Case Definitions for Investigations of Human Infection with Avian Influenza A Viruses in the United States | Bird Flu

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data-post-id="95" href="/bird-flu/hcp/clinicians-evaluating-patients/index.html" tabindex="0"> Clinical Overview </a> <a data-post-id="1002" href="/bird-flu/hcp/novel-av-treatment-guidance/index.html" tabindex="0"> Interim Guidance on the Use of Antiviral Medications for Treatment of Human Infections with Novel Influenza A Viruses Associated with Severe Human Disease </a> <a data-post-id="96" href="/bird-flu/hcp/detecting-diagnostics/index.html" tabindex="0"> Clinical Testing and Diagnosis </a> <a data-post-id="1528" href="/bird-flu/hcp/guidance-exposed-persons/index.html" tabindex="0"> Interim Guidance on Influenza Antiviral Chemoprophylaxis of Persons Exposed to Birds with Avian Influenza A Viruses Associated with Severe Human Disease or with the Potential to Cause Severe Human Disease </a> <a data-post-id="97" href="/bird-flu/hcp/novel-flu-infection-control/index.html" tabindex="0"> Infection Control Guidance </a> <a data-post-id="1884" href="/bird-flu/hcp/animals/index.html" tabindex="0"> Considerations for Veterinarians: Evaluating and Handling of Cats Potentially Exposed to Highly Pathogenic Avian Influenza A(H5N1) Virus in Cats </a> <a data-post-id="1860" href="/bird-flu/hcp/unpasteurized-raw-milk/index.html" tabindex="0"> Conversation Tips: Unpasteurized (Raw Milk) </a> <a class="view-all" href="/bird-flu/site.html"> View All </a> </div> </div> </header> <main class="container cdc-main" role="main" aria-label="Main Content Area"> <section class="cdc-page-title-bar cdc-page-offset noindex"> <time class="cdc-page-title-bar__item cdc-page-title-bar__item--date" datetime="2024-05-03 04:00:00"> May 3, 2024 </time> <div data-alt-langs class="cdc-page-title-bar__item cdc-page-title-bar__item--languages"> <a class="cdc-page-title-bar__item" href="https://espanol.cdc.gov/enes/bird-flu/hcp/case-definition/index.html">Español</a> </div> </section> <div class="cdc-page-title cdc-page-offset syndicate"> <h1>Case Definitions for Investigations of Human Infection with Avian Influenza A Viruses in the United States</h1> </div> <div id="content" class="cdc-page-content cdc-page-offset syndicate container"> <div class="cdc-dfe-body "> <div class="cdc-dfe-body__top "> <div class="dfe-section dfe-section--page-summary summary-blurb summary-paragraph" data-section="cdc_generic_summary"> <div class="dfe-section__header"> <h2 class="editor-block--title" id="heading-fvp6zhjcb2">What to know</h2> </div> <div class="dfe-section__content"> <p>This document provides guidance for state and local health departments conducting investigations of possible human infections with avian influenza A viruses in the United States. The following definitions are for the purpose of investigations of confirmed cases, probable cases, and cases of avian influenza A virus infection under investigation in the United States. Until further notification, CDC is requesting notification of all possible cases of avian influenza A virus infection (confirmed, probable and suspected/case under investigation).</p> <div class="dfe-section__nav hide" id="dfe-section__nav"> <div class="dfe-section__nav__header" id="dfe-section__nav__header"> </div> <div class="dfe-section__nav-links" id="dfe-section__nav-links"> </div> </div> </div> <div class="dfe-section__image" id="page-summary-image"> <figure class="dfe-image dfe-image__large"><div class="image-container calculated-ratio-16-9 aspect-ratio-16-9"><img src="/bird-flu/media/images/2024/10/lab-testing.jpg" alt="virus testing lab equipment" title="Lab Testing"></div></figure> </div> <div id="nav-buttons"> </div> </div> </div> <div class="cdc-dfe-body__center "> <div class="dfe-section" data-section="cdc_generic_section_1"> <a class="onThisPageAnchor" id="cdc_generic_section_1-human-infection-with-avian-influenza-virus-case-definitions" name="Human%20Infection%20with%20Avian%20Influenza%20Virus%20Case%20Definitions" title="Human Infection with Avian Influenza Virus Case Definitions"></a><h2 class="editor-block--title" id="heading-55sniwv8bn">Human Infection with Avian Influenza Virus Case Definitions</h2> <div class="dfe-block dfe-callout dfe-callout--calltoaction"><h3>Notice&lrm;</h3> <div class="dfe-callout__body"><div class="callout-desc">CDC has developed new interim recommendations for prevention, monitoring, and public health investigations of highly pathogenic avian influenza A(H5N1) virus in animals. Updates to this page are forthcoming.