Hepatitis A, Acute

2019 Case Definition

CSTE Position Statement Number: 18-ID-07

Clinical Criteria

An acute illness with a discrete onset since the date an outbreak was detected in the state* of any sign or symptom consistent with acute viral hepatitis (e.g., fever, headache, malaise, anorexia, nausea, vomiting, diarrhea, abdominal pain, or dark urine),

AND

Jaundice or elevated total bilirubin levels ≥3.0 mg/dL, OR
Elevated serum alanine aminotransferase (ALT) levels (>200 IU/L)

AND

the absence of a more likely diagnosis

Laboratory Criteria

Confirmatory laboratory evidence:

Immunoglobulin M (IgM) antibody to hepatitis A virus (anti-HAV) positive, OR

Nucleic acid amplification test (NAAT; such as PCR or genotyping) for hepatitis A virus RNA positive

* As determined by each state.

Case Classification

Confirmed:

A case that meets the clinical criteria and is IgM anti-HAV positive, OR
A case that has hepatitis A virus RNA detected by NAAT (such as PCR or genotyping), OR
A case that meets the clinical criteria and occurs in a person who had contact (e.g., household or sexual contact) with a laboratory-confirmed hepatitis A case 15–50 days prior to onset of symptoms

Case Classification Table: Criteria for defining a case of hepatitis A.

Criterion	Confirmed
Clinical Evidence:
Acute onset of illness	N	N	N		N	N	N
Jaundice	N				N		N
Fever	O	O	O		O	O	O
Headache	O	O	O		O	O	O
Malaise	O	O	O		O	O	O
Anorexia	O	O	O		O	O	O
Nausea	O	O	O		O	O	O
Vomiting	O	O	O		O	O	O
Diarrhea	O	O	O		O	O	O
Abdominal Pain	O	O	O		O	O	O
Dark urine	O	O	O		O	O	O
Absence of a more likely diagnosis	N	N	N		N	N	N
Laboratory Evidence:
Elevated bilirubin levels, ≥3.0 mg/dL		N				N
Elevated serum ALT levels >200 IU/L			N
Hepatitis A IgM (anti-HAV) positive	N	N	N
Hepatitis A RNA positive by NAAT				N
Not otherwise ruled out by IgM anti-HAV or NAAT for hepatitis A virus testing performed in a public health laboratory	N	N	N	N			N
Epidemiological Evidence:
Contact (e.g., household or sexual) with a laboratory-confirmed hepatitis A case 15–50 days prior to onset of symptoms					N	N
Criteria to distinguish a new case:
Not counted as a case within the previous 6 months	N	N	N	N	N	N	N
2018 Template

N = All “N” criteria in the same column area 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 (e.g., clinical evidence, laboratory evidence, epidemiological evidence, and criteria to distinguish a new case) 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.

Date Posted: September 14, 2026