NH Department of Health and Human Services Division of Public Health Services Norovirus Activity New Hampshire, Beth Daly, MPH Communicable Disease Epidemiologist Communicable Disease Surveillance Section NHICEP Meeting March 13, 2007

NH Department of Health and Human Services Division of Public Health Services Viral Gastroenteritis Several viruses cause gastroenteritis –rotavirus, noroviruses, adenoviruses, sapoviruses, and astroviruses Symptoms are often similar among etiologies, often unable to distinguish clinically CDC: each year 23 million cases of acute gastroenteritis are due to norovirus infection At least 50% of all foodborne outbreaks of gastroenteritis can be attributed to noroviruses

NH Department of Health and Human Services Division of Public Health Services Norovirus Genus name of a group of of related, single- stranded RNA, nonenveloped viruses Member of the Caliciviridae family which includes four viral genera: –Lagovirus, Vesivirus, Sapovirus, Norovirus Only sapovirus and norovirus can infect humans Previously known as “Norwalk-like Viruses” Norwalk virus is just one type of virus in the Norovirus genus Norwalk virus named for original strain which caused an outbreak in Norwalk, Ohio in 1968

NH Department of Health and Human Services Division of Public Health Services Norovirus Genogroups There are five norovirus genogroups (divided into at least 31 genetic clusters) –Only 3 of these genogroups can infect humans (GI, GII, GIV) –Genogroup GI: Norwalk virus, Southampton virus, Desert Shield virus –Genogroup GII: Hawaii virus, Snow Mountain agent, Toronto virus (GII/3) –Genogroup GIV: Ft. Lauderdale virus

NH Department of Health and Human Services Division of Public Health Services Clinical Presentation Incubation period: hours –median in outbreaks 36 hours Acute-onset: – vomiting, watery non-bloody diarrhea, abdominal cramps, nausea Symptoms may vary based on genogroup Dehydration most common complication Results in reversible lesions in jejunum –precise mechanism diarrhea and vomiting unknown Symptoms last 24 to 60 hours Recovery is complete and no evidence of serious long- term effects Asymptomatic in 30% of infections –role in transmission unknown

NH Department of Health and Human Services Division of Public Health Services Transmission Humans only known reservoir –Some noroviruses present in swine, cattle, and mice, but these genogroups do not infect humans Transmitted primarily fecal-oral –consumption of contaminated food/water –direct person-to-person spread –Environmental/fomite contamination Good evidence exists for transmission due to aerosolization of vomitus –droplets contaminating surfaces or entering oral mucosa and swallowed Multiple routes seen in outbreaks HANDS AIR ES FOOD H2O

NH Department of Health and Human Services Division of Public Health Services Transmission Highly infectious –As few as 10 viral particles may be sufficient for infection Viral shedding usually begins with onset of symptoms –Presymptomatic shedding may occur Shedding may continue for 2 weeks after recovery –Unclear to what extent viral shedding 72 hours after recovery signifies continued infectivity

NH Department of Health and Human Services Division of Public Health Services MMWR 2001; 50: RR-9

NH Department of Health and Human Services Division of Public Health Services Immunity Immunity may be strain-specific lasts only a few months individuals are likely to be repeatedly infected throughout their lifetimes. Antibodies to the virus are noted initially in young children ages 3 to 4 Antibody prevalence exceeds 50% by age 50

NH Department of Health and Human Services Division of Public Health Services Immunity and Blood Type Susceptibility to infection may be genetically determined People with blood group O at greatest risk for severe infection Noroviruses bind to several histo-blood group antigens and different genogroups have differing affinity for ABO antigens GI noroviruses preferentially recognize blood group antigens A and O GII noroviruses preferentially recognize blood group antigens A and B

NH Department of Health and Human Services Division of Public Health Services Diagnosis RT-PCR detects norovirus RNA –can be used to test stool and emesis samples NH PHL requests stool –Identification of virus can be best made from stool taken within 48 to 72 hours after onset good results can be obtained on samples taken as long as 5 days after onset Virus can sometimes be found in stool samples taken 2 weeks after recovery

NH Department of Health and Human Services Division of Public Health Services Epidemiology CDC estimates 23 million cases of norovirus each year in US In NH, norovirus is not reportable Outbreaks are reportable What defines an outbreak? –Transmission within the facility? –Higher than normal number of cases?

NH Department of Health and Human Services Division of Public Health Services Reported Outbreaks of Viral Gastroenteritis, YearFoodbornePerson-to-personTotal YTD046 Total Note: Number of outbreaks includes all outbreaks with a suspect or confirmed viral etiology YTD: as of 3/1/2007

NH Department of Health and Human Services Division of Public Health Services Reported Outbreaks of Viral Gastroenteritis,

NH Department of Health and Human Services Division of Public Health Services Norovirus Season Between December 1 st -March 1 st –64 outbreaks of norovirus/norovirus-like illness in institutional settings 55 (86%) in longterm care facilities 4 (6%) in acute care hospitals 5 (8%) in schools –50 (78%) outbreaks submitted stool specimens 25 (39%) met CDC criteria for a confirmed norovirus outbreak ( ≥ 2 positive specimens) 18 (28%) had one positive stool specimen Increase seen across the United States CDC believes increase due to new strain

NH Department of Health and Human Services Division of Public Health Services Control- Public Health Notify the NH DHHS Disease Control Section immediately if you suspect an outbreak in your facility Follow NH DHHS Guidelines for Control of GI Outbreaks in Institutional Settings Collect stool specimens –Be sure to label lab requisition form with the word “OUTBREAK” and your Facility Name –Also helpful if you could write name of NH DHHS public health nurse you’re working with

NH Department of Health and Human Services Division of Public Health Services Control- Patient/Resident Stop all group activities Consider alternate ways of feeding the ill to prevent them from dining in common areas Restrict/defer admission to affected areas for two incubation periods after last case Notify visitors and encourage handwashing during/after visits

NH Department of Health and Human Services Division of Public Health Services Control- Staffing Issues Staff with GI symptoms should remain out of work until 48 hours after symptom resolution Exclude non-essential staff from affected areas Interrupt movement of inter-department staff if possible Staff should frequently wash hands using soap and water during suspect norovirus outbreaks Use gloves and aprons whenever contacting an affected individual or contaminated environment

NH Department of Health and Human Services Division of Public Health Services Control- Environmental Noroviruses resistant to environmental challenge –they are able to survive freezing –temperatures as high as 60°C –and have even been associated with illness after being steamed in shellfish –can survive in up to 10 ppm chlorine well in excess of levels routinely present in public water systems CDC recommends cleaning surfaces with 1000 ppm household bleach –equivalent to 5 tablespoons per gallon –Can other cleaners be used?

NH Department of Health and Human Services Division of Public Health Services What about Alcohol Based Hand Sanitizers? Attacks protein envelope of the virus Noroviruses are non-enveloped! Lipid-protein envelope Protein shell (capsid) Nucleic acid genome (DNA or RNA) nanometers diameter

NH Department of Health and Human Services Division of Public Health Services Thank you! Questions/Comments? Contact NH DHHS to report suspect outbreaks and to receive disease control recommendations and support Office: After Hours: ext. 5300