Typhoid fever and paratyphoid fevers: rare in mainland France

Typhoid fever and paratyphoid fevers are systemic salmonella infections that originate in the digestive tract. Typhoid fever is caused by the bacterium Salmonella enterica serotype Typhi. Paratyphoid fevers A, B, and C are caused, respectively, by Salmonella enterica serotypes Paratyphi A, Paratyphi B, and Paratyphi C.

Salmonella Paratyphi B comprises two types:

• the Java type (known as “d-tartrate positive”), which is a minor salmonella strain most commonly responsible for febrile gastroenteritis;

• the non-Java type (known as “d-tartrate negative”), which causes paratyphoid fever B.

The reservoir for Salmonella Typhi and Paratyphi is strictly human (except for certain strains of Salmonella Paratyphi B: human and animal).

Typhoid fever and paratyphoid fevers are found worldwide. They are endemic in developing countries with poor hygiene (Asia, Africa, South America) and are rare and mostly sporadic in mainland France, where most cases are imported following a stay in an endemic area. In contrast, typhoid fever is endemic in Mayotte and French Guiana, with frequent outbreaks.

In 2020, the reduction in travel due to the global COVID-19 pandemic had a significant impact on the number of imported cases of typhoid and paratyphoid fever.

Transmission via feces

The source of contamination lies in the feces of sick individuals or asymptomatic carriers who shed Salmonella Typhi or Paratyphi. Transmission is possible as long as the bacteria continue to be shed in the stool, typically starting in the first week of illness and continuing throughout the recovery period.

For typhoid fever, approximately 10% of untreated patients continue to shed the bacteria for 3 months after the onset of symptoms, and 2 to 5% become chronic carriers with persistent Salmonella Typhi in the gallbladder.

Transmission is fecal-oral, either direct through ingestion of bacteria from the feces of infected individuals (failure to wash hands, contaminated doorknobs, etc.), or more commonly indirect through ingestion of water or raw foods (seafood, vegetables, etc.) that has been contaminated by the feces of infected individuals (sewage, manure spreading, etc.).

Vaccination for travelers

Prevention relies on good personal and food hygiene, avoiding the consumption—especially when traveling in endemic areas—of unchecked water and raw or poorly washed food. Typhoid fever and paratyphoid fevers are “dirty hands diseases” whose transmission chain can be broken by thoroughly washing hands after contact with feces and before handling food.

There is a vaccine against typhoid fever, currently recommended for travelers planning an extended stay (more than one month) or in poor conditions in countries where hygiene is poor and the disease is endemic, particularly in the Indian subcontinent and Southeast Asia. This vaccine can be administered starting at age 2. It consists of a single injection to be given at least 15 days before departure. Protection lasts for 3 years. Note, however, that this vaccine provides only 50–65% protection against typhoid fever and does not protect against paratyphoid fevers: it should not replace precautionary measures regarding water, food, or handwashing.

Varied symptoms

The incubation period (the time between infection and the onset of the first symptoms) is usually 7 to 14 days but can range from 3 days to 1 month, depending on the individual and the amount of bacteria ingested.

Typhoid and paratyphoid fevers typically present with prolonged fever, headaches, loss of appetite, splenomegaly (enlargement of the spleen), a rash on the trunk or abdomen, drowsiness (or even confusion), diarrhea, or, more commonly, constipation in adults. Clinical presentation may also be atypical, mild, or even asymptomatic, particularly in endemic areas. Paratyphoid fever generally has a less severe clinical presentation than typhoid fever. Without treatment, complications may arise in approximately 10% of cases, including gastrointestinal (bleeding, perforation), cardiac, pulmonary, and neurological involvement. The case-fatality rate can reach 10% without treatment. In France, it is approximately 1‰ with appropriate antibiotic therapy.

Diagnosis relies on the isolation of the causative bacterium (Salmonella Typhi, Salmonella Paratyphi A, B, or C) in the blood, bone marrow, urine, or stool.

Serology (Widal test) to detect antibodies against Salmonella Typhi has little diagnostic value and should not be performed.

Management of typhoid and paratyphoid fevers with antibiotics

Management of typhoid or paratyphoid fever may require hospitalization. Treatment is based on antibiotics.