Case Definition / Clinical Features

Health Protection Agency revised interim guidelines for investigation and reporting of suspected human cases of avian influenza

Introduction

Case Definition

Investigation

Isolation & Infection Control

Management

Reporting

SARS Advisory Note

Comments to: Respiratory Disease Department, Centre for Infections, Health Protection Agency respcdsc@hpa.org.uk, 44 (0)20 8327 7768

Link to PDF format (PDF, 98 KB)
Health Protection Agency revised interim guidelines for investigation and reporting of suspected human cases of avian influenza

Introduction

• The following guidelines are based on WHO guidelines for case investigation in countries without any A/H5 (avian) influenza activity in animals. WHO is recommending enhanced surveillance for A/H5 influenza infection in humans.
   
• February and March is peak influenza season in parts of East Asia cases of normal human influenza in people entering the UK from Asia can be expected.
   
• Cases meeting all the components of the definition below (clinical, travel and contact) should be
  a. Investigated for influenza A/H5 as below,
  b. Reported using the report form on this website,
  c. Discussed with the local Health Protection Team at an early stage.
   
• The WHO published case definitions on 29 August 2006. The following is the HPA's case definition.

 

Case Definition

Please note that if epidemiological criteria are definitely fulfilled and patient is severely unwell but with no respiratory symptoms the case should be discussed with the HPA Centre for Infections.

 

1. Clinical presentation

Fever ( ? or = 38°C) OR history of fever AND respiratory symptoms (cough or shortness of breath) requiring hospitalisation.
OR
Death from unexplained respiratory illness
AND

2. Epidemiological criteria

History of travel in the 7 days prior to onset of symptoms to an area affected by avian influenza A (H5N1) ( click here to see updated list in the Algorithm A3) AND close contact (within 1 metre) with live or dead domestic fowl, wild birds, or swine in any setting, including bird markets.

Please see the list of affected countries.

 

OR one of the following:

• Close contact ( touching/speaking distance) with other case(s) of severe respiratory illness or unexplained death from above areas.
• Part of a Health Care Worker cluster of severe unexplained respiratory illness.
• A Laboratory worker with potential exposure to influenza A (H5N1)

Investigation

• Microbiological guidance for taking and handling specimens from individuals at risk of avian influenza

• Local and regional laboratories with appropriate biosafety and diagnostic facilities should confirm influenza A infection in above cases using IFA or other method.
   
• WHO recommends that specimens from such cases are handled using biosafety level 2 standards and biosafety level 3 work practices. See: http://www.who.int/csr/disease/avian_influenza/guidelines/handlingspecimens/en/ [external link]
   
• If influenza A infection is diagnosed, or if local diagnosis is not possible (click here for a list of regional influenza A (H5) testing laboratories) , consultation must be sought with Dr Maria Zambon,Virus Reference Division (VRD), HPA Colindale: http://www.hpa.org.uk/srmd/div_vrd_ernvl/index.htm, tel.: 020 8327 6269
  The following specimens will be required for confirmation of A (H5) infection:

1. Viral specimen - NPA or throat swab
2. Specimen for PCR - NPA or throat swab

 

Isolation and infection control

• Although human to human transmission of A (H5) has not yet been described the consequences of transmission are potentially severe.
   
• WHO is recommending the use of high-efficiency masks, contact and droplet precautions. See: http://www.who.int/csr/disease/avian_influenza/guidelines/infectioncontrol/en [external link]
   
• Pending the development of UK specific infection control guidelines, it is recommended that all cases of suspected A/H5 influenza (see case definition) be managed as for cases of suspected SARS. See:
  http://www.hpa.org.uk/infections/topics_az/SARS/hosp_infect_cont.htm [external link]
   
• In addition, health care workers caring for cases of suspected A/H5 should be considered for prophylaxis with oseltamivir.

 

 

Magement

Specialist advice should be sought. Antiviral treatment with either oseltamivir or zanamivir should be actively considered.

 

Reporting

Initial report of a suspected case should be to a Consultant in Communicable Diseases Control (CCDC) at your local Health Protection Unit.

• A case report form is available on the HPA website.
   
• CCDCs should inform their Regional Epidemiologist and the Respiratory Diseases Department at the Centre for Infections by telephone (020 8327 7768)

 

Advisory note re: SARS

The possibility of SARS should also be considered in patients admitted with a severe unexplained respiratory illness with a history of recent travel to an area classified by WHO as having recent local transmission: http://www.who.int/csr/sars/en/index.html [external link]

Current case definitions for SARS may be found at: http://www.hpa.org.uk/infections/topics_az/SARS/casedef.htm
 

• Health Protection Agency SARS pages

 

Last reviewed: 1 December 2011