Friday, May 14, 2004

         This Week in the News

Foege, WH., et al., 
International Journal of Epidemiology
1976; 5:29-37

►New Events to Unfold at This Year's Statewide Epidemiology Seminar
Now in its ninth year, the event promises to be the best ever, with more attendees, more opportunities to network, and more opportunities to learn and share ideas.

A R T I C L E S

Members of the public health team at the Florida Department of Health this week participated in an Emergency Notification Proficiency Test conducted by the Centers for Disease Control and Prevention. Phone calls, pager messages, and e-mails simulating an emergency similar to one which might be declared in the case of a bioterrorist attack were issued to selected users of Epi-X, the CDC-sponsored Epidemic Information Exchange Web site and emergency notification system. 

Test participants were asked to respond to the emergency calls, either by calling a telephone response line or logging on to the Epi-X Web site, viewing a special alert message from CDC, and adding a time-stamped comment to the posting. These participants represented a variety of functional areas within the public health community such as county health departments and state laboratories as well as communicable disease and environmental epidemiology. 

Users were also asked to complete a short survey indicating how they received the alert and their primary methods of receiving and responding to these types of notifications. From this, judges of the test results will be able to calculate how well and how quickly the participants reacted and followed the instructions in the alert message, as well as to gather information about how future emergencies might be handled better. 

The Florida Department of Health and the Bureau of Epidemiology wish to thank the participants, on behalf of CDC and the citizens and visitors in Florida, for their dedication to the improvement of the public health response capabilities. 

Additional information about Epi-X and how to participate in this surveillance program is available at http://www.cdc.gov/epix. 

Editor?s Note: Florida?s own EpiCom system of information exchange and emergency notification is modeled after CDC?s Epi-X and monitors public health events occurring in and affecting Florida. Interested readers can apply for EpiCom registration at https://www.epicomfl.net.
 

► Outbreak of Norovirus Gastroenteritis, Fernandina Beach, January 2004

Introduction:
On Friday, January 30, 2004, the Nassau County Health Department (NCHD) received a complaint of gastrointestinal illness among attendees of a business conference held the week of January 25-31, 2004 at a large resort. During the course of the investigation, the NCHD was notified of three other groups attending conferences at the same facility, from January 22 to February 3, 2004, also experiencing gastrointestinal illness. Several food service employees of the implicated resort experienced gastroenteritis during from January 20-31, and were working at the conferences during the course of their illness.  

Methods:
The NCHD Environmental Health Division, Epidemiology Program nurse and the regional environmental epidemiologist (Bureau of Community Environmental Health, Florida Department of Health), began an epidemiological investigation on Friday, January 30, 2004. The Florida Department of Business and Professional Regulation conducted an inspection of the resort food service facilities on February 2, 2004. 

Questionnaires were prepared and were administered by telephone to three of the four groups of conference attendees identified as having illness. One large group of 570 attendees was surveyed by e-mail for history of illness only. Twenty-three stool samples were collected from ill attendees and food service workers and analyzed for bacterial and viral pathogens. 

Statistical analysis of the data obtained from the interviews was conducted using EpiInfo version 6. A case was defined as any attendee of the meetings and/or a restaurant employee experiencing three or more episodes of vomiting and/or diarrhea and/or any three of the following symptoms: nausea, low-grade fever, cramps, headache, chills or fatigue between January 25 and February 2, 2004. 

Results:
Group A completed 78 interviews with 45 cases. Group B completed 37 interviews with six cases. Group C completed 18 interviews with three cases. Group D, surveyed by e-mail, reported 40 cases. There were eight ill food service workers.  

The primary onset date of illness for Group A was Wednesday, January 28 with an average incubation time of 36 hours. The onset dates of illness for Group B ranged from Sunday, January 25 to Friday, January 30. Onset dates of illness for Group C ranged from Tuesday, January 27 to Saturday, January 31. The onsets of illness for Group D ranged from Monday, January 26 to Monday, February 2. The onsets of illness for the eight ill employees were from Tuesday, January 20 to Saturday, January 31 (See Figure 1). 

The average duration of illness for Groups A-D and the food service workers was two to three days. The primary symptoms for Groups A-D combined were diarrhea, nausea, cramps and fatigue (See Table 1). The primary symptoms for the ill food service workers were nausea, fatigue, gas, diarrhea and vomiting (See Table 2). Twelve enteric stools and eleven viral stools were collected for analysis. All enteric results were negative for bacterial pathogens. Five of the eleven viral samples were positive for Norovirus G2.  

There were also several reports of secondary cases of gastroenteritis among family members of ill persons as well as illness among some of their coworkers who did not attend the conferences.

