Guidelines for the Investigation and Management of Typhoid Fever Cases, Carriers and Contacts

I. INTRODUCTION

Typhoid fever is an illness caused by the bacterium Salmonella Typhi (S. Typhi). The disease is common in developing countries of Asia, Africa and Latin America. Most U.S. cases occur among travelers to these areas.

Incubation period: ranges from 3 days to 1 month (usually 8 to 14 days).

Symptoms:

• sustained fever,
• malaise,
• loss of appetite,
• constipation more commonly than diarrhea (in adults),
• rose spots on trunk;

In severe cases

• confusion,
• delirium and intestinal perforation;
• with prompt treatment,death rarely.

Period of communicability: usually from the first week of illness throughout convalescence.

Source: stool and/or urine of an infected person; no animal reservoir is known.

Mode of transmission: ingestion of food or water contaminated by the feces of an infected person.

II. DEFINITIONS

A. Case Definition

A probable case is defined as a person who has clinical symptoms that are compatible with typhoid fever and who is epidemiologically linked to a confirmed case.

A confirmed case is defined as a person who has clinical symptoms that are compatible with typhoid fever and who is lab-confirmed by isolation of S. Typhi from blood, stool, or other clinical specimen.

B. Outbreak Definition

An outbreak is defined as two or more cases (probable or confirmed) of typhoid fever (includes S. Tyhpi cases and/or carriers).

C. Carrier Definition

A typhoid fever chronic carrier is defined as a person who excretes S. Typhi in the stool at 12 months following acute illness, or following mild or asymptomatic infection. A chronic carrier state occurs in approximately 5 percent of infected persons.

A possible typhoid fever chronic carrier is defined as a person who does not show the presence of S. Typhi in their stool, however, this person has an elevated Vi antibody serological titer. This result indicates that the person may have had typhoid fever in the past and that they may continue to shed S. Typhi in their stool.

III. CONTROL MEASURES

A. Infection Control Precautions

1. Prophylaxis

Immunization is not routinely recommended for household and close contacts of active cases. Immunization is recommended for household and close contacts of typhoid fever carriers. Two vaccines are currently available: Ty21a (oral vaccine) and ViCPS (parenteral vaccine). Consult with DHMH for recommendations regarding use of the appropriate vaccine.

2. Education

Educate household members and employees in group settings (e.g., food handlers, daycare staff and personnel in long-term care facilities) to do the following:

• Thorough handwashing with soap and running water before food preparation and eating, after using the bathroom, handling soiled diapers, bed linen, commodes, etc., and personal hygiene in general.
• Use scrupulous cleanliness in food preparation and handling of food, especially salads and other cold-serve foods.
• Make sure to properly refrigerate of food.

B. Environmental Health Measures

If the case(s) appear to be endemic or domestically acquired, ask about exposures to the following during the incubation period (one month prior to onset of symptoms):

• Commercial food-service facilities
• Grocery stores and markets
• Day care facilities

Each food-service facility determined to be a possible source of infection should be inspected by a local health department sanitarian within 24 hours of notification by the communicable disease investigation team. If particular food items are recalled by the case(s), conduct a HACCP review or collect a list of ingredients for the item and review the steps involved in preparation of the item.

If a case is associated with a day-care facility, ask about symptoms among staff members and other children at the facility. Also inquire about any international travel among daycare staff and attendees within the two months prior to the onset of the known case.

C. Epidemiological Investigation

Determine the most probable source of infection by inquiring about recent (within one incubation period) exposure to:

• Person(s) with similar symptoms (e.g., household members, sexual
  partners, daycare-age children)
• Food consumed at home, restaurants, parties, during travel, etc., that may have been contaminated, undercooked or improperly stored; obtain the name and location of restaurant(s), food store(s), bakery(ies); inquire about group meals (e.g., receptions, meetings, conventions).
• Possibly contaminated water.
• Foreign travel (especially to countries where typhoid fever is endemic, primarily developing countries in Asia, Africa and Latin America).
• Foreign visitors (especially from countries where typhoid fever is endemic, primarily developing countries in Asia, Africa and Latin America).

If the source is known or suspected, expand the investigation as appropriate. Such investigation may include inspecting restaurants, calling or visiting child care facilities, or obtaining the names and telephone numbers of guests who attended group events to determine if others are ill.

D. Specimen Collection

S. Typhi can be isolated from the blood early in the disease. Isolation from urine and feces is possible after the first week of illness. Bone marrow culture is the best confirmation method. Additionally, pulsed-field gel electrophoresis (PFGE) can be useful for characterizing S. Typhi isolates and establishing links between individual cases.

