Elaine H. Cramer

Norovirus transmission on cruise ship.

We documented transmission by food and person-to-person contact; persistence of virus despite sanitization onboard, including introductions of new strains; and seeding of an outbreak on land.

A review of outbreaks of foodborne disease associated with passenger ships: evidence for risk management.

Objective. Foodborne disease outbreaks on ships are of concern because of their potentially serious health consequences for passengers and crew and high costs to the industry. The authors conducted a review of outbreaks of foodborne diseases associated with passenger ships in the framework of a World Health Organization project on setting guidelines for ship sanitation. Methods. The authors reviewed data on 50 outbreaks of foodborne disease associated with passenger ships. For each outbreak, data on pathogens/toxins, type of ship, factors contributing to outbreaks, mortality and morbidity, and food vehicles were collected. Results. The findings of this review show that the majority of reported outbreaks were associated with cruise ships and that almost 10,000 people were affected. Salmonella spp were most frequently associated with outbreaks. Foodborne outbreaks due to enterotoxigenic E. coli spp, Shigella spp, noroviruses (formally called Norwalk-like viruses), Vibrio spp, Staphylococcus aureus, Clostridium perfringens, Cyclospora sp, and Trichinella sp also occurred on ships. Factors associated with the outbreaks reviewed include inadequate temperature control, infected food handlers, contaminated raw ingredients, cross-contamination, inadequate heat treatment, and onshore excursions. Seafood was the most common food vehicle implicated in outbreaks. Conclusions. Many ship-associated outbreaks could have been prevented if measures had been taken to ensure adequate temperature control, avoidance of cross-contamination, reliable food sources, adequate heat treatment, and exclusion of infected food handlers from work.

Disease transmission and passenger behaviors during a high morbidity Norovirus outbreak on a cruise ship, January 2009.

BACKGROUND Norovirus continues to pose a significant burden on cruise ships, causing an average of 27 confirmed outbreaks annually over the past 5 years. In January 2009, the report of a suspected norovirus outbreak among passengers on a cruise ship prompted an investigation. METHODS A retrospective cohort study among passengers was conducted on board the ship. Questionnaires about health care-seeking behaviors, hygiene practices, and possible norovirus exposures were placed in every cabin. Stool samples from several ill passengers were tested for norovirus by quantitative reverse-transcriptase polymerase chain reaction (RT-qPCR) and confirmed by sequence analysis. RESULTS Of 1842 passengers, 1532 (83.2%) returned questionnaires, and 236 (15.4% of participants) met the case definition. Of these, 95 (40%) did not report to the infirmary. Case passengers were significantly more likely to have an ill cabin mate (relative risk [RR] = 3.0; P < .01) and to have witnessed vomiting during boarding (RR = 2.8; P = .01). Over 90% of all passengers reported increased hand hygiene practices following the outbreak; 38% of ill passengers and 11% of well passengers decreased participation in public activities. Of 14 samples tested, 12 were positive for norovirus by RT-qPCR; 5 of these were confirmed by sequence analysis and typed as GII.4 Minerva. CONCLUSIONS Person-to-person transmission, including an incident of public vomiting during boarding, likely contributed to this high morbidity outbreak. Infirmary surveillance detected only 60% of acute gastroenteritis (AGE) cases involved in this outbreak. Adjustments to outbreak reporting thresholds may be needed to account for incomplete voluntary AGE reporting and to more rapidly implement control measures.

Practice patterns of naturopathic physicians: results from a random survey of licensed practitioners in two US States

BackgroundDespite the growing use of complementary and alternative medicine (CAM) by consumers in the U.S., little is known about the practice of CAM providers. The objective of this study was to describe and compare the practice patterns of naturopathic physicians in Washington State and Connecticut.MethodsTelephone interviews were conducted with state-wide random samples of licensed naturopathic physicians and data were collected on consecutive patient visits in 1998 and 1999. The main outcome measures were: Sociodemographic, training and practice characteristics of naturopathic physicians; and demographics, reasons for visit, types of treatments, payment source and visit duration for patients.ResultOne hundred and seventy practitioners were interviewed and 99 recorded data on a total of 1817 patient visits. Naturopathic physicians in Washington and Connecticut had similar demographic and practice characteristics. Both the practitioners and their patients were primarily White and female. Almost 75% of all naturopathic visits were for chronic complaints, most frequently fatigue, headache, and back symptoms. Complete blood counts, serum chemistries, lipids panels and stool analyses were ordered for 4% to 10% of visits. All other diagnostic tests were ordered less frequently. The most commonly prescribed naturopathic therapeutics were: botanical medicines (51% of visits in Connecticut, 43% in Washington), vitamins (41% and 43%), minerals (35% and 39%), homeopathy (29% and 19%) and allergy treatments (11% and 13%). The mean visit length was about 40 minutes. Approximately half the visits were paid directly by the patient.ConclusionThis study provides information that will help other health care providers, patients and policy makers better understand the nature of naturopathic care.

