Norovirus. Dr Bhakti Vasant Public Health Physician. Metro South Public Health Unit

Transcription

1 Metro South Public Health Unit Norovirus Dr Bhakti Vasant Public Health Physician Source of image: n_hospital_fights_norovirus_outbreak/

2 Outline Background Epidemiology At risk groups Symptoms Diagnosis Transmission Treatment Prevention Source of image:

3 Background Norovirus is a very contagious virus Can infect anyone but spreads rapidly in institutional settings Risk for the elderly Leading cause of endemic diarrhoeal disease Leading cause of foodborne disease Causes half of all gastroenteritis outbreaks worldwide Acknowledgement: Dr Kari Jarvinen, Hall AJ. Noroviruses: The perfect human pathogens? The journal of infectious diseases 2012; 11(1):

4 Background Rapid and prolific shedding in faeces / vomitus Constantly evolving Evokes limited immunity Most people fully recover Presents infection control challenges Source: Hall AJ. Noroviruses: The perfect human pathogens? The journal of infectious diseases 2012; 11(1):

5 Background: The guidelines Source: Australian Government Department of Health and Ageing. Guidelines for the public health management of gastroenteritis outbreaks due to norovirus or suspected viral agents in Australia. Available from URL:

6 Epidemiology Worldwide: Most common cause of epidemic gastroenteritis Account for >90% of viral gastro outbreaks 50% of all-cause outbreaks worldwide Up to 200,000 deaths in children <5 years of age each year in low income countries Source of text: Dolin R and Treanor JJ. Noroviruses and Sapoviruses (Caliciviruses). From: Mandell, Douglas and Bennett s Principles and Practice of Infectious Diseases, Updated Edition, Hall AJ. Noroviruses: The perfect human pathogens? The journal of infectious diseases 2012; 11(1):

7 Source of image: CDC. Available from:

8 Epidemiology Australia: Estimated 1.8 million cases (95% CI million cases) Most common in late winter to early summer Affects all age groups Source of text: Dolin R and Treanor JJ. Noroviruses and Sapoviruses (Caliciviruses). From: Mandell, Douglas and Bennett s Principles and Practice of Infectious Diseases, Updated Edition.

9 At risk groups of severe disease Young children The elderly Immunocompromised people Source of text: Dolin R and Treanor JJ. Noroviruses and Sapoviruses (Caliciviruses). From: Mandell, Douglas and Bennett s Principles and Practice of Infectious Diseases, Updated Edition. Source of image: article/2017/03/one-fourelderly-australian-womenhas-dementia

10 Facilities at risk of outbreaks Closed settings Hospitals Residential aged care facilities Cruise ships Schools The military Source: Dolin R and Treanor JJ. Noroviruses and Sapoviruses (Caliciviruses). From: Mandell, Douglas and Bennett s Principles and Practice of Infectious Diseases, source of image:

11 Symptoms Acute onset vomiting Watery, non-bloody diarrhoea with abdo cramps Nausea Some people may have low-grade fever, headaches and myalgias (body aches) Source of text: source of image:

12 Suspected case of norovirus 1. Three or more loose stools or bowel movements in a 24 hour period that are different from normal AND / OR 2. Two or more episodes of vomiting in a 24 hour period Source: Australian Government Department of Health and Ageing. Guidelines for the public health management of gastroenteritis outbreaks due to norovirus or suspected viral agents in Australia. Available from URL:

13 Suspected gastroenteritis outbreak Two or more associated cases of diarrhoea and / or vomiting in a 24 hour period (excluding cases which have a known cause, e.g. bowel disease, alcohol or pregnancy) Source: Australian Government Department of Health and Ageing. Guidelines for the public health management of gastroenteritis outbreaks due to norovirus or suspected viral agents in Australia. Available from URL:

14 Diagnosis Confirmed cases of norovirus must meet the suspected case definition along with a positive laboratory test from one of the following: Detection of human norovirus by antigen detection Detection of human norovirus by nucleic acid assays Visualisation of norovirus by electron microscopy Source: Australian Government Department of Health and Ageing. Guidelines for the public health management of gastroenteritis outbreaks due to norovirus or suspected viral agents in Australia. Available from URL:

