In three separate experiments, 2- or 5-day-old commercial turkey poult
s were inoculated orally with astrovirus and examined for clinical sig
ns and for gross and microscopic lesions over a period of 14 days. By
day 2 postinoculation (PI), inoculated poults had developed diarrhea,
generalized loss of intestinal tone, and dilated ceca that contained l
ight-yellow fluid feces and gas; these changes persisted through day 1
0 PI. Mild crypt hyperplasia was the only change discernible by light
microscopy, and it was first noted in the proximal jejunum on day 1 PI
, in the distal jejunum and ileum on day 3 PI, and in the duodenum on
day 5 PI. A significant (P < 0.05) increase in crypt depth and area wa
s documented by image analysis on day 3 PI. Ultrastructural evaluation
revealed intracytoplasmic aggregates of astrovirus in enterocytes on
the sides and base of villi in the ileum and distal jejunum on day 3 P
I. Based on the findings, it was concluded that astrovirus caused lesi
ons and replicated in both upper and lower segments of the small intes
tine in turkey poults.