Page content: Victorian statutory requirement | Infectious agent | Identification | Incubation period | Public health significance & occurrence | Reservoir | Mode of transmission | Period of communicability | Susceptibility & resistance | Control measures | Outbreak measures | International measures | Additional sources of information

Victorian statutory requirement

Salmonella (Group A disease) must be notified immediately by telephoneor fax followed by written notification within five days.

School exclusion: exclude until approved to return by the Departmentof Human Services.
Work exclusion: exclusions apply to food-handlers and some healthcare workers (see below).

Infectious agent

Salmonella typhi, the typhoid bacillus and Salmonella paratyphi,with three recognised serovars A, B and C are the infectious agents.

Identification

Clinical features
Typhoid fever (enteric fever) is a septicaemic illness characterisedinitially by fever, bradycardia, splenomegaly, abdominal symptomsand 'rose spots' which are clusters of pink macules on the skin.

Complications such as intestinal haemorrhage or perforation candevelop in untreated patients or when treatment is delayed.

Paratyphoid fever presents a similar clinical picture but is usuallymilder, shorter in duration and with fewer complications.

Method of diagnosis
Diagnosis is made by culture of typhoid or paratyphoid bacillifrom the blood, urine or faeces. Repeated sampling may be necessary.Serology in the form of the Widal test is no longer routinely used.

Phage typing is used for characterising S. typhi and S. paratyphiisolates for epidemiological purposes and in outbreak settings. A number of phage types are recognised.

Incubation period

The incubation differs for typhoid and paratyphoid fever:

• typhoid fever is usually 8-14 days but this depends on the infective dose and can vary from three days to one month
• paratyphoid fever is usually one to ten days.

Public health significance & occurrence

Typhoid and paratyphoid infections occur worldwide. Outbreaks occur in areas with poor sanitation and inadequate sewerage systems. Approximately 30-35 cases of enteric fever occur in Victoria each year. The majority of these are returned travellers, especially from the Indian subcontinent.

Reservoir

Reservoirs for typhoid and paratyphoid fever are:

• typhoid fever: Human gallbladder carriers and rarely human urinary carriers
• paratyphoid fever: Humans and rarely domestic animals.

Mode of transmission

Salmonella is transmitted by contaminated water and food and rarelyby direct contact. Water, ice (if unboiled water used), raw vegetables,salads and shellfish are important sources for travellers. The diseasecommonly occurs in association with poor standards of hygiene in foodpreparation and handling.

Period of communicability

It is communicable as long as typhoid or paratyphoid bacilli arepresent in excreta. Some patients become permanent carriers.

Susceptibility & resistance

Everyone is susceptible to infection. Immunity following clinicaldisease or immunisation is insufficient to protect against a large infectious dose of organisms.

Control measures

Preventive measures
Vaccination is not routinely recommended, except for travellers who will be exposed to potentially contaminated food and water incountries such as in Asia, the Middle East, Africa, Latin America and the Pacific Islands.

Vaccination should be considered for laboratory workers in potential contact with Salmonella typhi.

Three typhoid vaccines are currently available in Australia. Thelive oral vaccine and Vi capsular polysaccharide injectable vaccine generally cause few adverse reactions.

A combination hepatitis A and typhoid injectable vaccine is also available. All formulations are equally effective.

Vaccination does not offer full protection from infection and travellersshould be advised to exercise care in selecting food and drink.

No vaccine is available against paratyphoid fever.

The community should be educated about personal hygiene, especially thorough hand washing after toilet use and before food preparation.

Control of case
Hospitalisation is usually required for acute infections.

Antibiotic therapy may include one or more to the following agents:ciprofloxacin, ceftriaxone, chloramphenicol, amoxycillin or co-trimoxazole. However, strains resistant to chloramphenicol, amoxycillin and co-trimoxazoleare common in south Asia. Failure to respond to ciprofloxacin hasbeen reported from Vietnam. In the UK decreased susceptibility tociprofloxacin has been exhibited with increasing numbers of treatment failures particularly in patients with a travel history to India and Pakistan. A similar picture is emerging in Victoria with ongoing S.typhi and S. paratyphi after treatment being noted. Consult the current version of Therapeutic guidelines: antibiotic (Therapeutic GuidelinesLimited).

Education should be given to the patient regarding the importanceof completing the course of antibiotics, the possibility of relapse,persisting excretion, the need for good personal hygiene and precautions in food preparation.

Follow-up of all patients is conducted by the Department of HumanServices to identify possible sources of infection, other cases, andto manage ongoing risks.

If the patient is a food-handler or works in a profession that posesa high risk of transferring infection to others, such as health careworkers, or child care workers, they should be advised to cease work until advised by the Department.

The Department arranges the collection and testing of weekly faecal specimens for S. typhi or S. paratyphi to be taken over three consecutive weeks, commencing no sooner than at least 48 hours after cessationof antibiotic treatment. Food handlers and workers in high risk professionsare generally excluded from high risk work or patient care until they have had three consecutive negative faecal specimens.

Control of contacts
Contacts should be educated about the disease so as to reduce therisk of transmission and to allow for early identification if they develop symptoms.

The decision to screen contacts of cases is dependent upon the extentof contact and the likely source of the patient's infection. Faecal screening is generally arranged for:

• Household contacts of a case who are food-handlers or in a high risk profession. Screening is more intensive and includes the entire household if the patient has no history of travel to a typhoid-endemicarea.
• Fellow travellers.

Use of typhoid vaccine for contacts is not generally recommended.Typhoid vaccination is only recommended for persons with intimateexposure to a documented typhoid fever carrier, such as occurs with continued household contact.

Control of environment
A public health investigation is carried out to determine the mostlikely source of infection. A history of travel to an endemic area is usually found.

If there is no history of travel, local sources of infection are investigated to identify further cases, asymptomatic carriers, and contaminated food items.

Food industry
If a case is involved in commercial food preparation, the Department will determine the appropriate management of the workplace on an individual basis.

Outbreak measures

All cases are intensively investigated, whether sporadic or part of a cluster. Further actions to reduce the risk of infection during an out break may include:

• selective elimination of suspected contaminated food
• ensuring pasteurisation of milk
• ensuring appropriate chlorination or boiling of drinking waterprior to consumption
• reviewing the integrity of waste and sewerage systems.

Widespread use of typhoid vaccine is not generally recommended.

International measures

Typhoid vaccination is recommended for prolonged travel to endemicareas.

Additional sources of information

Skull, SA, Tallis, G 2001, "An evidence-based review of current guidelines for the public health control of typhoid in Australia:a case for simplification and resource savings", Aust N Z J PublicHealth, vol. 25, no. 6, pp. 539?42.