'Salmonellosis' in poultry

Pashu Sandesh, 10th August 2021

Pratibha Yadav, Vinay Waskel, Rahul Khatri, Daljeet Chhabra, Rakesh Sharda, Joycee Jogi, Rakhi Gangil and Ravi Sikrodia

Department of Veterinary Microbiology, Co.V.Sc. & A.H., Mhow

NDVSU, Jabalpur

INTRODUCTION

Salmonellosis is an important bacterial infection in poultry caused by the bacteria Salmonella. The bacteria was initially discovered and isolated by Theobald Smith in 1855 from pigs infected with Hog cholera or Classical Swine Fever (CSF), while Dr Daniel Elmer Salmon identified the bacterial strain. 

Salmonella sp. is a gram-negative rod-shaped bacteria that is one of the most common infectious agents in the tropics, especially in areas with poor hygiene. Fowl typhoid and Pullorum disease are two distinct septicaemic diseases specific to avian species that are caused by two different species Salmonella Gallinarum and Salmonella Pullorum, respectively. Fowl typhoid is an acute or chronic septicaemic disease that usually affects adult birds, although birds of all ages may be susceptible whereas Pullorum disease affects the young chickens of mostly 2-3 weeks of age. Pullorum disease is also known as bacillary white diarrhoea.

MORBIDITY AND MORTALITY

Morbidity (no of birds affected) is higher than mortality (no of birds that die) in fowl typhoid and has a 10 to 90% infection rate while pullorum disease has upto 100% mortality. 

TRANSMISSION

Transmission of Salmonella is through contaminated feed, water and litter. Affected chicks would shed S. Pullorum in faeces and is majorly responsible for transmission among chicks. Various risk factors are involved in the transmission of Salmonella.

1. Animal factors: Chickens are natural hosts and highly adapted to these pathogens and become carriers. Depending on the age, the ability to survive increases with age and mortality is greatest in newly hatched chicks.
2. Environmental and Management Risk Factors: Environmental factors responsible for the infection are overcrowding, malnutrition, other stressful conditions, unhygienic surroundings. Moist feed and other organic materials promote bacterial growth.

CLINICAL SIGNS AND SYMPTOMS

Important clinical signs include depression, somnolence, anorexia, huddling after infection, droopy wings, dehydration, laboured breathing, ruffled feathers, weakness and adherence of faeces to the vent. In chicks, Salmonella Pullorum causes typical white diarrhoea and high mortality. In adult chickens, fowl typhoid causes listlessness and sulfur (yellow) coloured diarrhoea. 

DIAGNOSIS 

Diagnosis can be done on the basis of history, clinical signs and symptoms. Bacterial isolation and identification are done from the faecal samples. Other more specific diagnoses may include serological tests such as ELISA.

TREATMENT

Isolation should be done of the affected birds with other flocks immediately. Antibiotics therapy can be done either by intramuscular or oral route to reduce the infection. Antimicrobial therapy should be done after conducting an antimicrobial susceptibility test. Furazolidone 0.022% in feed is an effective antimicrobial therapy.

PREVENTION AND CONTROL

There are various programs run under national poultry improvement plans to prevent the economic losses caused because of Salmonellosis. Fowl typhoid is an economically important disease without their effective control the profitable production of poultry would be impossible. 

All the infected birds should be destroyed and the carcass of the infected birds should be discarded properly either by cremation or buried under lime. 

As preventive measures both live & killed vaccines are used for the prevention of Pullorum disease in birds, in which 9R strain is most commonly used.

Management Strategies: The principal managemental steps should include strict biosecurity measures. Repeated testing and removal of carriers can be effective in eliminating the infection from a flock. Poultry producers should not buy chickens from live bird markets or from uncertified or unknown sources, especially during outbreaks of disease. 

Poultry makers should not be accepting chickens from live bird markets or from uncertified particularly during episodes of infection.