Prevalence and risk factors of gastrointestinal nematode infestation of horses, donkeys and mules in tropical, dry and temperate regions in Mexico.

The aims of this study were to determine the prevalence of gastrointestinal nematodes (GIN) in horses, donkeys and mules and its associations with age, sex and climatic factors (derived from satellite data) to identify the potential risk factors of different climate regions in four Mexican states. From May 2017 to April 2018, a total of 560 farm owners or managers answered the questionnaire, and the data were used to establish three Köppen climate classes (tropical, dry, temperate). The overall prevalence of GIN parasites in equines was 77.9% (436 out of 560). The highest percentage of GIN was detected in mules (87.5%). In addition, the highest prevalence among the climate regions was found in the temperate climate (79.9%). The identified nematodes were strongyle type (77.9%), Parascaris equorum (5.7%), Strongyloides (0.7%) and Oxyuris equi (2.9%). The highest mean value of strongylid eggs per g faeces was found in the dry climate (632.6 ± 96.8), followed by that in the tropical climate (518.3 ± 49.7) and temperate climate (383.8 ± 30.2); however, a similar prevalence was observed between different climate regions. Age and sex were identified as risk factors for high shedding of strongyle eggs: the odds ratios for higher shedding intensities were 3.858 for geldings compared to mares, 2.602 for 6-10-year-old equines and 3.597 for ≤16-year-olds compared to young equines (≤5 years old).