15 Specimens to collect Faecal Vomitus Testing of faecal specimens Microscopy, culture and sensitivity Viruses (esp norovirus) Parasites Source of text: Australian Government Department of Health and Ageing. Appendix 3: collection of clinical specimens in an outbreak. Available from URL: nsf/content/cda-cdna-norovirus.htm-l~cda-cdnanorovirus.htm-l-app3, source of image:

16 Complications Dehydration Acute kidney injury Serum potassium loss cardiovascular instability Malnutrition Hospitalisation and death Source: Source: Dolin R and Treanor JJ. Noroviruses and Sapoviruses (Caliciviruses). From: Mandell, Douglas and Bennett s Principles and Practice of Infectious Diseases, Mattner F. Risk groups for clinical complications of norovirus infections: an outbreak investigation. Clinical Microbiology and Infection 2006; 12(1): 69 74

17 Transmission: Vomiting Larry Source of image:

18 Transmission Person to Person Faecal-oral route Ingestion of aerosolised vomitus Indirect: fomites, contaminated environmental surfaces Foodborne Contaminated by infected food handlers Upstream (Distribution syst): contaminated water Waterborne outbreaks Recreational / drinking water contamination Acknowledgement: Dr Kari Jarvinen, Australian Government Department of Health and Ageing. Guidelines for the public health management of gastroenteritis outbreaks due to norovirus or suspected viral agents in Australia. Available from URL:

19 Period of shedding and infectivity Did not extend >72 hours after symptoms onset in human volunteers One study of RACF outbreak found that symptoms lasted 3 4 days and median excretion time for norovirus was 8.6 days Prolonged shedding can occur Source: Australian Government Department of Health and Ageing. Guidelines for the public health management of gastroenteritis outbreaks due to norovirus or suspected viral agents in Australia. Available from URL:

20 Transmission Source of image:

21 Transmission: why does norovirus spread so rapidly? 1. Low infectious dose ( 18 viral particles) Copious viral shedding 5 billion infectious doses in each gram of faeces 2. Environmentally stable Survives freezing and heating Resistant to many common disinfectants Can persist on surfaces for up to 2 weeks 3. Many ways of spread Source: Hall AJ. Noroviruses: The perfect human pathogens? The journal of infectious diseases 2012; 11(1):

22 Treatment Supportive measures only Oral fluid replacement Rarely intravenous fluids Symptomatic treatment of headache and myalgia Anti-nausea medication Source of text: Dolin R and Treanor JJ. Noroviruses and Sapoviruses (Caliciviruses). From: Mandell, Douglas and Bennett s Principles and Practice of Infectious Diseases, Updated Edition.

23 Prevention of person-to-person outbreaks in RACFs Infection control policies Exclusion of infected staff until 48 hours after symptoms cease Limited movement of residents, staff and visitors Daily environmental cleaning and use of appropriate disinfectants Effective handwashing Personal protective equipment Source: Australian Government Department of Health and Ageing. Appendix 3: collection of clinical specimens in an outbreak. Available from URL: Greig JD, Lee MB. Enteric outbreaks in long-term care facilities and recommendations for prevention: a review. Epidemiology and Infection 2009; 137:

24 Prevention of foodborne outbreaks in RACFs Safe food handling Temperature controls for foods Appropriate environmental cleaning and disinfection Exclusion of infected staff until 48 hours after symptoms cease Source: Australian Government Department of Health and Ageing. Appendix 3: collection of clinical specimens in an outbreak. Available from URL: Greig JD, Lee MB. Enteric outbreaks in long-term care facilities and recommendations for prevention: a review. Epidemiology and Infection 2009; 137:

25 Conclusions Norovirus is highly infectious Constantly evolving A risk for elderly residents of aged care facilities Presents infection control challenges Prevention and control are important

26 Acknowledgement Dr Kari Jarvinen Dr Gayle Pollard Metro South Public Health Unit

27 Contact Source of image: