Division of Disease Control and Health Protection

"The reason for collecting, analyzing and disseminating information on a disease is to control that disease. Collection and analysis should not be allowed to consume resources if action does not follow."

--Foege WH et al. Int. J of Epidemiology 1976; 5:29-37.

Please print out this material and share with epidemiology staff, county health department directors, administrators, medical directors, nursing directors, environmental health directors and others with an interest in information of this type. Thank you.

1. Grand Rounds for February 29, 2000

"Trends in Obesity in Florida and the Nation - Who's getting fat and why and what are the health consequences?"

2. Arbovirus Encephalitis Surveillance Summary, Florida, 1999

3. Tetanus Primer (Bureau of Epidemiology "One-Pager" series)

4. Florida Influenza Program Summary Update: Week 5 (week ending February 5, 2000)

5. Weekly Disease Table: Week 6

11:00 AM – 12:00 PM EST

This presentation will describe trends in adult obesity in Florida based on Behavioral Risk Factor Surveillance System data; and trends in child and adult obesity in the US, based on National Health and Nutrition Examination Survey data. Changes in eating and exercise behaviors will be explored, along with changes in the social environment that promote over-eating and under-activity, that may be related to the observed increases in obesity. Special attention will be paid to the association between obesity and type 2 diabetes in children and adults, based on Florida data.

Further details regarding the audioconference call and PowerPoint files will be posted on the DOH Intranet site. Information about upcoming topics and presenters will also be posted in future Epi Updates.

Additional information and tips about accessing information about the Grand Rounds may be found on the Bureau of Epidemiology Intranet website.

Lisa Conti, DVM, MPH, State Public Health Veterinarian

The Bureau of Epidemiology would like to take the opportunity to thank all of players who were involved with arbovirus surveillance during 1999. The agencies in the Florida cooperative mosquito-borne encephalitis surveillance program are:

• 56 mosquito control agencies and 67 county health departments
• Florida Department of Health, Bureau of Laboratories
• Florida Department of Health, Bureau of Epidemiology
• Florida Department of Agriculture and Consumer Services, Bureau of Entomology and Pest Control
• Florida Department of Agriculture and Consumer Services, Division of Animal Industry
• Florida Medical Entomology Laboratory, University of Florida, and Public Health Entomology Research and Education Center (PHEREC), Florida A & M University

The components of the arbovirus surveillance program included:

1. Human cases of mosquito-borne encephalitis
2. Sentinel avian (chicken) serosurveillance
3. Equine cases of eastern equine encephalomyelitis (EEE)
4. Mosquito surveillance
5. Special projects

Human Arbovirus Encephalitis Cases - During the year, three St. Louis encephalitis (SLE) and two eastern equine encephalitis (EEE) cases were reported in people. All survived their infections.

The Florida Department of Health (DOH) issued a press release on October 5, 1999, informing the public that health advisories were issued for SLE in Charlotte, Collier, DeSoto, Glades, Hendry, Lee and Sarasota counties. The advisories followed the reporting of the year's first human case of SLE in Sarasota County. This human case was concurrent with an increased SLE virus activity in sentinel chickens. Advisories were used to encourage people to take basic precautions to help limit their exposure to mosquitoes and prevent encephalitis. The advisories were lifted on December 6, due to a significant drop in mosquito activity and a reduction in positive tests among sentinel chicken flocks.

Because antibodies toward West Nile virus (WNV) might cross react with SLE test reagents, SLE-positive sera were retested using WNV serum neutralization at the Centers for Disease Control and Prevention and the DOH Tampa Branch Laboratory. All were negative for WNV.

Sentinel Avian (Chicken) Serosurveillance - During 1999, Dr. Lillian Stark and staff (DOH Tampa Branch Laboratory) performed 19,344 hemagglutination and antibody inhibition (HAI) examinations on sera from 1,765 susceptible chickens maintained in 173 flocks in 28 participating counties. Annual St. Louis encephalitis (SLE) and EEE virus seroconversion rates were similar to the 10-year historical mean for all regions. Most sentinel chicken seroconversions to SLE virus occurred during August through December.

Equine EEE Cases - During 1999, Dr. Michael Slayter and staff (Department of Agriculture and Consumer Services [DACS], Diagnostic Laboratory) tested 129 horses for arboviruses (EEE virus, Western equine encephalomyelitis virus [WEE], Venezuelan equine encephalomyelitis virus and SLE virus) of which 46 were considered positive for exposure to EEE virus. In most years, between 50 and 75 cases are reported. Cases occurred from January through December with the peak in August. All cases occurred north of Lake Okeechobee. Because equine arbovirus vaccines are polyvalent (for EEE and WEE viruses) and many horses in Florida have been vaccinated, DACS guidelines for interpreting titers for presence of exposure to EEE virus include a EEE titer four times greater then WEE titer.

Mosquito Surveillance - During weekly interagency arbovirus conference calls, mosquito control agencies discussed Culex nigripalpus activity.