</div> </div><div class="dfe-callout__button"><a href="https://www.cdc.gov/bird-flu/prevention/hpai-interim-recommendations.html" class="button hollow">Recommendations</a></div></div> <h3 id="heading-d-lnvqwurj">Confirmed Case:</h3> <p>Avian influenza A virus infection in a person that is confirmed by CDC's Influenza Division Laboratory or a CDC designated laboratory using methods mutually agreed upon by CDC and the Council of State and Territorial Epidemiologists (CSTE).</p> <h3 id="heading-eahhp_fge3">Suspected Case (also called Case Under Investigation):</h3> <p>A person meeting criteria for avian influenza A virus infection below and for whom confirmatory laboratory test results are unknown or pending.</p> <h3 id="heading-lwo1srmi59">Probable Case:</h3> <p>A person meeting criteria for avian influenza A virus infection below and<strong> for whom laboratory test results do not provide a sufficient level of detail to confirm <a href="/bird-flu/prevention/hpai-interim-recommendations.html">HPAI</a> A H5 virus infection</strong>.</p> </div> <div class="dfe-section" data-section="cdc_generic_section_2"> <a class="onThisPageAnchor" id="cdc_generic_section_2-criteria-for-avian-influenza-a-virus-testing" name="Criteria%20for%20Avian%20Influenza%20A%20Virus%20Testing" title="Criteria for Avian Influenza A Virus Testing"></a><h2 class="editor-block--title" id="heading-abta_amprb">Criteria for Avian Influenza A Virus Testing</h2> <p>Testing should be performed on persons who meet Epidemiologic criteria <strong>AND either</strong> Clinical <strong>OR </strong>Public Health Response criteria.</p> <h3 id="heading-tqwipdoath">Epidemiologic Criteria</h3> <p><strong>Persons with recent exposure (within 10 days) to avian influenza A viruses through one of the following:</strong></p> <ul class="nested-list"> <li class="level-1"><strong>Exposure to A(H5), A(H7), or A(H9) virus infected birds </strong>is defined as follows:<ul> <li class="level-2">Close exposure (within 2 meters) to birds, with confirmed avian influenza A virus infection by A(H5), A(H7), or A(H9) viruses. Bird exposures can include, but are not limited to handling, slaughtering, defeathering, butchering, culling, or preparation of birds for consumption; <strong>OR</strong><ul> </ul> </li> <li class="level-2">Direct contact with surfaces contaminated with feces or bird parts (e.g., carcasses, internal organs) from infected birds; <strong>OR</strong><ul> </ul> </li> <li class="level-2">Visiting a live poultry market with confirmed bird infections or associated with a case of human infection with avian influenza A virus.<ul> </ul> </li> </ul> </li> <li class="level-1"><strong>Exposure to an infected person</strong><em> –</em> Close (within 2 meters) unprotected (without use of respiratory and eye protection) exposure to a person who is a confirmed, probable, or symptomatic suspected case of human infection with avian influenza A virus (e.g. in a household or healthcare facility).<ul> </ul> </li> <li class="level-1"><strong>Laboratory exposure</strong> – Unprotected (without use of respiratory and eye protection) exposure to avian influenza A virus in a laboratory.<ul> </ul> </li> </ul> <h3 id="heading-qclqsxo9wg">Clinical Criteria</h3> <p>Persons with signs and symptoms consistent with acute or lower respiratory tract infection or conjunctivitis, or complications of acute respiratory illness without an identified cause. Examples include but are not limited to:</p> <ul class="nested-list"> <li class="level-1">Mild flu-like illness (cough, sore throat, fever or feeling feverish, rhinorrhea, fatigue, myalgia, arthralgia, headache) or conjunctivitis (red eye, discharge from eye)<ul> </ul> </li> <li class="level-1">Moderate to severe illness: shortness of breath or difficulty breathing, altered mental status, seizures<ul> </ul> </li> <li class="level-1">Complications: pneumonia, respiratory failure, acute respiratory distress syndrome, multi-organ failure, meningoencephalitis<ul> </ul> </li> </ul> <h3 id="heading-nqkbh-ndhl">Public Health Response Criteria</h3> <p>Asymptomatic persons whom public health authorities, in consultation with CDC, determine that testing is needed in order to assess the clinical spectrum of infection with avian influenza A virus as part of public health investigations.