Norovirus Epidemiology i Update: Outbreak Surveillance, Prevention, and Control

Transcription

1 Norovirus Epidemiology i Update: Outbreak Surveillance, Prevention, and Control Aron J. Hall, DVM, MSPH Viral Gastroenteritis Team Centers for Disease Control and Prevention ajhall@cdc.gov Presented at the 5 th Annual OutbreakNet Meeting, Snowbird, Utah September 24, 2009

2 Disease Burden Leading cause of acute gastroenteritis in U.S. 1 in 14 Americans become ill each year Affects all ages, though greatest burden in children and elderly Annual foodborne norovirus estimates (rank among known agents) 5,700,000 cases of disease (#1) 30,000 hospitalizations (#1) 300 deaths (#3)

3 Clinical Disease Incubation period: hours Acute-onset vomiting and/or diarrhea Most recover after hours Up to 10% seek medical attention Severe illness and death most likely in elderly and those with co-morbidities ~30% of infections asymptomatic Genetic susceptibility associated with secretor status and blood type No persistent cross-protective immunity

4 Transmission Virus shed for at least 2-3 weeks Peaks 4 days after exposure (10 12 viral particles) Infectious dose: viral particles Fecal-oral routes Direct person-to-person p contact Food or water vehicles Fomites or contaminated environment Ingestion of aerosolized vomitus

5 Setting of Norovirus Outbreaks Reported to CDC, (n=226) 31% nursing homes and hospitals 28% restaurants and catered events 16% vacation settings 8% schools and daycare 16% other Blanton 2006 JID

6 utbreaks No. of O Foodborne and Non-foodborne Outbreaks of Gastroenteritis in Six States, Foodborne Nonfoodborne CT GA MD MN OR TN Preliminary CDC Data

7 Confirmed and Suspected Etiology of 1270 Foodborne Outbreaks Reported to CDC, 2006 Other/Multiple 2% Unknown 29% Norovirus 40% Chemical 5% Parasites 1% Bacteria 23% CDC 2009 MMWR

8 Etiology of Foodborne Outbreaks Reported to CDC mean annual total Bacteria Parasites Chemical Unknown Other/M r/multiple Etiology CDC 2009 MMWR Norovirus No No. of Outbre eaks

9 Single Food Commodities Involved in Norovirus Outbreaks, Outbreaks Illnesses Commodity No. (%) No. (%) Leafy vegetables 124 (31.6) 3771 (33.7) Fruits-nuts 58 (14.8) 2511 (22.4) Mollusks 54 (13.8) 749 (6.7) Poultry 40 (10.2) 645 (5.8) Pork 26 (6.6) 564 (5.0) Beef 23 (5.9) 369 (3.3) Dairy 16 (4.1) 862 (7.7) 7) Grains-beans 13 (3.3) 157 (1.4) Vine-stalk 11 (2.8) 447 (4.0) Total 392 (100) (100) Preliminary CDC Data

10 Norovirus Classification Tree Patel 2009 J Clin Virol

11 Norovirus Classification Tree Patel 2009 J Clin Virol

12 GII.4 Pandemics Winter Season Strain Name Other Names Grimsby Farmington Hills Hunter a Laurens, Yerseke b Minerva, Den Haag

13 GII.4 Strain Prevalence in Outbreaks Tested at CDC Siebenga 2009 JID

14 Proportion of Norovirus Genotypes by Outbreak Setting, Oregon, GII.4 Other GII GI Long-term care Hospitals Schools and Restaurants Other settings facilities day care and catering centers Preliminary CDC Data

15 Seasonality of Norovirus Outbreaks in Oregon, GII.4 Other GII GI No. of Outbreaks Winter Spring Summer Fall Winter Spring Summer Fall Winter Spring Summer Fall Winter Spring Summer Fall Preliminary CDC Data

16 Prevention and Control Promote appropriate p hand hygiene Wash with soap and water 20 seconds Alcohol-based hand sanitizers? Single use gloves

