Published on November 6, 2007
Norovirus Outbreaks: Norovirus Outbreaks Steve Hinitt, MD MPH MPA Health Manager – EPW Shell Health Services Today’s Topics: Today’s Topics The Norovirus Norovirus Outbreaks Disinfectants for Norovirus Hand Hygiene Recent Outbreaks on Shell offshore facilities Norovirus Infection Symptoms: Norovirus Infection Symptoms Vomiting Diarrhea Nausea Abdominal cramps Headache, muscle aches Fever Dehydration in young and elderly victims Up to 30% may be asymptomatic Norovirus: Norovirus SRSV (Small Round Structured Virus) Norwalk Virus, Norwalk-like virus, NLV 2002 Family – Caliciviridae Genus – Norovirus Genogroups – I, II, III, IV Multiple clusters/strains Norovirus: Norovirus Non-enveloped ssRNA virus 27-35 nm in size (SRSV) Infectious dose of 10-100 virus particles Viral shedding of 3 weeks or more Survives 0°C, 60°C, chlorine 10 ppm Limited (few months) immunity Natural History of Human Calicivirus Infection:A Prospective Cohort StudyB Rockx; CID 2002, 35: 246-53: Natural History of Human Calicivirus Infection: A Prospective Cohort Study B Rockx; CID 2002, 35: 246-53 99 people infected with Norovirus Viral Shedding (via RT-PCR): Day 1 78% Day 8 45% Day 15 35% Day 22 26% Norovirus Transmission: Norovirus Transmission “Oral-fecal” route Mouth Gut (Replication) Anus Hands Air Environmental surfaces Food Water Evidence for airborne transmission of Norwalk-like virus (NLV) in a hotel restaurant;PJ Marks; Epidemiol. Infect. 2000, 124: 481-487: Evidence for airborne transmission of Norwalk-like virus (NLV) in a hotel restaurant; PJ Marks; Epidemiol. Infect. 2000, 124: 481-487 Hotel restaurant with 126 patrons Patron ( ) vomited at table 52 of 83 survey responders ill 63% overall attack rate Attack rates higher at closer tables Consistent with airborne transmission of NLV Widespread environmental contamination with NLV detected in a prolonged hotel outbreak of gastroenteritis; JS Cheeseborough; Epidemiol Infect 2000, 125: 93-98: Widespread environmental contamination with NLV detected in a prolonged hotel outbreak of gastroenteritis; JS Cheeseborough; Epidemiol Infect 2000, 125: 93-98 RT-PCR environmental surface testing + Carpets (known vomiting) 5/8 (62%) Carpets (no vomiting) 9/12 (75%) Toilet rims/seats 8/11 (73%) Toilet handles, taps, basins 13/39 (39%) Horizontal surfaces below 1.5 m 11/29 (37%) Horizontal surfaces above 1.5 m 6/12 (50%) Phones, door handles, etc. 7/29 (24%) Soft furnishings 2/10 (20%) Total 61/144 (42%) Norovirus Transmission: Norovirus Transmission Food (39%) Hands (12% “person to person”) Water (3%) Environmental surfaces (fomites) Air (aerosolization with vomitus) 46% unknown or no data available MMWR 2001; 50: RR-9 Life Cycle of Virus: Life Cycle of Virus Norovirus Detection: Norovirus Detection Reverse transcriptase polymerase chain reaction (RT-PCR) of stool, vomitus and environmental surfaces Sequencing for genotype and cluster ID Direct & immune EM of stool samples 4-fold increase in acute and convalescent IgG serum antibodies Kaplan Criteria for Norovirus: Kaplan Criteria for Norovirus Stool specimens negative for bacterial pathogens Vomiting in 50% or more of cases Average/median duration of illness of 12-60 hours Average/median incubation period of 24-48 hours Many consider absence of fever to be another indicator for Norovirus infection Norovirus Infection Treatment: Norovirus Infection Treatment Symptomatic therapy PO, IV fluids Antispasmodics Analgesics Antipyretics NorovirusCritical Characteristics: Norovirus Critical Characteristics Highly contagious Multiple modes of transmission Stabile in the environment Resistant to routine disinfection methods Asymptomatic infections Limited immunity Norovirus Response Plan: Norovirus Response Plan Isolation Containment Disinfection Investigation Information/Education Containment: Containment Restrict access to soiled/contaminated areas until cleaned and disinfected Utilize specially trained “Hit Squads” or “SWAT Teams” for vomitus or diarrhea contamination incidents Provide medical evaluation for those with active vomiting or diarrhea in an area away from non-afflicted patients or in their cabins Disinfectants for Norovirus: Disinfectants for Norovirus The Norovirus cannot be grown in culture Efficacy testing of disinfectants for Norovirus is done using a surrogate virus, typically the feline calicivirus (FCV), a similar non-enveloped ssRNA virus Inactivation of Feline Calicivirus, a Norwalk Virus Surrogate; JC Doultree; J Hosp Infect 1999, 41:51-57: Inactivation of Feline Calicivirus, a Norwalk Virus Surrogate; JC Doultree; J Hosp Infect 1999, 41:51-57 Effective disinfection agents Glutaraldehyde 0.5% Iodine 