Statistical analysis of data from Group A showed a slight risk association of illness with consumption of pizza from the Monday, January 26 lunch (OR = 4.13, 95% Confidence Interval = 1.22 < OR < 14.35, P-value = 0.008). No other foods or beverages showed significant risk in the initial analysis. Statistical analysis of all the data is continuing.  

Conclusions:
This outbreak is the result of Norovirus transmission among the resort food service food workers, beginning with the first onset of worker gastroenteritis on Tuesday, January 20 and progressing among seven other food service workers everyday thereafter until Saturday, January 31. The ill food service workers continued to work at the resort, some working double shifts, during the course of their active infections. Food workers continued to work while ill because of economic pressures including anecdotal reports that they were discouraged from taking sick leave. This behavior exposed attendees of several conferences to multiple sources of the pathogenic viruses, and ultimately resulted in infecting at least 94 persons. 

The spread of the viruses via fomites, person-to-person and possibly aerosolization, accounts for the widespread days of onsets for Groups B-D, as well as an extended exposure related to the conference attendees? length of stay at the resort.  

Group A had a shorter exposure time and had the majority of illnesses occurring on Wednesday, January 28. This is indicative of a point source exposure to the viruses. There was some slight statistical risk of illness associated with the Monday, January 26 lunch pizza.  

However, the incubation period typical to Norovirus (average ~34 hours) would implicate the Monday, January 26 dinner and/or casino event as the exposure point. This would indicate that multiple foods, beverages or even fomites (e.g., surfaces, casino chips for example), could have served as vehicles for virus transmission. 

Recommendations:
Norovirus is an enteric virus of human origin only. It is shed in human feces during infection in high numbers and can continue to be shed for up to 22 days after symptoms have ceased. It is highly infective even at doses as low as 10 viral particles. Fecal contamination of hands after toilet use and subsequent lack of hand washing or inadequate hand washing can spread viral particles to foods, surfaces and to other persons. Norovirus is also effectively spread to persons or surfaces by aerosolization during vomiting. This often accounts for the secondary transmission of Norovirus to persons that care for or clean up after ill family members. 

Norovirus particles are very hardy, resistant to chlorine and can remain viable outside of the human host for weeks. Proper hand washing after toilet use is the best method for preventing food borne Norovirus infection. Hand washing is especially critical prior to preparation of foods.  

Food service workers who are ill with gastrointestinal symptoms must be restricted from duties during illness. Norovirus can continue to be shed fecally for up to 22 days after infection; therefore, ill workers must be restricted from food preparation and serving duties for at least 72-96 hours after cessation of symptoms.
 

Several new activities have been added to the program this year. For the first time, the event will begin with an evening dessert reception and the opportunity to pre-register for the seminar. Coffee and dessert will be served from 7:00 ? 9:00 p.m. on Monday, May 17^th in Salons ABC on the first floor of the hotel, giving attendees the opportunity to network with other healthcare professionals from across the state. Pre-registration will be held concurrently, to allow early arrivals a chance to pick up their seminar materials in a relaxed setting and avoid the morning rush. The following day, the seminar will begin in earnest, with the registration desk opening at 7:30 a.m. and opening remarks scheduled to begin at 8:15. 

The bureau will also be hosting ?County Showcasing,? which will provide county health departments a venue for displaying educational resources they have developed for healthcare professionals and sharing them with their colleagues. These items will be on exhibit throughout the seminar. If you would like to participate in this event, please contact Melanie Black. 

A record number of persons have submitted abstracts for the poster session this year!  The poster session and reception for the 41 entrants will be held the evening of May 18^th  with awards given for the best infectious disease poster, the best presentation by a Florida EIS fellow, the best chronic disease poster and, finally, the best county health department display. The winners will be announced at the following day?s luncheon and awards presented by Deputy Health Director Dr. Bonnie Sorensen, Florida Department of Health. Another added feature to this year?s program will be the Golden Partnership Awards, to be presented to county health departments and state health offices which have made significant contributions to public health this past year in disease control and surveillance.  

Further information can be found on the Bureau of Epidemiology Internet website at http://www.doh.state.fl.us/disease_ctrl/epi/conf/training.html, or contact Melanie Black at the Bureau of Epidemiology in Tallahassee at 850.245.4444, ext. 2448.
 

The peoples of Malaysia, Singapore and Bangladesh are already familiar with the new virus known as Nipah. First identified in 1999 in Malaysia, this cousin of the Hendra, an equine virus primarily found in Australia, is a member of the family Paramyxoviridae. Epidemiologic evidence shows that human cases are acquired by direct contact with pigs, although exposure through other animals, such as fruit bats, has not been ruled out. No human-to-human transmission has been documented.