Special Projects - Supported by South Walton and Beach mosquito control districts and CDC, Drs. Eric Schreiber (PHEREC) and Nick Komar (CDC) collected about 500 samples of song bird sera and 120 mosquito pools in Bay and Walton counties to test for EEE, SLE and WNV. While serologic examination is ongoing, preliminary results show six Culiseta melanura pools and one Aedes atlanticus were positive for EEE virus, and no SLE or WNV viruses have been detected in any of the samples.

Summary - Two children in panhandle counties were diagnosed with EEE some after reports of increased cases of EEE in horses and ratites in Louisiana, Alabama and Georgia. In Florida, reported equine EEE cases peaked in August, concurrent with the human cases.

SLE activity was considered moderate in 1999. Recent years' public health messages regarding arboviral encephalitis in Florida may have contributed to the likelihood of serologic testing and therefore explain the young age of two of the three diagnosed cases.

Antibodies to SLE and WNV are likely to cross react. Therefore, the DOH Tampa Branch Laboratory began testing SLE-positive sera during late 1999 for WNV-specific antibodies. To date, WNV has not been identified in Florida.

Carina Blackmore, M.S. Vet. Med., PhD, DOH Regional Epidemiologist

Henry T. Janowski, MPH, DOH, Chief, Bureau of Immunization

Tetanus is caused by a toxin-producing, spore-forming, anaerobic Gram-positive bacillus, Clostridium tetani. Spores are ubiquitous in soil and animal feces and infection occurs when they come in contact with human and animal tissues through wounds, burns and other injuries. Germination takes place in the body. The bacteria’s potent exotoxin affects nerves controlling muscle function. Tetanus has been an important disease worldwide for many generations. It is described both in the bible and in writings by ancient Greek and Egyptian physicians.¹ After the introduction of the tetanus toxoid vaccine in the 1940 and 1950’s, tetanus has become rare in industrialized countries. Improved hygienic conditions at childbirth and better wound care have also contributed to the reduction of the number of disease cases. Tetanus remains a significant health problem in other parts of the world; in 1997 the global number of neonatal tetanus was estimated as 355,000 with 248,000 deaths.²

Infections are diagnosed based on clinical signs when other causes of disease can be excluded. The toxin-induced nerve damage results in painful muscle contractions, especially in the muscles controlling the neck and jaws. Symptoms can progress to generalized spasms, which often are worsened by external stimuli. Onset of disease is gradual over 1-7 days after a 2 day to 2 month incubation period. Shorter incubation periods are associated with more heavily contaminated wounds. A common first sign of tetanus is muscular stiffness in the jaw (lockjaw), followed by stiffness of the neck, difficulty in swallowing, rigidity of abdominal muscles, spasms, sweating and fever. Complications include spasm of the vocal cords and/or spasms of the respiratory muscles causing interference with breathing. Other complications include fractures of the spine or long bones, hypertension, abnormal heartbeats, coma, generalized infection, clotting in the blood vessels of the lung, pneumonia and death. Localized tetanus, limited to the area around the contaminated wound, also occur.

Due to widespread immunization, tetanus is now a rare disease in the United States. Tetanus vaccination is currently required in 49 of 50 states before school admission and it is estimated that > 96% of all children have received three or more doses of the DTP vaccine by the time they start school. However, despite widespread availability of the vaccine in this country, 124 cases of tetanus were reported between 1995-1997.³ Only 13% of these had received the primary series of tetanus toxoid. The vaccine-induced protective antibody levels also decline over time.⁴ Tetanus occurs more often in older people and in agricultural workers where contact with animal manure is more likely and immunization is inadequate. During the 3 year time-period discussed above, adults aged > 59 years had both higher tetanus morbidity and mortality rates than people in other age groups. The case-fatality rate for ³ 60 year-old patients was 18%, 7% higher than the case fatality rate for tetanus in the population overall. Intra-venous drug use also appears to be a risk factor for disease. Neonatal tetanus is rarely seen in the US with only one case reported between 1995-1997.

Wounds should be thoroughly cleaned, and dead or devitalized tissue removed. If the patient has not had a tetanus toxoid booster in the previous 10 years, a single booster dose should be administered on the day of the injury. For severe wounds, a booster may be given if more than five years have elapsed since the last dose. Tetanus immune globulin (TIG), antitoxin and antibiotics may be given if the patient has not been previously immunized with a series of at least three doses of toxoid. Recovery from tetanus may not result in immunity. Second attacks can occur and immunization is indicated after recovery.

The single most effective preventative measure is maintenance of a high level of immunization in the community. An effective vaccine called tetanus toxoid has been available for many years. Tetanus toxoid in combination with diphtheria toxoid and pertussis vaccine (DTP) is given at two, four, six and 15 months of age, and between four and six years of age. Children who are seven years of age or older should receive Td (tetanus and diphtheria) toxoid. A tetanus booster with Td is recommended for children at 11 years of age and every 10 years thereafter throughout adulthod.

