Hide glossary Glossary Study record managers: refer to the Data Element Definitions if submitting registration or results information. Search for terms. Save this study. Warning You have reached the maximum number of saved studies New Challenge Pool of Norwalk Virus Inoculum The safety and scientific validity of this study is the responsibility of the study sponsor and investigators.
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Last Update Posted : May 9, Study Description. The main objective of this study is to see the number of volunteers that get sick from a Norwalk virus NV inoculation with typical symptoms of nausea, vomiting, and diarrhea. If this NV preparation is shown to cause Norwalk illness, then it can be used to test new vaccines in the future. Additionally, researchers hope to determine the lowest dose of NV inoculum that can be given to volunteers and cause illness.
Study participants will include 57 healthy adults, ages Participants will either be given the NV inoculum or placebo water without virus. Participants will be hospitalized for a maximum of 7 days and a minimum of 4 days following the NV challenge.
Study procedures include physical exam, blood testing, and collection of saliva, urine, and stool samples. Participants will be involved in study related procedures for up to days. Detailed Description:. Noroviruses are the cause of most acute, epidemic, non-bacterial gastroenteritis hour intestinal flu and Norwalk virus NV is the prototype strain of this group of viruses.
Although NV was identified some 30 years ago, progress in understanding its molecular characteristics has been slow due to the inability to grow the virus in cell culture and the lack of an animal model.
As such, most work must be performed in human volunteers. The quantities of NV were sufficient to characterize the entire genome and significant advances have been made. Using stored stool specimens obtained from an otherwise healthy subject who was infected approximately 14 years ago with NV NIH-8fIIa , a new pool filtrate was produced. The safety and infectivity of the new NV challenge pool will be established by this protocol.
The clinical attack rate of Lot will be determined. Initially, 20 subjects will be challenged with a dose of NV Lot that approximates the dose used in previous challenge studies.
Approximately two-thirds of infected subjects are expected to become symptomatic. However, for some people — especially infants, older adults and people with underlying disease — vomiting and diarrhea can be severely dehydrating and require medical attention. Norovirus infection occurs most frequently in closed and crowded environments such as hospitals, nursing homes, child care centers, schools and cruise ships.
Signs and symptoms usually begin 12 to 48 hours after exposure to norovirus and last one to three days. You can continue to shed virus in your feces for up to two weeks after recovery. This shedding can last weeks to months if you have an underlying health condition. Some people with norovirus infection show no signs or symptoms.
However, they are still contagious and can spread the virus to others. Seek medical attention if you develop diarrhea that doesn't go away within several days. Also, call your doctor if you have severe vomiting, bloody stools, stomach pain or dehydration. Noroviruses are highly contagious and are shed in the feces of infected humans and animals.
You can get norovirus by:. Occasionally patients may need to be hospitalized to receive intravenous fluids. Navigation menu. Who gets norovirus infection? Anyone can become infected. It only occurs in humans and is found worldwide.
How is it spread? What are the symptoms? How soon after exposure do symptoms appear? Outline the importance of improving care coordination among interprofessional team members to improve outcomes for patients affected by norovirus. Access free multiple choice questions on this topic.
These could lead to clinically significant dehydration, requiring hospitalizations. In addition to clinical effects, norovirus also has a major financial impact in developed nations. There are seven known genogroups of norovirus, but only genogroups I and II are responsible for the vast majority of human cases. An extremely small number of cases are attributed to norovirus GIV.
Additionally, illness produced by GII. Studies have shown that waterborne outbreaks tend to be associated with genogroup I strains, while healthcare-related and winter outbreaks are more likely to have genogroup II strains as a causative agent. Noroviruses are classified into genogroups and genotypes based on amino acid diversity in VP1 and ORF1 proteins. The primary mode of transmission is fecal-oral. Sources include ingestion of contaminated water or food or direct transmission from a contaminated surface or infected person.
The virus is resistant and can stay on surfaces even after disinfecting. The virus also has a low viral inoculum to cause infection. As few as ten viral particles are needed to cause infection. Norovirus is responsible for an estimated 21 million cases of gastrointestinal illness in the United States each year. Because patients with mild disease may not seek medical treatment, the number of cases may exceed the estimate.
In a review of reported norovirus outbreaks, a food-related transmission was the most common source of widespread disease. Food-related transmission may be due to the ingestion of food that is contaminated during production or the ingestion of food that was contaminated by food service workers during preparation. High-risk food for norovirus contamination include foods that are served raw, like fruits and vegetables, as well as oysters and fish.
Outbreaks are common in a number of different settings. Norovirus is known to cause outbreaks of gastroenteritis in hospitals and other healthcare facilities.
In addition to healthcare settings, outbreaks may occur in schools, military barracks, cruise ships, and resorts. Person-to-person transmission is the most common form of transmission, but contaminated surfaces also contribute to disease propagation. Surfaces may be contaminated with viral particles by splashing of emesis or stool or by aerosolized viral particles. The importance of good hand hygiene and effective surface cleaning should be stressed during norovirus outbreaks.
Studies suggest that washing hands with soap and running water for at least 20 seconds is the most effective form of hand hygiene for eliminating norovirus. Studies on the effectiveness of alcohol-based hand rubs are inconclusive. Some studies suggest that high-concentration ethanol-based hand sanitizers decrease viral concentration on the hands, but these types of cleaners should be used as a supplement to hand-washing with soap and water. Surfaces such as sinks, toilets, tables, chairs, and beds should be cleaned with a hypochlorite bleach solution, and adequate contact time should be ensured.
Furthermore, items that have been contaminated with infected emesis or stool that cannot be properly disinfected should be discarded. Although people of all age groups are at risk of contracting norovirus, those at the extremes of age and the immunocompromised are at highest risk of poor outcomes. Similarly, neonates have an increased rate of serious complications, such as necrotizing enterocolitis. Of all age groups, young children have the highest incidence of norovirus.
Estimates suggest an annual incidence of norovirus to be 21, per , for children under 5 years of age. Norovirus infections are also more prevalent in developing nations.
Nguyen et al. Patients with compromised immune systems have a higher risk of infection of norovirus, higher rates of complications, and increased potential for prolonged asymptomatic viral shedding. Noroviruses are difficult to culture in a lab setting. Because of this, it has been difficult to predict exactly how norovirus infects and replicates in humans. Studies suggest that norovirus infection is multi-faceted, with the involvement of multiple cell types in the human gut.
The predominant cell type lining the human gut is a single layer of intestinal epithelial cells called enterocytes. Lying deep to the enterocytes are numerous immune cells. Several studies have confirmed that norovirus infects and replicates in immune cells including macrophages, dendritic cells, and B cells.
It is postulated that noroviruses have a way of bypassing enterocytes to enter the human hosts. Proposed mechanisms include entering through M cells, a specialized type of cell in the gut that overlies the Peyer patches and lymphoid follicles in the gut.
M cells lack microvilli and do not secrete mucus, making it easier for the norovirus to enter the host and invade immune cells. However, although definitive data are lacking, other studies suggest norovirus may directly invade enterocytes lining the gut lumen. It has been proposed that norovirus interacts with bacteria in the gut to enhance infection and replication.
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