What are the symptoms of Salmonella Typhi infection? What is the transmission route?

Salmonella infections are extremely common and have a high mortality rate, so what is Salmonella? What are the routes of infection of Salmonella? What are the symptoms of Salmonella?

Introduction to Salmonella

Salmonella infection is a zoonosis that is widely distributed, occurs worldwide every year, and has a high mortality rate. The main symptoms are acute onset, fever, joint swelling and diarrhea.

Generally speaking, Salmonella is a Gram-negative bacillus with more than 2,500 serotypes, of which more than 1,400 can cause disease in humans and livestock and poultry. The more common ones include Salmonella choleraesuis, Salmonella typhimurium, Salmonella Enteritidis, and Salmonella Gallinarum. These bacteria cause tens of millions of human infections or outbreaks in poultry and livestock worldwide each year.

The pathogen of salmonellosis is a Gram-negative enteric bacillus belonging to the family Enterobacteriaceae, and nearly a thousand species (or strains) have been discovered. According to its antigenic components, Salmonella can be divided into basic bacterial groups such as A, B, C, D, and E. Among them, the main ones related to human diseases include Group A Paratyphi A Bacillus, Group B Paratyphi B and Salmonella typhimurium, Group C Propionibacterium paratyphi and Bacillus choleraesuis, Group D Typhi Salmonella and Enteritidis bacteria, etc. Except for Salmonella typhi, Salmonella paratyphi A and Salmonella paratyphi B that cause diseases in humans, most of them can only cause diseases in animals such as livestock, rodents and poultry, but sometimes they can also contaminate human food and cause food poisoning.

Salmonella does not reproduce easily in water, but can survive for 2-3 weeks, 3-4 months in the refrigerator, and 1-2 months in feces in the natural environment. The optimal reproduction temperature of Salmonella is 37°C, and it can multiply in large quantities above 20°C. Therefore, storing food at low temperatures is an important preventive measure.

Transmission

Salmonella is mainly transmitted between humans and animals through the fecal-oral route. The disease is caused by eating food or drinking water contaminated with Salmonella. The patients, sick livestock and poultry then excrete the bacteria through their feces and spread the disease. Salmonella can survive outside the body for about a week. If the source of infection cannot be effectively controlled, it will cause a widespread epidemic.

1. Sources of infection: Sick pigeons and carriers are the main sources of infection. Humans, poultry, livestock, rodents and other wild birds infected with Salmonella are also important sources of infection. The bacteria mainly exist in the digestive tract and are widely spread through fecal contamination. Chronic carriers are also an important source of infection.

2. Transmission route: Through contaminated food and water, as well as contaminated feeding troughs, drinking fountains, etc.

3. Susceptible pigeons are generally susceptible, especially young pigeons, where the incidence rate is higher. Adult pigeons often become latent carriers and are also easily overlooked sources of infection.

4. Epidemic characteristics Salmonella is widely distributed throughout the world, with a high incidence in areas with poor sanitary conditions. The disease can occur throughout the year, with the peak incidence in summer and autumn.

Symptoms

It is mainly characterized by fever, diarrhea, joint swelling and motor nerve dysfunction. There are four types:

1. Intestinal type: Due to inflammation of the intestine, digestion and absorption dysfunction occur, appetite is significantly reduced, and gray-green, foul-smelling loose stools are discharged with foam;

2. The joint type can cause joint swelling and effusion, which is usually unilateral, with drooping wings and a reluctance to fly;

3. Visceral type may cause damage to multiple organs, including the heart, brain, and kidneys. Sick pigeons may show depression, difficulty breathing, weakness, and even death.

4. Neurological type: When the pathogen invades the brain or spinal cord, central nervous system symptoms appear, manifested as movement disorders, staggering gait, and twisting of the head and neck.

5. The acute type often causes death due to sepsis in young pigeons. If the disease survives, it will also cause many sequelae, especially latent carriers and excretion of bacteria that may contaminate other pigeons.