thereafter, an increased incidence of community-wide rotavirus infection occurred.7 This led to an increase in the number of children admitted to our hospital with rotavirus diarrhea. During the epidemic a nosocomial outbreak of the disease was also documented. MATERIALS
AND
METHODS
The study was conducted from Oct. 15, 198 1, through Jan. 15, 1982, on the 74-bed acute-care pediatric ward of the UCLA Hospital. On the pediatric ward, patients are segregated to a limited extent by age (Fig. 1). There are desig-
From the Department of Infection Control and Clinrcal Laboratones, UCLA Hosprtal and Clinics; and the Department of Pedtatrics, UCLA School of Medicine, Center for the Health Sciences, Los Angeles, Calif. Presented at the Associatron trol meeting, New Orleans,
for Practitroners in Infection La., May 12, 1982.
PePrlnt requests: James D. Cherry, Pediatrics, UCLA School of Medrcine, Sciences, Los Angeles, CA 90024
88
gastroenteritis
M.D., Center
Con-
Department of for the Health
nated rooms for infants, toddlers, and adolescents and several rooms to which children of all ages are admitted. There is a common playroom available on the floor. However, none of the children who acquired nosocomial infection participated in playroom activities. Those children were mainly confined to their rooms. In the infant area, one room is used as a threebed isolation ward to which all but strict isolation cases are admitted. A nosocomial case in this investigation was defined as any child who had been in the hospital for 3 or more days prior to the occurrence of rotavirus gastroenteritis and the identification of rotavirus antigen in the stool. Specific diagnosis was made by the ELISA method with the Abbott Rotazyme kit. For this test, either 5 gm of fresh stool in a sterile container or a rectal swab in a “Culturette” was used. During the rotavirus outbreak, the epidemiologist visited the ward 5 days a week in order to identify all patients and/or employees with community-acquired or nosocomial infections. Clinical and epidemiologic data were collected on standard line listing forms from the hospital records of all patients suspected of having rotavirus gastroenteritis. The specific data recorded included patient name, hospital number, age, sex, date of admission, discharge date, underlying diagnosis, date of onset, symptoms, laboratory results, and the patient’s location. Special note was made of any possible pattern of occurrence of infection. RESULTS
Thirty patients had rotavirus gastroenteritis (Table 1). Twenty-two cases were communityacquired and eight were nosocomial. The chil-
Volume June.
11 Number
3
Rotavims gastroeuteritis outbreak on pediatric. unit
1983
Infants Toddlers Mixed f%@. 1. Patient
areas on the 74-bed
Adolescent Protective
acute-care
dren ranged in age from 2 to 29 months, and 22 (83%) were less than 1 year of age. Nineteen (63%) were boys. No cases were reported in hoz@al employees . In the mxxxomial cases, the interval between admission and onset of diarrhea was 5 to 87 days. Vomiting was present in 95% of community-acquired disease: in contrast, vomiting occurred in 37% of those with nosocomial infection. Dehydration occurred only in patients with community-acquired infection.
