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.

• Life threatening cause 1
• Life threatening cause 2
• Life threatening cause 3

Common Causes

• Common cause 1
• Common cause 2
• Common cause 3
• Common cause 4
• Common cause 5

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

Initial Management of Acute Gastroenteritis

Assess of 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