Infections caused by Salmonella enterica serotype Typhi (S. Typhi) or Salmonella enterica serotypes Paratyphi A, B (tartrate negative), and C (S. Paratyphi) that are often characterized by insidious onset of sustained fever, headache, malaise, anorexia, relative bradycardia, constipation or diarrhea, and non-productive cough. However, mild and atypical infections may occur. Carriage of S. Typhi and S. Paratyphi A, B (tartrate negative), and C may be prolonged.
One or more of the following:
Confirmatory laboratory evidence:
Presumptive laboratory evidence:
Confirmatory laboratory evidence:
Presumptive laboratory evidence:
* Serologic testing (i.e., detection of antibodies to S. Typhi or S. Paratyphi A, B, or C) should not be utilized for case classification.
Confirmed:
Probable:
Confirmed:
Probable:
Criteria to distinguish a new case of this disease or condition from reports or notifications which should not be enumerated as a new case for surveillance.
A new case should be created when a positive laboratory result is received more than 365 days after the most recent positive laboratory result associated with a previously reported case in the same person.
A new case should be created when either:
Calculating and Interpreting the 365-Day Time Period to Distinguish a New Case from a Previously Reported Case of S. Typhi and S. Paratyphi Infections
Date* of current positive laboratory result – Date* of most recent positive laboratory result associated with the previously reported case = X days
* Hierarchy of dates: Available information can vary between laboratory results. To account for this, a hierarchy of dates to be used in the above calculation follows (highest priority to lowest priority):
Persons with isolation of S. Paratyphi B (tartrate positive) from a clinical specimen should be categorized as a salmonellosis case.
Several serological tests have been developed to detect antibodies to S. Typhi and S. Paratyphi A, B, and C. However, no current serological test is sufficiently sensitive or specific to replace culture-based tests for the identification of S. Typhi and S. Paratyphi infections. Whether public health follow-up for positive serologic testing is conducted and how is at the discretion of the jurisdiction.
It is estimated that approximately 2-5% of persons infected with S. Typhi become chronic intestinal carriers who continue to shed S. Typhi for more than one year. These people are typically referred to as chronic carriers. The percentage of persons with S. Paratyphi A, B (tartrate negative), or C infections that become chronic carriers is not known.
Differentiating whether a person became a chronic carrier or is experiencing a new infection often relies on a variety of factors, including advanced laboratory testing (e.g., pulsed-field gel electrophoresis [PFGE], whole genome sequencing [WGS]) to compare the isolate from the previous infection to the new isolate. While these methodologies can provide detailed information about the genetic make-up of the organisms, there is still significant variability in how two organisms can be defined as different. Given the potential for inconsistent application of the label “different” across jurisdictions, this case definition does not exclude persons with a previously reported S. Typhi or S. Paratyphi Infection case from being counted as a new case if the subsequent positive laboratory result is more than 365 days from the most recent positive laboratory result associated with the existing case.
S = This criterion alone is SUFFICIENT to classify a case.
N = All “N” criteria in the same column are NECESSARY to classify a case. A number following an “N” indicates that this criterion is only required for a specific disease/condition subtype (see below). If the absence of a criterion (i.e., criterion NOT present) is required for the case to meet the classification criteria, list the absence of criterion as a necessary component.
O = At least one of these “O” (ONE OR MORE) criteria in each category (categories=clinical evidence, laboratory evidence, and epidemiologic evidence) in the same column—in conjunction with all “N” criteria in the same column—is required to classify a case. A number following an “O” indicates that this criterion is only required for a specific disease/condition subtype.
| Criterion | S. Typhi Infection | S. Paratyphi Infection | ||||
|---|---|---|---|---|---|---|
| Probable | Confirmed | Probable | Confirmed | |||
| Clinical evidence | ||||||
| Fever | O | O | O | O | ||
| Diarrhea | O | O | O | O | ||
| Abdominal cramps | O | O | O | O | ||
| Constipation | O | O | O | O | ||
| Anorexia | O | O | O | O | ||
| Relative bradycardia | O | O | O | O | ||
| Laboratory evidence | ||||||
| Isolation of S. Typhi from a clinical specimen | N | |||||
| Detection of S. Typhi in a clinical specimen using a CIDT | N | |||||
| Isolation of S. Paratyphi A, B (tartrate negative), or C from a clinical specimen | N | |||||
| Detection of S. Paratyphi A, B (tartrate negative), or C in a clinical specimen using a CIDT | N | |||||
| Epidemiological evidence | ||||||
| Epidemiologically linked to a confirmed S. Typhi Infection case | O | |||||
| Epidemiologically linked to a probable S. Typhi Infection case with laboratory evidence | O | |||||
| Epidemiologically linked to a confirmed S. Paratyphi Infection case | O | |||||
| Epidemiologically linked to a probable S. Paratyphi Infection case with laboratory evidence | O | |||||
| Member of a risk group as defined by public health authorities during an outbreak | O | O | ||||
| Criteria to distinguish a new case | ||||||
| A positive laboratory result reported more than 365 days after the most recent positive laboratory result associated with a previously reported case in the same person | N | N | O | O | ||
| Two or more different serotypes identified in one or more specimens from the same person | O | O | ||||
Date Updated: