Fowl Typhoid in Laying Hens: Description of the disease and Protection Conferred by a Live Salmonella Enteritidis Vaccine
Published:March 2, 2016
Summary
Introduction. Salmonella Gallinarum with the biotypes Gallinarum and Pullorum causes two septicaemic diseases in poultry: Fowl Typhoid and Pullorum Disease. The former Salmonella Pullorum serovar is not recognised anymore as such. Both biotypes are differentiated by a few biochemical and molecular tests. This bacterium is highly adapted to produce a septicaemic disease in birds. In general all...
With no antibiotics use what is the suitable and probably sustainable means of alleviating fowl typhoid incase a farmer is not too willing to cull infected flocks
Dear Ruth Tariebi Seimiekumo Ofongo
Thank you for your comment!
I quite understand the attitude of some farmers because after culling it is necessary to undergo a period of emptiness of the farm and afterwards it is necessary to adopt plenty of strict biosecurity measures, many times impossible to fulfill due to the structure of the farm or because the disease is widespread on neighboring farms and the Government authorities are unable or unwilling to implement a national eradication plan.
In such cases a simultaneous parenteral administration of antibiotics plus bacterins may be given and, a few days later when the antibiotic/s is/are removed from the birds, live vaccines should be administered, either based on the S. gallinarum 9R strain or attenuated S. Enteritidis, both live vaccines may administered either by oral or parenteral routes .
We have to bear in mind that no drug or drug combination is able to eliminate the infection and should be considered that the treatment of birds often produces resistance to the drugs used. Furthermore, antibiotic treatment often confers resistance to strains that persist in affected farms, so replacement of antibiotics having a different mode of action or alternately rotation is required. Isolation of wild S. gallinarum strains and performing antibiograms to the isolates may be helpful.
Legislation regarding live vaccines that are permitted by government agencies in each country varies. In several countries, vaccination with the rough strain of Salmonella gallinarum 9R is allowed only for laying hens but generally forbidden in all type of breeders. In other countries vaccination with 9R it is completely forbidden. This strain was developed around 60 years ago after been passaged in culture media with minimal nutrients. Although 9R strain provides a solid immunity it should be noted that retains some degree of pathogenicity. Live vaccines based on strain 9R can be administered by injection or drinking water. In case of severe outbreaks the best is to simultaneously administer 9R vaccine by oral and subcutaneous routes in order to stimulate both types of immunity (humoral and cellular).
Nevertheless, many farms of laying hens that are repeatedly vaccinated with Salmonella gallinarum 9R frequently suffer outbreaks of fowl typhoid. Therefore, it is necessary to admit that the rough vaccine strain 9R decreases, but not completely eliminate the infection caused by pathogenic smooth S. gallinarum strains. This situation and the remaining pathogenicity of 9R strain has determined that, in many of the farms, 9R is removed from the vaccination plan and replaced by the live attenuated vaccines against S. Enteritidis given together with inactivated vaccines (bacterins) against S. gallinarum and/or S. Enteritidis (both exert cross-protection against S. gallinarum), sometimes using autogenous isolates from the same farm.
Finally, we have to understand that once S. gallinarum enters into a farm it will persist causing some mortality and loss of posture from time to time. So, it is only possible to diminish clinical disease but up to a certain extent.
Best regards,
Dr. Horacio Raúl Terzolo
I recently visited an open poultry farm,having a capacity of 1000 birds.there was daily mortality of 40 birds approx.It was LSL layer breed,with age of more than one year.About 10 percent birds were lazy in the flock,with mortality of approx.40 birds from previous three days.litter was wet,with light green droppings.on post mortem,in some birds I found liver turning to slight greenish,but in most of birds,liver color was turning to yellow.spleen and other systems were normal.in some birds,liver was turning to bronze color.I suggested florfenicol and silymarin but was no response.
That excellent discutions about the use of live salmonella Enteritidis live vaccine.but my view that theire is no cross protection between the different strains of salmonellae so we need to control other types of salmonellae but its may be usefull for health of poultry consumers.
Dear Dr.Talapaneni.Kotaiah:
You are quite right, the best is to close the farm at the earliest and restart somewhere else with clean chicks. BUT Ruth (see above) have asked for something to do because the owner/s /does/do not want to eliminate the chickens and maybe they do not have any possibility to go somewhere else as you suggested. Ruth is asking for something to alleviate the disease until being able to start again. If the disease is severe in the geographical area it would be wise to restart with less susceptible genetic lines (white eggs instead of brown eggs).
Dr. Horacio Raúl Terzolo
Dear Dr. Syed Anjum Naqi:
I think that you have to be sure that the lesions and symptoms are really produced by Fowl Typhoid and not by Fowl Cholera. In some stages of both diseases the lesions are quite similar. In Fowl Typhoid the liver tends to acquire a green colour due to bile extravasation and always the splenomegalia is quite important. In both diseases there are hepatomegalia. BUT in Fowl Cholera the splenomegalia is absent or not quite so important. I think that you need bacteriological confirmation.
Best regards,
Dr. Horacio Raúl Terzolo
Dear Dr. Emad:
Your comment is very true. In Salmonella there are many serotypes (around 40 are important as pathogens) and even among serotypes there are different strains with different degrees of pathogenicity. Furthermore in vivo passages increase pathogenicity and in vitro ones decrease.
In laying hens S. Enteritis and in second place S. Typhimurium are the most important because of their high pathogenicity for humans and the transmission through eggs. There are many others but as we cannot control all we mainly focus the control over these two serotypes.
In broilers the epidemiological situation is quite different as many diverse serotypes may be found and the control should be more ample (in addition to these two serotypes). Some serotypes predominate in certain geographical areas and frequently one serotype replaces other, being the epidemiological situation variable.
