Sckrabulis et al. 2020 - Direct onshore wind predicts daily swimmer's itch (avian schistosome) incidence at a Michigan beach
Jason P. Sckrabulis: jason.sckrabulis@gmail.com
Alan R. Flory: arflory@yahoo.com
Thomas R. Raffel: raffel@oakland.edu
Conceptualization: TRR, JPS, & ARF. Methodology: TRR, JPS, & ARF. Analysis: JPS & TRR. Writing - review & editing: JPS & TRR. Funding: ARF. Literature searching: JPS & TRR.
Please email jason.sckrabulis@gmail.com with any issues or suggestions with the supplemental dataset, or submit via the GitHub issues tab for this repository. For questions concerning the manuscript, please email the corresponding author at jason.sckrabulis@gmail.com.
- May 18, 2022: Added statistical code as .R files to
code - Apr 30, 2021: Moved .csv files to
data - Oct 21, 2020: Added complete citation information
- Jan 7, 2020: First full commit
Please cite work as:
Sckrabulis JP, Flory AR, Raffel TR (2020). Direct onshore wind predicts daily swimmer's itch (avian schistosome) incidence at a Michigan beach. Parasitology 147(4): 431-440. https://doi.org/10.1017/S0031182020000074
Swimmer’s itch (SI) is a painful rash caused by skin penetration by free-swimming infectious cercariae of avian schistosomes, snail-borne helminth parasites related to the causative agents of human schistosomiasis. The goal of this study was to determine if commonly collected environmental data could be used to predict daily fluctuations in swimmer’s itch incidence at an inland beach in northwestern Michigan. Lifeguards collected daily data over four summers, including the number of self-reported SI cases, total swimmers, water temperature, wind speed, and wind direction. Mixed-effects binomial regression revealed that wind direction, wind speed, and time of day were the best predictors of daily SI risk. Swimmers entering the water in the morning or on days with direct onshore wind perpendicular to the shoreline had the greatest SI risk. However, there was a negative effect of wind speed after accounting for direction, where SI risk was greatest on days with a gentle breeze originating directly offshore. These results suggest that at this beach, direct onshore winds generate a surface-water current that causes SI cercariae to aggregate in the shallow waters used by swimmers. Data are needed from additional sites to confirm whether onshore wind is a generally important driver of SI incidence.
- README.md
- LICENSE.txt
- code
Folder of statistical code as .R files
CSA statisical analysis.R
- data
Folder of experimental data as .csv files used in data analysis for manuscriptCSA data among day variation.csv(dataset without time of day effect)CSA data within day variation.csv(dataset with time of day effect)
CSA data among day variation.csv
| Variable Name | Description |
|---|---|
| Date | Date of data collection |
| CalDay | Calendar day (categorical variable) |
| SiAM | Number of SI cases reported in the morning session |
| SiPM | Number of SI cases reported in the afternoon session |
| SiTotal | Total number of SI cases reported per day (SiAM+SiPM) |
| PrevSi1/3/5/7 | Average number of SI cases reported in the previous 1/3/5/7 days |
| WaterTempF | Surface water temperature within the swim area, measured in Farenheit |
| WaterTempC | Calculated surface water temperature within the swim area in Celsius (from WaterTempF) |
| AvgPrevTemp1/3/5/7 | Average surface water temperature in the swim area in the previous 1/3/5/7 days |
| WindDir | Nearest 8-way wind direction (N, NE, E, SE, S, SW, W, NW) |
| WindDirGroup1 | Nearest 4-way 'paired' wind direction (N+NE, E+SE, S+SW, W+NW) |
| WindDirGroup2 | Nearest 4-way 'paired' wind direction (NE+E, SE+S, SW+W, NW+N) |
| WindVel | Wind velocity in miles per hour |
| SwimAM | Number of swimmers reported in the morning session |
| SwimPM | Number of swimmers reported in the afternoon session |
| SwimTotal | Total number of swimmers reported per day (SwimAM+SwimPM) |
| NWSprecip1 | Precipitation present, where 'trace' was reported as present (binary variable) |
| NWSprecip2 | Total inches of precipitation per day, where 'trace' was reported as 0 (continuous variable) |
CSA data within day variation.csv
All variables are the same as the among day variation dataset except for the following differences (Note that the temporal variables are still described as averages of the previous day):
| Variable Name | Description |
|---|---|
| TimeOfDay | Time of day where AM = morning session and PM = afternoon session) |
| SiTotal | Number of SI cases reported during that session |
| SwimTotal | Number of swimmers reported during that session |