Paratyphoid (PT) is an important bacterial disease of chickens worldwide. It is one of several types of diseases caused by infection with Salmonella
species. The outcome of exposure to Salmonella
is influenced by a variety of factors which include the chicken's age, general health, level of nutrition, breed, and whether they had any earlier exposure to the disease that might have allowed the bird to develop a natural immunity. Management and environmental factors that cause stress to the bird, such as overcrowding, concurrent parasitic infections, improper or poor diet, getting picked on by other birds, left out in the cold, etc. all compromise the birds’ ability to resist infection, and increase vulnerability to developing clinical disease.
How Paratyphoid is Transmitted
PT is transmitted to chickens multiple ways, however it is typically through other apparently healthy or recovered chickens that serve as carriers of the Salmonella
bacteria. Infected birds will shed Salmonella
in their droppings, which in turn contaminate the environment, where they will survive and multiply. This is why it's important to regularly clean the environment of where chickens are kept, because accumulation of droppings can lead to high levels of the organism in the environment. Salmonella
favors damp, warm conditions, where they can continue to replicate and survive for extended periods of time, without good management practices and regular cleaning occurs.
How Paratyphoid is Diagnosed
Paratyphoid is diagnosed in chickens through the identification of the presence of the Salmonella
bacteria associated with disease. Simply detecting the presence of Salmonella here is not a diagnosis of paratyphoid. The two most common tests performed for your veterinarian to obtain a diagnosis are:
- Bacterial culture: Using a swab, your veterinarian will obtain material from the suspected site, either internally (from a dead bird during a necropsy), or from the chicken's cloaca, throat, droppings or surgery site. Once collected, the swab is sent off to a diagnostic lab where it is cultured (i.e. grown) and bacteria identified. A follow up antibiotic sensitivity test is also useful in order for your veterinarian to determine which antibiotic will be most effective against the organism.
- Antigen Detection Test: A simple test which detects the presence of protein on the surface of the bacteria. The sample can be obtained during a necropsy on a dead chicken or from a live bird.