Fowl Typhoid in Laying Hens: Description of the disease and Protection Conferred by a Live Salmonella Enteritidis Vaccine

bonjour est ce qu'ont vaccinant s.entertidis ont protege contre s.pullorum merci

Thank you for an exhaustive ,practical and yet scientific analysis of the pathogenesis of salmonella infection in poultry.In a community where antibiotic therapy in early brooding is still a norm, most especially against most other bacteria such as clostridium, strep, staph, and even E. coli , will such not affect a live salmonella vaccine.?i would have also loved your study to incooporate an oil based salmonella vaccine for any variation of result. Also can't simultaneous probiotic intake affect the live vaccine? Pls advise. Thanks.

Salmonella is still a problem in many poultry producing countries. Recently, it had been shown that Salmonella Kentucky should be well monitored in the farms. Vaccines against SE & ST are being used in the breeders and layers. Some farmers are using the LIVE and the OIL BASED vaccines too depending on the epidemiological situation in the region. A study in the backyard poultry in Africa on the 6 major salmonella will be very helpful for the respective countries.

Nice informative article.What vaccination schedule you will suggest for broiler breeders.Whats your opinion about vaccination with 9R strain.

Dear Dr. Bouayad: This a very interesting question. In fact there no publications reporting trials regarding the protection of SE live vaccine against S. pullorum. Unpublished field experience from Brazil and China suggest certain levels of vertical protection when the vaccination schedule applies the 3rd dose by the subcutaneous route. This makes a lot of sense because S. gallinarum and S. pullorum have exactly the same antigenic formula and both biotypes are now considered to be only one serovar designed as S. Gallinarum (with capital letters). Best regards, Dr. Horacio Raúl Terzolo

Dear Dr. Alo Thank you for your comments regarding the article. I am glad to know that it is useful for you! As a general rule, never administer antibiotics when a live bacterial vaccine is used. You have to be sure that the antibiotic/s are completely withdrawn some days before and after vaccination, depending upon the vaccine; for that carefully read the instructions of the manufacturer and also take into account the pharmacology of each drug. When a dead or inactivated vaccine is injected, if necessary, antibiotics may be administered simultaneously. Antibiotics are unable to control or eliminate Salmonella, just they temporarily diminish excretion of salmonellas. Inactivated vaccines have a different mechanism of action as compared with live vaccines. These vaccines elicit anti-IgY, which passes to the eggs offering protection to the offspring of chickens (in breeders) or the human who consumes the egg (in laying hens). Therefore, during the rearing period, a combination of live (given first) and dead (given after) vaccines is the best. Always administer 2 doses of dead vaccine given the 2nd dose around 3 weeks before the pick of lay. During the lay period administer live vaccine by oral route every 3 months. Regarding probiotics, if you vaccinate SE at the 1st day of life this vaccine has a real probiotic effect as around 10% of the faecal flora is the SE vaccine strain, SE vaccine strain will disappear between 10 and 20 days after oral vaccination. Afterwards probiotics may be used but avoid to simultaneously administered them some days before and after oral vaccination. Best regards, Dr. Horacio Raúl Terzolo

Dear Dr. Anil Phadke: For broilers reared up to 6 weeks of age, a single dose given at one day of age of AviPro® Salmonella Vac E or Vac E and T live vaccine is enough. This dose may be given in the incubation plant o to the just arriving chicks in their boxes before depositing them on the bedding. Further protection to the chicks via anti- Salmonella antibodies in the incubation eggs may be given applying an inactivated live vaccination schedule to the parent female broiler breeders. Protection may be afforded against S. Enteritidis and S. Typhimurium together by means of dual vaccines, either live or dead, the latter only to the broiler breeders and laying hens. The vaccines based on 9R strain should only be applied to broilers at 4 weeks of age and only in cases of severe exposition to S. Gallinarum. This vaccine is pathogenic to 1 day-old or very young chicks.

bBONJOUR Dr HORACIO si je devait suivre un elisa indirect qu'elles serait selon vous les titres en vaccins vivants et en vaccins inactives vous avez dit qu'ont peut avoir dans le meme batiment ou la meme exploitation plusieurs types de salmonelles je voudrait s'avoir le titre en salmonelles infections et est ce que ont aura un titre eleve apres vaccination ajoutez a une infection je pense qu'ont vaccinant ont arrete l'infection mais pas le portage merci

Thanks Dr Horacio Terzolo,for information.We are using two shots of 9r at 7 & 16 weeks,followed by Salmonella entritides killed vaccine at 21wks.This gives good protection in broiler breeders & progeny.