0.8% Hypochlorite 1000 ppm (freshly reconstituted) Household bleach required 5000 ppm Ineffective disinfection agents QUAT 1:10 Ethanol 75% Anionic detergent 1% Inactivation of Feline Calicivirus, a Norwalk Virus Surrogate; JC Doultree; J Hosp Infect 1999, 41:51-57: Inactivation of Feline Calicivirus, a Norwalk Virus Surrogate; JC Doultree; J Hosp Infect 1999, 41:51-57 Heat inactivation of FCV 56°C for 60 minutes, complete inactivation 70°C for 3 minutes, 6.5 log10 reduction 70°C for 5 minutes, complete inactivation 100°C for 1 minute, complete inactivation Inactivation of Feline Calicivirus, a Norwalk Virus Surrogate; JC Doultree; J Hosp Infect 1999, 41:51-57: Surface survival of dried FCV 4°C, > 60 days 20°C (RT), 21-28 days 37°C, less than 1 day Inactivation of Feline Calicivirus, a Norwalk Virus Surrogate; JC Doultree; J Hosp Infect 1999, 41:51-57 Disinfectants for Norovirus: Disinfectants for Norovirus Consider: Efficacy Spectrum Versatility Ease of use Safety profile Cost Disinfectants for Norovirus: Disinfectants for Norovirus Proven efficacy (against FCV): Accelerated Hydrogen Peroxide™ (AHP™) Hypochlorite (bleach) Parachlorometaxylenol (EcoTru®) Peroxomonosulphate (Virkon®) Phenols (Mikro-Bac II™) Disinfectants for Norovirus: Disinfectants for Norovirus Probable efficacy (against FCV) Chlorine dioxide + QUAT (Cryocide 20™) AcceleratedHydrogen Peroxide™: Accelerated Hydrogen Peroxide™ AHPTM 0.5% hydrogen peroxide solution Broad spectrum biocide Cleans and disinfects Concentrate, wet-wipes and RTU liquid Hypochlorite (bleach): Hypochlorite (bleach) Broad spectrum biocide Inexpensive and readily available Must use freshly prepared (daily) solution reconstituted from a dry hypochlorite compound to ensure the 1000 ppm effective concentration required for Norovirus Hypochlorite (bleach): Hypochlorite (bleach) Organic debris reduces its effectiveness Cleaning of surface required prior to disinfection Used mainly on hard, non-porous surfaces Damaging to many textiles Corrosive to metals Hypochlorite (bleach): Hypochlorite (bleach) May produce toxic chlorine gas if combined with certain other compounds Can be irritating to skin, eyes, mucous membranes and lungs (fumes) The gold (“plated”) standard for Norovirus disinfection Disinfectants for Norovirus: Disinfectants for Norovirus To make an informed choice of disinfectants: Request/demand company and independent testing data from the manufacturer or distributor that supports their efficacy claims against FCV/Norovirus Test the disinfectant for adverse effects on your own environmental surfaces Fogging: Fogging Applies small droplets of disinfectants to the air and environmental surfaces Rapid environmental surface coverage Effective for disinfection of horizontal surfaces and air but not vertical surfaces, under surfaces, or shadowed areas Fogging: Fogging Should be considered an adjunct to thorough surface cleaning and disinfection Allows for supplemental disinfection of known and potentially contaminated surfaces Soft surface coverage – furniture, drapes, carpets, wall coverings Fog cabin for about 1 minute Let stand for at least 1 hour Open room to outside air if possible Disinfection: Disinfection Consider any and all heavy hand contact surfaces to be contaminated Door handles, push plates Railings, elevator buttons Telephones, keyboards Pens, pencils Tables, counters Sports equipment Etc., etc., etc. Disinfection: Disinfection Steam cleaning Soiled carpets and furniture Must reach 70°C for 5 minutes at the contaminated surface to be effective against FCV/Norovirus Consider chemical disinfection of soiled areas prior to steam cleaning CDCU.S. Centers for Disease Control and Prevention: CDC U.S. Centers for Disease Control and Prevention “Handwashing is the single most important procedure for preventing the spread of infection.” Basic Handwashing Procedure: Basic Handwashing Procedure Wet hands with water Apply soap Scrub hands together vigorously for at least 10 seconds Rinse with running water Dry Handwashing: Handwashing Handwashing is especially important before eating and after using the restroom In Norovirus outbreaks, alcohol based hand sanitizers should be considered an adjunct to handwashing and not a replacement Clean Hands in Just a Minute Handwashing and Respiratory Illness Among Young Adults in Military TrainingMA Ryan; AJPM 2001, 21(2): 79-83: Handwashing and Respiratory Illness Among Young Adults in Military Training MA Ryan; AJPM 2001, 21(2): 79-83 ~90% attack rate for URI in 1996 Operation Stop Cough 1997 through 1998 Ordered to wash hands 5 times/day Incidence of URI decreased by 45% Norovirus Outbreak Bonga Project: Norovirus Outbreak Bonga Project