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]

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

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.

Tips for Healthy Cruising

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 are safe
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

Approach to Norovirus Outbreak

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 ❑ Necrotising enterocolitis (in neonates) ❑ Chronic diarrhea (in immunosuppressed) ❑ Irritable bowel syndrome

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

Kaplan Criteria ❑ 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 found.

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

All 4 criteria present?

Norovirus negative

Norovirus positive

Yes

No

❑ Treat as acute gastroenteritis

❑ Take measures to prevent and contain an outbreak ❑ Treat acute gastroenteritis

Norovirus outbreak highly likely

Norovirus outbreak cannot be ruled out

❑ Measures to Contain an 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.

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 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

CBC: Complete Blood Count

Do's

• Settings prone to outbreaks are:
  

❑ Health care settings

❑ Restaurants

❑ Cruise ships

❑ Schools and other institutional settings

• Symptoms of norovirus gastroenteritis typically resolve in 3 days.
• Outbreak is considered as norovirus positive if stool or vomitus specimens from 2 or more patients are found to be positive for norovirus by RT-PCR, EIA or electron microcopy.
• Outbreaks are reported to CDC by local and state health departments through NORS (National Outbreak Reporting System).

Dont's

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