Passenger Behaviors During Norovirus Outbreaks on Cruise Ships

BACKGROUND Norovirus causes a majority of outbreaks of gastrointestinal (GI) illness on cruise ships calling on the United States. Control measures include patient isolation, hand washing, and facility closure. Little is known about the behaviors and practices of people who have become ill with norovirus GI illness compared to those who remained well during an outbreak. METHODS Passenger surveys were distributed during three cruise ship outbreaks caused by norovirus. Surveys inquired about illness symptoms, ill contacts, illness reporting status, hand sanitation beliefs and practices, and availability of public hand sanitizer. A case was a passenger reporting three or more episodes of loose stool in a 24-hour period, three or more episodes of vomiting in a 24-hour period, or one or more episodes each of loose stool and vomiting in a 24-hour period. Controls reported that they were not ill during the cruise. RESULTS In total, 1,323 responses were compared. All ships had passengers who were ill prior to embarkation. Most cases delayed or did not report their illness to the ships infirmary because they did not believe it was serious (43%-70% of responses). Cases were less likely to believe that isolation was effective in preventing disease spread [Mann-Whitney-Wilcoxon (MWW) p value <0.0001]. Cases were less likely to believe that hand washing or hand sanitizer are effective means of preventing disease spread (MWW p values 0.002 and 0.04, respectively), wash their hands after restroom use (MWW p value 0.02), or believe that hand sanitizer was available for public use prior to/after knowing about an outbreak (MWW p values 0.002 and 0.03, respectively). CONCLUSIONS Prevention and control of norovirus GI illness may be improved by routine screening of embarking passengers, education about GI illness and its impact on public health, a focus on improving hand-washing practices, and identification of public hand sanitizer dispensing locations.

Passenger Behaviors Associated With Norovirus Infection On Board a Cruise Ship—Alaska, May to June 2004

BACKGROUND During May 2004, the Vessel Sanitation Program (VSP) investigated an outbreak of norovirus gastroenteritis on board a cruise ship sailing in Alaska waters. The objectives were to identify a common food item source and explore behavioral risk factors for person-to-person transmission among passengers. METHODS A case was defined as three or more episodes of loose stools within 24 hours or two or fewer episodes of loose stools accompanied by one or more episodes of vomiting. Vomitus and stool samples from affected passengers were tested for norovirus by reverse transcriptase-polymerase chain reaction. Environmental health officers performed an environmental investigation following VSP protocol. Questionnaires about food items consumed and behavioral risk factors were placed in cabin mailboxes (n = 2,018). A case-control study design using multivariable logistic regression tested associations between risk factors and disease. RESULTS A total of 359 passengers (24.1% of respondents) met the case definition. Four of seven clinical specimens tested positive for norovirus. No significant deficiencies in environmental health practices were identified, and no meal servings were associated with disease. Having a cabin mate sick with diarrhea or vomiting [odds ratio (OR): 3.40; 95% confidence interval (CI) = 1.80-6.44] and using a specific womens toilet that was contaminated with vomit (OR: 5.13; 95% CI = 1.40-18.78) were associated with disease. Washing hands before meals was protective (OR: 0.25; 95% CI = 0.12-0.54) against disease. CONCLUSIONS Widespread person-to-person norovirus outbreaks can occur on board cruise ships, even with appropriate environmental health practices. Programs to prevent and control norovirus outbreaks on board cruise ships should involve strategies that disrupt person-to-person spread and emphasize hand washing.

Diarrheal disease on cruise ships, 1990-2000: the impact of environmental health programs.

BACKGROUND In 1975, the then-Center for Disease Control (CDC) established the Vessel Sanitation Program (VSP) to minimize the risk for diarrheal disease among passengers and crew aboard ships by assisting the cruise ship industry in developing and implementing comprehensive environmental health programs. OBJECTIVES To evaluate the relationship between cruise ship sanitation scores and diarrheal disease incidence and outbreaks among cruise ship passengers. METHODS Retrospective cohort study of ship inspection and diarrheal disease data from 1990 through 2000 from the National Center for Environmental Health, CDC database, for cruise ships entering the United States. OUTCOMES Yearly trends in number of ships inspected, number of inspections conducted, inspection scores, and risks of failing inspections; rates of diarrheal disease among passengers, by inspection year, cruise duration, incidence of outbreaks, and passing- or failing-score status of the associated ship. RESULTS From 1990 through 2000, inspection scores gradually increased from a median of 89 in 1990 to 93 in 2000 (p<0.001), with an associated statistically significant 21% increase in likelihood of passing. The total baseline level of diarrhea among passengers was 2.0 cases per cruise (13243/6485), or 23.6 cases per 100,000 passenger-days (13243/56129096). The latter rate declined significantly from 29.2 in 1990 to 16.3 in 2000 (p<0.0001). Diarrheal disease incidence rates among passengers sailing on ships that passed environmental inspections were significantly lower than rates among passengers sailing on ships that failed inspections (21.7 vs 30.1; RR = 1.39; 95% CI: 1.31-1.47). Diarrheal disease outbreak-related illnesses decreased from 4.2 to 3.5 per 100000 passenger-days from 1990-1995 to 1996-2000. CONCLUSIONS Environmental sanitation inspections conducted among ships sailing into the United States appear to continue to decrease diarrheal disease rates and outbreaks among passengers.

