Topic: Salmonella
Question: Who is a chronic carrier of typhoid. In whom is chronic carriage likely. How to detect chronic carriers. Give details. What is the public health importance of detecting a chronic carrier.
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Who is a chronic carrier of typhoid?
– A chronic carrier is someone who continues to harbor Salmonella enterica serovar Typhi in their body for more than 1 year after the initial acute infection.
In whom is chronic carriage more likely to occur?
– Chronic carriage is more likely in individuals who have recovered from a prior episode of typhoid fever.
– It is more common in middle-aged women, who were infamously dubbed as “Typhoid Marys” in the early 1900s.
– People with gallstones have an increased risk of becoming chronic carriers since bacteria can hide in the gallbladder.
– Those with altered immunity like HIV infection, malnutrition, chemotherapy are also at higher risk.
How to detect chronic carriers?
– Perform stool cultures every month for at least one year after acute infection to detect chronic shedding.
– Culture bile or duodenal contents to isolate S. Typhi since it may be present only in the biliary system.
– Check urine for the presence of Vi antigen using typhoid Vi immunoglobulin assays.
– Use advanced molecular tests like PCR on blood, stool or urine samples.
What is the public health importance of detecting carriers?
– Chronic carriers intermittently shed bacteria in their stool and serve as a reservoir for disease spread.
– Finding carriers allows public health authorities to exclude them from being food handlers, nurses or other high-risk occupations.
– Carriers can be treated with a 4-6 week course of antibiotics to try and eradicate the bacterial persistence.
– In some cases, cholecystectomy may be done to remove the gallbladder if it is the site of bacterial persistence.
– Identifying and managing carriers, especially “Typhoid Marys”, is critical to control typhoid transmission in endemic areas.
