Typhoid fever is a serious illness caused by bacteria belonging to the Salmonellagenus.
The typhoid fever agent
The typhoid and paratyphoid fever agents are bacteria belonging to the Salmonellagenus, which only affect human beings (Salmonella typhi, Salmonella paratyphi A, and some strains of Salmonella paratyphi B and Salmonella paratyphi C).
Transmission of typhoid fever
The only reservoir for the Salmonella responsible for typhoid and paratyphoid fever is humans, and infection occurs when drinking water or eating food contaminated by human faeces. The countries most affected are those with poor hygiene (Asia, Africa, Latin America), although episodic infections also occur in industrialised countries. More than 20 million cases are recorded each year, with more than 200,000 deaths.
Symptoms of typhoid fever
The initial symptoms develop after an incubation period of one to two weeks, with a continuous high temperature combined with headache, anorexia, prostration (tuphos, torpor in Greek) and abdominal pain with diarrhoea or constipation. There is a mild form in which the patient remains stable for around two weeks, after which convalescence takes several weeks. There are also severe and occasionally fatal forms of the disease, which cause complications in the bowel, heart or gall bladder. Untreated, its mortality rate rises as high as 10%.
Paratyphoid fever, which is caused by Salmonella paratyphi bacteria, is less severe and has a far lower mortality rate.
Treatment of typhoid fever
Antibiotics reduce the risk of death to less than 1%, although unfortunately, antibiotic-resistant strains have emerged. In addition, after recovering from typhoid fever, fewer than 5% of people continue to be infected (chronic carriers).
An anti-typhoid vaccine is also available, which only requires a single injection. This is generally given to travellers to high-risk countries.
Typhoid fever particularly affects developing countries (2006 map). © Percherie, Wikimedia, by-sa 3.0