Sharon Watkins

Neurotoxic Shellfish Poisoning

Neurotoxic shellfish poisoning (NSP) is caused by consumption of molluscan shellfish contaminated with brevetoxins primarily produced by the dinoflagellate, Karenia brevis. Blooms of K. brevis, called Florida red tide, occur frequently along the Gulf of Mexico. Many shellfish beds in the US (and other nations) are routinely monitored for presence of K. brevis and other brevetoxin-producing organisms. As a result, few NSP cases are reported annually from the US. However, infrequent larger outbreaks do occur. Cases are usually associated with recreationally-harvested shellfish collected during or post red tide blooms. Brevetoxins are neurotoxins which activate voltage-sensitive sodium channels causing sodium influx and nerve membrane depolarization. No fatalities have been reported, but hospitalizations occur. NSP involves a cluster of gastrointestinal and neurological symptoms: nausea and vomiting, paresthesias of the mouth, lips and tongue as well as distal paresthesias, ataxia, slurred speech and dizziness. Neurological symptoms can progress to partial paralysis; respiratory distress has been recorded. Recent research has implicated new species of harmful algal bloom organisms which produce brevetoxins, identified additional marine species which accumulate brevetoxins, and has provided additional information on the toxicity and analysis of brevetoxins. A review of the known epidemiology and recommendations for improved NSP prevention are presented.

Ciguatera Fish Poisoning: Treatment, Prevention and Management

Ciguatera Fish Poisoning (CFP) is the most frequently reported seafood-toxin illness in the world, and it causes substantial physical and functional impact. It produces a myriad of gastrointestinal, neurologic and/or cardiovascular symptoms which last days to weeks, or even months. Although there are reports of symptom amelioration with some interventions (e.g. IV mannitol), the appropriate treatment for CFP remains unclear to many physicians. We review the literature on the treatments for CFP, including randomized controlled studies and anecdotal reports. The article is intended to clarify treatment options, and provide information about management and prevention of CFP, for emergency room physicians, poison control information providers, other health care providers, and patients.

The costs of respiratory illnesses arising from Florida Gulf Coast Karenia brevis blooms

Background Algal blooms of Karenia brevis, a harmful marine algae, occur almost annually off the west coast of Florida. At high concentrations, K. brevis blooms can cause harm through the release of potent toxins, known as brevetoxins, to the atmosphere. Epidemiologic studies suggest that aerosolized brevetoxins are linked to respiratory illnesses in humans. Objectives We hypothesized a relationship between K. brevis blooms and respiratory illness visits to hospital emergency departments (EDs) while controlling for environmental factors, disease, and tourism. We sought to use this relationship to estimate the costs of illness associated with aerosolized brevetoxins. Methods We developed a statistical exposure–response model to express hypotheses about the relationship between respiratory illnesses and bloom events. We estimated the model with data on ED visits, K. brevis cell densities, and measures of pollen, pollutants, respiratory disease, and intra-annual population changes. Results We found that lagged K. brevis cell counts, low air temperatures, influenza outbreaks, high pollen counts, and tourist visits helped explain the number of respiratory-specific ED diagnoses. The capitalized estimated marginal costs of illness for ED respiratory illnesses associated with K. brevis blooms in Sarasota County, Florida, alone ranged from

Algorithm for the diagnosis of anaphylaxis and its validation using population-based data on emergency department visits for anaphylaxis in Florida

0.5 to

A population-based epidemiologic study of emergency department visits for anaphylaxis in Florida

4 million, depending on bloom severity. Conclusions Blooms of K. brevis lead to significant economic impacts. The costs of illness of ED visits are a conservative estimate of the total economic impacts. It will become increasingly necessary to understand the scale of the economic losses associated with K. brevis blooms to make rational choices about appropriate mitigation.

Hospitalizations, costs, and mortality among infants with critical congenital heart disease: How important is timely detection?