Infection by the Nipah virus brings symptoms within 4-18 days of exposure. Some persons experience myalgia or influenza-like symptoms requiring no hospitalization. Some cases progress to inflammation of the brain with disorientation, convulsions and coma and patients are hospitalized, but may recover with neurological problems. Others, about 40% of all seriously ill patients, will die. According to the University of Malaysia, the first outbreak was noted in 1998, and by the middle of June 1999, more than 265 cases, including 105 deaths, had been reported. More recently, in April 2004, Bangladesh reported and CDC confirmed a cluster of 30 human cases, including 16 deaths attributable to the virus. 

Since the virus is a recent discovery, further research needs to be performed to limit future human cases; but biosecurity is an important consideration for the CDC, which states that there is no effective treatment or vaccine for animals or humans. Nipah is an emerging pathogen that can be engineered for mass dissemination due to its availability, the ease with which it could be produced and spread, and its potential for high morbidity and mortality rates.

The World Health Organization held a consultation earlier this month on zoonoses and surveillance systems to monitor and control these agents. Its final recommendations included integrating medical disciplines to work synergistically on new surveillance and response tools; facilitating early detection of potential zoonotic public health events; and national and regional integration of animal and human health data for future preparedness and control.

www.cdc.gov/ncidod/drvd/spb/mnpages/dispages/nipah.htm

Trivedi, Bijal. "Deadly New Virus Draws Experts to Hot Zones." National Geographic News, January 21, 2003. http://news.nationalgeographic.com/news/2003/01/0121_030121_tvvirushunter.html

"Recommendations from WHO's Consultation on Zoonoses." World Health Organization. May 5, 2004. http://www.who.int/mediacentre/briefings/2004/mb3/en/

MacKenzie, John S. "Emerging Viral Diseases: An Australian Perspective." Emerging Infectious Diseases, Vol 5, Num 1, Jan-Mar 1999. http://www.cdc.gov/ncidod/EID/vol5no1/mackenzie.htm

Yee Ai, See. "Profile of a Virus." Star Online. April 10, 2000. http://agrolink.moa.my/jph/dvs/nipah/star000410/nipah-profile.html
 

I am often asked the question, why did you decide to leave veterinary medicine for public health, from working with animals to working with people? The question always takes me by surprise. Public health veterinarians don?t look at public health as a career change. It's just a shift in focus from four-legged to two-legged animals; it's still multi-species medicine, but with the emphasis shifting from species-specific diseases to diseases that cross species boundaries.  

Veterinarians are attracted to public health for several reasons. The list of diseases transmitted between animals and man is long and diverse. More than 30 diseases can be transmitted between humans and their dogs alone. This makes the field exciting and filled with opportunities for research and new discoveries. Zoonotic diseases can be bacterial, viral, parasitic, fungal, insect-borne, or of prion origin. They are transmitted by a wide variety of routes. Many naturally occurring zoonoses are rare in humans. However, the human disease outcome is often very severe. The transmissibility and pathogenicity of zoonotic pathogens make many of them excellent candidates for bioterrorism agents. To be able to diagnose diseases in multiple animal species, all with their unique disease presentations, veterinarians receive in-depth training in the basic principles of pathophysiology and microbiology. Having a thorough understanding of the principles of disease transmission and epidemiology is especially valuable during emerging disease investigations.  

The cost-effectiveness of population-based preventive medicine is also stressed in veterinary school and well understood among practitioners. Large animal veterinarians vaccinate, screen, quarantine and cull animals if necessary to eliminate diseases from the herd. A stimulating challenge more or less unique to veterinarians in public health is to develop disease prevention strategies aimed at modifying human behavior. 

The work of veterinarians has always affected human health, whether it is through supplying safe food products, caring for beloved four-legged family members, or helping build successful family businesses. Large animal and slaughterhouse veterinarians provide a critical link between agriculture and human medicine.

Veterinary public health professionals will continue to play an important role in animal and human disease prevention. The globalization of the food trade is continuing, food customs are changing, and the mobility of animals and people is increasing. Environmental health concerns associated with climate change, waste disposal and water quality issues and changing farm practices need to be addressed. Other emerging issues of veterinary public health concern are the increased prevalence of multi-drug resistant pathogens and the population explosion currently taking place in many parts of the world. If SARS, Ebola and HIV have taught us anything it is that when contacts between wildlife and people increase, the risk of new pathogens jumping from the animal species to humans is very real.