rst five cases of nosocomial infection occurred in the infant area (Fig. 2). Case 1 was a 2-month-old boy who was a the hospital on Oct. 10 with recurrent group B streptococcal sepsis. Ten days after admission. diarrhea and fever occurred. Although there was no knawn patient with rotavirus infection in the child’s room prior to the onset of symptoms, there W ted case in the infant area. 2 was a 7-month-old girl admitted Sept. 28 with chronic recurrent pulmonary disease. Symptoms of rotavirus gastroenteritis began 28 days after her &~&&MI. Although she did not share the room with any child with rotavirus infection, two documented cases of rotavirus diarrhea occurred in sr 371 and 372. ‘Case 3 was a 9-month-old boy who was
89
Isolation
pediatric
ward of the UCLA Hospital
Tdk I. CIinical features gastroenteritis categorized acquisition
Age (mo.) <6 6-11 12-23 24-29 Sex Male Female Findings Vomiting Diarrhea Fever Dehydration
in 30 patknts with rotavfrus by type of disease _-
1 (13%) 6 (75%) 1 (13%) 0
4 (18%) 11 (50%) 5 (23%) 2 (9%)
4 (50%) 4 (50%)
15 (Smq 7 (32%)
3 (37%) 8 (100%) 7 (88%) 0
21 22 18 22
(95%) (100%) (82%) (100%)
admitted July 31 with malnu matic hernia. The onset of his 88 days after admission. Rotavrrus m child was attributed to contaclt with Case I,. infants shared the same room far 6 days. &se 1 was symptomatic 3 days before Case 3. RsemSz*ca5@4w%sa7-
Oct. 30 with faiVre to thrive. gastroenteritis began on Nov. 3,s &ys aftbr cor&@t with Case 3 in whom rotavirus infection had been
American
90
Chapin,
Yatabe,
INFECTION
and Cherry
Journal
of
CONTROL
. lol24181 l lo/31181 . 11/l/81 l lllU81~
o 10/25/81 . 10/28/81
l 10/21/81 /
308 306 304 4 0 10/25/81 l 12119l81
o 10/2&81 o li/9/81 q 10126181 l 11110181 l 11/11/81 o 11/3/81 . 11112l81 . 11/13/81 l 11/24/81 Community-acquired 0 Nosocomial N.S. = Nursing Station BR = Bathroom K = Kitchen
1117/81 0 11122181 . 12/6/81 l 12M81 l l/22/82 l
l
0 Community-acquired 0 Nosocomial Fig. 3. Dates and location acquired rotavirus illnesses
of hospital and community on the 3 East wing.
Fig. 2. Dates and location of hospital- and communityacquired rotavirus illnesses on the 3 West infant’s unit.
documented 9 days before. In addition, a 20-monthold infant with diarrhea who was not tested for rotavirus antigen was also in this room. Room 370. Case 5 was a 6-month-old girl admitted Nov. 2 with Haemophilus influenzae meningitis; 7 days after admission, symptoms of rotavirus gastroenteritis began. This child had shared a room with a child with suspected rotavirus gastroenteritis who was not tested. Two previous cases of documented rotavirus diarrhea had also occupied the room. .
.
.
The remaining three nosocomial cases occurred on the opposite end of the pediatric unit on the 3 East wing (Fig. 3). Room 304. Case 6 was a 16-month-old girl admitted Oct. 17 for failure to thrive. She had no symptoms of gastroenteritis at the time of admission. Her symptoms began 5 days later. Factors that may have caused rotavirus gastroenteritis in this patient are not clear, since no previously documented cases had occurred in this wing of the East unit. However there
was one documented case in a room around the corner from the patient (Fig. 1). Room 308. Case 7 was an 1 l-month-old girl admitted Aug. 12 with intestinal lymphangectasia. Seventy-five days later she developed symptoms of gastroenteritis. Although there had been no documented cases of rotavirus diarrhea in this infant’s room, there was a case two doors away. The same nursing staff cared for both patients. Room 304. Case 8 was a lo-month-old boy admitted Nov. 13 with cyanosis. Nine days after admission, diarrhea occurred. This patient was admitted to a room that a child with rotavirus diarrhea had vacated approximately 2 hours before. DISCUSUOW
In this outbreak, all areas of the pediatric floor were not affected. Nosocomial infection occurred predominantly in areas where the largest number of patients with communityacquired infection had been or were housed. Three of the eight hospital-acquired infections occurred after patients were placed in
Volume June,
11 Number
3
1983
