Introduction
Introduction - paratyphoid fever and salmonellosis
Risk factors
Diagnosis
Introduction - rose spots
Causes
Skin changes
Treatment
Prevention
Typhoid fever, also known as enteric fever, is an infection caused by Salmonella enterica enterica, serovar Typhi. The symptoms of typhoid fever are nonspecific and can include:
The bacterial cause of typhoid fever is also known as Salmonella typhi and this is shortened to S. typhi.
Paratyphoid fever is an infection caused by Salmonella enterica serovar paratyphi, and can present similarly to enteric fever.
Both typhoid and paratyphoid fever are examples of salmonellosis, where the infectious agent originates from the genus of motile bacteria with a gram-negative staining pattern on microscopy, Salmonella.
Typhoid fever is contracted through contact with infected individuals and chronic carriers of typhoid fever (who are in good health but salmonella bacteria can be found in their faeces). Salmonella bacteria primarily infect humans and are transmitted through ingestion of contaminated water or food. This usually occurs in developing countries with poor hygienic practices but can occur anywhere.
Typically, individuals may have recently travelled to endemic areas (South East Asia, South America), ingested contaminated food or water, and experienced some of the symptoms listed above. The Salmonella bacteria can be found in faeces or blood. There may also be a rise in antibody levels observed in the blood.
Rose spots describe the rash that occurs in up to 30% of people infected with *Salmonella enterica serovar typhi. Characteristically, rose spots are seen in untreated typhoid fever.
Rose spots are thought to be bacterial emboli to the skin, in which clumps of bacteria spread through the bloodstream.
Rose spots have also been described in other infections (psittacosis, brucellosis, shigellosis, streptobacillosis, and leptospirosis).
Apart from rose spots, other rashes may arise in salmonella infections.
Typhoid fever is a bacterial infection, so is treated with antibiotics.
However, S. typhi is commonly resistant to several antibiotics, including trimethoprim + sulphamethoxazole, ampicillin, and chloramphenicol, and sometimes quinolones (eg, ciprofloxacin).
Ceftriaxone and azithromycin appear to be effective.
Prevention of typhoid fever is mainly achieved through vaccination and avoidance of high-risk foods.
Travellers to at-risk countries, for example, in South America and South-East Asia, are strongly recommended to be vaccinated in advance of travel. Two forms of salmonella vaccine are available:
If vaccinated previously, immunity can be checked by a blood test. Vaccine effectiveness declines with time. A booster may be necessary.
Good hygiene during food preparation and travel are essential.
