Evaluating temporal patterns of snakebite in Sri Lanka: the potential for higher snakebite burdens with climate change.

Background: Snakebite is a neglected tropical disease that has been overlooked by healthcare decision makers in many countries. Previous studies have reported seasonal variation in hospital admission rates due to snakebites in endemic countries including Sri Lanka, but seasonal patterns have not been investigated in detail. Methods: A national community-based survey was conducted during the period of August 2012 to June 2013. The survey used a multistage cluster design, sampled 165 665 individuals living in 44 136 households and recorded all recalled snakebite events that had occurred during the preceding year. Log-linear models were fitted to describe the expected number of snakebites occurring in each month, taking into account seasonal trends and weather conditions, and addressing the effects of variation in survey effort during the study and of recall bias amongst survey respondents. Results: Snakebite events showed a clear seasonal variation. Typically, snakebite incidence is highest during November-December followed by March-May and August, but this can vary between years due to variations in relative humidity, which is also a risk factor. Low relative-humidity levels are associated with high snakebite incidence. If current climate-change projections are correct, this could lead to an increase in the annual snakebite burden of 31.3% (95% confidence interval: 10.7-55.7) during the next 25-50 years. Conclusions: Snakebite in Sri Lanka shows seasonal variation. Additionally, more snakebites can be expected during periods of lower-than-expected humidity. Global climate change is likely to increase the incidence of snakebite in Sri Lanka.

Mapping the Risk of Snakebite in Sri Lanka - A National Survey with Geospatial Analysis.

BACKGROUND: There is a paucity of robust epidemiological data on snakebite, and data available from hospitals and localized or time-limited surveys have major limitations. No study has investigated the incidence of snakebite across a whole country. We undertook a community-based national survey and model based geostatistics to determine incidence, envenoming, mortality and geographical pattern of snakebite in Sri Lanka. METHODOLOGY/PRINCIPAL FINDINGS: The survey was designed to sample a population distributed equally among the nine provinces of the country. The number of data collection clusters was divided among districts in proportion to their population. Within districts clusters were randomly selected. Population based incidence of snakebite and significant envenoming were estimated. Model-based geostatistics was used to develop snakebite risk maps for Sri Lanka. 1118 of the total of 14022 GN divisions with a population of 165665 (0.8%of the country's population) were surveyed. The crude overall community incidence of snakebite, envenoming and mortality were 398 (95% CI: 356-441), 151 (130-173) and 2.3 (0.2-4.4) per 100000 population, respectively. Risk maps showed wide variation in incidence within the country, and snakebite hotspots and cold spots were determined by considering the probability of exceeding the national incidence. CONCLUSIONS/SIGNIFICANCE: This study provides community based incidence rates of snakebite and envenoming for Sri Lanka. The within-country spatial variation of bites can inform healthcare decision making and highlights the limitations associated with estimates of incidence from hospital data or localized surveys. Our methods are replicable, and these models can be adapted to other geographic regions after re-estimating spatial covariance parameters for the particular region.

Ketamine as Rescue Treatment for Difficult-to-Sedate Severe Acute Behavioral Disturbance in the Emergency Department.

STUDY OBJECTIVE: We investigate the effectiveness and safety of ketamine to sedate patients with severe acute behavioral disturbance who have failed previous attempts at sedation. METHODS: This was a prospective study of patients given ketamine for sedation who had failed previous sedation attempts. Patients with severe acute behavioral disturbance requiring parenteral sedation were treated with a standardized sedation protocol including droperidol. Demographics, drug dose, observations, and adverse effects were recorded. The primary outcome was the number of patients who failed to sedate within 120 minutes of ketamine administration or requiring further sedation within 1 hour. RESULTS: Forty-nine patients from 2 hospitals were administered rescue ketamine during 27 months; median age was 37 years (range 20-82 years); 28 were men. Police were involved with 20 patients. Previous sedation included droperidol (10 mg; 1), droperidol (10+10 mg; 33), droperidol (10+10+5 mg; 1), droperidol (10+10+10 mg; 11), and combinations of droperidol and benzodiazepines (2) and midazolam alone (1). The median dose of ketamine was 300 mg (range 50 to 500 mg). Five patients (10%; 95% confidence interval 4% to 23%) were not sedated within 120 minutes or required additional sedation within 1 hour. Four of 5 patients received 200 mg or less. Median time to sedation postketamine was 20 minutes (interquartile range 10 to 30 minutes; 2 to 500 minutes). Three patients (6%) had adverse effects, 2 had vomiting, and a third had a transient oxygen desaturation to 90% after ketamine that responded to oxygen. CONCLUSION: Ketamine appeared effective and did not cause obvious harm in this small sample and is a potential option for patients who have failed previous attempts at sedation. A dose of 4 to 5 mg/kg is suggested, and doses less than 200 mg are associated with treatment failure.

The Safety and Effectiveness of Droperidol for Sedation of Acute Behavioral Disturbance in the Emergency Department.

STUDY OBJECTIVE: We investigate the safety and effectiveness of droperidol for sedation of acute behavioral disturbance in the emergency department (ED). METHODS: This was a prospective observational study in 6 EDs (August 2009 to April 2013). Adult patients requiring parenteral sedation for acute behavioral disturbance received droperidol 10 mg. If this did not sedate the patient within 15 minutes, further sedation was allowed but droperidol 10 mg was recommended as part of a sedation protocol. The primary outcome was the proportion of patients with an abnormal QT interval, defined by the at-risk line on the QT nomogram. Secondary outcomes were effectiveness determined by the time to sedation measured on the Sedation Assessment Tool, use of additional sedation, adverse events, and injury to staff or patients. RESULTS: There were 1,009 patients with an ECG performed within 2 hours of droperidol administration, with a median dose of 10 mg (interquartile range [IQR]10 to 17.5 mg). Thirteen of the 1,009 patients had an abnormal QT (1.3%; 95% confidence interval 0.7% to 2.3%), but 7 of these had another cause attributed for prolonged QT (methadone, escitalopram, amiodarone, or preexisting). In 1,403 patients sedated with a median total dose of droperidol of 10 mg (IQR 10 to 20 mg), the median time to sedation was 20 minutes (IQR 10 to 30 minutes) and 97% were sedated within 120 minutes. Additional sedation was required for 435 patients (31.0%; 95% confidence interval 28.6% to 33.5%). Adverse events occurred in 70 patients (5%) and oversedation without complications in 109 (8%), the latter more common for patients receiving benzodiazepines as additional sedation (16/109 [15%]). There were no cases of torsades de pointes. Injuries occurred in 34 staff members and 4 patients. CONCLUSION: The study supports the use of high-dose droperidol as a safe sedating agent for patients with acute behavioral disturbance in the ED. There is no evidence of increased risk for QT prolongation with the doses used in this study.