Salmonella Surveillance Program in Laying Hens in Israel, 2017-2018

Salmonella infection of laying hens and contamination of eggs are recognized as major causes of foodborne illness, and are thus the focus of surveillance programs internationally. Since June of 2017 the Israeli Veterinary Services (IVS) in collaboration with the Egg and Poultry Board (EPB) have initiated an active Surveillance Program to estimate Salmonella prevalence in table-egg laying flocks across Israel. There are approximately 1900 laying hen farms in Israel housing a sum of 6 million chickens. Most chicken houses are located in the north of the country. Each laying hen flock is tested by different environmental samples of dust at regular time intervals. Chickens are also tested at pullet chicken houses (the pre-laying stage). Sampling is performed by either the EPB or the IVS. Each flock sampled approximately 5 times during its life span. Bacterial cultures are performed at the EPB Laboratories. Salmonella isolates are analyzed by Real-Time PCR (EPB or Kimron Veteinary Institute) and serotype is determined by the Kauffman-White Le Minor scheme at the Salmonella National Reference Laboratory (SNRL), Ministry of health. Since June 2017 and up until December 2018, 3100 flocks were sampled from 1900 farms. Approximately 30% of flocks were positive to salmonella spp., 2.5% were positive to Salmonella Enteritidis (SE) and 1% were positive to Salmonella Typhimurium (ST). Other serotypes that were recovered from the layer farms included S.infantis, S.Coeln, S.Bovismorbificans, S.Hadar, S.Bredeney, S.Altona and more. Chickens from farms diagnosed with SE or ST are humanely euthanized and all eggs are destroyed or sent to the industry after heat treatment (pasteurization). The aims of the Active Surveillance Program are to systematically monitor Salmonella prevalence in laying hen farms and to decrease the risk of a zoonotic egg-related infection to the human population.