A Review of Outbreaks of Waterborne Disease Associated with Ships: Evidence for Risk Management

Objective. The organization of water supply to and on ships differs considerably from that of water supply on land. Risks of contamination can arise from source water at the port or during loading, storage, or distribution on the ship. The purpose of this article is to review documented outbreaks of waterborne diseases associated with passenger, cargo, fishing, and naval ships to identify contributing factors so that similar outbreaks can be prevented in the future. Methods. The authors reviewed 21 reported outbreaks of waterborne diseases associated with ships. For each outbreak, data on pathogens/toxins, type of ship, factors contributing to outbreaks, mortality and morbidity, and remedial action are presented. Results. The findings of this review show that the majority of reported outbreaks were associated with passenger ships and that more than 6,400 people were affected. Waterborne outbreaks due to Enterotoxigenic Escherichia coli, noroviruses, Salmonella spp, Shigella sp, Cryptosporidium sp, and Giardia lamblia occurred on ships. Enterotoxigenic E. coli was the pathogen most frequently associated with outbreaks. One outbreak of chemical water poisoning also occurred on a ship. Risk factors included contaminated port water, inadequate treatment, improper loading techniques, poor design and maintenance of storage tanks, ingress of contamination during repair and maintenance, cross-connections, back siphonage, and insufficient residual disinfectant. Conclusions. Waterborne disease outbreaks on ships can be prevented. The factors contributing to outbreaks emphasize the need for hygienic handling of water along the supply chain from source to consumption. A comprehensive approach to water safety on ships is essential. This may be achieved by the adoption of Water Safety Plans that cover design, construction, operation, and routine inspection and maintenance.

Influenza A(H1N1)pdm09 during air travel

The global spread of the influenza A(H1N1)pdm09 virus (pH1N1) associated with travelers from North America during the onset of the 2009 pandemic demonstrates the central role of international air travel in virus migration. To characterize risk factors for pH1N1 transmission during air travel, we investigated travelers and airline employees from four North American flights carrying ill travelers with confirmed pH1N1 infection. Of 392 passengers and crew identified, information was available for 290 (74%) passengers were interviewed. Overall attack rates for acute respiratory infection and influenza-like illness 1-7 days after travel were 5.2% and 2.4% respectively. Of 43 individuals that provided sera, 4 (9.3%) tested positive for pH1N1 antibodies, including 3 with serologic evidence of asymptomatic infection. Investigation of novel influenza aboard aircraft may be instructive. However, beyond the initial outbreak phase, it may compete with community-based mitigation activities, and interpretation of findings will be difficult in the context of established community transmission.

Tuberculosis investigations associated with air travel: U. S. Centers for Disease Control and Prevention, January 2007-June 2008.

INTRODUCTION Contact investigations conducted in the United States of persons with tuberculosis (TB) who traveled by air while infectious have increased. However, data about transmission risks of Mycobacterium tuberculosis on aircraft are limited. METHODS We analyzed data on index TB cases and passenger contacts from contact investigations initiated by the U.S. Centers for Disease Control and Prevention from January 2007 through June 2008. RESULTS Contact investigations for 131 index cases met study inclusion criteria, including 4550 passenger contacts. U.S. health departments reported TB screening test results for 758 (22%) of assigned contacts; 182 (24%) had positive results. Of the 142 passenger contacts with positive TB test results with information about risk factors for prior TB infection, 130 (92%) had at least one risk factor and 12 (8%) had no risk factors. Positive TB test results were significantly associated with risk factors for prior TB infection (OR 23; p<0.001). No cases of TB disease among passenger contacts were reported. CONCLUSION The risks of M. tuberculosis transmission during air travel remain difficult to quantify. Definitive assessment of transmission risks during flights and determination of the effectiveness of contact-tracing efforts will require comprehensive cohort studies.