Hepatitis A Outbreak Toolbox

Hepatitis A Outbreak Toolbox

Updated | August 2024

Welcome to the Hepatitis A Outbreak toolbox

Key reference documents

 

Case definition

Case definitions may vary between organizations and may be adapted based on the specific context of an outbreak, available data, and evolving evidence. Users should refer to official guidelines from relevant public health authorities and adjust definitions as necessary to fit local epidemiological and operational needs.

WHO suggested case definition

Presumptive case:

A person with either or both of the following:

  • discrete onset of an acute illness with symptoms of acute infectious illness (fever, malaise, fatigue) AND signs of liver damage (anorexia, nausea, jaundice, dark urine, right upper quadrant tenderness

OR

  • raised alanine aminotransferase (ALT) levels more than ten times the upper limit of normal laboratory levels1
Probable case:

Not applicable

Laboratory confirmed case:
  • A person who meets the presumptive case definition and is positive for IgM anti-HAV.
Epidemiologically linked case:
  • A person who meets the presumptive case definition and is epidemiologically linked to a laboratory-confirmed case2

WHO surveillance case definition

Hepatitis A: Vaccine Preventable Diseases Surveillance Standard (Geneva: World Health Organization; 2018).

1. Ten times the upper limit of normal (400 IU/L) is the threshold used by the United States Council of State and Territorial Epidemiologists (CSTE). Countries may also select lower (more sensitive) or higher (more specific) thresholds.

2. Contact with a confirmed case/patient during the 2–6 weeks before onset. Contact can be among household members, sexual contact or drug-sharing contact.

 

Data collection tool

 

Laboratory confirmation

 

Response tools and resources