BACKGROUND Epidemiologic studies of anaphylaxis have been limited by significant underdiagnosis. OBJECTIVE The purpose of this study was to develop and validate a method for capturing previously unidentified anaphylaxis cases by using International Classification of Disease, Ninth Revision, Clinical Modification (ICD-9-CM) based datasets. METHODS Florida emergency department data for the years 2005 and 2006 from the Florida Agency for Health Care Administration were used. Patients with anaphylaxis were identified by using ICD-9-CM codes specifically indicating anaphylaxis or an ICD-9-CM algorithm based on the definition of anaphylaxis proposed at the 2005 National Institute of Allergy and Infectious Disease and the Food Allergy and Anaphylaxis Network symposium. Cases ascertained with the algorithm were compared with the traditional case-ascertainment method. Comparisons included demographic and clinical risk factors, proportion of monthly visits, and age/sex-specific rates. Cases ascertained with anaphylaxis ICD-9-CM codes were excluded from those ascertained with the algorithm. RESULTS One thousand one hundred forty-nine patients were identified by using anaphylaxis ICD-9-CM codes, and 1,602 patients were identified with the algorithm. The clinical risk factors and demographics of cases were consistent between the 2 methods. However, the algorithm was more likely to identify older subjects (P < .0001), those with hypertension or heart disease (P < .0001), and subjects with venom-induced anaphylaxis (P < .0001). CONCLUSION This study introduces and validates an ICD-9-CM-based diagnostic algorithm for the diagnosis of anaphylaxis to capture subjects missed by using the ICD-9-CM anaphylaxis codes. Fifty-eight percent of anaphylaxis cases would be missed without the use of the algorithm, including 88% of venom-induced cases.

Exposure and Effect Assessment of Aerosolized Red Tide Toxins (Brevetoxins) and Asthma

BACKGROUND Previous population-based analyses of emergency department (ED) visits for anaphylaxis have been limited to small populations in limited geographic areas and focused on children or have included patients who had allergic conditions other than anaphylaxis. OBJECTIVE We sought to describe the epidemiology and risk factors among patients with anaphylaxis presenting to Florida EDs. METHODS Two thousand seven hundred fifty-one patients with anaphylaxis were identified for 2005-2006 within ED records by using the International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM), and a validated ICD-9-CM-based algorithm. Age- and sex-specific rates were calculated. Regression analyses were used to determine relative risks for anaphylaxis caused by various triggers (food, venom, and medication) and risk factors (age, sex, race, and ethnicity). RESULTS The highest observed rates were among the youngest male subjects (8.2/100,000 Floridians aged 0-4 years) and among adult female subjects (15-54 years) grouped in 10-year age categories (9.9-10.9/100,000 Floridians). Male and black subjects were 20% and 25%, respectively, more likely to have a food trigger than female and white subjects. White, male, and older subjects were more likely to have an anaphylaxis-related ED visit caused by insect stings. Venom-induced anaphylaxis was more likely in August through October. Children were less likely than those older than 70 years (referent) to have medication-induced anaphylaxis (P < .03). CONCLUSION This is the only ED-based population study in a US lower-latitude state. The overall rate is considerably lower than other US ED-based population studies. The rates of anaphylaxis by age group differed by sex. Male and black subjects were more likely to have a food trigger.

Factors associated with late detection of critical congenital heart disease in newborns.