rooms with confirmed rotavirus-positive patients. Two nosocomial cases occurred in rooms adjacent to rooms in which documented patients with rotavirus diarrhea were being cared for. One patient who acquired disease was admitted to a room shortly after the discharge of a patient with confirmed rotavirus infection, Although the direct exposure of two patients was not known, they were in the hospital at the same time and in close proximity to other patients with rotavirus diarrhea. The observed epidemiologic patterns suggested either a common-source exposure with subsequent person-to-person transmission, or person-to-person spread by personnel or fomites. Direct person-to-person spread is not likely, since most patients were confined to bed and respiratory secretions have not been demonstrated to contain rotavirus. Cross-infection could have resulted from carriage of contaminated excretions on hands or clothing of the ward staff after they tended to patients with infection. Stool testing for blood and sugar by the ward staff was done in a common bathroom in the 3 West infant area and, to a lesser extent, in the utility room on the 3 East unit. Contaminated diapers were carried out of the patients’ rooms to these areas for testing. To prevent further nosocomial infection, on Oct. 30, 19& 1, all patients admitted with gastrointestinal symptoms were placed in private rooms with enteric precautions until stools were studied for rotavirus antigen. Known rotaviruspositive patients were placed together at one end of the ward. Asymptomatic contacts of known- positive patients were kept together in their original rooms. The nurses and parents were instructed to dispose of soiled diapers in the patients’ rooms in separate hampers clearly marked “Isolation.” Careful handwashing before and after contact with any of the patients or their belongings was emphasized. Testing of stools (i.e., for blood or sugar) was done inside the isolation room rather than in the bathroom or utility room. Patients were not allowed to leave their rooms and parents were required to wear gowns when in contact with the infants. Separate nursing staff was maintained whenever possible to take care of symptomatic children and their
Rotavirus gastroenteritis outbreak on pedianric unit
9*
contacts. Since the duration of symptoms is reported to be 5 to 7 days, with shed&~ up to 10 days,3 we used a negative BUM ancS cessation of symptoms as criteria to take patients off isolation precautions. The rate of nosocomial infection was markedly reduced by early identification of infected patients and possible vehicles of transmission plus the implementation of strict control measures. Prior to Oct. 30, 56% (5 of 9) cases were hospital-acquired, whereas after this date, only 14% (3 of 31) cases occurred in hospitalized children. After Jan. 15, 1982, patients with community-acquired infections continued to be admitted to the hospital but there were no further nosocomial infections. Our study as well as other recent studies confirm the importance of rotaviruses as causative agents in nosocomial infections in infants and children.8-12 Ref-8 1. Bishop RF, Davidson GP, Holmes IN, Rnck BJ: Virns particles in epithelial cells of duodenal muccsa from children with acute non-bacterial gastroeateritis. Lancet 2: 1281-1283, 1973. 2. Blacklow NR, Cukor G: Medical process viral gastroenteritis. N Engl J Med -397-406, 1981. 3. WHO Scientific Working Group: Rotavirus and other viral diarrhoeas. Bull WHO s t83-198 15QO. 4. Steinhoff MC: Rotavirus: the first five years. J Pediatr %:61 l-622, 1980. 5. San Joaquin VH, Marks MI: New agents in diarrhea. Pediatr Infect Dis 1:53-64, 1982. 6. Grautalle PC, Vestergaard BF, Meyling A, Genner J: Optimized enzyme-linked immunoaorbent assay for detection of human and bovine rotavinrs in stools. Comparison with electron-microscopy, immmmelectmosmophoresis, and fluorescent antibody techniques. J Med Virol 7:29-40, 1981. 7. Los Angeles County Public Health Letter, Vol. 3, No. 11, November 198 1. a. Flewett TH, Bryden AS, Davies H: Epidemic viral enteritis in a long-stay children’s ward. Lancet 1:4, 1975. 9. Tufvesson B, Johnsson T: Occurrence of mo-l&e viruses in young children with acute gastroen trtritis. Acta Path01 Microbial Stand [B] M:22, 1976. 10. Ryder RW, McGowan JE, Hatch MH, Palmer EL: Reovirus-like agent as a canse of noaocomial diarrhea in infants. J Pediatr %t698, 1977. 11. Bryden AS, Thouless ME, Hall CJ, Flewett ,TH, Wbarton BA, Mathew PM, Craig I: Rotavirus infoctivns in a special-care baby unit. J Infect 4:43-48, $982. 12. Rocchi G, Vella S, Resta S, Cochi S, Do&E G, Tangucci F, Menichella D, Varveri A, Ingleae Rz Outbreak of rotavirus gastroenterltis among premature? infants. Br Med J 283:886-888, 1981.
Chapin, R.N. Yatabe, Ph.D. D. Cherry, M.D.
