Full revision of guideline.
Edited re clearance for cases.
Typhoid: Salmonella enterica subsp. enterica serovar Typhi (commonly S. Typhi)
Paratyphoid: Salmonella enterica subsp. enterica serovar Paratyphi - A, B, C (commonly S. Paratyphi A, B and C)
Laboratory definitive evidence
Isolation or detection of S. Typhi or S. Paratyphi A, B or C from any clinical specimen.
(Exception: S. Paratyphi B biovar Java does not cause a typhoid-like enteric illness. It causes gastroenteritis and as such is coded as one of the salmonellae.)
Note: national case definition is only for S.Typhi – S. Paratyphi is combined with other Salmonellas.
Community outbreak criteria
Two or more geographically or temporally or epidemiologically linked cases.
To notify on microbiological confirmation by telephone or facsimile.
Blood cultures are the standard diagnostic method. A large volume of blood (15mL in adults) improves sensitivity. The sensitivity of blood culture is higher in the first week of illness. Culture of bone marrow is more sensitive than blood culture. The sensitivity of stool culture depends on the amount of faeces cultured and the positivity rate increases with the duration of the illness. Bacterial shedding in stools is irregular.
Report only confirmed cases.
Confirmed case: A confirmed case requires laboratory definitive evidence.
Objectives of surveillance
Occurs worldwide. Most of the burden of disease occurs in the developing world. Outbreaks occur in areas with poor sanitation and inadequate sewerage systems. In Queensland, approximately 10 cases of typhoid/paratyphoid are notified each year, the majority being in returned travellers. Paratyphoid presents a similar clinical picture to typhoid but it is usually milder, shorter in duration and with fewer complications. Of the three serotypes, A is most common, and C extremely rare.
A systemic bacterial disease with insidious onset of sustained fever, marked headache, malaise, anorexia, relative bradycardia, splenomegaly, non-productive cough in the early stage of the illness, rose spots on the trunk in 25% of white-skinned patients and constipation more often than diarrhoea in adults. The clinical picture varies from mild illness with low-grade fever to severe clinical disease with abdominal discomfort and multiple complications (15% – 20% of patients may experience relapses depending on the antimicrobials used). Case fatality is less than 1% with prompt antibiotic treatment. After beginning antibiotics, symptoms typically abate within four days to a week. Unapparent or mild illnesses particularly occur in endemic areas. Mild cases show no systemic involvement; the clinical picture is of gastroenteritis.
Paratyphoid fever presents a similar clinical picture, but tends to be milder (relapses occur in 3% - 4% of cases).
Typhoid: Human, especially gallbladder carriers and, rarely, urinary carriers.
Paratyphoid: Human and questionably domestic animals.
Faecal-oral route. Contaminated water and food, rarely by contact. For travellers important sources are water or ice, raw vegetables, salads, raw fruits and shellfish. Sexual transmission of typhoid fever from an asymptomatic carrier has been demonstrated.
Typhoid: 3 days to over 60 days (inoculum dependent), usually 8 – 14 days.
Paratyphoid: 1 – 10 days.
As long as the bacilli appear in excreta, usually from the first week of illness. Left untreated, about 10% of typhoid fever patients will discharge bacilli for three months after the onset of symptoms and about 2% to 5% become permanent carriers. However, with appropriate treatment, the rate of chronic carriage is extremely low. Fewer people with paratyphoid fever become permanent gallbladder carriers.
Susceptibility is general and is increased in individuals with gastric achlorhydria and possibly those who are HIV-positive.
Relative specific immunity follows recovery from clinical disease, inapparent infection and active immunisation.
Locally-acquired cases are unusual in developed countries, but the actual or probable source of infection of every case should be determined. In consultation with the attending medical practitioner, obtain a food history and ask questions about recent overseas travel (obtain the date), exposure to someone else known to have travelled overseas recently, or exposure to other known cases/carriers.
Proving clearance for cases
Ensuring clearance of S. Typhi and S. Paratyphi from the stool of cases forms the basis of public health follow up. Cure is expected for nearly all persons who take appropriate antibiotic therapy, with low rates of relapse or chronic carriage. The risk of transmission is unknown, but should be low where hygiene practices are good.
All cases, at least 48hrs after completion of antibiotic therapy, should have stool specimens taken one week apart until two consecutive specimens are negative.
Then repeat stool culture one month later or earlier if symptoms recur. Any positive specimen necessitates re-treatment and recommencement of follow-up.
This should be decided on a case by case basis. Mild cases with a good understanding of hygiene issues and who are compliant with medication could be treated at home. Otherwise, the patient should be admitted to hospital for treatment and to undertake enteric precautions, with the aim of reducing transmission and preventing further cases.
Persons at higher risk of transmitting the disease include food handlers, carers of patients, carers of children, carers of the elderly, those unable to maintain personal hygiene and their carers. Children unable to maintain personal hygiene should be excluded from school or childcare until stool clearance is proven. For cases in higher-risk occupations (food handlers, carers of patients, carers of children, carers of the elderly), exclude from higher-risk duties until two consecutive stool specimens taken one week apart are negative. Case may return to work to undertake other duties (not higher risk) once they have recovered and diarrhoea has stopped. Cases not in higher-risk occupations may return to work or school once they have recovered and diarrhoea has stopped. These exclusions include cases who are chronic carriers.