Dear Dr. Bouayad, regarding your question about serology of Salmonella in animals vaccinated with live or inactivated vaccines, live vaccines do not usually elicit a high humoral response when orally administered. In contrast, inactivated vaccines are able to give higher titres, depending on the adjuvant used in the formulation and the vaccination schedule. Anyhow, since protection of the animals against salmonella not only depends the level of antibodies but also on the cellular immune response of the birds, there is no simple rule to follow about level of antibodies detected by ELISA and protection. Use of ELISA to determine whether a vaccinated flock is infected would only be a choice when the infective Salmonella belongs to a different serogroup from the vaccine. Regards, Pablo

Dear Dr Bouayad As per my opinion to control salmonella on Breeder or layer till yet no vaccine is succsessfully able to control salmonella because the source of salmonella not only vertically transmitted but other sources remain likebpersonnel,rodents,litter .my opinion to control salmonella with feed hygiene program if is mash or pellet with Formic + formaldehyde based product which helps to reduce contamination level in feed itself

BONJOUR Mr PABLO les tests ELISA sont utilise pour un but qui est surtous un serodiagnostic et une serovaccination il ya aussi des testes specifique pour chaque serotype ont a des ELISA pour dignostic s.entertidis D'autres s.pullorum ect est ils sont specifique pour detection IGG OU IGM selon le type d'ELISA donc il y'a une panoplies de testes je voudrais sinplement s'avoir par qu'elle methode vous avez obtenue les dates de vaccinations et les rapelles c'est que vous avez controler la cinetique ou avec la bacteriologie votre suivie de vaccination et une question selon vous le type d'ADJUVANT jusqu'a combien fait changer le titre d'anticorps est ce que des valeurs tres importantes ou peu significatif je suis interessant de le savoir MERCI

BONJOUR DR AZIMUL vous avez raison mais c'est un tout il faut vacciner et avoir une biosecurite faire une bonne desinfection est la verifier et utiliser des acides dans l'eau et l'aliment analyse l'aliment et l'eau donc c'est un tous

Dear Dr. Azimul, Regarding your comment about the importance of feed treatments, we have to be aware that herein we are mainly discussing about fowl typhoid. In paratyphoid salmonellosis feed transmission is essential because these paratyphoid salmonellas are able to survive in feed and feed additives and are very widespread in the environment; many feed additives are contaminated due to bulk transportation, which is highly exposed to contamination by faeces from rodents and birds. On the contrary, typhoid salmonella are highly adapted to the avian host and usually are not as widespread as paratyphoid in feed additives; although it is possible to isolate S. gallinarum from rodents, insects, red mites and wild birds, among others, survival of S. gallinarum in dried food is completely different from the resistant paratyphoid salmonellas. Nevertheless, mixed typhoid and paratyphoid infections in the same farm and even in the same bird (for instance, S. Enteritis together with S. gallinarum) are commonly found (when applying new molecular techniques) and for that reason it is wise to always adopt complete biosecurity and hygienic measures. Of course, vaccines are very important but unable to control outbreaks of clinical disease if the challenge is too high. For fowl typhoid eradication should be the final goal, meanwhile vaccines may help a bit. For paratyphoid infections a complete vaccination schedule, including live and dead vaccines if necessary, together with complete biosecurity and hygienic measures are the most efficient approach. Also we must vaccinate in paratyphoid infections to protect the humans who consume eggs; on the contrary, S. gallinarum is unable to produce disease in humans, therefore we only vaccinate to protect the hen from fowl typhoid. Best regards, Dr. Terzolo

Mr. Pablo Chacana erred in replying to Dr. Bouayad that one cannot set a level of antibody titer to differentiate vaccinated birds protected by vaccine from those that are inadequately protected. This is the most critical part that any developer of an ELISA or other immunological assays must have in mind ( or else, the test is useless).Secondly, the generalization that inactivated vaccines give higher antibody titers than live vaccine is not correct. Salmonella is a very large group of microorganisms. Their antigenic properties are shared in complicated manner and therefore It is very difficult to predict which among them give cross reactions to antibodies generated from the vaccination. The constant exposure to varied strains of Salmonella may bring down the antibody titers ( the latter are cross -reacted with other Salmonella strains which possess similar antigenic components to the Salmonella gallinarum as the real target of the vaccination). Protection becomes variable in vaccinated flocks of birds and vaccine break may happens at different times for different flocks. The use of ELISA or any other immunological become crucial to monitor the health status of vaccinated flocks. Managers must use this as a tool to decide when to give booster dose. The opinion of Dr. Bouayad is very close to this idea that a scientific/reliable tools must be used to manage flocks vaccinated with Salmonella gallinarum vaccine, so that boosters can be given as soon as necessary instead of relying on recommendation of vaccine manufacturer as evidenced by the recommendation of booster dose to be given every 3 months in this article.

