Off-host egg production capacity of Ascaridia galli

Experimental infection of a host with nematodes requires embryonated eggs. Embryonable eggs can be isolated either directly from the uteri of adult worms or from host faeces. This study investigated whether mature female Ascaridia galli worms recovered from the intestines of naturally infected laying hens can produce and release substantial numbers of eggs during a short off-host incubation, and whether such an incubation reduces uterine egg reserves. Seventy mature female A. galli worms were allocated to 14 replicate batches of five worms. Seven replicates were processed immediately for uterine egg recovery, while the remaining seven replicates were incubated in phosphate-buffered saline at 40 °C for 48 h. Nematode eggs released into the medium were quantified after 24 and 48 h, after which uterine eggs were recovered from the incubated worms. Egg counts from uteri of worms processed immediately at day 0 had an average of 32,420 (SD = 15,369) eggs per female with no significant difference (P = 0.544) from the uterine eggs of those processed after 48 h of incubation which had 29, 942 (SD =10,010) eggs. The incubated worms released 7548 (SD = 4438) eggs per female during day 1 and 7739 (SD = 3369) eggs per female during day 2, with no significant difference between the two days (P = 0.921). The daily egg release represented 28.3-36.4% of the uterine egg reserves, suggesting that mature female A. galli can release approximately one-third of their uterine eggs within 24 h as fully mature eggs. We conlcude that mature A. galli females can maintain short-term egg release outside the host without depletion of uterine egg reserves. The short-term off-host incubation offers a practical means of increasing egg recovery from a limited number of adult worms, and may thus contribute to reducing the number of chickens and worms required for the preparation of A. galli infection material.