Ciguatera fish poisoning and climate change: analysis of national poison center data in the United States 2001-2011 Público

Gingold, Daniel Benjamin (2013)

Permanent URL: https://etd.library.emory.edu/concern/etds/6969z1516?locale=es
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Abstract

Ciguatera fish poisoning (CFP) is the world's most common seafood-toxin disease. CFP occurs when humans consume fish that have fed on ciguatera toxin-producing organisms, and is characterized by acute gastrointestinal upset followed by neurological symptoms such as numbness, weakness, and disruption of temperature sensation. Recent studies have demonstrated a relationship between CFP incidence and warmer sea surface temperatures (SST). Also, increased severe storm frequency may create more suitable habitat for ciguatoxic organisms. Climate change is expected to affect SST and storm frequency in the Caribbean, and may cause an increase in CFP prevalence and expansion beyond its current tropical range.

The purpose of this hypothesis-generating ecological time-series study was to determine if CFP incidence is associated with periods of warmer SST and increased storm frequency in the Caribbean over the last decade to inform predictions regarding climate change and CFP.

1,272 CFP-related calls to US poison control centers between 2001-2011 were identified from the National Poison Data System and analyzed using descriptive analysis and Poisson regression. Results showed an independent association between monthly CFP calls and warmer SST and tropical storm frequency, using fishing yields as an offset. The optimal lag period for SST was between 5 and 16 months; the variable selected links current monthly CFP calls to the peak August SST of the previous year. The optimal lag period for storms was 18 months. The rate ratio for an increase in storms by one per month was 1.113 (95% CI [1.03, 1.234]), and the rate ratio of a one-degree increase in SST temperature was 1.612 (95% CI [1.167, 2.243]).

These estimates imply that if the maximum Caribbean SST increases by 2.5°C as projected, and storm frequency increases by 10% from 2001-2011 levels, approximately 239 additional calls per year can be expected (95% CI [49.5, 665.9]), a two- to four-fold increase.

Using CFP calls as a marker of CFP incidence, these results support the hypothesis that CFP incidence is positively associated with warming SST and increased tropical storm frequency, and should inform adaptation measures to limit the potential public health impacts of unmitigated climate change.

Table of Contents

Chapter I: Literature Review......................................................................1

Chapter II: Manuscript.............................................................................16

Title, Authors, Abstract............................................................................16

Introduction...........................................................................................18

Climate Change and Public Health

Ciguatera Toxin Production

Ciguatoxin in Fish

Ecology of Ciguatera

Epidemiology of Ciguatera

Ciguatoxin Pharmacology

Ciguatoxin Detection

CFP Treatment

Ciguatera and Climate Change

Methods................................................................................................19

Ciguatera Cases Data

Sea Surface Temperature (SST) Data

Caribbean SST Anomaly Index Data

Severe Tropical Storms Data

Fishing Yields Data

Lagged Variables

Analysis Methods

Results................................................................................................. 25

Descriptive Analysis of Ciguatera Calls

Descriptive Analysis of Regression Variables

Poisson Regression Analysis of the Multivariate Model

Discussion............................................................................................. 31

Summary

Comparison of Results to Literature

Limitations

Public Health Impacts

Conclusions

References............................................................................................ 40

Tables.................................................................................................. 43

Table 1: Descriptive statistics of ciguatera call variables

Table 2a: Frequency of clinical effects for all calls

Table 2b: Frequency of selected clinical effects

Table 3a: Frequency of therapies for all calls

Table 3b: Frequency of selected therapies

Table 4: Descriptive statistics for regression analysis variables

Table 5: Individual variable regression results

Table 6: Rate ratios and excess CRP calls expected for hypothetical scenarios compared to 2001-2011 baseline

Table 7: Sensitivity of beta estimates to multivariate model selection

Figures................................................................................................. 49

Figure 1: Ciguatera fish poisoning distribution

Figure 2: Number of ciguatera calls by region and year, 2001-2011

Figure 3: Number and percent of calls by age group, 2001-2011

Figure 4: Total number of calls by month, 2001-2011

Figure 5: Recorded and imputed fishing yields

Figure 6: Yearly SST time series

Figure 7: August max SST and yearly storm total time series

Figure 8: August max SST and ciguatera calls by year

Figure 9: Regional SST, Poisson beta estimates by lag time

Figure 10: Warm SST extent, Poisson beta estimates by lag time

Figure 11: SST at parallels, Poisson beta estimates by lag time

Figure 12: Storm variables, Poisson beta estimates by lag time

Figure 13: Data analysis flowchart

Chapter III............................................................................................56

Summary..............................................................................................56

Public Health Implications........................................................................58

Possible Future Directions........................................................................60

Appendix: IRB Approval Letter..................................................................62

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