Cases should not cook or prepare food for others in households until proven stool clearance. If they must cook, they should be absolutely scrupulous about hygiene until two consecutive stool specimens are negative.
All cases should refrain from using public swimming pools until stool clearance is proven.
Consult the latest edition of Therapeutic Guidelines: Antibiotic.
Good hygiene is the single most effective way of preventing the spread of typhoid in the home. The importance of hand washing, especially after using the toilet and before preparing or handling food must be emphasised and reinforced at each contact with the infected person.
An asymptomatic person who sheds S. Typhi for more than 12 months.
Consult an infectious disease physician. 750mg ciprofloxacin or 400mg norfloxacin twice daily for 28 days successfully treats carriers in 80-90% of cases.
Manage chronic carriers the same as others with a positive specimen (ie. faecal clearance and exclusion as above), but also assess gall bladder function and consider cholecystectomy if gallstones present. Investigate the urinary tract if a possible urinary carrier (biliary and urinary stasis are associated with carriage and removal of gallstones or surgery for urinary anomalies can clear the organism).
Yes, with the aim of detecting unapparent cases/carriers and counselling contacts about hygiene, symptoms to watch for and to seek prompt medical assessment if symptoms develop.
Household contacts, (and travel companions if the disease was acquired overseas). Consider incubation period of case (illness onset minus 60 days) and infectious period of case (illness onset until stool clearance)
Contact of an acute case - acquired overseas
Generally send a letter to travel group advising to seek prompt medical attention if symptoms develop. Beyond this, assess each situation individually. Travel contacts may have been exposed to same source as the case, may have acquired infection from the case or may be the source of infection of the case. Thus, investigate the nature of the contact with the case. If travel companions have had ‘household-like’ contact with the case (eg. sharing bathroom facilities, preparing food for the case, having food prepared by the case), arrange stool clearance as follows: two stool specimens 24 hours apart.
If the contact is employed in a higher-risk occupation, exclude from high-risk duties until two consecutive specimens are negative.
Household contacts employed in higher-risk occupations
In this scenario, household contacts cannot be the source of infection of the case, but may acquire the infection from the case. Hence, obtain two stool specimens 24 hours apart upon diagnosis of the case and a third specimen taken a minimum of 14 days after last contact with infectious case. Reinforce scrupulous hygiene measures and avoidance of high-risk duties until negative. Contact may return to work after first 2 specimens are negative.
Household contacts not employed in higher-risk occupations
Obtain two stool specimens 24 hours apart upon diagnosis of the case and a third specimen taken a minimum of 14 days after last contact with the infectious case. Can remain at work while awaiting results.
Contact of an acute case - acquired in Australia
In this scenario, contacts may be the source of infection of the case, may have been exposed to the same source as the case or may acquire infection from the case. Obtain two stool specimens 24 hours apart and a further specimen 14 days after last contact with infectious case. If the contact is employed in a higher-risk occupation, exclude from high-risk duties until two consecutive specimens are negative. Reinforce scrupulous hygiene and avoidance of high-risk duties until third specimen is negative.
Contact of a chronic carrier
Chronic carriers may continue to excrete while being treated or awaiting screening. Chronic carriers may infect others in their household while being treated and followed up, although this is considered unlikely.
Encourage early referral if symptoms develop. Re-educate about hygienic practices, in particular hand-washing before eating and preparing food, and after going to the toilet.
Other control measures
Typhoid vaccination is recommended for all travellers two years of age and over going to endemic regions where food hygiene may be suboptimal and drinking water may not be adequately treated. Travellers include the military. Vaccination should be completed at least two weeks prior to travel.
Laboratory personnel routinely working with S. Typhi should also be considered for vaccination.
Oral and parenteral vaccines are available. See the latest Australian Immunisation Handbook for further information.
Other preventive measures include:
Prepare a report of the investigation for the Communicable Diseases Branch, Queensland Health, on request.
Complete report form for OzFoodNet.
Antibiotic Expert Group. 2006. Therapeutic Guidelines: Antibiotic: version 13. Therapeutic Guidelines Ltd: Melbourne.
Bhan MK, Bahl R, Bhatnagar S. 2005. Typhoid and paratyphoid fever. Lancet, 366: 749-62.
Heymann D (Ed). 2008. Control of Communicable Diseases Manual, 19th ed. American Public Health Association: Washington.
NHMRC (2008) The Australian Immunisation Handbook, 9th ed. NHMRC: Canberra.
Parry CM, Dougan G, White NJ, Farrar JJ. 2002. Typhoid fever. New Eng J Med 347(22):1770-1782.
Skull SA, Tallis G. An evidence-based review of current guidelines for the public health control of typhoid in Australia: a case for simplification and resource savings. Australian & New Zealand Journal of Public Health 2001;25:539-42.