Typhoid Fever v1

Query purpose: 

Created by the CDC National Syndromic Surveillance Program (NSSP) for use with emergency department data to develop queries for all National Notifiable Diseases defined by the National Notifiable Diseases Surveillance System (NNDSS). Please note that while the disease queries are developed using the NNDSS case definition as the basis for identifying patient visits of interest, the queried patient visits themselves may or may not represent a case patient in NNDSS and further public health investigation will most often be required. This query is intended to be a version 1 and may be further improved upon by the NSSP community of practice in the future. This query is intended to be narrow and capture visits with specific terms to support greater monitoring and actionable public health data. More complex and/or broader queries may exist that more broadly capture symptoms or travel-based terms.

How it was developed: 

1. The CDC team used the NNDSS case definition of typhoid fever to identify diagnostic codes (International Classification of Diseases, 9th & 10th Revision (ICD-9-CM, ICD-10-CM), SNOMED Clinical Terms (CT)) and chief complaint free-text for syndrome development.
2. The codes and free text were then categorized as inclusion or exclusion terms. These terms were formatted for querying in ESSENCE.
3. Text analysis was conducted on the initial query to find additional inclusion or exclusion terms.
4. The query was cross-checked internally by NSSP and by CDC subject matter experts as needed.

How it works:

The Chief Complaint Discharge Diagnosis (CCDD) parsed field is used to query both the discharge diagnosis codes and chief complaint free text, and exclusions are incorporated as necessary.

• Inclusion based on typhoid fever chief complaint free text terms:
  • The visit is included if it contains:
    1. A chief complaint related to alternative names – (“enteric fever”) OR
    2. A chief complaint related to disease agent – (“salmonella” and “typhi”) OR
    3. A chief complaint related to typhoid fever – (“typhoid”) ANDNOT
  • The visit is excluded if it contains:
    1. A chief complaint related to immunization – (“vac” or “vax” or “shot” or “immunization” or “injection”) OR
• Inclusion based on ICD-10 discharge diagnosis codes related to typhoid fever:
  • The visit is included if it contains:
    1. A discharge diagnosis code for typhoid fever – (A01.0) OR
• Inclusion based on ICD-9 discharge diagnosis codes related to typhoid fever:
  • The visit is included if it contains:
    1. A discharge diagnosis code for typhoid fever – (002.0) OR
• Inclusion based on SNOMED discharge diagnosis codes related to typhoid fever:
  • The visit is included if it contains:
    1. A discharge diagnosis code for typhoid fever – (4834000) OR
    2. A discharge diagnosis code for suspected typhoid fever – (772154007) OR
    3. A discharge diagnosis code for conditions caused by typhoid fever – (192648008 or 1084791000119106) ANDNOT
• All the above must exclude:
  • An ICD-10 discharge diagnosis code for Adverse reaction of other bacterial vaccines – (T50.A95) OR
  • An ICD-10 Code for Encounter for immunization – (Z23) OR
  • An ICD-10 discharge diagnosis code for Encounter for other specified prophylactic measures – (Z29.8)

Plain Language Description:

The definition uses discharge diagnosis codes and free-text chief complaint terms. The definition requires that an emergency department visit contains a reference to the disease by its discharge diagnosis code (in at least one of the following: ICD-9-CM, ICD-10-CM, SNOMED diagnostic codes), or by the disease name listed in the chief complaint text. The typhoid fever syndromic surveillance definition includes direct mentions of typhoid fever using “typhoid” or “enteric fever” in chief complaint text and mentions of the pathogen using combined terms for “salmonella” and “typhi”. To ensure that only acute typhoid fever infections were captured, diagnostic codes were excluded if there were diagnostic codes or chief complaint indicating vaccination.