Norovirus disease surveillance using Google Internet query share data.

Google Internet query share (IQS) data for gastroenteritis-related search terms correlated strongly with contemporaneous national (R(2) = 0.70) and regional (R(2) = 0.74) norovirus surveillance data in the United States.

The roles of Clostridium difficile and norovirus among gastroenteritis-associated deaths in the United States, 1999-2007.

Background: Globally, gastroenteritis is recognized as an important contributor to mortality among children, but population-based data on gastroenteritis deaths among adults and the contributions of specific pathogens are limited. We aimed to describe trends in gastroenteritis deaths across all ages in the United States and specifically estimate the contributions of Clostridium difficile and norovirus.

Methods: Gastroenteritis-associated deaths in the United States during 1999-2007 were identified from the National Center for Health Statistics multiple-cause-of-death mortality data.

Severe outcomes are associated with genogroup 2 genotype 4 norovirus outbreaks: a systematic literature review.

Background: Noroviruses (NoVs) are the most common cause of epidemic gastroenteritis; however, the relative impacts of individual factors underlying severe illness are poorly understood. This report reviews published NoV outbreak reports to quantify hospitalization and mortality rates and assess their relationship with outbreak setting, transmission route, and strain.

Methods: Using a string of terms related to "norovirus" and "outbreak," we 2435 nonduplicate articles identified in PubMed, EMBASE, and Web of Knowledge published between January 1993 and June 2011.

Environmental transmission of norovirus gastroenteritis.

The advent of molecular techniques and their increasingly widespread use in public health laboratories and research studies has transformed the understanding of the burden of norovirus. Norovirus is the most common cause of community-acquired diarrheal disease across all ages, the most common cause of outbreaks of gastroenteritis, and the most common cause of foodborne disease in the United States. They are a diverse group of single-stranded RNA viruses that are highly infectious and stable in the environment; both symptomatic and asymptomatic infections are common.

Potential intussusception risk versus health benefits from rotavirus vaccination in Latin America.

Background: With the recent postlicensure identification of an increased risk of intussusception with rotavirus vaccine, the 14 Latin American countries currently using rotavirus vaccine must now weigh the health benefits versus risks to assess whether to continue vaccination. To inform policy considerations, we estimated excess intussusception cases and mortality potentially caused by rotavirus vaccine for each of the 14 countries and compared these estimates to hospitalizations and deaths expected to be averted through vaccination.

Methods: We used regional rotavirus disease burden and rotavirus vaccine efficacy data, global natural intussusception and regional rotavirus vaccine-related risk estimates, and country-specific diphtheria, tetanus, and pertussus vaccination coverage rates to estimate rotavirus vaccine coverage rates.

Use of Internet search data to monitor impact of rotavirus vaccination in the United States.

Google-based Internet query share (IQS) for rotavirus search terms correlated well with US rotavirus laboratory detections from 2004 to 2010 (r = 0.88; P < .001), capturing the reduction observed during postvaccine years (2008-2010).

Remaining issues and challenges for rotavirus vaccine in preventing global childhood diarrheal morbidity and mortality.

Rotavirus vaccines have had a dramatic impact on morbidity and mortality from diarrhea among children in high- and middle-income countries that have introduced the vaccine into their national immunization programs. Widespread introduction of rotavirus vaccine in developing countries is imminent and their full potential in reducing the global burden from severe childhood diarrhea may soon be realized. The objectives of this paper are to describe the remaining issues and challenges in ensuring the success of the global rotavirus vaccination program and to discuss further research needed to help address them.

Reduction in morbidity and mortality from childhood diarrhoeal disease after species A rotavirus vaccine introduction in Latin America - a review.

Countries in Latin America were among the first to implement routine vaccination against species A rotavirus (RVA). We evaluate data from Latin America on reductions in gastroenteritis and RVA disease burden following the introduction of RVA vaccine. Published literature was reviewed to identify case-control studies of vaccine effectiveness and population-based studies examining longitudinal trends of diarrhoeal disease reduction after RVA vaccine introduction in Latin American countries.