BACKGROUND Critical congenital heart disease (CCHD) was recently added to the U.S. Recommended Uniform Screening Panel for newborns. States considering screening requirements may want more information about the potential impact of screening. This study examined potentially avoidable mortality among infants with late detected CCHD and assessed whether late detection was associated with increased hospital resource use during infancy. METHODS This was a state-wide, population-based, observational study of infants with CCHD (n = 3603) born 1998 to 2007 identified by the Florida Birth Defects Registry. We examined 12 CCHD conditions that are targets of newborn screening. Late detection was defined as CCHD diagnosis after the birth hospitalization. Deaths potentially avoidable through screening were defined as those that occurred outside a hospital following birth hospitalization discharge and those that occurred within 3 days of an emergency readmission. RESULTS For 23% (n = 825) of infants, CCHD was not detected during the birth hospitalization. Death occurred among 20% (n = 568/2,778) of infants with timely detected CCHD and 8% (n = 66/825) of infants with late detected CCHD, unadjusted for clinical characteristics. Potentially preventable deaths occurred in 1.8% (n = 15/825) of infants with late detected CCHD (0.4% of all infants with CCHD). In multivariable models adjusted for selected characteristics, late CCHD detection was significantly associated with 52% more admissions, 18% more hospitalized days, and 35% higher inpatient costs during infancy. CONCLUSION Increased CCHD detection at birth hospitals through screening may lead to decreased hospital costs and avoid some deaths during infancy. Additional studies conducted after screening implementation are needed to confirm these findings.

Associations between exposure to ambient benzene and PM2.5 during pregnancy and the risk of selected birth defects in offspring

Background In previous studies we demonstrated statistically significant changes in reported symptoms for lifeguards, general beach goers, and persons with asthma, as well as statistically significant changes in pulmonary function tests (PFTs) in asthmatics, after exposure to brevetoxins in Florida red tide (Karenia brevis bloom) aerosols. Objectives In this study we explored the use of different methods of intensive ambient and personal air monitoring to characterize these exposures to predict self-reported health effects in our asthmatic study population. Methods We evaluated health effects in 87 subjects with asthma before and after 1 hr of exposure to Florida red tide aerosols and assessed for aerosolized brevetoxin exposure using personal and ambient samplers. Results After only 1 hr of exposure to Florida red tide aerosols containing brevetoxin concentrations > 57 ng/m3, asthmatics had statistically significant increases in self-reported respiratory symptoms and total symptom scores. However, we did not see the expected corresponding changes in PFT results. Significant increases in self-reported symptoms were also observed for those not using asthma medication and those living ≥ 1 mile from the coast. Conclusions These results provide additional evidence of health effects in asthmatics from ambient exposure to aerosols containing very low concentrations of brevetoxins, possibly at the lower threshold for inducing a biologic response (i.e., toxicity). Consistent with the literature describing self-reported symptoms as an accurate measure of asthmatic distress, our results suggest that self-reported symptoms are a valuable measure of the extent of health effects from exposure to aerosolized brevetoxins in asthmatic populations.

Hospital use, associated costs, and payer status for infants born with spina bifida.

OBJECTIVES: Critical congenital heart disease (CCHD) was recently added to the US Recommended Uniform Screening Panel for newborns. This study assessed whether maternal/household and infant characteristics were associated with late CCHD detection. METHODS: This was a statewide, population-based, retrospective, observational study of infants with CCHD born between 1998 and 2007 identified by using the Florida Birth Defects Registry. We examined 12 CCHD conditions that are primary and secondary targets of newborn CCHD screening using pulse oximetry. We used Poisson regression models to analyze associations between selected characteristics (eg, CCHD type, birth hospital nursery level [highest level available in the hospital]) and late CCHD detection (defined as diagnosis after the birth hospitalization). RESULTS: Of 3603 infants with CCHD and linked hospitalizations, CCHD was not detected during the birth hospitalization for 22.9% (n = 825) of infants. The likelihood of late detection varied by CCHD condition. Infants born in a birth hospital with a level I nursery only (adjusted prevalence ratio: 1.9 [95% confidence interval: 1.6–2.2]) or level II nursery (adjusted prevalence ratio: 1.5 [95% confidence interval: 1.3–1.7]) were significantly more likely to have late-detected CCHD compared with infants born in a birth hospital with a level III (highest) nursery. CONCLUSIONS: After controlling for the selected characteristics, hospital nursery level seems to have an independent association with late CCHD detection. Thus, perhaps universal newborn screening for CCHD could be particularly beneficial in level I and II nurseries and may reduce differences in the frequency of late diagnosis between birth hospital facilities.