Web Seminar Questions

Questions to Prof Tom Humphrey

Please find below the questions and answers from the Web seminar Controlling Salmonella in Poultry. Please click on the question to show or hide the answer.

It is my understanding that there are vaccines against the above mentioned Salmonellas.
Company comment: Nobilis SG9R is a live vaccines for the prevention of Salmonella Gallinarum.

Vaccinating the birds with inactivated vaccines will provide them with protection against the Salmonella strains which are present in the vaccines and will also provide passive protection for the chicks as antibodies will be transferred in egg yolk.

This treatment can offer some degree of protection but should not be relied on as the only control measure.

These insects have been shown to harbour Samonella and there is the possibility that they can allow the carry over of the pathogen from one flock to the next.

Dust is an excellent example to determine if Salmonella is present in the house. However this may require confirmation by analysis of samples from some birds.

With killed vaccines one can be certain that birds have received the dose of vaccines.

It is my understanding that some vaccine strains carry a marker or can be differentiated from wild type isolates.

There are so many techniques that may be used that it would be difficult to give specific advise. However in my laboratory in Bristol we use BPW followed by RV broth for environmental samples.

To combine the answer to the above two questions. It is quite probable that fishmeal will contain Salmonella. While those serovars that are found are not often Enteritidis or Typhimurum, it is possible that they might be there or that other potential invasive Salmonella might need be present. In these circumstances control strategies might be needed and certainly consideration should be given to vaccination.

Company comment: Monitoring in lay in the EU is done by booth swabs or by checking manure from the manure scrapers. This occurs every 15 weeks. Next to that one time per flock dust samples are collected.

Under cooked or not well prepared chicken meat in an internationally important vehicle for both SE and ST. Both can be invasive in broiler chickens and both SE and ST have been recovered from chicken muscle tissue. Broilers chickens need protection from these serovars. In the UK this was achieved by culling infected broiler breeders but vaccinating these birds would also be an option.

Please see the above answer. The important aspect is that both serovars are naturally invasive in chickens.

Company comment: Most inactivated vaccines can be monitored by serology

In the UK this is done by re-processing. Company comment: Some countries use acids or heat treat the feed in the feedmill.

The compounds are quite labile and will fall within 24-48 hours of stress removal.

There are no vaccines against these compounds, the key to control is to improve the environment of the animals.

Immunity will be a mix of innate and adaptive responses. Thus there will be enhanced cycotokine response to limit invasive and increased circulation antibody levels to minimize the effects invasion should this occur.

It is my view that live vaccines do not work by blocking receptors but by the immune mechanisms discussed above.