Seasonal dynamics of gastrointestinal helminths in naturally infected horses in Brazil.

This research study assesses the seasonal influence on gastrointestinal helminths in horses from a specific herd in Brazil. It finds that climatic conditions, particularly rainfall and temperature, significantly impact the population dynamics of these worms, with higher incidence during wetter, warmer periods.

Research Objective and Methodology

• The study is primarily concerned with understanding the seasonal dynamics of gastrointestinal helminths in horse populations to better plan treatments.
• The authors studied 147 horses, 64 females and 83 males, all from the same herd, over three study periods: 2015/2016, 2018/2019, and 2021/2022.
• Fecal samples were collected from each animal every 28 days for 12 months of each cycle and analysed for parasite eggs.
• The researchers recorded daily average air temperature, average relative humidity, and rainfall levels.
• These climatic data were collected by the Agroclimatological Station in Castilho, SP, just six kilometers from the study location.

Results and Findings

• The study found significant seasonal differences in parasite egg counts and rainfall averages across all three cycles.
• February consistently showed the highest egg count across all cycles (1626 in 2015/2016, 926.7 in 2018/2019, and 1885 in 2021/2022).
• The lowest average egg counts were recorded in July (642 in 2015/2016, 610.5 in 2018/2019, and 804 in 2021/2022).
• Rainfall was most concentrated during spring and summer, and these seasons coincided with higher parasite counts. Conversely, autumn and winter saw the least rainfall and lower parasite counts.

Conclusion and Implications

• The study concludes that climate conditions directly influence helminth population dynamics in horse herds. More specifically, wet, warm seasons encourage parasitic growth whereas dry, cold seasons do not.
• Given these findings, the authors suggest a strategic de-worming program focusing on spring and summer when parasites are most prevalent. This could maximize the effectiveness of treatments and minimize the overall impact of helminthiasis on horse health and productivity.