Norovirus outbreak 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]

Overview

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.

Prevention of Norovirus Outbreak

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

Before Cruising

❑ If you are sick before starting your cruise, consider alternative cruising options.

On the Cruise

Hand Hygiene ❑ Wash hands with soap and running water for 20 seconds. ❑ Hand sanitizers (with at least 60% alcohol) can be used as an adjunct to soap. ❑ Wash your hands: ❑ Before eating, drinking and smoking ❑ After visiting bathroom ❑ After changing diapers ❑ After touching things that other people might have touched ❑ Avoid touching your face. ❑ Do not touch any ready to eat foods with bare hands.
Food and water precautions ❑ Avoid eating raw fruits and vegetables unless they are washed and peeled by yourself. ❑ Avoid eating improperly cooked shellfish, oysters and clams. ❑ Prefer food which is cooked properly and served hot. ❑ Avoid ice. ❑ Safe beverages include: ❑ Bottled or canned water ❑ Bottled carbonated soda ❑ Hot tea, coffee, beer and wine ❑ Boiled water, or water which has been treated appropriately with chlorine ❑ Beverages from sealed containers
Isolation of infected people ❑ If you see someone getting sick, move away from the area and report to the cruise staff. ❑ Infected patients should be isolated during period of illness and up to 48-72 hours following recovery. ❑ Asymptomatic but norovirus positive food handlers should also be isolated.
Disinfection of the environment ❑ Clean contaminated surfaces to remove organic loads. ❑ Use freshly prepared 5000 ppm chlorine bleach solution. ❑ Apply disinfecting agent for up to 4 min on fecally soiled surfaces. ❑ Other disinfecting agents include: ❑ Ozone ❑ Hydrozen peroxide

PPM: Parts Per Million

Management

Shown below is an algorithm summarizing the approach to norovirus infection outbreak according to recommendations by CDC.

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

Inquire about exposure to settings prone to outbreaks: ❑ Health care settings ❑ Restaurants ❑ Cruise ships ❑ Schools and other institutional settings

Laboratory tests can be done

Laboratory tests cannot be done

❑ Collect samples

❑ Assess The Kaplan criteria

❑ 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 Storage: ❑ If testing done < 3 weeks ❑ Refrigerate samples at 39 °F ❑ If testing done > 3 weeks ❑ Refrigerate samples at - 4 °F Transportation: ❑ The specimens are bagged, sealed and transported on ice packs in an insulated and waterproof container. ❑ Vomitus sample ❑ Environmental samples: ❑ Water sample ❑ Shellfish samples ❑ Environmental surface swabs

❑ Mean duration of illness is 12-60 hours. ❑ Mean incubation period is 24-48 hours. ❑ Vomiting is present in more than 50% of ill people. ❑ No bacterial agent is found.

Diagnostic tests: ❑ Enzyme immunoassays (RIDASCREEN) ❑ Real time RT-PCR ❑ Geno-typing ❑ Electron microscopy

Are all 4 criteria present?

Norovirus negative

Norovirus positive

Yes

No

❑ Treat as acute gastroenteritis

❑ Treat the acute gastroenteritis

Norovirus outbreak is highly likely

Norovirus outbreak is less likely but cannot be ruled out

❑ Implement measures to contain the outbreak ❑ Isolate the infected patients and food handlers for a minimum period of 48 hours after recovery from symptoms. ❑ Disinfect routinely touched surfaces. ❑ Promote hand hygiene among people during an outbreak. ❑ Avoid any group activities. ❑ Notify local and state health departments. ❑ Activate outbreak prevention and response protocol (OPRP) on cruise ships as per CDC recommendations. ❑ Report the outbreak to National Outbreak Reporting System

RT-PCR: Reverse Transcription Polymerase Chain Reaction

Initial Management of Acute Gastroenteritis

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

❑ Assess the 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) ❑ Consider starting ORT for replacement of stool losses

❑ Start ORT at a volume of 50-100 mL/kg ❑ Start altered diet ❑ Reassess the patient's status every 4 hours

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

When the patient is 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 hours

CBC: Complete Blood Count; ORT: Oral replacement therapy

Do's

• Consider an outbreak of norovirus when norovirus is positive in stool or vomitus specimens from 2 or more patients are found to be positive for norovirus by RT-PCR, EIA or electron microcopy.

Dont's

• Do not obtain serum samples for routine norovirus detection.
• Do not use hand sanitizers as a substitute for washing hands with soap and water.