Remote project with Flotel 120 km off Nigerian coast Incident lasted for months 240 documented cases (550 POB) 2 – 8 cases per day Containment after down manning, intensive cleaning, and rotation of Flotel off site. NOROVIRUS OUTBREAKSEPCO Offshore Platform: NOROVIRUS OUTBREAK SEPCO Offshore Platform During a three week period between June and July 2005, 56 people became ill with vomiting and diarrhea. Ongoing SIMOPS Drlg/Const/Prod – 100 + POB Average 1-4 persons/day becoming ill Overwhelmed medical isolation capacity Had to shut down Drilling/Construction & downsize POB Required 3RD party decon crew to disinfect all accomodations and break illness cycle Slide40: Working Environment: The close living quarters on an offshore installation make transmission of Noro particularly difficult to interrupt. Some of the factors include: Close, communal living and the sharing of bathroom facilities. Communal eating and the preparation of food in one area. Intensive working hours and shared work items, computers, phone etc. Shared social time and items such as gym equipment. Multiple handrails and door knobs and high frequency contact surfaces. NOROVIRUS OUTBREAK SEPCO Offshore Platform Slide41: Mitigation Strategy: Interruption of the chain of infection Understanding clearly that it is impossible to provide a totally sterile environment Breaking the chain requires and demands that all personnel understand the importance of frequent handwashing and general hygiene measures NOROVIRUS OUTBREAK SEPCO Offshore Platform Slide42: Disinfecting the Environment: Use of Foggers, Specific Disinfectant (Virkon, Virox) Bunks, lockers should also be sprayed Toilet areas and communal bathing areas should be equipped with spray bottles of Virkon and personnel encouraged to spray down toilets and wash basins after use, particularly if they have vomited or had diarrhea. The solution should be changed regularly, and if the pink color dissipates AC return ducts should be sealed to facilitate a longer dwell time for the product during fogging. More focus on cleaning the high-frequency contact surfaces, particularly handrails, which are frequently implicated in transmission. NOROVIRUS OUTBREAK SEPCO Offshore Platform Slide43: Disinfecting the Environment (contd): Galley areas fogged after removing all foodstuffs and food contact surfaces rinsed down with potable water Pots, pan washed at high temp. (CDC recommends a temp goal of 165 F) All linen should be washed at high temperature. If it is not possible to have your machines reach 170 degrees F consideration should be given to using Virkon as an additive to the detergent in the wash cycle. Blankets should also be laundered this way. Safety gloves should be considered contaminated, and when staff are removing them they should wash their hands before touching their face, eating or smoking. During outbreak discourage hand shaking NOROVIRUS OUTBREAK SEPCO Offshore Platform Slide44: Helicopter seats and belts, lifejackets, and hearing protectors should be routinely disinfected using EcoTru (30 minute contact time) Installation of a dedicated handwash station in the galley/kitchen area, if not present. Use of a food server to serve food, wearing food prep gloves, during this outbreak. The provision of snacks and communal bins of food, such as cookies and candy should be discontinued during this outbreak. Consideration of provision of individually wrapped knives/forks instead of the communal provision of cutlery. Elimination of communal condiments, and their replacement with unit dose/or individually wrapped products. NOROVIRUS OUTBREAK SEPCO Offshore Platform Slide45: Disinfecting the Environment (contd): Increased training and supervision of food service personnel, with particular emphasis on isolating themselves when they begin to have symptoms. Confirmation of the maintenance of potable water at 2 ppm available chlorine. All personnel should understand the importance of handwashing using soap, water and drying hands with a paper towel. The use of alcohol hand sanitizers should not be encouraged Crew members who are ill should be isolated for up to 72 hours after their last episode of diarrhea or vomiting. NOROVIRUS OUTBREAK SEPCO Offshore Platform Slide46: Conclusion It is possible to mitigate the impact of Noro virus on our operations and reduce the economic impact, but it requires a substantial investment of time and effort in training and re-education of personnel, and some changes to the environment to make frequent hand-washing easier. NOROVIRUS OUTBREAK SEPCO Offshore Platform
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GCSPNORO; Norovirus Outbreaks Steve Hinitt, MD MPH MPA Heal ...