17 Efficacy of Hand Sanitizers Against Human Norovirus Surrogates Active Ingredient Alcohol Contact Log 10 Reduction time Murine Feline (min) Norovirus Calicivirus 5 > (60-70%) 5 >2.5 > Triclosan 5 >3.4 > >4.4 Chlorhexidine Park 2008 ICEID

18 Prevention and Control Promote appropriate p hand hygiene Wash with soap and water 20 seconds Alcohol-based hand sanitizers? Single use gloves Prompt and thorough disinfection Bleach solution for contaminated surfaces Other EPA-approved disinfectants?

19 Efficacy of Surface Disinfectants Against Human Norovirus Surrogates Active Ingredient Contact t Log 10 Reduction time Murine Feline (min) Norovirus Calicivirus Sodium hypochlorite 1000 ppm ppm Phenol 10 0 >4.6 Quaternary ammonium 10 0 >4.6 Park 2005 ASM Park 2008 ICEID

20 Prevention and Control Promote appropriate p hand hygiene Wash with soap and water 20 seconds Alcohol-based hand sanitizers? Single use gloves Prompt and thorough disinfection Bleach solution for contaminated surfaces Other EPA-approved disinfectants? Exclude ill workers Exclude ill workers hrs after symptom resolution Accommodating sick pay/leave policies Non-food handling activities and reinforced hand washing upon return

21 Challenges Asymptomatic infections Persistent in the environment Resistant t to common disinfectantsi t Very low infectious dose No persistent cross-protective immunity

22 Ongoing and Future Study Epidemiology Upstream food contamination Duration of infectivity Sporadic disease burden Zoonotic potential Laboratory Diagnostics and treatment for food Animal model; cell culture system Sensitive, specific clinical assay (EIA) Immunology and vaccine possibilities

23 National Outbreak Reporting Expansion of efors System (NORS) Web-based reporting of all gastrointestinal outbreaks in U.S. Foodborne, waterborne, person-to-person, animal contact, and environmental contamination Better estimate epidemic norovirus burden Modes of transmission Affected settings Launched February 2009

24 CaliciNet Electronic surveillance system for norovirus sequences Data shared between public health labs and CDC Link outbreaks and identify common sources Identify emergent variants Implementation begun in selected states

25 Revised Recommendations for Outbreak Management

26 Thank You Questions? Di l i Th fi di d l i i thi t ti Disclaimer: The findings and conclusions in this presentation are those of the author and do not necessarily represent the views of the Centers for Disease Control and Prevention.

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28 Norovirus Challenge Outcomes Lindesmith 2005 Nat Med

29 Recent Advances Cultivable murine norovirus (MNV) Different physiochemical properties than feline calicivirus (FCV) Being utilized for disinfection studies

30 Survival of Human Norovirus Surrogates in the Environment Refrigeration (4 C) Room Temperature (20 C) 7 7 ( log PFU/ml) Infec ctivity reduction ( dry MNV dry FCV wet MNV wet FCV ( log PFU/ml) Infec ctivity reduction dry MNV 6 dry FCV wet MNV wet FCV Time (days) Time (days) Cannon 2006 J Food Prot

31 Survival of Human Norovirus Surrogates in the Environment Refrigeration (4 C) Room Temperature (20 C) 7 7 ( log PFU/ml) Infec ctivity reduction ( dry MNV dry FCV wet MNV wet FCV ( log PFU/ml) Infec ctivity reduction dry MNV 6 dry FCV wet MNV wet FCV Time (days) Time (days) Cannon 2006 J Food Prot

32 Recent Advances Cultivable murine norovirus (MNV) Different physiochemical properties than feline calicivirus (FCV) Being utilized for disinfection studies Widespread use of RT-PCR Available at all 50 state public health labs Many can also perform quantitative realtime RT-PCR and genetic sequencing