Norovirus infection resident survival guide

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Twinkle Singh, M.B.B.S. [2]

Definition

Norovirus is one of the extremely contagious viruses leading to 50% of the gastroenteritis outbreaks worldwide. An outbreak of norovirus is defined as an occurrence of 2 or more similar illnesses resulting from a common exposure that is either suspected or laboratory-confirmed to be caused by norovirus.

Causes

Life Threatening Causes

Life-threatening causes include conditions which may result in death or permanent disability within 24 hours if left untreated. Severe dehydration can be a life threatening without medical attention.

Common Causes

• Norovirus infection

Approach to Norovirus Outbreak

Shown below is an algorithm summarizing the approach to norovirus infection outbreak.

Characterize the symptoms ❑ Non bloody diarrhea ❑ Vomiting ❑ Nausea ❑ Abdominal cramps ❑ Low grade fever ❑ Body aches ❑ Necrotising enterocolitis (in neonates) ❑ Chronic diarrhea (in immunosuppressed) ❑ Irritable bowel syndrome

Collect samples

❑ Whole stool sample Collection: ❑ Within 48 to 72 hrs after onset ❑ From at least 5 ill patients ❑ 10-50 ml of whole stool sample in a stool cup is preferred. Storage: ❑ If testing done < 3 weeks ❑ Refrigerate samples at 39 F ❑ If testing done > 3 weeks ❑ Refrigerate samples at - 4 F Transportation: ❑ Bagged, sealed and transported on ice packs in an insulated and waterproof container.

❑ Vomitus sample ❑ Collected, stored and transported in same ways as mentioned above for stool sample.

❑ Environmental samples: ❑ Water sample ❑ Shellfish samples ❑ Environmental surface swabs (Pursued in consultation with CDC)

Diagnostic tests: ❑ Enzyme immunoassays ❑ Reverse transcription-polymerase chain reaction ❑ Geno-typing

Norovirus positive

Norovirus negative

❑ Take measures to prevent and control outbreak (see below) ❑ Treat acute gastroenteritis

❑ Treat as acute gastroenteritis

Prevention and Control of Norovirus Outbreak

Shown below is an algorithm summarizing the approach to prevention and control of a norovirus infection outbreak.

Initial Management of Acute Gastroenteritis

Shown below is an algorithm summarizing the approach to initial management of acute gastroenteritis irrespective of the causes.

Assess volume status General condition Normal Irritable/less active* Lethargic/comatose§ Eyes Normal Sunken - Mucosa Normal Dry - Thirst Normal Thirsty Unable to drink§ Radial pulse Normal Low volume* Absent/ uncountable§ Skin turgor Normal Reduced - † Some dehydration = At least two signs, including at least one key sign (*) are present. ‡ Severe dehydration = Signs of “some dehydration” plus at least one key sign (§) are present.

No dehydration

Some dehydration

Severe dehydration

Start altered diet ❑ Stop lactose products ❑ Avoid alcohol and high osmolar supplements ❑ Drink 8-10 large glasses of clear fluids (Fruit juices, soft drinks etc) ❑ Eat frequent small meals (Rice, potato, banana, pastas etc) Can start oral rehydration therapy (ORT) for replacement of stool losses

❑ Start ORT at a volume of 50-100 mL/kg ❑ Start altered diet ❑ Reassess status every 4 hr

❑ Start IV fluids: Ringer lactate at 30ml/kg in the first 1/2hr and 70ml/kg for the next 2 1/2 hr, if unavailable use normal saline ❑ CBC ❑ Electrolytes ❑ Assess status every 15 mins until strong pulse felt and then every 1 hr

Patient stable and able to drink ❑ Start ORT at a volume of 100 mL/kg over 4 hour ❑ Calculate the continuing stool and emesis losses every hour for additional maintenance ORT therapy ❑ Reassess status every 4 hr

Do's

• Settings prone to outbreaks:
  

❑ Health care settings
❑ Restraunts
❑ Cruise ships
❑ Schools and other institutional settings