Salmonella among chickens

[Baby Astronaut]

If a chicken lays an egg with salmonella, does that mean its other eggs from that same day will also have salmonella?

 

How does the bacteria spread among chickens/livestock?

 

There's only mention of how it spreads to people, rather than among chickens/livestock.

[Psycho]

Not necessarily (but don't eat them ), there are two methods of infection one is via the stool when the chicken is sitting on the egg, the other is via the ovaries which the bacteria can also infect if it escapes the intestinal tract. The chicken has no way to remove the infection so it will be prevalent until slaughtered or antibiotics are administered. The salmonella bacteria can sustain itself inside the chickens intestines and is endemic in nature, but normally doesn't lead to mortality in mature chickens, its spread occurs when it is excreted in faeces and other chickens come in contact with it.

 

However, most commercially produced eggs are from chickens vaccinated for salmonella, in the UK this can be verified by the British Lion Mark, however other eggs without it may also have been vaccinated.

Edited October 16, 2011 by Psycho

[Baby Astronaut]

Ah, vaccination makes sense.

 

So, if a chicken house is free of salmonella and you don't introduce any new chickens, will there be no cases of salmonella for as long as no outside contamination is allowed to enter? (Test/vaccinate all new chickens)

 

The same for livestock?

[Psycho]

Ah, vaccination makes sense.

 

So, if a chicken house is free of salmonella and you don't introduce any new chickens, will there be no cases of salmonella for as long as no outside contamination is allowed to enter? (Test/vaccinate all new chickens)

 

The same for livestock?

This should be the case assuming a new strain of salmonella immune to the vaccine doesn't evolve, however this is very unlikely and depending on the vaccine maybe almost impossible.

[Greg Boyles]

If a chicken lays an egg with salmonella, does that mean its other eggs from that same day will also have salmonella?

 

How does the bacteria spread among chickens/livestock?

 

There's only mention of how it spreads to people, rather than among chickens/livestock.

 

I believe that Salmonella, including the species that causes food poisoning in humans, are part of the normal gut flora of chickens and many other bird species.

[CharonY]

It is indeed so. Not only of birds, mind. Something like "normal" is probably not an ideal way to describe something complex as microbial community, but asymptomatic humans often also have (a low) titer of Salmonella. In the end, it depends on a combination of health status, type of strains and their amount whether it results in adverse health effects.

Edited October 17, 2011 by CharonY

[Egg Doc]

Chickens can be infected by Salmonella from a number of routes; feed, water, rodent droppings, fecal material from penmates, fecal material from wild birds, fecal material from wild animals, fecal material carried on the feet or hands of humans, contaminated flies, contaminated equipment brought into the house, etc. Vaccination is but one intervention (an important one) used to prevent Salmonellosis. Treatment of feed, rodent control, fly control, biosecurity (preventing all the physical carriers of disease agents into a flock), cleaning and disinfection of houses between flock placements (normally, flocks are taken in and out as a group of one age), and the use of preventative feed additives (non-antibiotics) that aid intestinal health and improve the resistence of the intestinal tract to Salmonella invasion. Salmonella enteritidis (SE) gained the ability gain access to the ovary and become incorporated into the egg itself, sequestered from egg shell washing and disinfection. Other Salmonellae are gut-borne and contaminate the shell and are washed off during the egg washing process. Refrigeration is a very important intervention to prevent SE from growing during storage to numbers that can infect a human.

 

One question I failed to answer was if other eggs laid by a chicken would be contaminated. Yes, a chicken that is infected with Salmonella enteritidis (SE) will lay contaminated eggs on a regular basis until she gains sufficient immunity to the disease to cease laying contaminated eggs. Todays modern laying hen lays about one egg a day.