</p> <h3 id="heading-qqhxlot8qn">Additional Resources</h3> <ul class="nested-list"> <li class="level-1"><a href="https://www.cdc.gov/flu/avianflu/avian-flu-summary.htm" class="ce-selection">Avian Influenza Current Situation Summary</a><ul> </ul> </li> <li class="level-1"><a href="/bird-flu/php/avian-flu-summary/reported-human-infections.html">Reported Human Infections with Avian Influenza A Viruses</a><ul> </ul> </li> </ul> </div> <div class="dfe-section" data-section="cdc_generic_section_3"> <a class="onThisPageAnchor" id="cdc_generic_section_3-guidance-type" name="Guidance%20Type" title="Guidance Type"></a><h2 class="editor-block--title" id="heading-1vvy4utrvr">Guidance Type</h2> <div class="dfe-block dfe-block--cdcmodule dfe-block--width-standard"><div class="dfe-block__inner"><div class="cdc-dfe-content-table"> <div class="cdc-content-table header-column" role="table" aria-label="table"> <div role="rowgroup"> <div class="row" role="row"> <div class="col-4"> <div role="cell"> <p><strong>Summary for Clinicians</strong></p> </div></div> <div class="col-8"> <div role="cell"> <p><a href="https://www.cdc.gov/bird-flu/hcp/clinicians-evaluating-patients/">Summary of guidance for all viruses that have the potential to cause severe disease</a></p> </div></div> </div> <div class="row" role="row"> <div class="col-4"> <div role="cell"> <p><strong>Testing and Reporting</strong></p> </div></div> <div class="col-8"> <div role="cell"> <p><a href="https://www.cdc.gov/bird-flu/php/severe-potential/">Guidance for all viruses that have the potential to cause severe disease</a></p> </div></div> </div> <div class="row" role="row"> <div class="col-4"> <div role="cell"> <p><strong>Case Definitions</strong></p> </div></div> <div class="col-8"> <div role="cell"> <p><a href="https://www.cdc.gov/bird-flu/hcp/case-definition/">Avian Influenza A Viruses in the United States</a></p> </div></div> </div> <div class="row" role="row"> <div class="col-4"> <div role="cell"> <p><strong>Infection Control</strong></p> </div></div> <div class="col-8"> <div role="cell"> <p><a href="https://www.cdc.gov/bird-flu/hcp/novel-flu-infection-control/">Guidance for all viruses that are associated with severe disease</a></p> </div></div> </div> <div class="row" role="row"> <div class="col-4"> <div role="cell"> <p><strong>Treatment</strong></p> </div></div> <div class="col-8"> <div role="cell"> <p><a href="https://www.cdc.gov/bird-flu/hcp/novel-av-treatment-guidance/">Guidance for all viruses that are associated with severe disease</a></p> </div></div> </div> <div class="row" role="row"> <div class="col-4"> <div role="cell"> <p><strong>Chemoprophylaxis of Persons Exposed to Birds</strong></p> </div></div> <div class="col-8"> <div role="cell"> <p><a href="https://www.cdc.gov/bird-flu/hcp/guidance-exposed-persons/">Guidance for all viruses that have the potential to cause severe disease</a></p> <p><a href="https://www.cdc.gov/bird-flu/hcp/guidance-exposed-persons/">Guidance for all viruses that are associated with severe disease</a></p> <p> </p> </div></div> </div> <div class="row" role="row"> <div class="col-4"> <div role="cell"> <p><strong>Chemoprophylaxis of Follow-up of Close Contacts</strong></p> </div></div> <div class="col-8"> <div role="cell"> <p><a href="https://www.cdc.gov/bird-flu/php/novel-av-chemoprophylaxis-guidance/">Guidance for all viruses that are associated with severe disease</a></p> </div></div> </div> </div> </div> </div></div></div> </div> </div> <div class="cdc-dfe-body__right page-right-rail"> <aside class="page-right-rail__static noindex" role="complementary"> <div class="on-this-page " data-sid=""> <h2 class="on-this-page__heading"> On This Page </h2> <div class="card-body"> <ul> <li><a href="#cdc_generic_section_1-human-infection-with-avian-influenza-virus-case-definitions">Human Infection with Avian Influenza Virus Case Definitions</a></li> <li><a href="#cdc_generic_section_2-criteria-for-avian-influenza-a-virus-testing">Criteria for Avian Influenza A Virus Testing</a></li> <li><a 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