INFLUENZA A / HINI

SWINE INFLUENZA A/H1N1 VIRUS CASE DEFINITIONS

The following case definitions are for the purpose of reporting, suspected, probable and confirmed cases of Swine Influenza A/H1N1 virus infection to CPRC, Disease Control Division.
1. A Suspected Case of Swine Influenza virus infection is defined as an individual after 17th of April 2009, presenting with
high fever >38°C, AND
One or more of the following respiratory symptoms: cough, shortness of breath, body ache, difficulty in breathing, AND
One or more of the following: close contact with a person diagnosed as Swine Influenza OR recent travel to an area reporting cases of confirmed Swine Influenza
(Acute febrile respiratory illness (fever > 38 °C) with the spectrum of disease from influenza-like illness to pneumonia)

2. A Probable Case of Swine Influenza A/H1 virus infection is defined as an individual that fulfill the criteria for a suspected case, with an influenza test that is positive for influenza A, but is unsubtypable by reagents used to detect seasonal influenza virus infection
OR
An individual with a clinically compatible illness or who died of an unexplained acute respiratory illness who is considered to be epidemiologically linked to a probable or confirmed case.

3. A Confirmed Case of Swine Influenza A/H1N1 virus infection is defined as an individual with laboratory confirmed Swine Influenza A/H1N1 virus infection by one or more of the following tests*:
real-time RT-PCR
viral culture
four-fold rise in swine influenza A(H1N1) virus specific neutralizing antibodies
* Note: The test(s) should be performed according to the most currently available guidance on testing.
Definition of cluster
A cluster is defined as two or more persons presenting with manifestations of unexplained, acute respiratory illness with fever > 38ºC or who died of an unexplained respiratory illness that are detected with onset of illness within a period of 14 days and in the same geographical area and/or are epidemiologically linked.
Triggers/signals
The primary focus of early investigation is to trigger the initial investigation. Specific triggers include:
Clusters of cases of unexplained ILI or acute lower respiratory disease
Severe, unexplained respiratory illness occurring in one or more health care workers who provide care for patients with respiratory disease
Changes in the epidemiology of mortality associated with the occurrence of ILI or lower respiratory tract illness, an increase in deaths observed from respiratory illness or an increase in the occurrence of severe respiratory disease in previously healthy adults or adolescents
Persistent changes noted in the treatment response or outcome of severe lower respiratory illness.
#Close contact: having cared for, lived with, or had direct contact with respiratory secretions or body fluids of a probable or confirmed case of swine influenza A (H1N1).

Prepared by:
Crisis Preparedness and Response Centre
Ministry of Health Malaysia
29 April 2009