Typhoid fever is an infectious disease that is present (endemic) in many parts of the world. It is caused by the bacterium Salmonella typhi, which belongs to the Salmonella group of bacteria. There are more than 2,000 different types of Salmonella, most of which cause gastroenteritis, or food poisoning.
Typhoid is spread via the faecal-oral route and this can be through food or drink that has been contaminated by the faeces of a typhoid patient or a carrier of the bacteria. Direct faecal-oral transmission can also occur.
The disease varies in severity from a mild illness to a severe life threatening disease. The incubation period depends on the quantity of the bacteria swallowed and can vary from one to three weeks. Clinical symptoms include fever, headache, diarrhoea, muscle pain, loss of appetite and nausea. Typhoid can have serious complications, but these are more likely in untreated cases or those who present late for treatment, and includes intestinal haemorrhage and perforation. The case fatality rate is less than 1% with prompt antibiotic therapy but may be as high as 20% in untreated cases.
After recovery from the disease, about 10% of patients continue to excrete S. typhi in their faeces for up to three months, and 2-5% become long-term carriers (more than one year) of the bacteria.
Typhoid mainly affects low income regions of the world, where sanitation is poor and there is a lack of clean water. The majority of cases occur in Asia, Africa and South America. The World Health Organization (WHO) estimates that there are 16 to 33 million cases of typhoid world wide each year, with 500,000 to 600,000 deaths. Typhoid is rare in developed countries such as the UK, but it may be imported by a traveller who has visited an endemic region or by contact with someone who has travelled.
The risk of contracting typhoid fever when travelling depends on the country visited, and is highest in India, Pakistan and Bangladesh. The risk to a traveller when visiting high income countries such as those in Europe, North America and Australasia is very low. Areas where typhoid is endemic can change and so it is important to check for the latest information before travelling. In the UK, typhoid fever usually occurs in travellers who have visited endemic areas. The most common reason reported for visiting an endemic area is to visit friend and relatives. These travellers are less likely to seek pre-travel advice.
Typhoid fever can be successfully treated with antibiotic therapy, however drug-resistant strains have emerged. A relapse of disease can occur in a small number of cases despite antibiotic treatment. The symptoms are usually milder than the original illness and shorter in duration.
To help prevent the disease travellers should exercise scrupulous personal, food and water hygiene measures. Vaccination is recommended for travellers whose planned activities will put them at risk for typhoid in areas where sanitation and food hygiene are likely to be poor.