Best regards,
Dr. Horacio Raúl Terzolo
Even if he builds a new farm, He should start with fresh chicks. The mortality in the flock will stop with injection of Gentamycin 10mg/Kg body weight to be given to all the flock(100% birds to be injected). Even other antibiotics like Amicacin injection will help.
This is just to stop the mortality as a veterinarian.
As a food producer, I should advise the farmer not to sell the eggs from the flock.
If he is restarting the farm there only with a gap, vaccination for growers will be an additional insurance.
cher Dr talapaneni quand vous utilise de la gentamicine en injectable mais pour combien de jours moi j'utilise de la colistine sulfonate en double dose pour 48heures deux fois de suite
Dr.Ninad Mokal is right.
The same works for Fow Cholera also.
But the trend is No use of antibiotics. Hence better the affected flock is removed and go for total cleaning and disinfection
Syed Anjum Naqi,
Mentioned lesions are suggestive of Fowl Typhoid infection so at this stage its better to control disease by treating birds with antibiotic but it is not the permanent solution. I have noted FT (& SE) can also be controlled by vaccinating flocks with inactivate vaccine like SALMOVAX (manufactured by Indovax Pvt. Ltd). SALMOVAX contains SG & SE strains which confer protection against Group D salmonellae i.e. SG, SP & SE.
Follow salmonella intervention programme, as - Salmonella infected birds can be identified by Salmonella Coloured Plate Agglutination Test using Sal.coloured antigen and simultaneously collecting cloacal swabs for bacteriological isolation and positive birds can be segregated and treated separately.
Further need strict control on water quality, feed, rodents, waste material disposal system, etc.
Follow this procedure for few consecutive batches, gradually you will find encouraging results.
For salmonell control we should keep approach like "prevention is better than cure". for that we have to tight loopholes in biosecurity also we have to analyse from where salmonella infection is catching. for that we can randomly send some weak chicks for isolation & we have to carry 100 % salmonella testing rigorously to identify birds maybe 5 -7 times in a life cycle. Cull those birds. also monthly random serum sample checking for salmonella isolation.
Dear Sayed Anjum Naqi
I had an same experience in layer hi line breed & with my suggestion farmer also get good result.
You can give all the weak bird gentamicin 10mg/kg bw one dose in morning ,0ne in evening & rest in the next day morning single dose. Try also with supportive treatment with liver tonic . Suggest the farmer to use captor 300gm/mt of feed & good acidifier with sanitizer on water helps to solve the issue
Dr. Terzolo is one of the best researcher worldwide in this subject and so an authority for discussing and comment it. I ask permission to add some tips very useful in FT outbreaks in Brazil. This is my opinion and experience. Pay attention that we are talking about Fowl Typhoid. 1. Even in very poor production systems, try to apply basic rules of biosecurity. Of course if you are not be able to apply all the procedures, try at least, the basic ones. 2. The worse scenario is to treat the flock with antibiotics, in all aspects. You are just postponing the problem. Remember, SG is an intracellular microorganism and so it is impossible to eliminate it in a flock through this procedure alone. 3. Segregate the brown egg layers in one house 4. As Dr. Terzolo has suggested, if possible try to use just white layers in your farm for a period. Be aware that these layers are more resistant to mortality but are equally infected by SG, so an excellent source of infection. 5. Check the red mite situation. Not any procedure absolutely will succeed to diminishing the mortality with high Dermanyssus gallinae infestation. If it is present, this is the very first point to attack. 6. The same counts for other parasites mainly in flocks reared over floor litter (black beetle) 7. We are using SG 9R vaccine especially developed for oral application in Brazil with excellent results in the beginning of an outbreak. This is not new (Silva et al. Avian Diseases. 25: 38-52, 1981), but it necessary to utilize a SG 9R strain that is capable to infect all the vaccinated birds through oral administration. The SG 9R vaccines developed for parenteral administration are not suitable for that.
All the comments are very useful. Thank you very much to all for sharing experiences!
In some countries the disease was eradicated only because there was Government support and strict regulations for everybody to fulfil without exceptions. The situation for the veterinarians is quite different in countries where the disease is endemic in laying hens. In these countries usually fowl typhoid is controlled in breeders but there is no use receiving new salmonella free chicks if these birds will be rapidly infected in a contaminated farm. Also it is no point in eradicating the disease in a farm located very near of other contaminated neighbouring farms. So, even the best is eradication this only applies to isolated farms with very good installations to apply biosecurity measures. This could be done in isolated geographical areas within a contaminated country but with governmental strict polices to avoid the entrance of infected chickens.
The real situation is to try to do the best to maintain production with laying hens chronically infected. To maintain infected chickens without severe outbreaks we need to immunise the pullets during rearing combining live (oral, eventually the last dose subcutaneous) and dead (parenteral, 2 doses, separated by 3-4 week interval, the second dose 3 weeks before the pick of posture) vaccines and periodically (oral each 2-3 months) vaccinations in the drinking water. If an outbreak appears we may combine a dead vaccine with antibiotic treatment but never administer antibiotics together with live vaccines. I agree that in chronically infected flock’s administration of 9R vaccine is the best. Once the disease was eradicated in laying hen farms or salmonella free breeders, 9R vaccine should not be allowed to be used anymore and should be replaced by Salmonella Enteritidis mutants. We have to understand that antibiotics are only useful if in parallel we strongly immunise the chickens.
Finally the recommendations of Dr. Paulo from Brazil are very important to diminish the challenge of the infected farm. Remember that if the challenge is too high no vaccine or antibiotic is able to stop outbreaks or mortality. Biosecurity measures keep the dose to a tolerable level.
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