A serological testing method, called the Vi antibody test, is available for identification of typhoid fever carriers. The presence of elevated antibody titers to a S. Typhi antigen (purified Vi polysaccharide) is highly suggestive of a chronic carrier state. Consult with DHMH regarding the use of this test.

E. Code of Maryland Regulations (COMAR) Applications

1. Reporting Requirements

Typhoid fever case
Code of Maryland Regulations (COMAR) 10.06.01.03 and 10.06.01.04 require health care providers, school and child care facility* personnel, masters of vessels or aircraft, and medical laboratory personnel to report a typhoid fever case to the local health department immediately via telephone. Upon receipt of a report of typhoid fever the Health Officer or designee shall notify the Maryland Department of Health and Mental Hygiene (DHMH), Office of Office of Epidemiology and Disease Control Programs (EDCP) immediately by telephone (410-767-6700).

*Child care facility means a licensed, registered, or unlicensed facility, institution, establishment, or home where children receive care or supervision for which money is paid when the child’s parent has given the child’s care over to another on a regular basis for some portion of a 24-hour day as a supplement to the parent’s primary care of the child.

Typhoid fever carrier
Upon receipt of a laboratory report of a S. Typhi-positive stool, the Health Officer or designee shall report the result immediately, by telephone, to the DHMH Epidemiology and Disease Control Program (410-767-6700).

The local health department should begin an investigation immediately to determine if the patient has illness with clinical symptoms. If the patient has symptoms consistent with typhoid fever, follow the guidelines in Section 2. Management of Cases and Contacts of COMAR.

2. Case and contact management

Typhoid fever case
Manage case and contacts according to COMAR 10.06.01.23:

• A case may not attend a child care facility and may not participate in occupations involving food handling, direct patient care, or care of young children or elderly persons until 3 consecutive stool specimens are Salmonella-free; these specimens should be collected not less than 24 hours apart and not sooner than 48 hours after discontinuation of antibiotics. (NOTE: The Health Officer can grant readmission of the case to a child care facility based on the low likelihood of transmission)
• A case may be released from supervision only after 3 consecutive negative stool specimens are submitted; these specimens should be collected at least 24 hours apart, at least 48 hours after discontinuation of antibiotics, and at least 1 month after onset of illness.
• If any of the clearance specimens are positive, at least 3 consecutive negative stool specimens at one-month intervals within the 12 months following onset shall be required for release from supervision.
• If a person continues to excrete S. Typhi at 12 months, he/she should be considered a chronic carrier of S. Typhi and followed as such.
• A household, sexual and other close contact of a case may not participate in any of the above stated occupations until 2 consecutive negative stool specimens, taken at least 24 hours apart, are submitted.

Typhoid fever carrier
Manage the chronic carrier and the household, sexual and other close contacts according to COMAR 10.06.01.23 and 10.06.01.06 (D and E):

A carrier of S. Typhi may not attend a child care facility and may not participate in occupations involving food handling, patient care, or care of young children or elderly persons.NOTE: The Health Officer can grant approval for readmission of the carrier to a school or child care facility based on:

• The behavior, neurological development and physical condition of the carrier;
• The precautions that may be taken to minimize or eliminate the danger of transmission;
• The susceptibility to typhoid fever of those likely to be exposed to the carrier in the school or child care facility;
• Precedents in the practice of public health.

2. The contacts of a chronic carrier may not participate in any of the occupations stated above until 2 consecutive negative stool specimens, taken at least 24 hours apart, are submitted.

3. Initiate and maintain a complete file of all pertinent information on the carrier.

4. Issue written instructions to the carrier concerning the restrictions upon and responsibilities of the carrier. The carrier shall abide with the restriction stated above and notify the Health Officer at once of any change in address or occupation.

5. Release the carrier from supervision only after 3 consecutive stool specimens are negative; these specimens should be taken 1 month apart and at least 48 hours after antibiotic treatment.

6. Contact the carrier at intervals of no longer than one year to verify the carrier’s occupation and address and to determine if all instructions are being followed.

7. Forward a report immediately to DHMH Epidemiology and Disease Control Program if a carrier relocates outside the Health Officer’s jurisdiction for referral to the health official of the proper jurisdiction.

IV. REFERENCES

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Maryland Department of Health and Mental Hygiene
Office of Office of Epidemiology and Disease Control Programs
Revised, March 2003