Rotavirus vaccines: update on global impact and future priorities.

Early rotavirus vaccine adopter countries in the Americas, Europe, and in Australia have documented substantial declines in rotavirus disease burden following the introduction of vaccination.  However, the full public health impact of rotavirus vaccines has not been realized as they have not been introduced into routine immunization programs in countries of Africa and Asia with the highest rotavirus disease morbidity and mortality burden.  In this article, we review the epidemiology of rotavirus disease, the development and current status of rotavirus vaccines including newly available vaccine impact data from early-introducer countries, and future priorities for implementation and monitoring of rotavirus vaccination programs in developing countries.

Modeling rotavirus strain dynamics in developed countries to understand the potential impact of vaccination on genotype distributions.

Understanding how immunity shapes the dynamics of multistrain pathogens is essential in determining the selective pressures imposed by vaccines. There is currently much interest in elucidating the strain dynamics of rotavirus to determine whether vaccination may lead to the replacement of vaccine-type strains. In developed countries, G1P[8] strains constitute the majority of rotavirus infections most years, but occasionally other genotypes dominate for reasons that are not well understood.

Infant rotavirus vaccination may provide indirect protection to older children and adults in the United States.

Following the introduction of rotavirus vaccination in the United States, rotavirus and cause-unspecified gastroenteritis discharges significantly decreased in 2008 in the 0-4, 5-14, and 15-24-year age groups, with significant reductions observed in March, the historic peak rotavirus month, in all age groups. We estimate that 15% of the total 66 000 averted hospitalizations and 20% of the $204 million in averted direct medical costs attributable to the vaccination program were among unvaccinated 5-24 year-olds. This study demonstrates a previously unrecognized burden of severe rotavirus in the population >5 years and the primacy of very young children in the transmission of rotavirus.

Impact of an emergent norovirus variant in 2009 on norovirus outbreak activity in the United States.

In October 2009, a new genogroup II, type 4 (GII.4) norovirus variant was identified in the United States. We collected norovirus outbreak data from 30 states to assess whether this new strain was associated with increased acute gastroenteritis activity.

Incidence of acute gastroenteritis and role of norovirus, Georgia, USA, 2004-2005.

Approximately 179 million cases of acute gastroenteritis (AGE) occur annually in the United States. However, lack of routine clinical testing for viruses limits understanding of their role among persons seeking medical care. Fecal specimens submitted for routine bacterial culture through a health maintenance organization in Georgia, USA, were tested with molecular diagnostic assays for norovirus, rotavirus, astrovirus, sapovirus, and adenovirus.

Direct and indirect effects of rotavirus vaccination upon childhood hospitalizations in 3 US Counties, 2006-2009.

Background: Routine rotavirus vaccination of US infants began in 2006. We conducted active, population-based surveillance for rotavirus gastroenteritis hospitalizations in 3 US counties to assess vaccine impact.

Methods: Children <36 months old hospitalized with diarrhea and/or vomiting were enrolled from January through June each year during the period 2006-2009 and tested for rotavirus.

Decline in diarrhea mortality and admissions after routine childhood rotavirus immunization in Brazil: a time-series analysis.

Background: In 2006, Brazil began routine immunization of infants <15 wk of age with a single-strain rotavirus vaccine. We evaluated whether the rotavirus vaccination program was associated with declines in childhood diarrhea deaths and hospital admissions by monitoring disease trends before and after vaccine introduction in all five regions of Brazil with varying disease burden and distinct socioeconomic and health indicators.

Methods And Findings: National data were analyzed with an interrupted time-series analysis that used diarrhea-related mortality or hospitalization rates as the main outcomes.

Influence of birth rates and transmission rates on the global seasonality of rotavirus incidence.

Rotavirus is a major cause of mortality in developing countries, and yet the dynamics of rotavirus in such settings are poorly understood. Rotavirus is typically less seasonal in the tropics, although recent observational studies have challenged the universality of this pattern. While numerous studies have examined the association between environmental factors and rotavirus incidence, here we explore the role of intrinsic factors.