Angeles,
California
Rotaviruses were first observed by Bishop et al.’ in 1973 by electron microscopic examination of duodenal biopsy tissues from acutely ill infants and young children with diarrhea. Since that time, studies in many countries throughout the world have documented rotaviruses as a major cause of gastroenteritis in infants and young childrenFP4 The incubation period of rotavirus is approximately 1 to 3 days.5 Recently an enzyme-linked immunosorbent assay (ELISA) has become commercially available, making the detection of rotavirus antigen more practical in the hospital diagnostic laboratory.*’ 6 On Oct. 15, 198 1, this test was instituted on a routine basis at our hospital. Shortly thereafter, an increased incidence of community-wide rotavirus infection occurred.7 This led to an increase in the number of children admitted to our hospital with rotavirus diarrhea. During the epidemic a nosocomial outbreak of the disease was also documented. MATERIALS
AND
METHODS
The study was conducted from Oct. 15, 198 1, through Jan. 15, 1982, on the 74-bed acute-care pediatric ward of the UCLA Hospital. On the pediatric ward, patients are segregated to a limited extent by age (Fig. 1). There are desig-
From the Department of Infection Control and Clinrcal Laboratones, UCLA Hosprtal and Clinics; and the Department of Pedtatrics, UCLA School of Medicine, Center for the Health Sciences, Los Angeles, Calif. Presented at the Associatron trol meeting, New Orleans,
for Practitroners in Infection La., May 12, 1982.
PePrlnt requests: James D. Cherry, Pediatrics, UCLA School of Medrcine, Sciences, Los Angeles, CA 90024
88
gastroenteritis
M.D., Center
Con-
Department of for the Health
nated rooms for infants, toddlers, and adolescents and several rooms to which children of all ages are admitted. There is a common playroom available on the floor. However, none of the children who acquired nosocomial infection participated in playroom activities. Those children were mainly confined to their rooms. In the infant area, one room is used as a threebed isolation ward to which all but strict isolation cases are admitted. A nosocomial case in this investigation was defined as any child who had been in the hospital for 3 or more days prior to the occurrence of rotavirus gastroenteritis and the identification of rotavirus antigen in the stool. Specific diagnosis was made by the ELISA method with the Abbott Rotazyme kit. For this test, either 5 gm of fresh stool in a sterile container or a rectal swab in a “Culturette” was used. During the rotavirus outbreak, the epidemiologist visited the ward 5 days a week in order to identify all patients and/or employees with community-acquired or nosocomial infections. Clinical and epidemiologic data were collected on standard line listing forms from the hospital records of all patients suspected of having rotavirus gastroenteritis. The specific data recorded included patient name, hospital number, age, sex, date of admission, discharge date, underlying diagnosis, date of onset, symptoms, laboratory results, and the patient’s location. Special note was made of any possible pattern of occurrence of infection. RESULTS
Thirty patients had rotavirus gastroenteritis (Table 1). Twenty-two cases were communityacquired and eight were nosocomial. The chil-
Volume June.
11 Number
3
Rotavims gastroeuteritis outbreak on pediatric. unit
1983
Infants Toddlers Mixed f%@. 1. Patient
areas on the 74-bed
Adolescent Protective
acute-care
dren ranged in age from 2 to 29 months, and 22 (83%) were less than 1 year of age. Nineteen (63%) were boys. No cases were reported in hoz@al employees . In the mxxxomial cases, the interval between admission and onset of diarrhea was 5 to 87 days. Vomiting was present in 95% of community-acquired disease: in contrast, vomiting occurred in 37% of those with nosocomial infection. Dehydration occurred only in patients with community-acquired infection.
