Stephens CB, Spackman E, Pantin-Jackwood MJ. Effects of an H7 Highly Pathogenic and Related Low Pathogenic Avian Influenza Virus on Chicken Egg Production, Viability, and Virus Contamination of Egg Contents and Surfaces. Avian Dis. 2020;64(2):143-148
Both highly pathogenic (HP) and low pathogenic (LP) avian influenza virus (AIV) can cause decreases or even cessation of egg production in chickens and turkeys. Production of abnormal eggs (deformed, thin-shelled, soft-shelled) can also be caused by AIV infection. Additionally, egg surfaces and contents may also be contaminated with virus. Because data quantifying these effects are lacking, white Plymouth Rock hens were inoculated with HP or LP AIV while in production. No decreases in egg production or abnormal eggs were observed with LPAIV-infected hens. No lesions or viral antigen staining in ovary and oviduct were observed in LPAIV-infected hens 3 days postchallenge. LPAIV RNA was detected on eggs collected from 12 hr to 11 days postinoculation (PI) and was on or in 6.4% (15/234) of the eggs. Titer equivalents of LPAIV ranged from 1.3-2.5 log10 50% egg infectious doses (EID50). No virus was detected in embryo tissue from eggs laid by LPAIV-infected hens. In contrast, egg production by HPAIV-inoculated hens decreased at 72 hr PI and 18.4% (16/87) of the eggs were abnormal. However, viability was similar to that of the sham inoculates. HPAIV RNA was detected in or on 11.1% (9/81) of the eggs from 36 hr through 96 hr PI, when the hens were euthanatized. HPAIV RNA was detected on 6.2% of eggshells, in 4.2% of albumin/yolk samples, and in 8.3% of embryo tissue. Forty percent of the abnormal eggs were positive for HPAIV RNA. Titer equivalents on or in HPAIV-contaminated eggs ranges from 1.0-4.0 log10 EID50. Lesions and viral antigen staining were present in the ovary and all sections of the oviduct of infected hens 3 days postchallenge. These data will inform models using production-based triggers for LPAIV monitoring and for risk assessments to determine the disposition of eggs from flocks infected with LPAIV or HPAIV.
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