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Typhoid and paratyphoid for health professionals

Typhoid and paratyphoid are systemic illnesses collectively called enteric fever. Typhoid is caused by the bacterium Salmonella enterica, serovar Typhi (commonly referred to as S. Typhi) and paratyphoid is caused by S. enterica, serovars Paratyphi A, B, and C (with the exception of S. Paratyphi B biovar Java).

Typhoid and paratyphoid are common in areas of the world where hygiene standards are poor and water is likely to be contaminated with sewage, such as parts of:

  • Asia, particularly the Indian subcontinent
  • Middle East
  • Central and South America
  • Western Pacific islands
  • Africa.

Typhoid and paratyphoid are uncommon in Australia but may occur in returned international travellers. Locally acquired cases (in Australia) are almost always the result of secondary transmission, often in the same household, from an infectious returned international traveller.

Typhoid and paratyphoid are characterised by a gradual onset of sustained high fever, headache, malaise and anorexia. A dry cough may occur in the early stage of the illness and a macular rose-coloured rash is sometimes visible on the trunk. Hepatosplenomegaly may occur. Constipation or diarrhoea may occur, with constipation being more frequent than diarrhoea in adults.

Paratyphoid has similar symptoms to typhoid, although the illness tends to be milder.

Illness varies from mild with low-grade fever, to severe with multiple complications. Complications may include intestinal perforation, peritonitis, intestinal haemorrhage, septic shock, and neurological complications. Relapses occur.

Without treatment, fever may continue for weeks or months, and as many as 20% may die from complications of the infection. With treatment, the death rate falls to about 1%.

Some people become chronic carriers and excrete the bacteria in the faeces or urine for more than 1 year after the acute infection. Carriage is more common in people with biliary tract abnormalities such as cholelithiasis, or urinary tract abnormalities such as urolithiasis or schistosomiasis.

Transmission

  • Faecal-oral spread.
  • Humans are the only reservoir for S. Typhi and S. Paratyphi.
  • People with active disease and carriers shed the bacteria in their faeces and urine.

Common vehicles of infection in endemic countries are:

  • water or ice
  • raw vegetables
  • salads
  • shellfish.

Incubation period

The incubation period ranges from 3 days to more than 60 days and depends on the size of the inoculum, vehicle and host factors such as gastric acidity. The usual incubation period is:

  • typhoid - 8 to 14 days
  • paratyphoid - 1 to 10 days.

Infectious period

Cases are infectious as long as the bacteria are shed in the faeces or urine, usually from the first week of illness until completely recovered.

About 10% of untreated typhoid patients will be infectious for 3 months after onset of symptoms, and 2 to 5% become permanent carriers. Compared to those with typhoid, fewer people with paratyphoid become carriers.

Diagnosis

Diagnosis requires a compatible clinical illness and laboratory testing.

Early in the illness diagnosis is made by blood culture or bone marrow culture. Later in the illness the diagnosis may be through culture or nucleic acid amplification test (often PCR) on a faeces or urine specimen.

Notification

Typhoid and paratyphoid are notifiable conditions.

Treatment

Hospitalisation is usually required.

Antibiotic treatment is available and is necessary, particularly in severe cases. Antibiotic treatment reduces risk of death and other complications, reduces the duration of infectivity and can reduce carriage. People given antibiotics usually begin to improve within 2 to 3 days and deaths rarely occur. Resistance to available antibiotics is increasing. For specific antibiotic recommendations please see the current version of the Therapeutic Guidelines: Antibiotic www.tg.org.au

Infection control: cases

  • In hospitalised cases, contact precautions, in addition to standard precautions, should be used.
  • Exclude the case from childcare, preschool, school and work until at least 24 hours after resolution of symptoms and negative clearance specimen(s) for S. Typhi / S. Paratyphi as follows:
    • Food handlers, child care workers, health care workers and children less than 5 years of age who attend child care of any type require two negative stool specimens at least 24 hours apart and at least 48 hours after completion of antibiotic treatment. A negative urine culture is also required if a positive urine culture was initially found. Approval to return to work or child care for these cases must be given by Communicable Disease Control Branch medical officers.
    • In all other cases, exclude until at least 24 hours after resolution of symptoms and one negative faecal specimen is collected at least 48 hours after completion of antibiotic treatment.
  • Cases should not prepare food for others until specimen(s) demonstrate clearance.

Infection control: contacts

In South Australia this is coordinated by the Communicable Disease Control Branch.

  • Household contacts, household-like contacts and travel companions require screening of a faecal sample for the presence of S. Typhi / S. Paratyphi.
    • The following contacts require two faecal specimens collected at least 24 hours apart:
      • food handlers
      • child care workers
      • health care workers
      • children less than 5 years of age who attend child care.
    • All other contacts require the screening of one faecal sample.
  • Food handlers require exclusion from work until cleared by Communicable Disease Control Branch medical officers; this will require two negative clearance specimens. Other contacts do not require exclusion if well, however education on hand hygiene should been given.

Prevention

Most cases of typhoid notified in South Australia occur in Australians travelling to the Indian sub-continent to visit family and friends.

  • Recommend, unless contraindicated, typhoid vaccination for travellers to areas with endemic typhoid or paratyphoid. This includes those born in those areas who are returning for visits. Typhoid vaccines are available as monovalent oral live attenuated vaccine, parenteral monovalent vaccine, or in combination with hepatitis A vaccine. There is no vaccine available for paratyphoid, but the typhoid vaccine may provide some cross-protection.
  • Provide pre-travel advice prior to travel where typhoid and paratyphoid are endemic including:
  • Do not eat raw fruit and raw vegetables unless you can peel them yourself.
  • Cooked food that is served hot is usually safe. However, if eating meat or eggs, only eat meat or eggs that are thoroughly cooked.

Only consume safe beverages:

  • Water or other beverages in tamper proof containers which are bottled or canned by reputable manufacturers.
  • Water treated effectively at point of use. Boiling is the preferred method of treatment - whereby the water is brought to a rolling boil (i.e. lots of bubbling) then allowed to cool without ice. Alternatively water can be filtered or clarified then treated water with iodine-based or chlorine-based compounds. Filtering or clarifying is important to ensure effectiveness of the disinfectants. Iodine-based compounds (without a post-disinfection iodine removal step) are not recommended for long term use in infants, pregnant women, or people with a history of thyroid disorders or iodine hypersensitivity.
  • Hot beverages made with boiled water, kept hot and stored in clean containers.
  • Do not eat ice or add ice to drinks.
  • Use safe water to clean teeth. Do not use tap water.
  • Wash hands after using the toilet and before eating, drinking and smoking. If hand washing facilities are not available use an alcohol based hand rub (use moist hand wipes prior if hands are visibly soiled).

Information for patients 

 

 

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