Pediatric Infectious Disease Journal:
Transmission of rotavirus and other enteric pathogens in the home
DENNEHY, PENELOPE H. MD
From Brown University School of Medicine and Division of Pediatric Infectious Diseases, Rhode Island Hospital, Providence, RI.
Address for reprints: Penelope H. Dennehy, M.D., Division of Pediatric Infectious Diseases, Rhode Island Hospital, 593 Eddy Street, Providence, RI 02903. Fax 401-444-5650; E-mail Penelope_Dennehy@brown.edu.
In the United States gastroenteritis is a common infection second only to viral respiratory infections. The Centers for Disease Control and Prevention has estimated that in children <5 years of age ∼35 million episodes of diarrhea occur yearly, resulting in >200 000 hospitalizations and ∼500 deaths. Rotavirus is the cause of ∼50% of diarrhea-related pediatric admissions to hospitals and 20 to 25% of pediatric diarrhea in outpatient clinics, resulting in a significant number of physician visits, hospitalizations and deaths. 1–4
Rotavirus infections in children can be very costly. In addition to the direct medical costs, the indirect expenses associated with parental lost wages and changes in child care arrangements because of the illness must be considered. 5, 6 To control the transmission of rotavirus, parents, child care providers and health care personnel must be able to recognize the clinical symptoms of rotavirus infection, the modes of rotaviral transmission and how rotaviral transmission can be minimized once a child is infected.
CLINICAL MANIFESTATIONS AND OUTCOME
In the United States rotavirus causes seasonal peaks of gastroenteritis from November to May each year, with activity beginning in the Southwest United States and spreading to the Northeast. 7, 8 The spectrum of rotavirus illness ranges from mild, watery diarrhea of limited duration to severe, dehydrating diarrhea with vomiting and fever, possibly resulting in death. 4, 9, 10 Virtually all children become infected in the first 3 to 5 years of life, but severe diarrhea and dehydration occur primarily among children 3 to 35 months of age. 3, 4, 11 Most children are infected more than once although subsequent infections tend to be milder. 11 Protective immunity acquired from infection is incomplete, but is strongest against moderate to severe infection.
Rotavirus infection is characterized by the abrupt onset of fever and vomiting followed by watery diarrhea. Neonatal infections are often asymptomatic. 12 Symptomatic cases among adult family contacts are infrequent, although subclinical infections occur frequently. 13 In any single patient illness caused by rotavirus is not distinguishable from that caused by other enteric viruses, although rotavirus diarrhea may be more severe and is more frequently associated with fever and vomiting than is acute diarrhea caused by other agents. Therapy for rotavirus infection is focused on replacement of fluids and electrolytes, given that no antiviral agents are currently available.
Rotavirus is a major cause of nosocomial diarrhea in infants and young children 3, 14 and has been associated with outbreaks of gastroenteritis in the day-care setting. 15, 16 In day-care centers rotavirus has been identified in 25 to 40% of outbreaks of diarrheal illness with an attack rate of 40 to 70%. 16 The tendency of rotavirus to rapidly involve many children in a day-care center indicates the need for intervention strategies or disease control practices to be in place before the identification of rotavirus illness.
MANAGEMENT OF ROTAVIRUS INFECTION: PREVENTION OF TRANSMISSION
Rotavirus has a short incubation period of 1 to 3 days. Viral shedding begins before symptoms develop, and children may be shedding the virus for up to 48 h before they exhibit symptoms. 17 High rates of asymptomatic shedding of rotavirus have been reported in young children. The virus is shed in feces for a mean of 4 days although excretion of virus for >30 days has been reported in immunocompromised patients.
Rotavirus is known to be transmitted person-to-person by the fecal oral route. 18 In developing countries rotavirus can also be transmitted via fecally contaminated water. 19 It is also suspected that rotavirus can spread from child to child via the contamination of caretaker’s hands by infected fomites or surfaces. 19–21
Respiratory spread by small particle aerosol has also been suspected, although not proved in humans. 22 Evidence for the airborne spread of rotavirus gastroenteritis is primarily circumstantial and includes the short incubation period of 1 to 3 days and the fact that the virus often occurs in explosive outbreaks. Rotavirus has also been detected in respiratory secretions in a small number of patients, 23, 24 and cases of pneumonia have been described. 25, 26 In addition some studies have noted the presence of respiratory symptoms and otitis media in up to 50% of patients with rotavirus. 27 The preliminary findings of rotavirus RNA from air samples taken from rooms of hospitalized children with rotavirus infections suggest that airborne spread may be a major route of transmission of rotavirus in the hospital and day-care settings. 28
Transmission of rotavirus is facilitated in child day-care centers, including family day-care homes, by frequent and intimate exposure among susceptible hosts, with diaper changing as the highest risk procedure for such transmission. Investigators have found rotavirus on diaper disposal containers, toys, faucets, diaper changing areas, handwashing areas and even in food preparation areas, 20, 29 demonstrating that rotavirus can be spread all over a home or day-care center, not just in areas directly contaminated by stool.