rst five cases of nosocomial infection occurred in the infant area (Fig. 2). Case 1 was a 2-month-old boy who was a the hospital on Oct. 10 with recurrent group B streptococcal sepsis. Ten days after admission. diarrhea and fever occurred. Although there was no knawn patient with rotavirus infection in the child’s room prior to the onset of symptoms, there W ted case in the infant area. 2 was a 7-month-old girl admitted Sept. 28 with chronic recurrent pulmonary disease. Symptoms of rotavirus gastroenteritis began 28 days after her &~&&MI. Although she did not share the room with any child with rotavirus infection, two documented cases of rotavirus diarrhea occurred in sr 371 and 372. ‘Case 3 was a 9-month-old boy who was
89
Isolation
pediatric
ward of the UCLA Hospital
Tdk I. CIinical features gastroenteritis categorized acquisition
Age (mo.) <6 6-11 12-23 24-29 Sex Male Female Findings Vomiting Diarrhea Fever Dehydration
in 30 patknts with rotavfrus by type of disease _-
1 (13%) 6 (75%) 1 (13%) 0
4 (18%) 11 (50%) 5 (23%) 2 (9%)
4 (50%) 4 (50%)
15 (Smq 7 (32%)
3 (37%) 8 (100%) 7 (88%) 0
21 22 18 22
(95%) (100%) (82%) (100%)
admitted July 31 with malnu matic hernia. The onset of his 88 days after admission. Rotavrrus m child was attributed to contaclt with Case I,. infants shared the same room far 6 days. &se 1 was symptomatic 3 days before Case 3. RsemSz*ca5@4w%sa7-
Oct. 30 with faiVre to thrive. gastroenteritis began on Nov. 3,s &ys aftbr cor&@t with Case 3 in whom rotavirus infection had been
American
90
Chapin,
Yatabe,
INFECTION
and Cherry
Journal
of
CONTROL
. lol24181 l lo/31181 . 11/l/81 l lllU81~
o 10/25/81 . 10/28/81
l 10/21/81 /
308 306 304 4 0 10/25/81 l 12119l81
o 10/2&81 o li/9/81 q 10126181 l 11110181 l 11/11/81 o 11/3/81 . 11112l81 . 11/13/81 l 11/24/81 Community-acquired 0 Nosocomial N.S. = Nursing Station BR = Bathroom K = Kitchen
1117/81 0 11122181 . 12/6/81 l 12M81 l l/22/82 l
l
0 Community-acquired 0 Nosocomial Fig. 3. Dates and location acquired rotavirus illnesses
of hospital and community on the 3 East wing.
Fig. 2. Dates and location of hospital- and communityacquired rotavirus illnesses on the 3 West infant’s unit.
documented 9 days before. In addition, a 20-monthold infant with diarrhea who was not tested for rotavirus antigen was also in this room. Room 370. Case 5 was a 6-month-old girl admitted Nov. 2 with Haemophilus influenzae meningitis; 7 days after admission, symptoms of rotavirus gastroenteritis began. This child had shared a room with a child with suspected rotavirus gastroenteritis who was not tested. Two previous cases of documented rotavirus diarrhea had also occupied the room. .
.
.
The remaining three nosocomial cases occurred on the opposite end of the pediatric unit on the 3 East wing (Fig. 3). Room 304. Case 6 was a 16-month-old girl admitted Oct. 17 for failure to thrive. She had no symptoms of gastroenteritis at the time of admission. Her symptoms began 5 days later. Factors that may have caused rotavirus gastroenteritis in this patient are not clear, since no previously documented cases had occurred in this wing of the East unit. However there
was one documented case in a room around the corner from the patient (Fig. 1). Room 308. Case 7 was an 1 l-month-old girl admitted Aug. 12 with intestinal lymphangectasia. Seventy-five days later she developed symptoms of gastroenteritis. Although there had been no documented cases of rotavirus diarrhea in this infant’s room, there was a case two doors away. The same nursing staff cared for both patients. Room 304. Case 8 was a lo-month-old boy admitted Nov. 13 with cyanosis. Nine days after admission, diarrhea occurred. This patient was admitted to a room that a child with rotavirus diarrhea had vacated approximately 2 hours before. DISCUSUOW
In this outbreak, all areas of the pediatric floor were not affected. Nosocomial infection occurred predominantly in areas where the largest number of patients with communityacquired infection had been or were housed. Three of the eight hospital-acquired infections occurred after patients were placed in
Volume June,
11 Number
3
1983