(Ed Note:  Be sure to catch Dr. Blackburn's presentation on trans species migration of infectious diseases next week at the statewide epidemiology seminar.)
 

We're proud of the successes of these graduates who worked very hard to achieve their goals, and wish both of them all the best as they look to the future.
 

► May Grand Rounds Presents Analysis of Locally Acquired Malaria Risk Factors

               Bureau of Epidemiology Grand Rounds Program

Date: Tuesday, May 25, 2004 11:00 a.m. ? 12:00 p.m. EST
Topic:  Malaria Risk Factors Associated with Hospitalization and Death - Florida 1995-2003
Presenter: D. Fermin Arguello, MD, CDC Epidemic Intelligence Service Officer, Bureau of Epidemiology, Florida Department of Health
Abstract:
Over the summer of 2003, there was a significant outbreak of locally acquired mosquito-borne malaria in Palm Beach county, Florida. Malaria mortality rates for Florida are approximately 2% compared to the approximately 1% rate for the United States. The Florida Department of Health, Bureau of Epidemiology initiated an analysis of its malaria surveillance to identify Florida resident-specific malaria risk factors (e.g., recent travel to an endemic area, no prophylaxis when traveling to an endemic area, recent transfusion) and malaria deaths. Logistic regression analysis was used to test the association between malaria risk factors and death. This analysis will provide a summary of malaria activity in Florida between 1995 and 2003, and will demonstrate Florida resident-specific risk factors for death due to malaria infection. This state-specific information will guide the Florida Department of Health and the CDC in improving prevention measures for the residents of Florida. 

Additional Information:
The grand rounds presentation will begin promptly at 11:00 a.m. EDT on Tuesday, May 25, 2004. PowerPoint slides and the dial-in number will be available on the Bureau of Epidemiology intranet Website on Monday, May 24. CEUs will be provided for nursing. Please remember you must complete the entire registration form including the evaluation and test questions. Registration for CEUs will be accepted May 25-May 27, 2004. Registrations received prior to the beginning of the program will not be accepted. 
 

• How to prevent and control malaria in the US and abroad
• Facts and figures on the impact of malaria
• CDC malaria activities nationally and globally
• Interactive training using clinical and epidemiologic case studies
• Malaria treatment info for US clinicians
• Expanded info on malaria for travelers
• Malaria's biology, epidemiology, geographic distributions and health impact
• Extensive list of references and resources

- Nassau County reported 59 confirmed cases of Norovirus at a long-term health care facility.

- A Sarasota elementary school reported five cases of varicella in the same classroom. An investigation is ongoing.

- Giant African snails, immediate hosts of the lugworm which causes flu-like symptoms, have been found in several states in the Midwest. The outbreak originated in Miami. Humans can be infected through direct contact with snail secretions and by ingesting snails.

The Bureau of Epidemiology encourages Epi Update readers to not only register on the EpiCom system at https://www.epicomfl.net but to browse EpiCom frequently and contribute public health observations related to any suspicious or unusual occurrences or circumstances, as appropriate. EpiCom is the primary method of communication between the Bureau of Epidemiology and other state medical agencies during emergency situations.
 

No Florida counties are under medical alert. There have been no human cases confirmed yet this year. In areas with mosquitoes present, people are still encouraged to take precautions against mosquito bites.   

West Nile (WN) Virus activity: There were four seroconversions to WN virus reported this week in sentinel chickens, one in Hillsborough (4/6) County, one in Indian River (4/22) and two in Walton (4/5, 4/12) County. So far this year, there have been 70 sentinel seroconversions to WN virus in 13 counties, two WN-confirmed dead birds from Marion and Miami-Dade counties, four WN-positive live birds from three counties and one WN-confirmed horse from Polk County. To date, 19 counties have reported confirmed WN virus activity this year. 

St. Louis Encephalitis (SLE) Virus activity: None this week. So far this year, five sentinel chickens from Lee County have tested positive for SLE. 

Eastern Equine Encephalomyelitis (EEE) Virus activity: There was one seroconversion to EEE virus reported this week in a sentinel chicken from Flagler County (4/26). To date, 17 sentinel chickens, six horses and six live birds have tested positive for EEE virus, for a total of 12 counties reporting EEE virus activity this year. 

Highlands J (HJ) Virus activity: There were two seroconversions to HJ virus reported this week, one in Orange County (4/5) and one in Walton County (3/29). To date, there have been 12 seroconversions to Highlands J virus in sentinel chickens from four counties and one HJ-positive live bird from Santa Rosa County, for a total of five counties reporting HJ virus activity this year.

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