Increasing rates of gastroenteritis hospital discharges in US adults and the contribution of norovirus, 1996-2007.

Background: Diarrhea remains an important cause of morbidity, but until the mid 1990s, hospital admissions for diarrhea in the US adult population were declining. We aimed to describe recent trends in gastroenteritis hospitalizations and to determine the contribution of norovirus.

Methods: We analyzed all gastroenteritis-associated hospital discharges during 1996-2007 from a nationally representative data set of hospital inpatient stays.

Uptake, impact, and effectiveness of rotavirus vaccination in the United States: review of the first 3 years of postlicensure data.

Background: Rotavirus vaccine was recommended for routine use in US infants in 2006. Before the introduction of vaccine, rotavirus was the most common cause of severe gastroenteritis in children <5 years of age in the United States.

Methods: We reviewed published data to summarize the US experience during the first 3 years of its rotavirus vaccination program.

Sustained decline in rotavirus detections in the United States following the introduction of rotavirus vaccine in 2006.

Background: Following implementation of the rotavirus vaccination program in 2006, rotavirus activity in the United States declined dramatically in 2007-2008 but increased slightly in 2008-2009, despite greater vaccine uptake. To further evaluate impact of the vaccine program, we assessed trends in rotavirus testing and detection during 2009-2010.

Methods: We examined rotavirus testing data from July 2000 to June 2010 from the National Respiratory and Enteric Viruses Surveillance System to compare rotavirus season timing and peak activity in the pre- and postvaccine introduction eras.

Risk factors for symptomatic and asymptomatic norovirus infection in the community.

The objective of this study was to investigate risk factors for norovirus-associated infectious intestinal disease (IID) and asymptomatic norovirus infection. Individuals with IID and healthy controls were recruited in a community-based study in England (1993-1996). This is the first risk-factor study to use viral load measurements, generated by real-time RT-PCR, to identify cases of norovirus-associated IID and asymptomatic infections.

The impact of indirect benefits of vaccination on postlicensure vaccine effectiveness estimates: A scenario analysis.

Vaccine efficacy is measured in randomized, prelicensure clinical trials where vaccination typically affords only direct protection to the vaccinated individual. Vaccine effectiveness is measured in postlicensure observational studies where vaccination might provide indirect benefits to a population as a whole in addition to directly protecting the vaccinated individual. The potential discrepancy in effectiveness and efficacy estimates would depend on the postlicensure study design.

Causes and consequences of psychological distress among orphans in eastern Zimbabwe.

Substantial resources are invested in psychological support for children orphaned or otherwise made vulnerable in the context of HIV/AIDS (OVC). However, there is still only limited scientific evidence for greater psychological distress amongst orphans and even less evidence for the effectiveness of current support strategies. Furthermore, programmes that address established mechanisms through which orphanhood can lead to greater psychological distress should be more effective.

HIV decline in Zimbabwe due to reductions in risky sex? Evidence from a comprehensive epidemiological review.

Background: Recent data from antenatal clinic (ANC) surveillance and general population surveys suggest substantial declines in human immunodeficiency virus (HIV) prevalence in Zimbabwe. We assessed the contributions of rising mortality, falling HIV incidence and sexual behaviour change to the decline in HIV prevalence.

Methods: Comprehensive review and secondary analysis of national and local sources on trends in HIV prevalence, HIV incidence, mortality and sexual behaviour covering the period 1985-2007.

Asymptomatic rotavirus infections in England: prevalence, characteristics, and risk factors.

Rotavirus is a major cause of infectious intestinal disease in young children; a substantial prevalence of asymptomatic infection has been reported across all age groups. In this study, the authors determined characteristics of asymptomatic rotavirus infection and potential risk factors for infection. Healthy persons were recruited at random from the general population of England during the Study of Infectious Intestinal Disease in England (1993-1996).