rooms with confirmed rotavirus-positive patients. Two nosocomial cases occurred in rooms adjacent to rooms in which documented patients with rotavirus diarrhea were being cared for. One patient who acquired disease was admitted to a room shortly after the discharge of a patient with confirmed rotavirus infection, Although the direct exposure of two patients was not known, they were in the hospital at the same time and in close proximity to other patients with rotavirus diarrhea. The observed epidemiologic patterns suggested either a common-source exposure with subsequent person-to-person transmission, or person-to-person spread by personnel or fomites. Direct person-to-person spread is not likely, since most patients were confined to bed and respiratory secretions have not been demonstrated to contain rotavirus. Cross-infection could have resulted from carriage of contaminated excretions on hands or clothing of the ward staff after they tended to patients with infection. Stool testing for blood and sugar by the ward staff was done in a common bathroom in the 3 West infant area and, to a lesser extent, in the utility room on the 3 East unit. Contaminated diapers were carried out of the patients’ rooms to these areas for testing. To prevent further nosocomial infection, on Oct. 30, 19& 1, all patients admitted with gastrointestinal symptoms were placed in private rooms with enteric precautions until stools were studied for rotavirus antigen. Known rotaviruspositive patients were placed together at one end of the ward. Asymptomatic contacts of known- positive patients were kept together in their original rooms. The nurses and parents were instructed to dispose of soiled diapers in the patients’ rooms in separate hampers clearly marked “Isolation.” Careful handwashing before and after contact with any of the patients or their belongings was emphasized. Testing of stools (i.e., for blood or sugar) was done inside the isolation room rather than in the bathroom or utility room. Patients were not allowed to leave their rooms and parents were required to wear gowns when in contact with the infants. Separate nursing staff was maintained whenever possible to take care of symptomatic children and their
Rotavirus gastroenteritis outbreak on pedianric unit
9*
contacts. Since the duration of symptoms is reported to be 5 to 7 days, with shed&~ up to 10 days,3 we used a negative BUM ancS cessation of symptoms as criteria to take patients off isolation precautions. The rate of nosocomial infection was markedly reduced by early identification of infected patients and possible vehicles of transmission plus the implementation of strict control measures. Prior to Oct. 30, 56% (5 of 9) cases were hospital-acquired, whereas after this date, only 14% (3 of 31) cases occurred in hospitalized children. After Jan. 15, 1982, patients with community-acquired infections continued to be admitted to the hospital but there were no further nosocomial infections. Our study as well as other recent studies confirm the importance of rotaviruses as causative agents in nosocomial infections in infants and children.8-12 Ref-8 1. Bishop RF, Davidson GP, Holmes IN, Rnck BJ: Virns particles in epithelial cells of duodenal muccsa from children with acute non-bacterial gastroeateritis. Lancet 2: 1281-1283, 1973. 2. Blacklow NR, Cukor G: Medical process viral gastroenteritis. N Engl J Med -397-406, 1981. 3. WHO Scientific Working Group: Rotavirus and other viral diarrhoeas. Bull WHO s t83-198 15QO. 4. Steinhoff MC: Rotavirus: the first five years. J Pediatr %:61 l-622, 1980. 5. San Joaquin VH, Marks MI: New agents in diarrhea. Pediatr Infect Dis 1:53-64, 1982. 6. Grautalle PC, Vestergaard BF, Meyling A, Genner J: Optimized enzyme-linked immunoaorbent assay for detection of human and bovine rotavinrs in stools. Comparison with electron-microscopy, immmmelectmosmophoresis, and fluorescent antibody techniques. J Med Virol 7:29-40, 1981. 7. Los Angeles County Public Health Letter, Vol. 3, No. 11, November 198 1. a. Flewett TH, Bryden AS, Davies H: Epidemic viral enteritis in a long-stay children’s ward. Lancet 1:4, 1975. 9. Tufvesson B, Johnsson T: Occurrence of mo-l&e viruses in young children with acute gastroen trtritis. Acta Path01 Microbial Stand [B] M:22, 1976. 10. Ryder RW, McGowan JE, Hatch MH, Palmer EL: Reovirus-like agent as a canse of noaocomial diarrhea in infants. J Pediatr %t698, 1977. 11. Bryden AS, Thouless ME, Hall CJ, Flewett ,TH, Wbarton BA, Mathew PM, Craig I: Rotavirus infoctivns in a special-care baby unit. J Infect 4:43-48, $982. 12. Rocchi G, Vella S, Resta S, Cochi S, Do&E G, Tangucci F, Menichella D, Varveri A, Ingleae Rz Outbreak of rotavirus gastroenterltis among premature? infants. Br Med J 283:886-888, 1981.