For purposes of surveillance, tetanus disease is described as acute onset of hypertonia and/or painful muscular contractions (usually of the muscles of the jaw and neck) and generalized muscle spasms without other apparent medical cause (as reported by a health professional). A confirmed case is a clinically compatible illness.

In Florida, 44 cases of tetanus were reported between 1987 and 1998. The mean age was 53.1 and 36% of the patients were aged ³ 60 years. Tetanus infections were more common among men (61%). Sixty-eight percent of affected patients were white, 18% black, 11% hispanic and 2% were of Asian descent. Of the three confirmed cases of tetanus in 1998, two were related to apparent work injuries and one was related to a dirt-bike injury.

2. www.who.int/gpv-dvacc/diseases/NeonatalTetanus.htm

4. Tetanus. VPD surveillance manual. Chapter 13. pp 1

Roger Sanderson, RN, MA, Bureau of Epidemiology

Since October 3, 1999, the World Health Organization (WHO) and the National Respiratory and Enteric Virus Surveillance System (NREVSS) laboratories have tested 60,489 respiratory specimens for influenza, from which 11,087 (18%) influenza isolates have been recovered. Influenza A accounted for 11,067 of the 11,087 (99.8%) isolates with 20 isolates being influenza B (0.2%). Of the 2,756 influenza A viruses sub-typed 2,740 (99.4%) were A (H3N2) and 16 (0.6%) were A (H1N1). Both influenza A and B were isolated in Florida during this time period. During Week 5, influenza activity was reported as widespread in 8 states (Arizona, Delaware, Missouri, New York, Ohio, Rhode Island, Tennessee, and Virginia). Regional influenza activity was reported in 17 states (Alabama, Colorado, Idaho, Indiana, Kentucky, Louisiana, Maryland, Massachusetts, Michigan, Minnesota, Mississippi, New Hampshire, North Carolina, South Carolina, Vermont, Washington, and Wisconsin). Sporadic influenza activity was reported in 21 states and 4 states did not report. This continues the decrease in overall influenza activity seen in previous weeks. During Week 4 widespread influenza activity was reported in 15 states, regional activity in 24 states and sporadic in 11 states.

During Week 5, the proportion of deaths due to pneumonia and influenza (P&I) was 10.7% as reported by the vital statistics offices of 122 U.S. cities. This percentage is above the epidemic threshold of 7.5% for Week 5 and is unusually high. The percentage of pneumonia and influenza deaths has exceeded threshold values for this time of year for 19 of the past 20 weeks. The current season’s P&I figures must be interpreted with caution because important changes have taken place in this year’s case definition that may be contributing to higher estimates of P&I mortality than in previous years. Tampa, St. Petersburg, Jacksonville and Miami are the Florida cities that contributed to this report.

During the current season, the overall national percentage of respiratory specimens positive for influenza peaked at 33% during Week 51. During the previous 3 years (1996-97, 1997-98, and 1998-99), the peak percentages of respiratory specimens testing positive for influenza viruses ranged from 28% to 34%. For this season, the percentage of overall patient visits for influenza-like illness peaked at 6% during Week 52. During the previous 3 years, the peak percentages for such visits ranged between 5% and 7%. During Week 4, the proportion of deaths attributed to pneumonia and influenza (P&I) began to decline, from a high of 11.0% during Week 3 and is currently 10.7%. During the previous 3 years, P&I mortality levels peaked between 8.8% and 9.1%.

Since the beginning of Week 5 (January 30, 2000) laboratory confirmed isolates of influenza A H3N2/Sydney-like were reported from Broward, Duval, and Hillsborough counties. Influenza A H3N2 has also been isolated from Alachua, Baker, Brevard, Clay, Collier, Escambia, Gadsden, Indian River, Lake, Leon, Martin, Miami-Dade, Orange, Pasco, Palm Beach, Pinellas, Sarasota, and Volusia counties since October 1, 1999. Influenza B/Yamanashi-like has been isolated from Indian River County. Untyped isolates of influenza A have been reported from Brevard, DeSoto, and Manatee counties. Antigens from both influenza A/Sydney and influenza B/Yamanashi are included in the 1999-2000 influenza vaccine. Of the total patient visits to sentinel physicians for Week 5, 2% were due to ILI. This was a decrease from the 3% ILI reported in week 4 and is within the expected range of 0-3%. This week influenza-like illness was reported from providers in 16 (Broward, Collier, Duval, Escambia, Hillsborough, Indian River, Leon, Marion, Miami-Dade, Palm Beach, Pasco, Pinellas, Polk, Seminole, Sarasota, and St. Lucie counties) of the 29 Florida counties participating in the National Sentinel Physicians Surveillance Network.

Florida has experienced a decline in influenza activity during the last four weeks. The ILI in Florida peaked at 5% during Week 1. This was one week later than the national peak at 6% during Week 52. Reports of institutional outbreaks of influenza have also decreased.