Rotavirus-infected children excrete 100 billion virus particles per g of stool. 30 These viruses may survive days to weeks on environmental surfaces, are viable on hands for at least 4 h and can survive for weeks in recreational or drinking water. Studies on adult volunteers have shown that ingestion of as few as 10 infectious rotavirus particles can cause infection. 31, 32 Almost one-half of the children with rotavirus diarrhea tested in the 2 days before symptoms appeared were already shedding virus, and high rates of asymptomatic shedding of rotavirus have also been reported in young children. 17 Presymptomatic shedding and the high rate of asymptomatic rotavirus infections may be important factors in the introduction and transmission of rotavirus.
Similar rates of illness among children in industrialized and less developed countries indicate that further improvements in water supply and hygiene are unlikely to decrease the incidence of rotavirus diarrhea. Vaccines to prevent rotavirus infection are also not currently available. A rotavirus vaccine, RotaShield, licensed in 1998, was voluntarily withdrawn from the US market in October, 1999, after a review of scientific data from several studies suggested that intussusception occurred with significantly increased frequency in the first 1 to 2 weeks after vaccination. 33, 34 The primary means to prevent rotavirus infection involve infection control measures. 33
Control measures for rotavirus must deal with the difficulties in removing rotaviruses from hands or contaminated surfaces. Rotaviruses are relatively resistant to inactivation by chemical disinfectants and antiseptics commonly used in hospitals and other institutions. 19 Environmental surfaces should be disinfected with effective agents. To become active against rotavirus, chlorhexidine gluconate (the active ingredient in Hibiclens) and quaternary ammonium compounds should be used in preparations that contain a high proportion of alcohol. Formulations of chlorhexidine gluconate 0.5% w/v in 70% ethanol by volume (Hibitane in ethanol) or quarternary ammonium compounds that contain >40% isopropyl alcohol by volume inactivate rotavirus. Ethanol 95% by volume is equally effective. Lysol Brand Disinfectant spray (79% ethyl alcohol, 0.1%o-phenylphenol) successfully blocked transmission of rotavirus infection to humans when sprayed on inanimate surfaces experimentally contaminated with infectious rotavirus. 35 Handwashing with plain soap is ineffective against rotavirus and may further spread virus over a larger area on the hands. 19 None of the disinfectants commonly used for handwashing completely inactivate rotavirus in the time taken for a normal handwashing. Handwashing before and after contact with infected children should be with a waterless hand-cleaning agent containing alcohol.
OTHER GASTROINTESTINAL PATHOGENS
Rotavirus is the major cause of gastrointestinal illness in young children, but other enteric viruses that are less prevalent include the Norwalk virus, calicivirus, astrovirus and enteric adenoviruses. The mode of transmission of these other enteric viruses is less well-studied. Person-to-person spread by the fecal oral route is thought to be the most likely route of transmission. 36 Norwalk virus is transmitted by contaminated food and water and may also spread by aerosols generated by vomiting. 37 Caliciviruses may spread via infected fomites on environmental surfaces. Little is known about the activities of disinfectants and handwashing agents against these viruses.
Enteric bacterial pathogens, such as Salmonella and Shigella, are transmitted person-to-person primarily by the fecal oral route. Infected persons excrete as many as 100 million bacteria per g of feces. Standard handwashing agents and environmental disinfectants are active against the enteric bacteria. Salmonella requires a large number of organisms (inoculum) for transmission, so proper handwashing is usually adequate to prevent its spread. 38–40 However, Salmonella often contaminates raw poultry and eggs. 41 Transmission frequently occurs via cross-contamination of other foods from contaminated food preparation utensils and surfaces. Shigella requires a small inoculum for transmission. 42 Therefore it can be more readily transmitted and may be more problematic in day-care settings than Salmonella.21
Rotavirus is the most common gastrointestinal pathogen present in day-care settings. 21 Control and prevention of rotavirus infection are difficult because of the lack of a licensed vaccine, the absence of any effective treatment other than palliative measures and the presence of asymptomatic children shedding virus. Rotavirus is transmitted by fecal-oral contact and possibly by contaminated surfaces and hands and respiratory spread. Other gastrointestinal pathogens are also transmitted primarily by the fecal oral route, although contaminated surfaces, hands or food may also serve to transmit infection in some cases. Control and prevention measures for all enteric pathogens include isolating infected children from others, thoroughly cleaning and disinfecting environmental surfaces with effective agents and strictly following handwashing procedures before and after contact with infected persons and/or potentially contaminated surfaces.
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Rotavirus; enteric pathogens; transmission; home
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