The Norovirus

Features, Detection, and Prevention of Foodborne Disease

Paul K S Chan, Hoi Shan Kwan, Martin C.W. Chan

• Publisher: Academic Press
• Year: 2016
• Print ISBN: 9780128041772
• eBook ISBN: 9780128041949
• Topic: Medicine
• Subtopic: Medical Microbiology & Parasitology

The Norovirus: Features, Detection and Prevention of Foodborne Disease is a unique and valuable reference for both researchers in industry and students who need to understand how this specific pathogen behaves in order to improve control of food as a transmission of this infectious biological agent. The information in the book provides essential, specific information to help further understand potential new strains of the pathogen, offering detection analysis and prevention strategies of the pathogen to assist in combatting the spread of foodborne illness. Written by national and international experts in the field, this book will be a practical source of information for food scientists, food microbiologists, food technologists, food industry workers, public health workers, and students. - Provides detailed knowledge of food as a mode of transmission, of detection, and of the biology and impact of Norovirus - Includes applications to other relevant strains of foodborne pathogens - Presents foodborne disease outbreak case studies to enhance learning

Part I

Health Impact

Outline

• Chapter 1 Global Disease Burden of Foodborne Illnesses Associated With Norovirus
• Chapter 2 Overview of Norovirus as a Foodborne Pathogen
• Chapter 3 Shellfish and Berries

Chapter 1

Global Disease Burden of Foodborne Illnesses Associated With Norovirus

Minesh P. Shah and Aron J. Hall, Centers for Disease Control and Prevention, Atlanta, GA, United States>

Abstract

Noroviruses are the most common etiology of acute gastroenteritis worldwide, causing an estimated 685 million illnesses, 210,000 deaths, and 15 million disability-adjusted life years annually. Approximately 14–23% of all norovirus illnesses are attributed to foodborne transmission, making norovirus the leading cause of foodborne illnesses and fourth-leading cause of death from foodborne illness. Although the number of illnesses and the severity of outcomes vary by geographic region and mortality strata, norovirus is a major cause of foodborne illness in all countries. Young children and older adults are at higher risk for severe outcomes from norovirus disease. Challenges to estimating norovirus disease burden include the lack of widely available rapid diagnostic testing for norovirus, variation in health-seeking behavior and stool specimen testing, and inconsistent diagnostic coding for norovirus disease, particularly in lower- and middle-income countries.

Keywords

Global burden of disease; mortality; incidence; attributed portion of diarrhea; foodborne fraction

1.1 Background

Noroviruses are a genetically diverse group of viruses in the Caliciviridae family that cause the clinical syndrome of acute gastroenteritis. The first norovirus was described when a viral particle was observed by electron microscopy in a stool sample derived from a 1968 outbreak in Norwalk, Ohio, leading to the initial name of Norwalk virus (Kapikian et al., 1972). Norwalk virus was the first virus shown to cause gastroenteritis. Since then, other “Norwalk-like viruses” have been discovered; currently, noroviruses are classified into genogroups GI–GVII (Vinjé, 2015). Genogroups GI, GII, and, to a lesser extent, GIV are known to cause human disease. According to several estimates using different methodologies detailed in this chapter, norovirus is the leading infectious cause of both sporadic (or endemic) cases and reported outbreaks of foodborne illness in the world (Havelaar et al., 2015; Pires et al., 2015; Kirk et al., 2015; Ahmed et al., 2014; Hall et al., 2014; Thomas et al., 2013; Havelaar et al., 2012; Thongprachum et al., 2016).

Norovirus infections cause acute gastroenteritis, presenting as acute-onset vomiting and/or diarrhea. Vomiting-only and diarrhea-only illness can occur with varying estimates of frequency, depending on the population and transmission mode studied (Gotz et al., 2001; Rockx et al., 2002; Arness et al., 2000; Lopman et al., 2004; Wikswo et al., 2013). When present, diarrhea is typically watery, nonbloody, and may be accompanied by abdominal cramps, nausea, and fever. Asymptomatic norovirus infection can be identified through stool shedding of norovirus in patients without gastroenteritis, and it has been found in 3–10% of children and adults in both lower- and higher-income countries (Ahmed et al., 2014).

