Diurnal fluctuations in nematode egg excretion in naturally and in experimentally infected chickens

Abstract

We investigated whether nematode egg excretion through feces of naturally or experimentally infected chickens follow certain patterns within a day, which may allow determining the most appropriate sampling time for the highest parasite egg concentration. Feces samples (. n=. 864) from chickens (. n=. 36) with naturally occurring mixed nematode infections (trials N1, N2) or with an experimental Ascaridia galli infection (E) were collected quantitatively every 4. h for four consecutive days. Number of eggs per gram of feces (EPG) was determined, and accumulative egg output (AEO) at each sampling time as well as total number of eggs excreted within 24. h (eggs per day, EPD) were then estimated. At the end of the collection period, the hens were necropsied and their worm burdens determined. Naturally infected hens harbored Heterakis gallinarum (100%), Capillaria spp. (95.7%) and A. galli (91.3%). The experimental A. galli infection produced patent infections in all the birds.In general, both fecal egg concentration (EPG) and the amount of feces increased (. P. 0.05) between effects of sampling hours and days on EPG and AEO, suggesting the existence of repeatable diurnal fluctuations within each day.Although an association between climatic parameters (e.g., ambient temperature and relative humidity) and the nematode egg excretion was quantified, a causal relationship could not be demonstrated. We conclude that nematode egg excretion through chicken feces in both natural and experimental infections shows repeatable diurnal fluctuations, which may indicate adaptive strategies by nematodes and eventually favor parasite spread. Since analytic sensitivity of fecal egg counts suffers from low egg concentrations in feces, samples taken during the daytime have a higher diagnostic value.