Textbook of Maritime Medicine

12.10.1   Handling and Treatment of Infections Caused by Specific Micro-Organisms

The doctor must immediately report any unusual number of cases (generally more than 10 per 7 day cruise or 6 cases within 6 hours) of gastroenteritis (diarrhea and or vomiting) or infection caused by specific micro-organisms to the Master and the MCA and keep them updated with regard to further cases.

If there appears to be an outbreak, efforts should be made to identify the causing organism by blood, vomit or stool samples and try to find the source as soon as possible.  (Legionnaires’ disease: shower heads, hot tubs, air conditioners; enteric bacterial infections - suspected water, food and food handlers).

Acute Gastroenteritis - Outbreak Prevention and Control

Cruise ships are isolated communi­ties with a high population density, crowded public rooms and living accommodation, shared sanitary facilities, and common water and food supplies. Hence, infectious diseases are easily transmitted aboard, and gastroenteritis has always been a major health concern aboard cruise ships. As the North American market covers 2/3 of the global cruise volume, the US Centers for Disease Control and Prevention (CDC) established in the 1970s the Vessel Sanitation Program (VSP), and it has been regularly updated. All foreign vessels visiting US ports with 13 or more passengers are subject to a comprehensive reporting system prior to entering a US port, as well as twice-yearly inspections and, when necessary, re-inspections. Each inspection results in a sanitation score, which is posted on the internet (‘Green Sheets’). High scores are used by the companies and travel agents for sales promotion, while scores below 85 (of a total of 100 possible) points can stop a ship from sailing.

Cruise lines with ships that are not able – or willing to try - to pass US inspections can only visit ports with less rigorous sanitation demands. However, they should not feel too confident: The ‘European Centre for Disease Control and Prevention’ (ECDC) has been established and presently coordinates European actions to ’prevent and control norovirus outbreaks on cruise ships, including development of practical and standardized guidelines based on best practices identified from previous experience’. Certainly more countries will follow, and hopefully they will not all attempt to ‘re-invent the wheel’. For the cruise industry it is very important to get the health authorities of all countries with ports to cooperate and agree on uniformity. Cruise ships move quickly between countries with different sanitation standards, and for them it is very time-consuming and frustrating to keep track of the various demands and in each port fill out new forms, with different requests and layouts.

 

The VSP has proven an effective tool to keep all involved in sanitation on their toes. For many years ‘food poisoning’ was the most feared type of gastrointestinal illness  on cruise ships, but lately gastroenteritis symptoms caused by norovirus have gotten much more attention. It usually causes vomiting, diarrhea and stomach cramping, lasts between 24 and 48 hours. It is very contagious and easily transmitted by person-to-person contact, making a closed environment like cruise ships a prime setting for an outbreak. Several ships have had to stop operations and cancel cruises following such outbreaks to decontaminate the vessels.

Since gastroenteritis outbreaks on ships are easy to spot and follow, norovirus have been referred to as the “cruise ship virus” or the “cruise bug” in media. This is rather undeserved, as the virus is always brought on board by someone or something from ashore. The risk of contracting norovirus is much greater shore-side than on a cruise ship, but outbreaks on land are far less visible – and seem to be of far less media interest.

Compulsory isolation of passengers and crew with gastroenteritis is a necessary measure to prevent and control norovirus outbreaks on ships. So far there is no quick diagnostic test for norovirus that has proven completely reliable. Therefore, to prevent outbreaks, cruise companies cooperating with US authorities demand that all patients with gastroenteritis symptoms are to be isolated for up to 3 days after their last symptom

Although viruses are shed longer than that, the danger of contamination is significantly reduced after the symptoms have subsided, especially if proper hand-washing procedures are followed. It is therefore a matter of continuous discussion how long and how rigorously the patients really must be isolated.

For updated CDCs VSP recommendations please see: see the Center for Disease Control's Vessel Sanitation Program Manual:

http://www.cdc.gov/nceh/vsp/manual/VSP%20Operations%20Manual%20-%20November%202000%20-%20No%20Index.pdf

Isolation is taxing, not only for the patient, but also for family and other travel and cabin mates, as well as for all the various ship employees who must get involved. The doctors’ unwanted role as warden puts a heavy strain on the doctor-patient relationship from the beginning. The medical staff members are regularly threatened, - with physical harm, poor service ratings or law suits, and all the extra work, especially during outbreaks, makes the MC staff less available for more serious emergencies. Furthermore, the obligatory isolation policy also increases the number of sick leave days for crew, and thereby impair daily ship operations. And simple fear of isolation has kept patients from seeking prompt medical attention, thus delaying diagnosis and treatment of life-threatening illnesses, i.e. peritonitis following appendicitis.

Influenza Protocols and Recommended Measures

The medical staffs of ships visiting US ports, especially those on Alaska and Caribbean itineraries, are expected to do active surveillance for influenza according to CDC recommendations. This means that the MC must have test kits for influenza A & B, as well as recommended medication for prophylaxis and treatment (oseltamivir), and obtain from CDC’s web-sites (www.cdc.gov) the clinical algorithms, including recommended isolation for passengers and crew, respiratory illness surveillance forms and respiratory illness logs, if an increased number of cases are seen.

CDC recommends full crew vaccination every year and most cruise ships aim for more than 80% coverage, not only to achieve CDC goodwill, but also to protect their (old, frail) passengers and reduce the number of crew sick days.

Lower Respiratory Infections – Pneumonia – Legionnaires’ Disease
 

All patients with suspected or confirmed pneumonia (by chest x-ray) should have a Legionella Urinary Antigen test performed.

The doctor shall maintain an adequate supply of antibiotics to treat the pneumonia and other symptoms that could be caused by Legionella pneumophilia, with particular attention given during the flu seasons.

For additional information, see the Center for Disease Control's Vessel Sanitation Program Manual:

http://www.cdc.gov/nceh/vsp/manual/VSP%20Operations%20Manual%20-%20November%202000%20-%20No%20Index.pdf

Notification to Public Health Authorities of Ill Passengers and Crew on Ships Destined for the United States

The CDC requires the Master of a ship destined for a US port to report immediately any death or any ill person among the ship's passengers or crew.  This includes those who have disembarked or have been removed from the ship due to illness or death.  Any illnesses or deaths that occur during the 15 days before the ship arrives at the port, or during the period since the ship left a U.S. port (whichever period of time is shorter, must be reported immediately to the CDC Quarantine Station at or closest to the U.S. port or arrival. The doctor must advise the Master accordingly.

Any reports made to a quarantine station is not instead of or in replacement of other applicable local, state and federal reporting requirements.