The incubation period lasts 12–48 hours, and the clinical syndrome is typically 12–72 hours. Although most infections will result in full recovery (Rockx et al., 2002), severe outcomes such as hospitalization and death do occur, particularly among children younger than age 5 years, adults older than age 65 years, and immunocompromised hosts (Hall et al., 2013b; O’Brien et al., 2016; de Wit et al., 2001b; Bok and Green, 2012). In higher-income countries, norovirus infections are responsible for 10–20% of gastroenteritis hospitalizations and deaths among older adults, with long-term care facilities experiencing frequent norovirus outbreaks (Lindsay et al., 2015). In lower-income countries, there is a younger age distribution, with most norovirus infections in children occurring between 6 and 23 months of age (Shioda et al., 2015).

Several traits contribute to the high incidence of norovirus infection. They are highly infectious, with estimates of infectious dose ranging from 18 to 2800 particles (Teunis et al., 2008; Atmar et al., 2014). There is a prolific period of viral shedding, which may begin before symptom onset, peaks 4 days after exposure, and may persist for several weeks after resolution of symptoms (Aoki et al., 2010). Noroviruses are stable in the environment, remaining infectious in experimentally spiked groundwater samples for more than 60 days and detectable for more than 3 years (Seitz et al., 2011). Although initial studies suggested that noroviruses produced immunity for approximately 6–24 months (Parrino et al., 1977), recent modeling studies suggest immunity lasts longer—from 4 to 9 years (Simmons et al., 2013). Regardless of the duration of immunity, reinfection with norovirus is common (Saito et al., 2014; Lopman et al., 2015). Host susceptibility to infection is influenced by genetic profiles; notably, individuals with nonfunctional FUT2 genes exhibit innate resistance to norovirus infections (Kambhampati et al., 2016).

1.2 Determining the Disease Burden of Foodborne Norovirus

In 2007, the World Health Organization (WHO) established the Foodborne Disease Burden Epidemiology Reference Group (FERG) to create a systematic approach to estimate the global burden of all foodborne diseases. FERG assessed a comprehensive list of hazards that cause foodborne disease, including enteric pathogens (including norovirus), invasive infectious agents (e.g., hepatitis A), helminths (e.g., ascaris), and chemicals and toxins (e.g., aflatoxin) (Kuchenmuller et al., 2009). The methodology employed by FERG provides a useful framework for understanding the various inputs necessary for generating such disease burden estimates (Kuchenmuller et al., 2013; Devleesschauwer et al., 2015). This chapter utilizes that framework to highlight the various data sources and estimates available, as well as remaining gaps. This approach involves the following steps:

1. 1. Estimate the global incidence of all-cause diarrheal disease.
2. 2. Estimate the proportion of total diarrheal disease caused by noroviruses.
3. 3. Adjust the norovirus diarrhea estimate for vomiting-only cases of norovirus.
4. 4. Estimate the fraction of all norovirus cases that are foodborne.
5. 5. Apply the foodborne fraction to various measures of norovirus disease burden, including incidence of cases, hospitalizations, deaths, and disability-adjusted life years (DALYs).

For each of the previous steps, there are a variety of methodological approaches and challenges that are reviewed herein.

1.2.1 Global Incidence of Diarrheal Diseases

In 1990, WHO and World Bank launched the Global Burden of Disease (GBD) study to comprehensively and systematically measure the state of health in the world (Murray and Lopez, 1996). The first GBD study estimated that diarrheal diseases were responsible for almost 3 million deaths in adults and children annually, accounting for the second highest age-adjusted death rate of all infectious etiologies (Murray and Lopez, 1997a,b). Since that time, advances in health, sanitation, and hygiene have led to a modest 7% decrease in diarrheal illnesses but a dramatic 50% reduction in diarrheal deaths by 2013, according to the most recent ...

Table of contents

• Cover image
• Title page
• Table of Contents
• Copyright
• List of Contributors
• About the Editors
• Introduction: Noroviruses at a Glance
• Part I: Health Impact
• Part II: Pathogen
• Part III: Pathogen and the Host
• Part IV: Detection and Diagnosis
• Part V: Control and Prevention
• Index