Dear Doctor,

There is talk of salmonella being on the rise recently. What exactly is it, how does it spread and who is prone? Marianne

Dear Marianne,

Salmonella is a bacteria that causes salmonellosis,( a type of food poisoning) and typhoid and paratyphoid fevers. It is one of the most common cause of food poisoning, world over. Infection occurs through ingestion of contaminated food products and water. Contaminated meat and milk products carry the greatest risk of transmitting infection. Some animals like cats, dogs and reptiles also carry the microbes and are capable of transmitting the infection.

An infected person passes the germs in his feces. It can pass on to an unaffected person by ingestion of any food or water contaminated by the fecal matter containing the germs. Some people may carry the germs but remain asymptomatic. They are still capable of transmitting infection to others.

The illness typically develops 1 to 3 days after exposure to the infection. Severity of illness depends on load of salmonella ingested and immune status of affected person. Abdominal pain, fever, diarrhea, vomiting are the common symptoms. Untreated, the infection can spread to the blood stream, causing sepsis. Via blood stream, bacteria can spread to the brain coverings causing meningitis. It can infect any joint causing septic arthritis. Perforation of the bowel can occur due to severe inflammation in typhoid. Diagnosis is made by blood tests and culture. Treatment is by suitable antibiotics and supportive therapy.

Poor personal hygiene, poor sanitation and sewage disposal, malnutrition, poverty and ignorance are some of the factors responsible for prevalence of salmonellosis and increase in urban areas.

Prevention lies in improving food hygiene. Food items need to be washed and cooked thoroughly before being consumed. Good hand washing before preparing, serving and eating food, is very useful in preventing infection. Vaccination against typhoid fever is available.