What is typhoid fever?
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:
- Abdominal pain
- Muscle aches
- A rash.
The bacterial cause of typhoid fever is also known as Salmonella typhi and this is shortened to S. typhi.
What are paratyphoid fever and salmonellosis?
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.
What are the risk factors for typhoid fever?
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.
How is typhoid fever diagnosed?
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.
What are rose spots?
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 usually occur between the second and fourth week of illness.
- Groups of 5–15 pink blanching papules (little bumps) appear on the anterior trunk.
- The papules range in size from 2–8 mm.
- They are usually distributed between the level of the nipples and umbilicus, but can also be found on proximal extremities and back.
- Each lasts 3–5 days.
What is the cause of rose spots?
Rose spots are thought to be bacterial emboli to the skin, in which clumps of bacteria spread through the bloodstream.
- Salmonella can be cultured from rose spots.
- Emboli may rarely be observed in skin biopsies.
Rose spots have also been described in other infections (psittacosis, brucellosis, shigellosis, streptobacillosis, and leptospirosis).
What other skin changes are seen with typhoid fever?
Apart from rose spots, other rashes may arise in salmonella infections.
- Erythema typhosum – a generalised rash
- Haemorrhagic bullae (blood-filled blisters)
- Pustular dermatitis
- Erythema multiforme
- Sweet syndrome
What treatment is used for typhoid fever?
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.
Can typhoid fever be prevented?
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:
- An oral vaccine taken in four capsules on alternate days
- A single-dose injection two weeks before travel.
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.
- Wash hands frequently and thoroughly with hot, soapy water, especially before eating or preparing food and after using the toilet.
- Carry an alcohol-based hand sanitiser for times when water isn't available.
- Avoid drinking untreated water. Contaminated drinking water is a particular problem in areas where typhoid is endemic. Drink only bottled water or canned or bottled carbonated beverages.
- Avoid ice as well as raw vegetables or fruits that cannot be peeled.
- Brush teeth using bottled water.
- Eat foods that have been thoroughly cooked and are still hot and steaming.
- Avoid foods and drinks from street stalls.