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

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.

Person-to-Person Hepatitis A Outbreak Case Definition

Confirmed Case:

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 has an epidemiologic link (household contact, drug partner, or sexual contact) with a laboratory-confirmed hepatitis A case 15–50 days prior to onset of symptoms

Exclusions

A case will be excluded if any of the following conditions apply:

In the absence of known risk factors (injection or non-injection drug use, men who have sex with men, homelessness, or incarceration), any case that occurs in a patient who reports travel to a country or U.S. territory with endemic hepatitis A during the 15–50 days before symptom onset, OR
Any case that is linked to a foodborne outbreak by related sequencing, OR
In the absence of known risk factors (injection or non-injection drug use, men who have sex with men, homelessness, or incarceration), any case that is epi-linked to a foodborne outbreak, OR
Any case with a specimen collected within four weeks of symptom onset that is negative for HAV RNA

Case Classification Table

N = All “N” criteria in the same column area Necessary to classify a case.

O = At least one of these “O” 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.

Criterion	Confirmed							Suspect
Clinical Evidence:
Acute onset of illness	N	N	N		N	N	N	N
Jaundice	N				N			N
Fever	O	O	O		O	O	O	O
Headache	O	O	O		O	O	O	O
Malaise	O	O	O		O	O	O	O
Anorexia	O	O	O		O	O	O	O
Nausea	O	O	O		O	O	O	O
Vomiting	O	O	O		O	O	O	O
Diarrhea	O	O	O		O	O	O	O
Abdominal Pain	O	O	O		O	O	O	O
Dark urine	O	O	O		O	O	O	O
Absence of a more likely diagnosis	N	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				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
No HAV IgM or NAT testing performed								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	N
In outbreak county without laboratory testing								N
No known epi-linkage to a known confirmed case								N
In a high-risk category (e.g., users of illegal substance, homeless persons, men that have sex with men)								N
Criteria to distinguish a new case:
Not counted as a case within the previous 6 months	N	N	N	N	N	N	N	N

Date Posted: December 12, 2019