Causes, Symptoms, Diagnosis and Treatment

Causes

Noroviruses are highly contagious and are shed in the feces of infected humans and animals.¹ You can get norovirus from an infected person, from contaminated food or water, or by touching contaminated surfaces.² The majority of norovirus outbreaks occur in food services settings like restaurants. Infected food workers are frequently the sources of the outbreaks, often by touching ready-to-eat foods.³ Any food served raw or handled after being cooked can get contaminated with norovirus.³ Additionally, noroviruses spread easily in crowded or confined spaces; for example cruise ships, classrooms, daycare centers, and nursing homes.²

Clarke & Lambden, 2000 J. Infect. Dis. 181:S309

Symptoms

People usually develop symptoms of gastroenteritis 12 to 48 hours after being exposed to norovirus. The typical signs and symptoms of norovirus infection include; acute-onset of vomiting, watery, non-bloody diarrhea with abdominal cramps, nausea, low-grade fever, headaches, myalgias (body aches), and muscle pain. Dehydration is the most common complication of gastroenteritis caused by norovirus.

People usually recover completely without any serious long-term problems, but norovirus illness can be serious, especially for young children, older adults, and people with compromised immune systems. Serious sickness from norovirus can lead to hospitalization and death. Not everyone who is exposed to norovirus will be infected. Some people who get infected with norovirus will not have symptoms, but they may still shed the virus in their stool.

Diagnosis

Diagnostic tests are available at all public health laboratories and many clinical laboratories. Real-time reverse transcriptase-polymerase chain reaction (RT-qPCR) is the most widely used diagnostic assay for detecting norovirus. The assay detects the genetic material (RNA) of the virus. It can be used to test stool, vomitus, and environmental specimens.⁴ The best way to detect norovirus is in stool specimens collected when a person has acute illness (within 48 to 72 hours after they get symptoms). Norovirus can sometimes be found in stool specimens collected 2 weeks after a person recovers.⁵ ⁶

Treatment

Currently, there is no specific therapy to treat people with gastroenteritis cause by norovirus infection.⁷ Due to the lack of treatment for norovirus, current treatments only focus on the symptoms of gastroenteritis. Treatment for dehydration, the most common complication of gastroenteritis, include replacing fluids lost from vomiting and diarrhea and correcting electrolyte disturbances.⁸ ⁹ Antimotility agents may also be helpful in older children and adults, particularly when used along with rehydration treatment.¹⁰ ¹¹ It should be noted that antibiotics are of no benefit in treating norovirus infections.¹²

Image - 3-D structure of norovirus polymerase (cartoon) in complex with viral RNA ( stick and tubes) and Mg2+ ions (sphere)

Dharmesh Patel, PhD, Department of Pediatrics, Emory University

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