Typhoid

What is it?

Typhoid and paratyphoid fever are caused by bacterial infections with the Salmonella enterica subspecies Typhi and Paratyphi (A, B and C). Collectively, typhoid and paratyphoid fever are known as enteric fever. Typhoid fever presents more commonly than paratyphoid fever and is associated with higher rates of severe complications and poorer outcomes. The similarities between typhoid and paratyphoid fever make it difficult to distinguish between the two diseases without diagnostic testing.

Enteric fever is different to the gastroenteritis that can be caused by other Salmonella bacteria.

What to look for

The incubation period of typhoid fever is usually 7 to 14 days but can range from 3 to 60 days. Typhoid and paratyphoid fever often present with prolonged fever and fatigue, headache, splenomegaly (enlargement of the spleen), abdominal symptoms (pain, lack of appetite, constipation or diarrhoea) and bacteraemia (bacteria in the bloodstream). A rash appearing as small pink clusters on the skin known as ‘rose spots’ can be seen in up to 30% of individuals with enteric fever. In severe cases, complications can include septic shock, gastrointestinal bleeding with perforation, altered conscious state. If left untreated, enteric fever can be fatal.

How is it transmitted?

Salmonella enterica is transmitted via the faecal–oral route and through ingestion of contaminated food and water sources. It is more common in developing countries with untreated drinking water and inadequate sanitation and food handling practices.

Approximately 10% of people infected with Salmonella enterica will excrete the bacteria for up to 3 months following acute infection. Approximately 1 in 20 infected individuals who do not receive treatment for typhoid fever will become an asymptomatic carrier of the disease.

Epidemiology

Although it is not prevalent in Australia, typhoid is a common disease in many parts of the world, especially Asia, southeast Asia and sub-Saharan Africa. In Australia, 100 to 200 returned travellers are diagnosed with typhoid every year

In 2019 it was estimated that 9 million cases of typhoid occur globally each year, resulting in 110,000 deaths. Children are disproportionately affected by infection.

Prevention

Prevention of typhoid fever includes both vaccination and undertaking food and water precautions whilst travelling in developing countries where typhoid is endemic.

Food and water precautions

Travellers should maintain the following precautions to limit exposure to infections: 

• undertake effective hand washing practices 
• drink bottled or boiled water 
• avoid ice ice unless it is made from safe water 
• ensure food is properly cooked
• avoid raw milk and products made from raw milk
• wash fruits and vegetables carefully, particularly if they are eaten raw
• when possible, peel vegetables and fruits. 

Vaccines

There are 3 vaccines available in Australia for protection against typhoid fever:

^{Blue shading = live-attenuated vaccine
§} While Vivaxim is not registered for use in children aged under 16 years, some immunisation specialists and travel medicine practitioners administer Vivaxim to children aged 2–15 years. Refer to Lau C. et al The tolerability of a combined hepatitis A and typhoid vaccine in children aged 2-16 years: an observational study Journal of Travel Medicine 2016: 15, 23 (2) for more information.
* There is no specific vaccine for paratyphoid fever however there is some evidence to suggest that administration of the oral typhoid fever vaccine (Vivotif) can provide some cross–protection against paratyphoid fever.

Precautions and contraindications

People taking both the oral typhoid vaccine (Vivotif) and the oral cholera vaccine (Dukoral) should separate these 2 vaccines by 8 hours, due to the risk of components of the cholera vaccine impacting how the typhoid vaccine is absorbed. 

Vivotif is live-attenuated vaccine and is therefore contraindicated in pregnant people and in individuals with immunocompromise.  

People who are currently receiving antibiotics, sulfonamides or antimalarial prophylaxis should receive one of the injected typhoid vaccines (Typhim Vi or Vivaxim) instead of Vivotif. Alternatively, time the last dose of the oral vaccine at least 3 days before commencing antibiotics, sulfonamides or antimalarial prophylaxis.

Vaccine side effects

Side effects from typhoid vaccination are usually mild and short lived.  

Injection site reactions commonly occur in people who have received injected typhoid vaccines (Typhim Vi and Vivaxim). Abdominal pain, diarrhoea, nausea, vomiting and urticaria (itchy rash) commonly occur after vaccination with the oral typhoid vaccine (Vivotif). 

Resources

• Australian Immunisation Handbook: Typhoid fever
• The blue book: guidelines for the control of infectious diseases
• World Health Organization: Typhoid