Dear Dr. Quang Vinh, thank you very much for your kind comment. I am not sure if you understand right the comment I did about Dr. Bouyard question. I think Dr. Bouyard wanted to know if there is a good correlation between levels of antibodies and protection. In pathogens as Salmonella gallinarum, protection depends mainly on cellular immunity and thus high levels of antibodies do no indicate a good protection of the flock. Regarding ELISA and vaccines, what this technique actually estimates is the immunogenicity of a vaccine, and may be usefull to discriminate between birds with high or low response. Microtitration is another technique that may be used since it not only detects primary interaction between antibodies and the antigen, but also some biological interaction such as agglutination. Anyhow, potency of a vaccine against fowl typhoid should be evaluated in a experimental o field trial involving the pathogen since it is the most reliable way to determine its efficacy. Finally, from my opinion, to determine if a flock is infected with Salmonella, detection of the microorganism by classical microbiological methods or molecular detection is the most accurate methods.

BONJOUR Dr PHAN GUANG je vous felicite pour votre commentaire tres scientifique et professionel je vous remercie d'avoir bien compris mon raisonement je suis tous les jours confronter a la realite du terain et qu'il faut la corele avec le developement la theorie et aboutir aux solutions MERCI

Dear Dr. Quang Vinh, More comments about vaccines. Interestingly ,despite egg yolk antibodies from vaccinated hens have certain degree of protection against colonization of 1-day-old chicks the administration of the same purified extracted anti- O antigens of Salmonella to 1-day-old chicks do not protect so effectively chicks of the same age. So protection should be something more than antibodies! A classical veterinary example is shown in fowl typhoid 9R vaccines. Chicks vaccinated with S. gallinarum 9R are protected without eliciting antibodies because this strain lacks many LPS of the cell wall. It is really true that dead vaccines elicit high and long lasting antibodies than live vaccines. This is because fixed dead antigens last unchanged for a long time in the tissues and their antigenic stimulus are enhanced by adjuvants. Therefore, inactivated vaccines elicit high titer lasting 7 months or more. Having antibodies not necessary means complete protection against challenge. But these antibodies protect the egg against contamination by salmonelas of related serovars to the vaccine strains. So, these inactivated vaccines protect the product (the egg) rather than the hen. On the other hand, in normal circumstances, most live vaccines protect chickens up to 3 months. These data are recommendation of the laboratories based on many challenge trials to evaluate protection of these vaccines. As challenge trials are not available for every farmer it is wise to follow up vaccination schedules recommended by the manufactures adapting them to every particular flock and farm. Best regards, Dr. Horacio Raúl Terzolo

Salmanella pullorum and gallinarum are vertically transmitted and surface contamination spreads the disease. Cages and nipple drinking system helped in eliminating salmanella. Regular bood testing of breeding flocks using colored antigen helped elimination of disease. 9R gallinarum vaccine evoking cellular reaction did not interfere with testing. Going back from cages to litter will increase cases of salmanella incidence. Contamination of floor laid eggs will be high. Salmanella may reemerge as a major challenge for poultry veterinarians especially with no antibiotics usage. Culling of flocks may be the only way

Dear Dr.Talapaneni.Kotaiah, Very practical all your comments! Regarding rapid whole blood test we have to take into account that this test should be only interpreted considering the flock as a whole because this rapid test has no individual value. A positive test in a chicken does not mean that this particular chicken was or it is really infected as there are many other bacteria that share antigens with S. pullorum/gallinarum giving a false positive test. The use of this test has a very important diagnostic value in an infected flock although the elimination of positive reactors is not successful to eradicate the disease. As Dr.Talapaneni.Kotaiah stated culling of flocks may be the only way to eliminate fowl typhoid or pullorum disease. Very true and interesting the other remarks! I would like to add the importance of the faeces deposited under the cages to disseminate the infection to flies, red mites and rodents and eventually wild birds. Consider that red mites may directly infect the hen when they bite. Care has to be taken when the accumulated faeces are removed in an infected flock of caged laying hens because the faecal dust may be aspirated by the hens and many times a severe outbreak of fowl typhoid is produced with a pick of mortality immediately after removal. Best regards, Dr. Horacio Raúl Terzolo