Environmental change impacts on hatching of ovine gastrointestinal nematodes
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BACKGROUND: Projections for climate change forecast up to ~5°C higher temperature for temperate zones, and more extreme and frequent warmer winters and summers. This environmental change is expected to impact on disease epidemiology, including parasitic gastroenteritis. The free living stages of ovine gastrointestinal nematodes, the main cause of parasitic gastroenteritis, may be sensitive to this environmental change. Our hypothesis is that an increase in environmental temperature will accelerate hatching of gastrointestinal nematode eggs. METHODS: For this study, Teladorsagia circumcincta eggs, extracted from faecal samples of monospecifically infected sheep donors, were incubated in vitro at eight different temperatures, i.e. from 5°C to 40°C with increments of 5°C. Incubation was stopped at specific time points and total number of unhatched eggs and hatched 1st stage larvae (L1) were counted in triplicated samples. Each incubation temperature was replicated three times. The percentage of hatched L1 was calculated from the total number of L1 and unhatched eggs counted. RESULTS: Larval hatching occurred at all temperature levels within 5°C – 40°C. By increasing temperature from 5°C to 25°C, hatching of gastrointestinal nematode eggs was accelerated. Every increment of 5°C between 5°C and 25°C halved the time required for the same percentage of eggs to hatch. The biological variation within the trials at the same temperature was relatively small. CONCLUSIONS: Our data support the view that a rise in environmental temperature increases the rate of larval hatching, which has implications for pasture infectivity. Thus, under the expected climate change scenarios, it might be predicted that hosts are infected earlier and more severely in the grazing season, resulting in earlier outbreaks of parasitic gastroenteritis.
Other Titles/Title of Conference
13th ICOPA: International Conference of Parasitology, Mexico City, Mexico
International Congress of Parasitology