Vaccination against typhoid fever is recommended if you're travelling to parts of the world where the condition is common.
Typhoid is found throughout the world, but it's more likely to occur in areas where there's poor sanitation and hygiene.
High-risk areas include:
Vaccination is strongly recommended if you're going to be staying or working with local people, or if you're going to be staying for prolonged periods in areas where sanitation and food hygiene are likely to be poor.
In the UK, most people who get typhoid fever develop it while visiting India, Pakistan or Bangladesh. It's therefore particularly important that you're vaccinated if you're visiting these countries.
Vaccination against typhoid fever is usually free on the NHS from GP surgeries. Private travel clinics also offer the vaccine for about £30.
In the UK, the 2 main vaccines available to prevent typhoid fever are:
Combined typhoid and hepatitis A injections are also available for people aged 15 or over. Protection against hepatitis A lasts 1 year and protection against typhoid lasts 3 years.
The vaccines work by stimulating your body to create antibodies (infection-fighting proteins) that prevent you getting ill if you become infected with the typhoid bacteria.
But neither typhoid vaccine is 100% effective, so you should always take precautions when eating food and drinking water abroad.
As the Ty21a vaccine contains a live sample of Salmonella typhi bacteria, it isn't suitable for people with a weakened immune system – for example, people receiving certain types of treatment, such as chemotherapy.
It also isn't usually recommended for children under 6, whereas children can have the Vi vaccine from 2 years of age.
It's unclear whether the Vi and Ty21a vaccines present a risk to pregnant or breastfeeding women. But vaccination should be considered if there's a significant risk of getting typhoid.
The typhoid vaccine should ideally be given at least 1 month before you travel, although if necessary it can be given closer to your travel date.
Booster vaccinations are recommended every 3 years if you continue to be at risk of infection with typhoid bacteria.
After having the typhoid fever vaccine, some people have temporary soreness, redness, swelling or hardness at the injection site.
About 1 in every 100 people have a high temperature (fever) of 38C (100.4F) or above.
Less common side effects include:
Severe reactions are rare for both typhoid vaccines.
Read more about routine NHS vaccinations.
Whether you have been vaccinated against typhoid or not, it's important to take basic precautions when travelling in countries where typhoid fever is present.
Read more about food and water abroad.