A lot of fanciers have carriers of paratyphoid in their lofts without knowing or suspecting it. This is exactly the main problem with paratyphoid. As soon as there are clear symptoms and the fancier can do some treatment and vaccination, there is a better health in the loft in general and better racing results. But as long as the symptoms are not clear, the birds just don’t seem to get in good condition without finding an indication why.
The disease can be acute or chronic. The acute disease only occurs when the birds were never infected with Salmonella or vaccinated in their lives and so don’t have any immunity for the disease. In the acute form there is diarrhea, sometimes even with blood, and anorexia. The pigeons also drink more water. And when there is no treatment there can be deaths because of the dehydration. When the disease gets chronic (in most cases) the Salmonella bacteria gets in internal organs and causes inflammation there, f.e. in kidneys, lungs, liver, spleen and reproductive organs. It can also in some cases (but not that often) cause arthritis or nervous symptoms. Because of the infection in reproductive organs the bacteria can get into the eggs and so cause infection of the hatchlings.
In the chronic form the symptoms are much less clear. In a lot of cases it is just not getting the birds in condition although there is no clear diagnosis of any disease. In a lot of cases the breeding is not always that good with sometimes “black” eggs (dead youngster in the egg) or bad reproductive results in general. Sometimes only one breeding hen just doesn’t seem to get in right condition and has trouble laying eggs. The birds also seem to have less appetite and lose some weight.
The diagnosis of the disease is often difficult. There are a lot of false negatives. This means there is no Salmonella found although the disease is present in the loft. One way of diagnosing is collecting droppings from all pigeons for five consecutive days and let it be investigated. Another good way is through autopsy of ill birds or birds that are strongly suspected of having the disease. A last way is by determining antibodies in blood samples, but also in these cases you only find antibodies in pigeons that have been recently infected.
Next to the difficulties in diagnosing the disease, the main problem is treatment. Actually there is no really good treatment for the illness. Antibiotics and vaccination are both not 100% effective. Most antibiotics can’t clear the carriers of the disease. There is even a lot of scientific data that most antibiotics induce more carriers than without treatment. Only enrofloxacine seems to have best effects also on carriers, but in practice there are still a lot of carriers of the disease after long treatment and high dosage. New scientific data show that with a very high dosage of enrofloxacine there couldn’t be any Salmonella found any more in internal organs after autopsy. Still in practice it is better to do a good vaccination schedule after antibiotic treatment.
The kind of vaccine seems to be less important than the vaccination schedule itself. There are dead and live vaccines. In Belgium there is only a commercial dead vaccine but if the bacteria has been isolated, the fancier can also have an autovaccine made. The advantage of live vaccines would be that there is a better cellular immunity. As this Salmonella is capable of surviving in macrophages, a sort of white blood cells, cellular immunity (killing of infected cells by the immune system) is more important than humoral immunity (immunity by antibodies in the blood). In practice it seems that also dead vaccines are effective, but as said they are not 100%. This means that in some cases the birds can still get ill, but certainly do not die any more.
More important is the vaccination schedule. In all cases it seems very good to vaccinate the birds twice the first time. This means that you should give them a prime vaccination and give a second vaccination one month later. Then, depending on the vaccine, the vaccination has to be repeated once or twice a year.
I always advise to vaccinate even if there is no real indication of problems in the loft. When the fancier doesn’t vaccinate there should be at least a regular examination of the droppings. But in a lot of cases when fanciers follow a good vaccination schedule the racing results are also better.